Salt. A class of compounds formed when the hydrogen of an acid is partially or wholly replaced by a metal or a metallic radical. Salts are formed by the action of acids on metals, or oxides and hydroxides, directly with ammonia and by other methods. See: sodium chloride.
Saltwater drilling fluid. A water-based drilling fluid whose external liquid phase contains sodium chloride or calcium chloride.
Saltwater mud. See: saltwater drilling fluid.
Samples. Cuttings obtained for geological information from the drilling fluid as it emerges from the hole. They are washed, dried, and labeled as to the depth.
Sand. (1) Particle-size classification for solids larger than 74 microns. (2) A loose, granular material resulting from the disintegration of rocks with a high silica content. See: API RP 13B, API sand.
Sand content. The solids particles retained on a U.S. Standard No. 200 test screen, expressed as the bulk percentage by volume of the drilling fluid slurry sample. The opening in this screen is 74 microns. The retained solids may be of any mineral or chemical composition and characteristic. For example, barite, shale, mica, silica, steel, chert, etc., larger than 74 microns are called API sand. See. API sand.
Sand trap. The first compartment and the only unstirred compartment in a well-designed drilling-fluid system intended as a settling compartment.
Scalping shakers. The first set of shale shakers after the flowline in a cascade shaker arrangement. These shakers are usually circular or elliptical motion shakers with coarse mesh screens that are used to remove the bulk of the large-diameter drilled solids or gumbo. This initial fluid preparation allows the second set of fine-screen shale shakers in the series to operate more efficiently with less possibility of flooding. See: fine-screen shale shakers, flooding, blinding.
Screen cloth. A type of screening surface, woven in square, rectangular, or slotted openings. See: wire cloth.
Screen support rubbers. Elastomers that cushion the contact between screens and shale shaker frames.
Screen underflow. The discharge stream from a screening device that contains a greater percentage of liquids than does the feed. See: liquid discharge.
Screening. A mechanical process resulting in a division of particles on the basis of size by their acceptance or rejection by a screening surface.
Screening surface. The medium containing the openings for passage of undersize material.
Scroll. See: flute.
Self-lubricating. Units that provide their own means of lubrication.
Separation potential. Separation potential of a shale shaker screen is the size distribution of equivalent spherical volumes calculated by determining the equivalent ellipsoidal volumes of at least 1500 openings in a screen as determined by image analysis. Also called the Cutt point distribution. See: Cutt point.
Separator. A tank in which mixed water, oil, and gas are allowed to separate by gravity or enhanced force.
Separator (open/atmospheric). A separator for drilling fluid/formation fluid that is open to atmospheric pressure.
Separator (closed/pressurized). A separator for drilling fluid/formation fluid that is closed and pressurized.
Separator (West Texas). A type of open separator. A large tank at atmospheric or 1–3 psi gauge that is used to separate gas from drilling fluid at the flowline.
Settling velocity. The velocity a particle achieves in a given fluid when gravity forces equal friction forces of the moving particle, that is, when the particle achieves its maximum velocity.
Shale. Stone of widely varying hardness, color, and compaction that is formed of clay-sized grains (less than two microns). See: natural clay.
Shale shaker. Any of several mechanical devices for removing cuttings and other large solids from drilling fluid. Common examples are the vibrating screen and rotating cylindrical screen.
Shale stabilizer. Drilling-fluid additive that reduces the rate of interaction of water with the clays in shale. Also known as shale shaker inhibitor.
Sharpness of cut. The slope of a straight line drawn between the solids separated at the 84% point and the 16% point on a graph of the percentage of solids separated versus particle size. The more vertical the slope, the sharper the cut. Also known as sharpness of separation.
Shear rate. The change of velocity with respect to the distance perpendicular to the velocity changes. See: rate of shear.
Shear stress. The force per unit of an area parallel to the force that tends to slide one surface past another. See: viscosity, Bingham model, plastic viscosity, yield point, gel strength.
Shear thinning. Opposite of dilatant. The apparent viscosity decreases instantaneously with increasing shear rate. See: apparent viscosity, viscosity, Bingham model, plastic viscosity, yield point, gel strength.
Short circuiting. A hydraulic condition existing in parts of the tank basin, reservoir, or hydrocyclone in which the time of travel of liquid/ solids is less than the normal flowthrough time—for instance, if the surface tanks contain very viscous fluid, but the returns from the flowline have a very low viscosity; the flowline returns might tend to channel across the top of the surface system toward the pump suction. In this case the flowline returns would be ‘‘short circuiting’’ or bypassing the solids-separation equipment. In hydrocyclones, separable solids that pass directly from the feed inlet and out through the vortex finder without passing through the cone section of the
hydrocyclone have ‘‘short circuited’’ the hydrocyclone processing system.
Shute. In a woven cloth, the direction of the wires running perpendicular to the loom or running across the roll of cloth. In wire cloth production, these are the short or transverse wires. See: weft.
Sieve. See: testing sieve.
Sieve analysis. The mass classification of solid particles passing through or retained on a sequence of screens of increasing mesh count. Analysis may be by wet or dry methods. See: particle size distribution.
Silencer. A tank or pit used to muffle the sound at the blooie line.
Silt. Materials whose particle size generally falls between 2 and 74 microns. A certain portion of dispersed clays and barite fall into this particle size range, as well as drilled solids.
Size distribution. See: particle size distribution.
Slip. The difference between synchronous speed and operating speed compared with synchronous speed, expressed as a percentage. If expressed in rpm, slip is the difference between synchronous speed and operating speed.
Sloughed solid. A solid entering the well bore from the exposed formation; not a drilled solid.
Sloughing. A situation in which portions of a formation fall away from the walls of a hole, as a result of incompetent unconsolidated formations, tectonic stresses, high angle of repose, wetting along internal bedding planes, or swelling of formations. See: caving, cuttings, heaving.
Slug. A small volume of weighted fluid pumped into the drill string to keep the drilling fluid liquid level below the rig floor while pulling drill pipe during a trip. This prevents drilling fluid from spilling on the rig floor as the pipe is pulled. See: pill.
Slug tank. A small compartment (normally adjacent to the suction compartment) used to mix special fluids to pump downhole. The most common use is to prepare a slug or a small volume of weighted mud before a trip. See: pill tank.
Slurry. A mixture or suspension of solid particles in one or more liquids.
Sodium bicarbonate. NaHCO3. A material used extensively for treating cement contamination and occasionally other calcium contamination of drilling fluids. It is the half-neutralized salt of carbonic acid. See: bicarb.
Sodium carboxymethylcelluose. An organic polymer, available in various grades of purity, used to control filtration, suspend weight material, and build low-shear-rate viscosity in drilling fluids. It can be used in conjunction with bentonite where low-solids drilling fluids (muds) are desired. See: CMC, low-solids drilling fluids.
Sodium chloride. NaCl. Commonly known as salt. Salt may be present in the drilling fluid as a contaminant or may be added purposely for inhibition. See: salt.
Sodium chromate. Na2CRO4. See: chromate.
Sodium hydroxide. NaOH. Commonly referred to as ‘‘caustic’’ or ‘‘caustic soda.’’ A chemical used primarily to raise pH.
Sodium polyacrylate. A synthetic, high-molecular-weight polymer of acrylonitrile used primarily for fluid loss control.
Sodium silicate drilling fluids. Special class of inhibited chemical drilling fluid using sodium silicate, saltwater, and clay.
Solid. A firm substance that holds its form; not gaseous or liquid.
Solids. All particles of matter in the drilling fluid, that is, drilled formation cuttings, barite, bentonite, etc.
Solids content. The total amount of solids in a drilling fluid. This is usually determined by distillation that measures the volume fraction of both the dissolved and the suspended, or undissolved, solids. The suspended solids content may be a combination of high– and low– specific gravity solids and native or commercial solids. Examples of dissolved solids are the soluble salts of sodium, calcium, and magnesium.
Suspended solids make up the wall cake; dissolved solids remain in the filtrate. The total suspended and dissolved solids contents are commonly expressed as percentage by volume and less commonly as percentage by weight. See: retort.
Solids discharge. That stream from a liquid/solids separator containing a higher percentage of solids than does the feed.
Solids discharge capacity. The maximum rate at which a liquid/solids separation device can discharge solids without overloading.
Solids removal equipment efficiency. A measure of the performance of surface equipment in removing drilled solids from the drilling fluid. It is a calculation based on a comparison of the dilution required to maintain the desired drilled-solids content with that which would have been required if no drilled solids were removed. Also called solids removal equipment performance and drilled solids removal system performance.
Solids separation equipment. Any and all of the devices used to remove solids from liquids in drilling, that is, shale shaker, desander, desilter, mud cleaner, and centrifuge.
Solubility. The degree to which a substance will dissolve in a specific solvent.
Solute. A substance that is dissolved in another (the solvent).
Solution. A mixture of two or more components that form a homogeneous single phase. An example of a solution is salt dissolved in water.
Solvent. Liquid used to dissolve a substance (the solute).
Souring. A term commonly used to mean fermentation.
Specific gravity (SG). The weight of a specific volume of a liquid, solid, or slurry in reference to the weight of an equal volume of water at a reference temperature of 3.89oC (water has a density of 1.0 g/cc at this temperature).
Specific heat capacity. The number of calories required to raise 1 g of a substance one degree Celsius.
Spray bar. A pipe located over the bed of a shale shaker through which dilution fluid is sprayed onto the screen surface during separation of the drilled solids. In practice, spray bars may supply a mist or small amount of liquid, not a hard spray, to prevent washing fine solids through the screen panels and back into the circulating system.
Spray discharge. See: spray underflow.
Spray underflow. The characteristic underflow of certain balanced hydrocyclones discharging to the atmosphere and not overloaded with separable solids.
Spud mud. The drilling fluid used when drilling starts at the surface often a thick bentonite-lime slurry.
Spudding in. The initiating of the drilling operations in the first top-hole section of a new well.
Spurt loss. The flux of fluids and solids that occurs in the initial stages of any filtration before pore openings are bridged and a filter cake is formed. See: surge loss.
Square mesh. Screen cloth with the same mesh count in both directions.
Square weave. See: square mesh.
Squeeze. A procedure whereby slurries of cement, drilling fluid, gunk plug, etc., are forced into the formation by pumping into the hole while maintaining a backpressure. This is usually achieved by closing the blowout preventers or by using a retrievable downhole packer.
Squirrel-cage motor. An induction motor that gets its name from the rotor assembly that looks like a squirrel cage, typical of those used earlier in the twentieth century. The cage consists of rotor bars secured at each end to the shorting rings. An induction motor is one in which there is no physical electrical connection to the rotor. Current in the rotor is induced by the magnetic field of the stator.
Stability meter. An instrument to measure the breakdown voltage of oil-based drilling fluids. This gives an indication of the emulsion stability.
Stacking a rig. Storing a drilling rig upon completion of a job when the rig is to be withdrawn from service for a period of time.
Starch. A group of carbohydrates occurring in plant cells. Starch is specially processed (pregelatinized) for use in drilling fluids to reduce filtration rate and occasionally to increase the viscosity. Without proper preservative, starch can ferment.
Static. Not moving, or at rest. Opposite of dynamic. See: quiescence.
Stearate. Salt of stearic acid, which is a saturated, 18-carbon fatty acid. Certain compounds, such as aluminum stearate, calcium stearate, and zinc stearate, have been used in drilling fluids for defoaming, lubrication, air drilling in which a small amount of water is encountered, etc.
Stiff foam. A foam in which a bentonite or long-chain polymer has been added.
Stirrer. See: agitator, mechanical agitator.
Stokes’ law. Stokes’ law states that the terminal settling velocity of a spherical particle is proportional to the square of the particle diameter, the acceleration of gravity, and the density difference between the density of the particle and the density of the liquid medium; the terminal settling velocity is inversely proportional to the viscosity of the liquid medium:
VT =[ gDP^2(ρS-ρL)(10^-6)]/116ρ
where
VT=terminal settling velocity, in in./sec
DP=particle diameter, in microns
ρS=density of the solids, in g/cm3
ρL=density of the liquid, in g/cm3
μ=viscosity of the feed slurry, in centipoise
Stormer viscometer. A rotational shear viscometer used for measuring the viscosity and gel strength of drilling fluids. This instrument has been largely replaced by the direct-indicating viscometer.
Streaming potential. The electrokinetic portion of the spontaneous potential (SP) electric-log curve that can be significantly influenced by the characteristics of the filtrate and filter cake of the drilling fluid.
Streamline flow. See: laminar flow.
Stroke. The distance between the extremities of motion or total displacement normal to the screen; that is, the diameter of a circular motion or twice the amplitude. See: amplitude.
Stuck. A condition whereby the drill pipe, casing or any other device inserted into the well bore inadvertently becomes lodged in the hole. Sticking may occur while drilling is in progress, while casing is being run in the hole, or while the drill pipe is being tripped. Frequently a fishing job results.
Stuck pipe. See: differential pressure sticking, stuck.
Suction compartment. (1) The area of the check/suction section from which drilling fluid is picked up by the suction of the mud pumps. (2) Any compartment from which a pump moves fluids.
Sump. (1) A disposal compartment or earthen pit for holding discarded liquids and solids. (2) The pan or compartment below the lowest shale shaker screen.
Supersaturation. If a solution contains a higher concentration of a solute in a solvent than would normally correspond to its solubility at a given temperature, a state of supersaturation exists. This is an unstable condition, because the excess solute separates when the solution is seeded by introducing a crystal of the solute. The term is frequently used erroneously for hot salt drilling fluids.
Support screen. A heavy, wire mesh either plain or calendered that supports a finer mesh screen for use in filtering or screen separation. See: backup screen.
Surface active materials. See: surfactant.
Surface tension. Generally the cohesive forces acting on surface molecules at the interface between a liquid and its own vapor. This force appears as a tensile force per unit length along the interface surface and is usually expressed in units of dynes per centimeter. Since the surface tension is between the liquid and the air, it is common practice to refer to values measured against air as surface tension, and to use the term ‘‘interfacial tension’’ for measurements at an interface between two liquids or a liquid and a solid. See: interfacial tension, emulsion.
Surfactant. Material that tends to concentrate at an interface of an emulsion or a solid/liquid interface. Used in drilling fluids to control degree of emulsification, aggregation, dispersion, interfacial tension, foaming, defoaming, wetting, etc.
Surfactant drilling fluid. A drilling fluid that contains a surfactant, usually to effect control over the degree of aggregation and dispersion or emulsification.
Surge. The pressure increase in a well bore caused by lowering tubulars. Viscous drilling fluid flowing up the annulus, displaced by drill pipe, tubing, or casing, creates the pressure surge.
Surge loss. This is a colloquial term used to describe a spurt of filtrate and solids that occurs in the initial stages of any filtration before pore openings are bridged and a filter cake is formed. The preferred term is ‘‘spurt loss.’’ See: spurt loss.
Suspensoid. A mixture that consists of finely divided colloidal particles floating in a liquid. The particles are so small that they do not settle but are kept in motion by the moving molecules of the liquid (Brownian movement).
Swabbing. When pipe is withdrawn from the hole in a viscous drilling fluid or if the bit is balled, a decrease in pressure in the well bore can cause formation fluid to flow into the well.
Swelling. See: hydration.
Synergism. Term describing an effect obtained when two or more products are used simultaneously to obtain a certain result. Rather than the result of each product being additive to the other, the result is a multiple of the effects.
Synergistic properties. See: synergism.
Monday, October 26, 2015
Monday, October 19, 2015
drilling fluid process glossary Q&R
Quebracho. An additive used extensively for thinning/dispersing to control low-shear-rate viscosity and thixotropy. It is a crystalline extract of the quebracho tree consisting mainly of tannic acid. See: thinner.
Quicklime. Calcium oxide, CaO. Used in certain oil-based drilling fluids to neutralize the organic acid.
Quiescence. The state of being quiet or at rest, being still. See: static.
Radial flow. Flow of a fluid outwardly in a 360 pattern. This describes the flow from a mechanical agitator in which fluid moves away from the axis of the impeller shaft (usually horizontally toward a mud tank wall). See: axial flow.
Radical. Two or more atoms behaving as a single chemical unit, that is, as an atom; for instance, sulfate and phosphate are nitrate are radicals.
Rate of penetration. The rate at which the drill bit penetrates the formation, expressed in lineal units of feet/minute. See: penetration rate.
Rate of shear. The change in velocity between two parallel layers divided by the distance between the layers. Shear rate has the units of reciprocal seconds (sec^-1). See: shear rate.
Raw drilling fluid. Drilling fluid, before dilution, that is to be processed by solids-removal equipment.
Rectangular screen. See: oblong mesh.
Reduced port. A valve whose bore size is less than the area of the pipe to which it is attached.
Removal section. The first section in the drilling-fluid system, consisting of a series of compartments and solids-removal equipment to remove gas and undesirable solids.
Reserve pit. (1) An earthen pit used to store drilling waste in land drilling operations. (2) A section of a surface system used to store drilling fluid.
Resin. A semisolid or solid complex or amorphous mixture of organic compounds having no definite melting point or tendency to crystallize.
Resin may be a component of compounded materials that can be added to drilling fluids to impart special properties to the system, that is, wall cake, fluid loss, etc.
Resistivity. Resistivity is a characteristic electrical property of a material and is equal to the electrical resistance of a 1-meter cube of the material to passage of a 1-ampere electric current perpendicular to two parallel faces. The electrical resistance offered to the passage of a current is expressed in ohm-meters. It is the reciprocal conductivity. Freshwater muds are usually characterized by high resistivity; saltwater muds by low resistivity. See: conductivity.
Resistivity meter. An instrument for measuring the electrical resistivity of drilling fluids.
Retention time. The time any given particle of material is retained in a region, for example, the time a particle is actually on a screening surface, within a hydroclone, or within the bowl of a centrifuge.
Retort. An instrument used to distill oil, water, and other volatile material in a drilling fluid to determine oil, water, salt, and total solids contents in volume percentage. See: mud still, mini still, API RP 13B.
Reverse circulation. The method by which the normal flow of a drilling fluid is reversed by circulating down the annulus, then up and out the drill string. See: circulation.
Reynolds number. A dimensionless number, Re, that occurs in the theory of fluid dynamics. The Reynolds number for a fluid flowing through a cylindrical conductor is determined by the equation:
Re = DVρ/μ.
D=diameter
V=velocity
ρ=density
μ=viscosity
The number is important in fluid-hydraulics calculations for determining the type of fluid flow, that is, whether laminar or turbulent. The transitional range occurs approximately from 2000 to 3000. Below 2000, the flow is laminar; and above 3000, the flow is turbulent. See: fluid flow.
Rheology. The science that deals with deformation and flow of matter. See: viscosity, Bingham model, plastic viscosity, yield point, gel strength.
Rig pump. The reciprocating, positive displacement, high-pressure pump on a drilling rig used to circulate the hole. See: mud pump.
Rig shaker. Slang term for a shale shaker.
Rigid frame panel. One of the two main screen panel types, consisting of a rigid panel to which the screen or layers of screen are attached. The screen panel fastening device can be designed for fast panel replacement. See: hook-strip panel.
ROP. See: rate of penetration, penetration rate.
Rope discharge. The characteristic underflow of a hydrocyclone so overloaded with separable solids that not all the separated solids can crowd out through the underflow opening (apex), causing those solids that can exit to form a slow moving, heavy, ropelike stream. Also referred to as ‘‘rope’’ or ‘‘rope underflow.’’
Rotary drilling. The method of drilling wells in which a drill bit attached to a drill string is rotated on the formation to be drilled. A fluid is circulated through the drill pipe to remove cuttings from the bottom of the hole, bring cuttings to the surface, and perform other functions. See: cable tool drilling.
Rotary mud separator (RMS). A centrifuge consisting of a perforated cylinder rotating inside of an outer cylinder housing. As drilling fluid flows outside of the perforated cylinder, only the very small particles pass through the perforations.
Round trip. See: trip.
rpm. Revolutions per minute.
Quicklime. Calcium oxide, CaO. Used in certain oil-based drilling fluids to neutralize the organic acid.
Quiescence. The state of being quiet or at rest, being still. See: static.
Radial flow. Flow of a fluid outwardly in a 360 pattern. This describes the flow from a mechanical agitator in which fluid moves away from the axis of the impeller shaft (usually horizontally toward a mud tank wall). See: axial flow.
Radical. Two or more atoms behaving as a single chemical unit, that is, as an atom; for instance, sulfate and phosphate are nitrate are radicals.
Rate of penetration. The rate at which the drill bit penetrates the formation, expressed in lineal units of feet/minute. See: penetration rate.
Rate of shear. The change in velocity between two parallel layers divided by the distance between the layers. Shear rate has the units of reciprocal seconds (sec^-1). See: shear rate.
Raw drilling fluid. Drilling fluid, before dilution, that is to be processed by solids-removal equipment.
Rectangular screen. See: oblong mesh.
Reduced port. A valve whose bore size is less than the area of the pipe to which it is attached.
Removal section. The first section in the drilling-fluid system, consisting of a series of compartments and solids-removal equipment to remove gas and undesirable solids.
Reserve pit. (1) An earthen pit used to store drilling waste in land drilling operations. (2) A section of a surface system used to store drilling fluid.
Resin. A semisolid or solid complex or amorphous mixture of organic compounds having no definite melting point or tendency to crystallize.
Resin may be a component of compounded materials that can be added to drilling fluids to impart special properties to the system, that is, wall cake, fluid loss, etc.
Resistivity. Resistivity is a characteristic electrical property of a material and is equal to the electrical resistance of a 1-meter cube of the material to passage of a 1-ampere electric current perpendicular to two parallel faces. The electrical resistance offered to the passage of a current is expressed in ohm-meters. It is the reciprocal conductivity. Freshwater muds are usually characterized by high resistivity; saltwater muds by low resistivity. See: conductivity.
Resistivity meter. An instrument for measuring the electrical resistivity of drilling fluids.
Retention time. The time any given particle of material is retained in a region, for example, the time a particle is actually on a screening surface, within a hydroclone, or within the bowl of a centrifuge.
Retort. An instrument used to distill oil, water, and other volatile material in a drilling fluid to determine oil, water, salt, and total solids contents in volume percentage. See: mud still, mini still, API RP 13B.
Reverse circulation. The method by which the normal flow of a drilling fluid is reversed by circulating down the annulus, then up and out the drill string. See: circulation.
Reynolds number. A dimensionless number, Re, that occurs in the theory of fluid dynamics. The Reynolds number for a fluid flowing through a cylindrical conductor is determined by the equation:
Re = DVρ/μ.
D=diameter
V=velocity
ρ=density
μ=viscosity
The number is important in fluid-hydraulics calculations for determining the type of fluid flow, that is, whether laminar or turbulent. The transitional range occurs approximately from 2000 to 3000. Below 2000, the flow is laminar; and above 3000, the flow is turbulent. See: fluid flow.
Rheology. The science that deals with deformation and flow of matter. See: viscosity, Bingham model, plastic viscosity, yield point, gel strength.
Rig pump. The reciprocating, positive displacement, high-pressure pump on a drilling rig used to circulate the hole. See: mud pump.
Rig shaker. Slang term for a shale shaker.
Rigid frame panel. One of the two main screen panel types, consisting of a rigid panel to which the screen or layers of screen are attached. The screen panel fastening device can be designed for fast panel replacement. See: hook-strip panel.
ROP. See: rate of penetration, penetration rate.
Rope discharge. The characteristic underflow of a hydrocyclone so overloaded with separable solids that not all the separated solids can crowd out through the underflow opening (apex), causing those solids that can exit to form a slow moving, heavy, ropelike stream. Also referred to as ‘‘rope’’ or ‘‘rope underflow.’’
Rotary drilling. The method of drilling wells in which a drill bit attached to a drill string is rotated on the formation to be drilled. A fluid is circulated through the drill pipe to remove cuttings from the bottom of the hole, bring cuttings to the surface, and perform other functions. See: cable tool drilling.
Rotary mud separator (RMS). A centrifuge consisting of a perforated cylinder rotating inside of an outer cylinder housing. As drilling fluid flows outside of the perforated cylinder, only the very small particles pass through the perforations.
Round trip. See: trip.
rpm. Revolutions per minute.
Thursday, October 15, 2015
drilling fluid processing glossary P
Packer fluid. A fluid placed in the annulus between the tubing and casing above a packer. The hydrostatic pressure of the packer fluid is utilized to reduce the pressure differentials between the formation and the inside of the casing and across the packer.
Panel-mounted units. Shale shaker screens mounted to a rigid frame.
Parallel flow. See: laminar flow.
Particle. A discrete unit of solid material that may consist of a single grain or of any number of grains stuck together.
Particle size. Particle diameter expressed in microns. See: ESD, equivalent spherical diameter.
Particle size distribution. The volume classification of solid particles into each of the various size ranges as a percentage of the total solids of all sizes in a fluid sample.
Parts per million. The unit weight of solute per million unit weights of solution (solute plus solvent), corresponding to weight percentage.
The results of standard API titration of chloride hardness, etc., are correctly expressed in milligrams (mg) per liter but not in ppm. At low concentrations mg/L is about numerically equal to ppm. A correction for the solution specific gravity or density in g/ml must be made as follows:
ppm = (milligrams/liter)/solution density(grams/liter)
weight%= (milligrams/liter)/[10,000*solution density (grams/liter)]
weight%= [ppm]/[10,000]
Thus, 316,000 mg/L salt is commonly called 316,000 ppm, or 31.6%, which correctly should be 264,000 pprn and 26.4%, respectively.
Pay zone. A formation that contains oil and/or gas in commercial quantities.
Penetration rate. The rate at which the drill bit penetrates the formation, usually expressed in feet per hour or meters per hour. See: rate of penetration, ROP.
Peptization. An increased flocculation of clays caused by the addition of electrolytes or other chemical substances. See: deflocculation dispersion, high-yield clay.
Peptized clay. A clay to which an agent has been added to increase its initial yield. For example, soda ash is frequently added to calcium montmorillonite clay to increase the yield. See: high-yield clay.
Percent open area. Ratio of the area of the screen openings to the total area of the screen surface.
Percent separated curve. A plot of mass distributions of solids sizes discarded from a solids-separation device divided by the mass distributions of each size of solids fed to the device.
Perforated cylinder centrifuge. A mechanical centrifugal separator in which the rotating element is a perforated cylinder (the rotor) inside of and concentric with an outer stationary cylindrical case.
Perforated panel screen. A screen in which the backing plate used to
provide support to the screen cloths is a metal sheet with openings.
Perforated plate screen. Shale shaker screens mounted on metal plates that have holes punched through.
Perforated rotor. The rotating inner cylinder of the perforated cylinder centrifuge. See: perforated cylinder centrifuge.
Permeability. Permeability is a measure of the ability of a formation to allow passage of a fluid. Unit of permeability is the darcy. See: darcy, porosity.
Pf. The phenolphthalein alkalinity of the filtrate is reported as the number of milliliters of 0.02 normal sulfuric acid required per milliliter of filtrate for the pH to reach the phenolphthalein endpoint, which is a pH of 8.3.
pH. The negative logarithm of the hydrogen ion concentration in gram ionic weights per liter. The pH range is numbered from 0 to 14, with 7 being neutral, and is an index of the acidity (below 7) or alkalinity (above 7) of the fluid. At a temperature of 70°F, a neutral pH is 7 or a hydrogen ion concentration of 10^-7. The neutral pH is a function of temperature. At higher elevated temperatures the neutral pH is lower. The pH of a solution offers valuable information as to the immediate acidity or alkalinity, in contrast to the total acidity or alkalinity, which may be determined by titratration.
Phosphate. Certain complex phosphates, commonly sodium tetraphosphate (Na6P4O13) and sodium acid pyrophosphate (SAPP, Na2H2P2O4), are used either as drilling-fluid thinners or for treatment of various forms of calcium and magnesium contamination.
Piggyback, -ing. The attachment of fine solids particles to the surface of larger solids particles due to surface attraction, fluid consistency, and particle concentration. This attachment phenomenon causes fine solids to be discharged from the screen that would normally pass through the screen.
Pill. A small volume of a special fluid slurry pumped through the drill string and normally placed in the annulus. See: slug.
Pilot testing. A method of predicting behavior of drilling-fluid systems by adding various chemicals to a small quantity of drilling fluid (usually 350 cc), then examining the results. One gram of an additive in 350 cc is equivalent to 1 lb/bbl.
Plastic flow. See: plastic fluid.
Plastic fluid. A complex, non-Newtonian fluid in which shear force is not proportional to shear rate. A definite pressure is required to start and maintain fluid movement. Plug flow is the initial flow type and only occurs in plastic fluids. Most drilling fluids are plastic fluids. The yield point, as determined by a direct-indicating viscometer, is in excess of zero.
Plastic viscosity. This is a measure of the internal resistance to fluid flow attributable to the concentration, type, and size of solids present in a given fluid and the viscosity of the continuous phase. This value, expressed in centipoise, is proportional to the slope of the shear stress/ shear rate curve determined in the region of laminar flow for materials whose properties are described by Bingham’s law of plastic flow. When using the direct-indicating viscometer, plastic viscosity is found by subtracting the 300-rpm reading from the 600-rpm reading. See: viscosity, yield point, API RP 13B.
Plasticity. The property possessed by some solids, particularly clays and clay slurries, of changing shape or flowing under applied stress without developing shear planes or fractures; that is, it deforms without breaking. Such bodies have yield points, and stress must be applied before movement begins. Beyond the yield point, the rate of movement is proportional to the stress applied, but movement ceases when the stress is removed. See: fluid.
Plug flow. The movement of material as a unit without shearing within the mass. Plug flow is the first type of flow exhibited by a plastic fluid after overcoming the initial force required to produce flow. See: Bingham model, Newtonian fluid, laminar flow, turbulent flow.
Plugging. The wedging or jamming of openings in a screening surface by near-size particles, preventing passage of undersize particles and leading to the blinding of the screen. See: blinding, coating.
Pm. The phenolphthalein alkalinity of drilling fluid is reported as the number of milliliters of 0.02 normaI (N/50) sulfuric acid required per milliliter of drilling fluid for the pH to reach the phenolphthalein endpoint of 8.3.
Polyelectrolytes. Long-chain organic molecules possessing ionizable sites that when dissolved in water become charges.
Polymer. A substance formed when two or more molecules of the same kind are linked end to end into another compound having the same elements in the same
proportion but higher molecular weight and different physical properties, for example, paraformaldehyde.Polymers are used in drilling fluids to maintain viscosity and control fluid loss. See: copolymer.
Polyurethane. A high-performance elastomer polymer used in construction of hydrocyclones for its unique combination of physical properties, especially abrasion, toughness, and resiliency.
Pool. (1) The reservoir or pond of fluid, or slurry, formed inside the wall of hydrocyclones and centrifuges and in which classification or separation of solids occurs due to the settling effect of centrifugal force.(2) The reservoir or pond of fluid that can form on the feed end of an uphill shaker basket, a shaker basket with positive deck angle.
Poor boy degasser. See: gas buster, mud/gas separator.
Porosity. The volume of void space in a formation rock usually expressed as percentage of void volume per bulk volume.
Ports. The openings in a centrifuge for entry or exit of materials. Usually applied in connection with a descriptive term, that is, feed ports, overflow ports, etc.
Positive deck angle. The angle of adjustment to a screen deck that causes the screened solids to travel ‘‘uphill’’ to reach the discharge end of the screen surface. This so-called uphill travel increases the fluid throughput of a screen but also shortens the life of a screen. See: negative deck angle.
Possum belly. The compartment on a shale shaker into which the flowline discharges, and from the drilling fluid is fed, either to the screens or to a succeeding tank. See: back tank, mud box.
Potassium. One of the alkali metal elements with a valence of 1 and an atomic weight of approximately 39. Potassium compounds, most commonly potassium hydroxide (KOH), are sometimes added to drilling fluids to impart special properties, usually inhibition.
Potential separation curve. A distribution curve of sizes determined by the optical image analysis for separation potential.
Pound equivalent. A laboratory unit used in pilot testing. One gram of a material added to 350 ml of fluid is equivalent to 1 lb of material added to one barrel. See: barrel, barrel equivalent.
ppm: Parts per million. See: parts per million.
Precipitate. Material that separates out of solution or slurry as a solid.
Precipitation of solids in a drilling fluid may follow flocculation or coagulation.
Preformed foam. Foam formed at the drill bit (obsolete).
Prehydration tank. A tank used to hydrate materials (such as bentonite, polymers, etc.) that require a long time (hours to days) to hydrate fully and disperse before being added to the drilling fluid. See: premix system.
Premix system. A compartment used to mix materials (such as bentonite, polymers, etc.) that require time to hydrate or disperse fully before they are added to the drilling
fluid. See: prehydration tank.
Preservative. Any material used to prevent starch or any other organic substance from fermenting via bacterial action. A common preservative is paraformaldehyde. See: fermentation.
Pressure drop. See: friction loss, pressure loss.
Pressure head. Pressure within a system equal to the pressure exerted by an equivalent height of fluid (expressed in feet or meters). See: head, hydrostatic head, centrifugal pump.
Pressure loss. The pressure lost in a pipeline or annulus due to the velocity of the liquid in the pipeline, the properties of the fluid, the condition of the pipe wall, and the configuration of the pipe. See: friction loss, pressure drop.
Pressure surge. A sudden, usually brief increase in pressure. When pipe or casing is run into a hole too rapidly or the drill string is set in the slips too quickly, an increase in the hydrostatic pressure results due to pressure surge which may be great enough to create lost circulation. See: ECD, annular pressure loss.
Pressurization. The process of supplying an enclosure with a protective gas with or without continuous flow at sufficient pressure to prevent the entrance of a flammable gas or vapor, a combustible dust, or an ignitable fiber.
Pretensioned screen. A screen cloth that is bonded to a frame or backing plate with proper tension applied prior to its installation on a shaker. See: backing plate, perforated panel screen.
Progressive gel. A condition wherein the 10-min gel strength is greater than the initial gel strength. Opposite of flat gel. See: flat gel, zerozero
gel.
Pseudoplastic fluid. A complex non-Newtonian fluid that does not possess thixotropy. A pressure or force in excess of zero will start fluid flow. The apparent viscosity or consistency decreases instantaneously with increasing rate of shear until at a given point the viscosity becomes constant. The yield point as determined by direct-indicating viscometer is positive, the same as in Bingham plastic fluids. However, the true yield point is zero. An example pseudoplastic fluid is guar gum in fresh- or saltwater. See: viscosity, Bingham model, plastic viscosity, yield point, gel strength.
Purging. The process of supplying an enclosure with a protective gas at a sufficient flow and positive pressure to reduce the concentration of any flammable gas or vapor initially present to an acceptable level.
Panel-mounted units. Shale shaker screens mounted to a rigid frame.
Parallel flow. See: laminar flow.
Particle. A discrete unit of solid material that may consist of a single grain or of any number of grains stuck together.
Particle size. Particle diameter expressed in microns. See: ESD, equivalent spherical diameter.
Particle size distribution. The volume classification of solid particles into each of the various size ranges as a percentage of the total solids of all sizes in a fluid sample.
Parts per million. The unit weight of solute per million unit weights of solution (solute plus solvent), corresponding to weight percentage.
The results of standard API titration of chloride hardness, etc., are correctly expressed in milligrams (mg) per liter but not in ppm. At low concentrations mg/L is about numerically equal to ppm. A correction for the solution specific gravity or density in g/ml must be made as follows:
ppm = (milligrams/liter)/solution density(grams/liter)
weight%= (milligrams/liter)/[10,000*solution density (grams/liter)]
weight%= [ppm]/[10,000]
Thus, 316,000 mg/L salt is commonly called 316,000 ppm, or 31.6%, which correctly should be 264,000 pprn and 26.4%, respectively.
Pay zone. A formation that contains oil and/or gas in commercial quantities.
Penetration rate. The rate at which the drill bit penetrates the formation, usually expressed in feet per hour or meters per hour. See: rate of penetration, ROP.
Peptization. An increased flocculation of clays caused by the addition of electrolytes or other chemical substances. See: deflocculation dispersion, high-yield clay.
Peptized clay. A clay to which an agent has been added to increase its initial yield. For example, soda ash is frequently added to calcium montmorillonite clay to increase the yield. See: high-yield clay.
Percent open area. Ratio of the area of the screen openings to the total area of the screen surface.
Percent separated curve. A plot of mass distributions of solids sizes discarded from a solids-separation device divided by the mass distributions of each size of solids fed to the device.
Perforated cylinder centrifuge. A mechanical centrifugal separator in which the rotating element is a perforated cylinder (the rotor) inside of and concentric with an outer stationary cylindrical case.
Perforated panel screen. A screen in which the backing plate used to
provide support to the screen cloths is a metal sheet with openings.
Perforated plate screen. Shale shaker screens mounted on metal plates that have holes punched through.
Perforated rotor. The rotating inner cylinder of the perforated cylinder centrifuge. See: perforated cylinder centrifuge.
Permeability. Permeability is a measure of the ability of a formation to allow passage of a fluid. Unit of permeability is the darcy. See: darcy, porosity.
Pf. The phenolphthalein alkalinity of the filtrate is reported as the number of milliliters of 0.02 normal sulfuric acid required per milliliter of filtrate for the pH to reach the phenolphthalein endpoint, which is a pH of 8.3.
pH. The negative logarithm of the hydrogen ion concentration in gram ionic weights per liter. The pH range is numbered from 0 to 14, with 7 being neutral, and is an index of the acidity (below 7) or alkalinity (above 7) of the fluid. At a temperature of 70°F, a neutral pH is 7 or a hydrogen ion concentration of 10^-7. The neutral pH is a function of temperature. At higher elevated temperatures the neutral pH is lower. The pH of a solution offers valuable information as to the immediate acidity or alkalinity, in contrast to the total acidity or alkalinity, which may be determined by titratration.
Phosphate. Certain complex phosphates, commonly sodium tetraphosphate (Na6P4O13) and sodium acid pyrophosphate (SAPP, Na2H2P2O4), are used either as drilling-fluid thinners or for treatment of various forms of calcium and magnesium contamination.
Piggyback, -ing. The attachment of fine solids particles to the surface of larger solids particles due to surface attraction, fluid consistency, and particle concentration. This attachment phenomenon causes fine solids to be discharged from the screen that would normally pass through the screen.
Pill. A small volume of a special fluid slurry pumped through the drill string and normally placed in the annulus. See: slug.
Pilot testing. A method of predicting behavior of drilling-fluid systems by adding various chemicals to a small quantity of drilling fluid (usually 350 cc), then examining the results. One gram of an additive in 350 cc is equivalent to 1 lb/bbl.
Plastic flow. See: plastic fluid.
Plastic fluid. A complex, non-Newtonian fluid in which shear force is not proportional to shear rate. A definite pressure is required to start and maintain fluid movement. Plug flow is the initial flow type and only occurs in plastic fluids. Most drilling fluids are plastic fluids. The yield point, as determined by a direct-indicating viscometer, is in excess of zero.
Plastic viscosity. This is a measure of the internal resistance to fluid flow attributable to the concentration, type, and size of solids present in a given fluid and the viscosity of the continuous phase. This value, expressed in centipoise, is proportional to the slope of the shear stress/ shear rate curve determined in the region of laminar flow for materials whose properties are described by Bingham’s law of plastic flow. When using the direct-indicating viscometer, plastic viscosity is found by subtracting the 300-rpm reading from the 600-rpm reading. See: viscosity, yield point, API RP 13B.
Plasticity. The property possessed by some solids, particularly clays and clay slurries, of changing shape or flowing under applied stress without developing shear planes or fractures; that is, it deforms without breaking. Such bodies have yield points, and stress must be applied before movement begins. Beyond the yield point, the rate of movement is proportional to the stress applied, but movement ceases when the stress is removed. See: fluid.
Plug flow. The movement of material as a unit without shearing within the mass. Plug flow is the first type of flow exhibited by a plastic fluid after overcoming the initial force required to produce flow. See: Bingham model, Newtonian fluid, laminar flow, turbulent flow.
Plugging. The wedging or jamming of openings in a screening surface by near-size particles, preventing passage of undersize particles and leading to the blinding of the screen. See: blinding, coating.
Pm. The phenolphthalein alkalinity of drilling fluid is reported as the number of milliliters of 0.02 normaI (N/50) sulfuric acid required per milliliter of drilling fluid for the pH to reach the phenolphthalein endpoint of 8.3.
Polyelectrolytes. Long-chain organic molecules possessing ionizable sites that when dissolved in water become charges.
Polymer. A substance formed when two or more molecules of the same kind are linked end to end into another compound having the same elements in the same
proportion but higher molecular weight and different physical properties, for example, paraformaldehyde.Polymers are used in drilling fluids to maintain viscosity and control fluid loss. See: copolymer.
Polyurethane. A high-performance elastomer polymer used in construction of hydrocyclones for its unique combination of physical properties, especially abrasion, toughness, and resiliency.
Pool. (1) The reservoir or pond of fluid, or slurry, formed inside the wall of hydrocyclones and centrifuges and in which classification or separation of solids occurs due to the settling effect of centrifugal force.(2) The reservoir or pond of fluid that can form on the feed end of an uphill shaker basket, a shaker basket with positive deck angle.
Poor boy degasser. See: gas buster, mud/gas separator.
Porosity. The volume of void space in a formation rock usually expressed as percentage of void volume per bulk volume.
Ports. The openings in a centrifuge for entry or exit of materials. Usually applied in connection with a descriptive term, that is, feed ports, overflow ports, etc.
Positive deck angle. The angle of adjustment to a screen deck that causes the screened solids to travel ‘‘uphill’’ to reach the discharge end of the screen surface. This so-called uphill travel increases the fluid throughput of a screen but also shortens the life of a screen. See: negative deck angle.
Possum belly. The compartment on a shale shaker into which the flowline discharges, and from the drilling fluid is fed, either to the screens or to a succeeding tank. See: back tank, mud box.
Potassium. One of the alkali metal elements with a valence of 1 and an atomic weight of approximately 39. Potassium compounds, most commonly potassium hydroxide (KOH), are sometimes added to drilling fluids to impart special properties, usually inhibition.
Potential separation curve. A distribution curve of sizes determined by the optical image analysis for separation potential.
Pound equivalent. A laboratory unit used in pilot testing. One gram of a material added to 350 ml of fluid is equivalent to 1 lb of material added to one barrel. See: barrel, barrel equivalent.
ppm: Parts per million. See: parts per million.
Precipitate. Material that separates out of solution or slurry as a solid.
Precipitation of solids in a drilling fluid may follow flocculation or coagulation.
Preformed foam. Foam formed at the drill bit (obsolete).
Prehydration tank. A tank used to hydrate materials (such as bentonite, polymers, etc.) that require a long time (hours to days) to hydrate fully and disperse before being added to the drilling fluid. See: premix system.
Premix system. A compartment used to mix materials (such as bentonite, polymers, etc.) that require time to hydrate or disperse fully before they are added to the drilling
fluid. See: prehydration tank.
Preservative. Any material used to prevent starch or any other organic substance from fermenting via bacterial action. A common preservative is paraformaldehyde. See: fermentation.
Pressure drop. See: friction loss, pressure loss.
Pressure head. Pressure within a system equal to the pressure exerted by an equivalent height of fluid (expressed in feet or meters). See: head, hydrostatic head, centrifugal pump.
Pressure loss. The pressure lost in a pipeline or annulus due to the velocity of the liquid in the pipeline, the properties of the fluid, the condition of the pipe wall, and the configuration of the pipe. See: friction loss, pressure drop.
Pressure surge. A sudden, usually brief increase in pressure. When pipe or casing is run into a hole too rapidly or the drill string is set in the slips too quickly, an increase in the hydrostatic pressure results due to pressure surge which may be great enough to create lost circulation. See: ECD, annular pressure loss.
Pressurization. The process of supplying an enclosure with a protective gas with or without continuous flow at sufficient pressure to prevent the entrance of a flammable gas or vapor, a combustible dust, or an ignitable fiber.
Pretensioned screen. A screen cloth that is bonded to a frame or backing plate with proper tension applied prior to its installation on a shaker. See: backing plate, perforated panel screen.
Progressive gel. A condition wherein the 10-min gel strength is greater than the initial gel strength. Opposite of flat gel. See: flat gel, zerozero
gel.
Pseudoplastic fluid. A complex non-Newtonian fluid that does not possess thixotropy. A pressure or force in excess of zero will start fluid flow. The apparent viscosity or consistency decreases instantaneously with increasing rate of shear until at a given point the viscosity becomes constant. The yield point as determined by direct-indicating viscometer is positive, the same as in Bingham plastic fluids. However, the true yield point is zero. An example pseudoplastic fluid is guar gum in fresh- or saltwater. See: viscosity, Bingham model, plastic viscosity, yield point, gel strength.
Purging. The process of supplying an enclosure with a protective gas at a sufficient flow and positive pressure to reduce the concentration of any flammable gas or vapor initially present to an acceptable level.
Friday, October 9, 2015
Drilling fluid process glossary O
Oblong mesh. A screen cloth that has more openings per inch in one direction than in the perpendicular direction. For example, a 70×30 mesh has 70 openings per inch in
one direction and 30 openings per inch in the perpendicular direction, creating a rectangular opening. The smaller opening dimension controls the sizing of spherical
material. See: rectangular screen.
Oblong weave. See: oblong mesh.
OD. Outside diameter of a pipe.
Ohm. The measurement of resistance or electrical friction.
Oil-based drilling fluid. The term ‘‘oil-based mud’’ is applied to a special type of drilling fluid in which oil is the continuous phase and water the dispersed phase.
Oil-based drilling fluid contains from 1 to 5% water emulsified into the system with lime and emulsifiers. Oil-based muds are differentiated from invert emulsion muds
(both water-in-oil emulsions) by the amounts of water used, the method of controlling viscosity, the thixotropic properties, wall-building materials, and fluid loss. See:
invert oil emulsion drilling fluid.
Oil breakout. Oil that has risen to the surface of a drilling fluid. This oil had been previously emulsified in the drilling fluid or may derive from oil-bearing formations
that have been penetrated.
Oil content. The oil content of any drilling fluid is the amount of oil in volume percentage.
Oil immersion. An oil-filled construction in which an electrical device has no electrical connections, joints, terminals, or arcing parts at or above the normal oil level.
Oil wet. A surface on which oil easily spreads. If the contact angle of an oil droplet on a surface is less than 90 , the surface is oil wet. See: lipophilic, water wet.
Oil-in-water emulsion drilling fluid. Any conventional or special waterbase drilling fluid to which oil has been added. A drilling fluid in which the oil content is usually
kept between 3 and 7% and seldom over 10% (it can be considerably higher). Commonly called ‘‘emulsion mud.’’ The oil becomes the dispersed phase and may be
emulsified into the mud either mechanically or chemically. The oil is emulsified into freshor saltwater with a chemical emulsifier
Overflow. The discharge stream from a centrifugal separation that normally contains a higher percentage of liquids than does the feed.
Overflow header. A pipe into which two or more hydrocyclones discharge their overflow.
Overslung. Field terminology denoting that the support ribs for the shaker screen are located below the screen surface. See: underslung.
one direction and 30 openings per inch in the perpendicular direction, creating a rectangular opening. The smaller opening dimension controls the sizing of spherical
material. See: rectangular screen.
Oblong weave. See: oblong mesh.
OD. Outside diameter of a pipe.
Ohm. The measurement of resistance or electrical friction.
Oil-based drilling fluid. The term ‘‘oil-based mud’’ is applied to a special type of drilling fluid in which oil is the continuous phase and water the dispersed phase.
Oil-based drilling fluid contains from 1 to 5% water emulsified into the system with lime and emulsifiers. Oil-based muds are differentiated from invert emulsion muds
(both water-in-oil emulsions) by the amounts of water used, the method of controlling viscosity, the thixotropic properties, wall-building materials, and fluid loss. See:
invert oil emulsion drilling fluid.
Oil breakout. Oil that has risen to the surface of a drilling fluid. This oil had been previously emulsified in the drilling fluid or may derive from oil-bearing formations
that have been penetrated.
Oil content. The oil content of any drilling fluid is the amount of oil in volume percentage.
Oil immersion. An oil-filled construction in which an electrical device has no electrical connections, joints, terminals, or arcing parts at or above the normal oil level.
Oil wet. A surface on which oil easily spreads. If the contact angle of an oil droplet on a surface is less than 90 , the surface is oil wet. See: lipophilic, water wet.
Oil-in-water emulsion drilling fluid. Any conventional or special waterbase drilling fluid to which oil has been added. A drilling fluid in which the oil content is usually
kept between 3 and 7% and seldom over 10% (it can be considerably higher). Commonly called ‘‘emulsion mud.’’ The oil becomes the dispersed phase and may be
emulsified into the mud either mechanically or chemically. The oil is emulsified into freshor saltwater with a chemical emulsifier
Overflow. The discharge stream from a centrifugal separation that normally contains a higher percentage of liquids than does the feed.
Overflow header. A pipe into which two or more hydrocyclones discharge their overflow.
Overslung. Field terminology denoting that the support ribs for the shaker screen are located below the screen surface. See: underslung.
Monday, September 28, 2015
drilling fluids glossary N
Natural clay. Natural clay, as opposed to commercial clay, are clay that are encountered when drilling various formations. The yield of these clay varies greatly, and they may or may not be purposely incorporated into the drilling fluid system. See: attapulgite clay, bentonite, high-yield clay, low-yield clay, clay.
Near-size plugging. A term used in describing screen plugging, referring to particles with a dimension slightly larger than the screen opening. See: blinding, plugging.
Neat cement. A slurry composed only of Portland cement and water.
Negative deck angle. The angle of adjustment to a screen deck that causes the screened solids to travel ‘‘downhill’’ (usual travel) to reach the discharge end of the screen surface. This downhill travel decreases the fluid throughput of a screen but usually lengthens the life of a screen. See: positive deck angle.
Neutralization. A reaction in which the hydrogen ion of an acid and the hydroxyl ion of a base unite to form water, the other ionic product being a salt.
Newtonian flow. See: Newtonian fluid.
Newtonian fluid. The basic and simplest fluids from the standpoint of viscosity, in which the shear force is directly proportional to the shear rate. These fluids will immediately begin to move when a pressure or force in excess of zero psi is applied. Examples of Newtonian fluids are water, diesel oil, and glycerine. The yield point as determined by direct-indicating viscometer is zero. See: Newtonian flow.
Non-conductive drilling fluid. Any drilling fluid, usually oil-based or invert emulsion drilling fluid, whose continuous phase does not conduct electricity. The spontaneous potential (SP) and normal resistivity cannot be logged, although such other logs as the gamma rays, induction, acoustic velocity, etc., can be run.
Non-dispersed. A condition in which the clays do not separate into individual platelets. Dispersion is inhibited.
Normal solution. A solution of such a concentration that it contains 1 gram equivalent of a substance per liter of solution.
Near-size plugging. A term used in describing screen plugging, referring to particles with a dimension slightly larger than the screen opening. See: blinding, plugging.
Neat cement. A slurry composed only of Portland cement and water.
Negative deck angle. The angle of adjustment to a screen deck that causes the screened solids to travel ‘‘downhill’’ (usual travel) to reach the discharge end of the screen surface. This downhill travel decreases the fluid throughput of a screen but usually lengthens the life of a screen. See: positive deck angle.
Neutralization. A reaction in which the hydrogen ion of an acid and the hydroxyl ion of a base unite to form water, the other ionic product being a salt.
Newtonian flow. See: Newtonian fluid.
Newtonian fluid. The basic and simplest fluids from the standpoint of viscosity, in which the shear force is directly proportional to the shear rate. These fluids will immediately begin to move when a pressure or force in excess of zero psi is applied. Examples of Newtonian fluids are water, diesel oil, and glycerine. The yield point as determined by direct-indicating viscometer is zero. See: Newtonian flow.
Non-conductive drilling fluid. Any drilling fluid, usually oil-based or invert emulsion drilling fluid, whose continuous phase does not conduct electricity. The spontaneous potential (SP) and normal resistivity cannot be logged, although such other logs as the gamma rays, induction, acoustic velocity, etc., can be run.
Non-dispersed. A condition in which the clays do not separate into individual platelets. Dispersion is inhibited.
Normal solution. A solution of such a concentration that it contains 1 gram equivalent of a substance per liter of solution.
Friday, September 25, 2015
Drilling fluids processing glossary M
Main shaker. The shale shaker that processes drilling fluid from the flowline through the finest-mesh screen.
Manifold. (1) A length of pipe with multiple connections for collecting or distributing fluid. (2) A piping arrangement through which liquids, solids, or slurries from one or more sources can be fed to or discharged from a solids-separation device.
Market grade cloth. A group of industrial wire cloth specifications selected for general-purpose work, made of high-strength, square mesh cloth in several types of metals. The common metal for oilfield use is 304 or 316 stainless steel. The wire diameters are marginally larger than mill grade cloth, resulting in a lower percentage of open area. Market grade and mill grade cloths are used mostly as support screens for fine-mesh screens. See: mill grade cloth, tensile bolting cloth, ultrafine wire cloth, support screen, and calendered.
Marsh funnel. An instrument used in determining the Marsh funnel viscosity. The Marsh funnel is a container with a fixed orifice at the bottom so that when filled with 1500 cc freshwater, 1 qt (946 ml) will flow out in 26±0.5 sec. For 1000 cc out, the efflux time for water is 27.5 ±sec. It is used for comparison values only and not to diagnose drilling fluid problems. See: API Bulletin RP 13B, funnel viscosity,
Marsh funnel viscosity, kinematic viscosity.
Marsh funnel viscosity. Commonly called funnel viscosity. The Marsh funnel viscosity is reported as the time, in seconds, required for 1 qt of fluid to flow through an API standardized funnel. In some areas, the efflux quantity is 1000 cc. See: API RP 13B, funnel viscosity, kinematic viscosity, Marsh funnel.
Martin’s radii. The distance from the centroid of an object to its outer boundary. The direction of this measurement is specified by the azimuth orientation of the line (the radii in the 0°, 90°, 180°, 270°angle from horizontal).
Mass. The inertial resistance of a body to acceleration, considered in classical physics, to a conserved quantity independent of speed. The weight of a body is the product of the mass of the body and the acceleration of gravity for the specific location. In space the mass would stay constant but the weight would disappear as the gravitational acceleration approaches zero.
MBT. Methylene blue test. See: methylene blue test.
Mechanical agitator. A device used to mix, blend, or stir fluids by means of a rotating impeller blade. See: agitator, mechanical stirrer.
Mechanical stirrer. See: agitator, mechanical agitator.
Median cut. The median cut is the particle size that reports 50% of the weight to the overflow 50% of the weight to the underflow. Frequently identified as the D50 point. See: cut point.
Medium (solids). Particles whose diameter is between 74 and 250 microns.
Membrane nitrogen. Air from which water and oxygen have been removed by a filter (membrane) system.
Meniscus. The curved upper surface of a liquid column, concave when the containing walls are wetted by the liquid and convex when they are not wetted.
Mesh. (1) The number of openings (and fraction thereof) per linear inch in a screen, counted in both directions from the center of a wire. (2) An indication of the weave of a woven material, screen or sieve. A 200 mesh sieve has 200 openings per linear inch. A 200 mesh screen with a wire diameter of 0.0021 inch (0.0533 mm) has an opening of 0.0029 in. (0.074) mm and will pass a spherical particle of 74 microns diameter. See: micron.
Mesh count. Such as 30X30, or often 30 mesh, indicating the number of openings per linear inch of screen; and a square mesh. A designation of 70X30 mesh indicates rectangular mesh with 70 openings per inch in one direction and 30 openings per inch in a perpendicular direction.
Mesh equivalent. As used in oilfield drilling applications, the U.S. Sieve number that has the same-size opening as the minimum opening of the screen in use.
Methylene blue test. A test that serves to indicate the amount of active clay in a fluid system, clay sample, or shale sample. Methylene blue is titrated into a slurry until all of the negative charge sites are covered with the methylene blue. This indicates the number of active charge sites present in the slurry. See: base exchange, methylene blue titration,
MBT, cation exchange capacity, CEC.
Methylene blue titration. Methylene blue is a cation that seeks all negative charges on a clay surface after the surface has been properly prepared (see API RP13B). By titrating with a known concentration, this test provides an indication of the amount of clay present in the drilling fluid. See: methylene blue test, MBT, cation exchange capacity, CEC.
Mf. The methyl orange alkalinity of the filtrate, reported as the number of milliliters of 0.02 normal sulfuric acid required per milliliter of filtrate to decrease the pH to reach the methyl orange endpoint (pH 4.3).
Mica. Naturally occurring mineral flake material of various sizes used in controlling lost circulation. An alkali aluminum silicate.
Micelles. Organic and inorganic molecular aggregates occurring in colloidal solutions. chains of individual structural units chemically joined to one another and deposited side by side to form bundles. When bentonite hydrates, certain sodium, or other metallic ions go into solution, the clay particle plus its complement of ions is technically known as a micelle.
Micron. A unit of length equal to one-thousandth of a millimeter. Used to specify particle sizes in drilling fluids and solids control discussions (25,400 microns¼1 inch).
Mil. A unit of length equal to 1/1000 inch.
Milk emulsion. See: oil-in-water emulsion drilling fluid.
Mill grade cloth. A group of industrial wire cloth specifications with lighter wire than market grade cloth. The standard wire diameter of the grade produces a median percentage of open area. Market grade and mill grade cloths are used mostly as support screens for fine-mesh screens. See: market grade cloth, tensile bolting cloth, ultra-fine wire cloth, support screen, and calendered.
Millidarcy. 1/1000 darcy. See: darcy.
Milliliter. A metric system unit for the measurement of volume. Literally 1/1000th of a liter. In drilling-fluid analyses, this term is used interchangeably with cubic centimeter (cc). One quart is equal to approximately 946 ml.
Mini still. An instrument used to distill oil, water, and any other volatile material in a drilling fluid to determine oil, water, and total solids contents as volume percentage. See: distillation, mud still.
Mist drilling. A method of rotary drilling whereby water and/or oil is dispersed in air and/or gas as the drilling fluid. See: foam. ml. See: milliliter.
Molecule. Atoms combine to form molecules. For elements or compounds, a molecule is the smallest unit that chemically still retains the properties of the substance in mass.
Monovalent. See: valence.
Montmorillonite. A clay mineral commonly used as an additive to drilling muds. Sodium montmorillonite is the main constituent of bentonite. Each platelet of the crystalline structure of montmorillonite has two layers of silicon tetrahedra attached to a center layer of alumina octhahedra. The platelets are thin and have a broad surface. Exchangeable cations are located on the clay surfaces between the platelets. Calcium montmorillonite is the main constituent in low-yield clays. See: gel,
bentonite.
Mud. See: drilling fluid, which is the preferred term.
Mud analysis. See: drilling fluid analysis, API RP 13B.
Mud balance. A beam-type balance used in determining drilling-fluid density (mud weight). It consists primarily of a base, a graduated beam with constant volume cup, lid, rider, knife-edge, and counterweight. See: API RP 13B.
Mud box. See: back tank, possum belly.
Mud cleaner. A device that places a screen in series with the underflow of hydrocyclones. The hydrocyclone overflow returns to the mud system, and the underflow reports to a vibrating screen. Solids discharged from the screen are discarded and the screen throughput returns to the system.
Mud compartment. A subdivision of the removal, additions, or check/ suction sections of a surface system. See: mud pits, mud tanks.
Mud ditch. A trough built along the upper edge of many surface systems that is used to direct flow to selected compartments of the surface system. See: mud pits, mud compartment.
Mud engineer. See: drilling fluid engineer.
Mud gun. A submerged nozzle used to stir the drilling fluid with a highvelocity stream. See gunning the pits.
Mud hopper. See: hopper.
Mud house. A structure at the rig to store and shelter sacks of materials used in drilling fluids.
Mud inhibitor. Additives such as salt, lime, lignosulfonate, and calcium sulfate that prevent clay dispersion.
Mud logging. A process that helps determine the presence or absence of oil or gas in the various formations penetrated by the drill bit, and assists with a variety of indicators that assist drilling operations. Drilling fluid and cuttings are continuously tested on their return to the surface, and the results of these tests are correlated with the drilling depth for depth of origin.
Mud mixing devices. The most common device for adding solids to the drilling fluid is by means of the jet hopper. Some other devices to assist mixing are eductors, mechanical agitators, paddle mixers, electric stirrers, mud guns, chemical barrels, etc.
Mud pit. See: mud compartments, mud tanks.
Mud pump. Pumps at the rig used to circulate drilling fluids.
Mud scales. See: mud balance.
Mud still. See: distillation, mini still.
Mud tanks. (1) Drilling-fluid system compartments constructed of metal and mounted so they can be moved from location to location, either as a part of the rig (such as on a semisubmersible rig) or separately on unitized skids (as on most land rigs). (2) Earthen or steel storage facilities for the surface system. Mud pits are of two types: circulating and reserve. Drilling-fluid testing and conditioning is normally done in the circulating pit system.
Mud weight. A measurement of density of a slurry usually reported in lb/gal, lb/cu ft, psi/1000 ft or specific gravity. See: density.
Mud/gas separator. A vessel into which the choke line discharges when a ‘‘kick’’ is being taken. Gas is separated in the vessel as the drilling fluid flows over baffle plates. The gas flows through a line to a flare. The liquid mud discharges into the shale shaker back tank. See: gas buster, poor boy degasser.
Mudding off. A condition promoting reduced production caused by the penetrating, sealing or plastering effect of a drilling fluid. See: formation damage.
Mudding up. Process of mixing drilling fluid additives to a simple, native clay water slurry to achieve some properties not possible with the previous fluid.
MW. Abbreviation for mud weight. See: density, mud weight.
Manifold. (1) A length of pipe with multiple connections for collecting or distributing fluid. (2) A piping arrangement through which liquids, solids, or slurries from one or more sources can be fed to or discharged from a solids-separation device.
Market grade cloth. A group of industrial wire cloth specifications selected for general-purpose work, made of high-strength, square mesh cloth in several types of metals. The common metal for oilfield use is 304 or 316 stainless steel. The wire diameters are marginally larger than mill grade cloth, resulting in a lower percentage of open area. Market grade and mill grade cloths are used mostly as support screens for fine-mesh screens. See: mill grade cloth, tensile bolting cloth, ultrafine wire cloth, support screen, and calendered.
Marsh funnel. An instrument used in determining the Marsh funnel viscosity. The Marsh funnel is a container with a fixed orifice at the bottom so that when filled with 1500 cc freshwater, 1 qt (946 ml) will flow out in 26±0.5 sec. For 1000 cc out, the efflux time for water is 27.5 ±sec. It is used for comparison values only and not to diagnose drilling fluid problems. See: API Bulletin RP 13B, funnel viscosity,
Marsh funnel viscosity, kinematic viscosity.
Marsh funnel viscosity. Commonly called funnel viscosity. The Marsh funnel viscosity is reported as the time, in seconds, required for 1 qt of fluid to flow through an API standardized funnel. In some areas, the efflux quantity is 1000 cc. See: API RP 13B, funnel viscosity, kinematic viscosity, Marsh funnel.
Martin’s radii. The distance from the centroid of an object to its outer boundary. The direction of this measurement is specified by the azimuth orientation of the line (the radii in the 0°, 90°, 180°, 270°angle from horizontal).
Mass. The inertial resistance of a body to acceleration, considered in classical physics, to a conserved quantity independent of speed. The weight of a body is the product of the mass of the body and the acceleration of gravity for the specific location. In space the mass would stay constant but the weight would disappear as the gravitational acceleration approaches zero.
MBT. Methylene blue test. See: methylene blue test.
Mechanical agitator. A device used to mix, blend, or stir fluids by means of a rotating impeller blade. See: agitator, mechanical stirrer.
Mechanical stirrer. See: agitator, mechanical agitator.
Median cut. The median cut is the particle size that reports 50% of the weight to the overflow 50% of the weight to the underflow. Frequently identified as the D50 point. See: cut point.
Medium (solids). Particles whose diameter is between 74 and 250 microns.
Membrane nitrogen. Air from which water and oxygen have been removed by a filter (membrane) system.
Meniscus. The curved upper surface of a liquid column, concave when the containing walls are wetted by the liquid and convex when they are not wetted.
Mesh. (1) The number of openings (and fraction thereof) per linear inch in a screen, counted in both directions from the center of a wire. (2) An indication of the weave of a woven material, screen or sieve. A 200 mesh sieve has 200 openings per linear inch. A 200 mesh screen with a wire diameter of 0.0021 inch (0.0533 mm) has an opening of 0.0029 in. (0.074) mm and will pass a spherical particle of 74 microns diameter. See: micron.
Mesh count. Such as 30X30, or often 30 mesh, indicating the number of openings per linear inch of screen; and a square mesh. A designation of 70X30 mesh indicates rectangular mesh with 70 openings per inch in one direction and 30 openings per inch in a perpendicular direction.
Mesh equivalent. As used in oilfield drilling applications, the U.S. Sieve number that has the same-size opening as the minimum opening of the screen in use.
Methylene blue test. A test that serves to indicate the amount of active clay in a fluid system, clay sample, or shale sample. Methylene blue is titrated into a slurry until all of the negative charge sites are covered with the methylene blue. This indicates the number of active charge sites present in the slurry. See: base exchange, methylene blue titration,
MBT, cation exchange capacity, CEC.
Methylene blue titration. Methylene blue is a cation that seeks all negative charges on a clay surface after the surface has been properly prepared (see API RP13B). By titrating with a known concentration, this test provides an indication of the amount of clay present in the drilling fluid. See: methylene blue test, MBT, cation exchange capacity, CEC.
Mf. The methyl orange alkalinity of the filtrate, reported as the number of milliliters of 0.02 normal sulfuric acid required per milliliter of filtrate to decrease the pH to reach the methyl orange endpoint (pH 4.3).
Mica. Naturally occurring mineral flake material of various sizes used in controlling lost circulation. An alkali aluminum silicate.
Micelles. Organic and inorganic molecular aggregates occurring in colloidal solutions. chains of individual structural units chemically joined to one another and deposited side by side to form bundles. When bentonite hydrates, certain sodium, or other metallic ions go into solution, the clay particle plus its complement of ions is technically known as a micelle.
Micron. A unit of length equal to one-thousandth of a millimeter. Used to specify particle sizes in drilling fluids and solids control discussions (25,400 microns¼1 inch).
Mil. A unit of length equal to 1/1000 inch.
Milk emulsion. See: oil-in-water emulsion drilling fluid.
Mill grade cloth. A group of industrial wire cloth specifications with lighter wire than market grade cloth. The standard wire diameter of the grade produces a median percentage of open area. Market grade and mill grade cloths are used mostly as support screens for fine-mesh screens. See: market grade cloth, tensile bolting cloth, ultra-fine wire cloth, support screen, and calendered.
Millidarcy. 1/1000 darcy. See: darcy.
Milliliter. A metric system unit for the measurement of volume. Literally 1/1000th of a liter. In drilling-fluid analyses, this term is used interchangeably with cubic centimeter (cc). One quart is equal to approximately 946 ml.
Mini still. An instrument used to distill oil, water, and any other volatile material in a drilling fluid to determine oil, water, and total solids contents as volume percentage. See: distillation, mud still.
Mist drilling. A method of rotary drilling whereby water and/or oil is dispersed in air and/or gas as the drilling fluid. See: foam. ml. See: milliliter.
Molecule. Atoms combine to form molecules. For elements or compounds, a molecule is the smallest unit that chemically still retains the properties of the substance in mass.
Monovalent. See: valence.
Montmorillonite. A clay mineral commonly used as an additive to drilling muds. Sodium montmorillonite is the main constituent of bentonite. Each platelet of the crystalline structure of montmorillonite has two layers of silicon tetrahedra attached to a center layer of alumina octhahedra. The platelets are thin and have a broad surface. Exchangeable cations are located on the clay surfaces between the platelets. Calcium montmorillonite is the main constituent in low-yield clays. See: gel,
bentonite.
Mud. See: drilling fluid, which is the preferred term.
Mud analysis. See: drilling fluid analysis, API RP 13B.
Mud balance. A beam-type balance used in determining drilling-fluid density (mud weight). It consists primarily of a base, a graduated beam with constant volume cup, lid, rider, knife-edge, and counterweight. See: API RP 13B.
Mud box. See: back tank, possum belly.
Mud cleaner. A device that places a screen in series with the underflow of hydrocyclones. The hydrocyclone overflow returns to the mud system, and the underflow reports to a vibrating screen. Solids discharged from the screen are discarded and the screen throughput returns to the system.
Mud compartment. A subdivision of the removal, additions, or check/ suction sections of a surface system. See: mud pits, mud tanks.
Mud ditch. A trough built along the upper edge of many surface systems that is used to direct flow to selected compartments of the surface system. See: mud pits, mud compartment.
Mud engineer. See: drilling fluid engineer.
Mud gun. A submerged nozzle used to stir the drilling fluid with a highvelocity stream. See gunning the pits.
Mud hopper. See: hopper.
Mud house. A structure at the rig to store and shelter sacks of materials used in drilling fluids.
Mud inhibitor. Additives such as salt, lime, lignosulfonate, and calcium sulfate that prevent clay dispersion.
Mud logging. A process that helps determine the presence or absence of oil or gas in the various formations penetrated by the drill bit, and assists with a variety of indicators that assist drilling operations. Drilling fluid and cuttings are continuously tested on their return to the surface, and the results of these tests are correlated with the drilling depth for depth of origin.
Mud mixing devices. The most common device for adding solids to the drilling fluid is by means of the jet hopper. Some other devices to assist mixing are eductors, mechanical agitators, paddle mixers, electric stirrers, mud guns, chemical barrels, etc.
Mud pit. See: mud compartments, mud tanks.
Mud pump. Pumps at the rig used to circulate drilling fluids.
Mud scales. See: mud balance.
Mud still. See: distillation, mini still.
Mud tanks. (1) Drilling-fluid system compartments constructed of metal and mounted so they can be moved from location to location, either as a part of the rig (such as on a semisubmersible rig) or separately on unitized skids (as on most land rigs). (2) Earthen or steel storage facilities for the surface system. Mud pits are of two types: circulating and reserve. Drilling-fluid testing and conditioning is normally done in the circulating pit system.
Mud weight. A measurement of density of a slurry usually reported in lb/gal, lb/cu ft, psi/1000 ft or specific gravity. See: density.
Mud/gas separator. A vessel into which the choke line discharges when a ‘‘kick’’ is being taken. Gas is separated in the vessel as the drilling fluid flows over baffle plates. The gas flows through a line to a flare. The liquid mud discharges into the shale shaker back tank. See: gas buster, poor boy degasser.
Mudding off. A condition promoting reduced production caused by the penetrating, sealing or plastering effect of a drilling fluid. See: formation damage.
Mudding up. Process of mixing drilling fluid additives to a simple, native clay water slurry to achieve some properties not possible with the previous fluid.
MW. Abbreviation for mud weight. See: density, mud weight.
Monday, September 14, 2015
Drilling fluids processing glossary L
LCM. Circulation material. See: lost circulation materials.
Lead. In a decanting centrifuge, the slurry-conducting channel formed by the adjacent walls of the flutes or blades of the screw conveyor.
Leonardite. Anaturally occurring oxidized lignite. See: humic acid, lignin.
Light solids. See: low-gravity solids.
Lignin. Mined lignin is a naturally occurring special lignite, for example, leonardite, produced by strip mining from special lignite deposits. The active ingredients are the humic acids. Mined lignins are used primarily as thinners, which may or may not be chemically modified. See: leonardite, humic acid.
Lignosulfonates. Organic drilling-fluid additives derived from by products of the sulfite paper manufacturing process from coniferous woods. Some of the common salts, such as ferrochrome, chrome, calcium, and sodium, are used as deflocculants while other lignosulfonates are used selectively for calcium-treated systems. In large quantities, the ‘‘heavy metal’’ ferrochrome and chrome salts are used for fluid loss control and shale inhibition.
Lime. Ca(OH)2. Commercial form of calcium hydroxide.
Lime-treated drilling fluids. Commonly referred to as ‘‘lime-based’’ muds. These high-pH systems contain most of the conventional freshwater drilling-fluid additives to which slaked lime has been added to impart special inhibition properties. The alkalinities and lime contents of the fluids may vary from low to high. See: calcium-treated drilling fluids.
Limestone. Ca(CO)3. See: calcium carbonate.
Line sizing. Ensuring that the fluid velocity through all piping within the surface system has the proper flow and pipe diameter combination to prevent solids from settling and pipe from eroding. A good rule of thumb is to ensure that fluid flow is between 5 and 9 feet per second, as determined by the following:
Linear motion. Linear motion of a shale shaker screen is produced by two counterrotational motors located above the shaker basket in such a way that a line connecting the two motor axes is perpendicular to a line passing through the center of gravity of the basket. Because the acceleration is applied directly through the center of gravity of the basket, the basket is dynamically balanced; the same pattern of motion will exist at all points along the shaker screen. The resultant screen motion is linear, and the angle of this uniform motion is usually 45° to 60°relative to the shaker screen deck.
Lipophile. Any substance, usually in the colloidal state or an emulsion, that is wetted by oil; that is, it attracts oil or oil adheres to it. See: hydrophile.
Lipophilic. A property of a substance having an affinity for oil or one that is wetted by oil. See: hydrophilic.
Liquid. Fluid that will flow freely and takes the shape of its container.
Liquid-clay phase. See: overflow.
Liquid discharge. See: underflow.
Liquid film. The liquid surrounding each particle discharging from the solids discharge of cyclones and screens. See: bound liquid, free liquid.
Live oil. Crude oil that contains gas and distillates and has not been stabilized or weathered. This oil can cause gas cutting when added to drilling fluid and is a potential fire hazard. See: aromatic hydrocarbons.
Load. A device connected to a motor that is receiving output mechanical power from the motor.
Logging. See: mud logging, electric logging.
Loom. See: warp.
Loss of circulation. See: lost circulation.
Lost circulation. The result of drilling fluid escaping into a formation, usually in fractures, cavernous, fissured, or coarsely permeable beds, evidenced by the complete or partial failure of the drilling fluid to return to the surface as it is being circulated in the hole.
Lost circulation additives. Materials added to the drilling fluid to gain control of or prevent the loss of circulation. These materials are added in varying amounts and are classified as fibrous, flake, or granular.
Lost circulation materials. See: lost circulation additives.
Lost returns. See: lost circulation.
Low-gravity solids. Salts, drilled solids of every size, commercial colloids, lost circulation materials; that is, all solids in drilling fluid, exceptbarite or other commercial weighting materials. Salt is considered a low–specific gravity solid. See: heavy solids, high-gravity solids.
Low-silt drilling fluid. An unweighted drilling fluid that has all the sand and a high proportion of the silts removed and has a substantial content of bentonite or other water–loss–reducing clays.
Low-silt mud. See: low-silt drilling fluid.
Low-solids drilling fluids. A drilling fluid that has polymers, such as ceramic matrix compound (CMC) or xanthan gum (XC) polymer, partially or wholly substituted for commercial or natural clays. For comparable viscosity and densities, a low-solids drilling fluid will have a lower volume percentage solids content. In general, the lower the solids content in a mud, the faster a bit can drill.
Low-solids muds. See: low-solids drilling fluids.
Low-solids nondispersed (LSND) drilling fluids. A drilling fluid to which polymers have been added to simultaneously extend and flocculate bentonite drilled solids. These fluids contain low concentrations of dispersed bentonite and do not contain deflocculants such as lignites, lignosulfonates, etc.
Low-yield clay. Commercial clay chiefly of the calcium montmorillonite type having a yield of approximately 15 to 30 barrels per ton. See: highyield clay, bentonite.
Lyophilic. Having an affinity for the suspending medium, such as bentonite in water.
Lyophlic colloid. A colloid that is not easily precipitated from a solution and is readily dispersible after precipitation by addition of a solvent.
Lyophobic colloid. A colloid that is readily precipitated from a solution and cannot be redispersed by addition of the solution.
Lead. In a decanting centrifuge, the slurry-conducting channel formed by the adjacent walls of the flutes or blades of the screw conveyor.
Leonardite. Anaturally occurring oxidized lignite. See: humic acid, lignin.
Light solids. See: low-gravity solids.
Lignin. Mined lignin is a naturally occurring special lignite, for example, leonardite, produced by strip mining from special lignite deposits. The active ingredients are the humic acids. Mined lignins are used primarily as thinners, which may or may not be chemically modified. See: leonardite, humic acid.
Lignosulfonates. Organic drilling-fluid additives derived from by products of the sulfite paper manufacturing process from coniferous woods. Some of the common salts, such as ferrochrome, chrome, calcium, and sodium, are used as deflocculants while other lignosulfonates are used selectively for calcium-treated systems. In large quantities, the ‘‘heavy metal’’ ferrochrome and chrome salts are used for fluid loss control and shale inhibition.
Lime. Ca(OH)2. Commercial form of calcium hydroxide.
Lime-treated drilling fluids. Commonly referred to as ‘‘lime-based’’ muds. These high-pH systems contain most of the conventional freshwater drilling-fluid additives to which slaked lime has been added to impart special inhibition properties. The alkalinities and lime contents of the fluids may vary from low to high. See: calcium-treated drilling fluids.
Limestone. Ca(CO)3. See: calcium carbonate.
Line sizing. Ensuring that the fluid velocity through all piping within the surface system has the proper flow and pipe diameter combination to prevent solids from settling and pipe from eroding. A good rule of thumb is to ensure that fluid flow is between 5 and 9 feet per second, as determined by the following:
Linear motion. Linear motion of a shale shaker screen is produced by two counterrotational motors located above the shaker basket in such a way that a line connecting the two motor axes is perpendicular to a line passing through the center of gravity of the basket. Because the acceleration is applied directly through the center of gravity of the basket, the basket is dynamically balanced; the same pattern of motion will exist at all points along the shaker screen. The resultant screen motion is linear, and the angle of this uniform motion is usually 45° to 60°relative to the shaker screen deck.
Lipophile. Any substance, usually in the colloidal state or an emulsion, that is wetted by oil; that is, it attracts oil or oil adheres to it. See: hydrophile.
Lipophilic. A property of a substance having an affinity for oil or one that is wetted by oil. See: hydrophilic.
Liquid. Fluid that will flow freely and takes the shape of its container.
Liquid-clay phase. See: overflow.
Liquid discharge. See: underflow.
Liquid film. The liquid surrounding each particle discharging from the solids discharge of cyclones and screens. See: bound liquid, free liquid.
Live oil. Crude oil that contains gas and distillates and has not been stabilized or weathered. This oil can cause gas cutting when added to drilling fluid and is a potential fire hazard. See: aromatic hydrocarbons.
Load. A device connected to a motor that is receiving output mechanical power from the motor.
Logging. See: mud logging, electric logging.
Loom. See: warp.
Loss of circulation. See: lost circulation.
Lost circulation. The result of drilling fluid escaping into a formation, usually in fractures, cavernous, fissured, or coarsely permeable beds, evidenced by the complete or partial failure of the drilling fluid to return to the surface as it is being circulated in the hole.
Lost circulation additives. Materials added to the drilling fluid to gain control of or prevent the loss of circulation. These materials are added in varying amounts and are classified as fibrous, flake, or granular.
Lost circulation materials. See: lost circulation additives.
Lost returns. See: lost circulation.
Low-gravity solids. Salts, drilled solids of every size, commercial colloids, lost circulation materials; that is, all solids in drilling fluid, exceptbarite or other commercial weighting materials. Salt is considered a low–specific gravity solid. See: heavy solids, high-gravity solids.
Low-silt drilling fluid. An unweighted drilling fluid that has all the sand and a high proportion of the silts removed and has a substantial content of bentonite or other water–loss–reducing clays.
Low-silt mud. See: low-silt drilling fluid.
Low-solids drilling fluids. A drilling fluid that has polymers, such as ceramic matrix compound (CMC) or xanthan gum (XC) polymer, partially or wholly substituted for commercial or natural clays. For comparable viscosity and densities, a low-solids drilling fluid will have a lower volume percentage solids content. In general, the lower the solids content in a mud, the faster a bit can drill.
Low-solids muds. See: low-solids drilling fluids.
Low-solids nondispersed (LSND) drilling fluids. A drilling fluid to which polymers have been added to simultaneously extend and flocculate bentonite drilled solids. These fluids contain low concentrations of dispersed bentonite and do not contain deflocculants such as lignites, lignosulfonates, etc.
Low-yield clay. Commercial clay chiefly of the calcium montmorillonite type having a yield of approximately 15 to 30 barrels per ton. See: highyield clay, bentonite.
Lyophilic. Having an affinity for the suspending medium, such as bentonite in water.
Lyophlic colloid. A colloid that is not easily precipitated from a solution and is readily dispersible after precipitation by addition of a solvent.
Lyophobic colloid. A colloid that is readily precipitated from a solution and cannot be redispersed by addition of the solution.
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