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.