Drilling waste recycling System Working

The process of drilling oil and gas wells generates large volumes of drill cuttings and used muds. Onshore and offshore operators have employed a variety of methods for managing these drilling wastes. In offshore, options are limited to cuttings reinjection, offshore discharge and transportation to onshore disposal facility. This is as a result of the limited space and stringent environmental regulations governing an offshore drilling operation. As a result some offshore wastes have to be transported to an onshore facility for treatment and disposal. Onshore operations however, have a wider waste management options. The selection of a disposal method for a particular location depends on other factors which must be evaluated extensively before implementation. The main aim should be towards ensuring an environmentally safe waste disposal approaches.

The solids control system forms the first waste management practice in any drilling operation. It removes drill cuttings from the drilling mud at the surface just before the mud re-enters the mud-pit for recirculation. Apart from drill cuttings, the solids control equipment also removes some gases and other contaminants in the mud before they are re-circulated. The early removal of these solids avoids accumulation and clogging of the system and the separation devices sizes of solids. The components of the solids control system will depend upon the types of drilling fluid used, these formations being drilled, the available equipment on the rig, and the specific requirements of the disposal option. But basically, standard solid control equipment will comprise of shale shakers, degassers, desanders and desilters. The mud passes over a shale shaker, which is basically a vibrating screen. This removes the larger particles, while allowing the residue to pass into settling tanks. The finer particles are further removed in the desanders and desilters. If the mud contains gas from the formation it will be passed through a degasser which separates the gas from liquid mud.

Cutting reinjection is common to both offshore and onshore operations. However, due to the availability of space for an onshore operation, there are a lot more management options available. The most common onshore disposal method is perhaps onsite burial. Other methods include the construction of a waste reserve pit, thermal methods like incineration, kilns, open burning etc. There are also biological methods like composting, land-spreading, land-farming etc. In an onshore environment, waste can be treated and used for other beneficial applications like road spreading, construction materials etc. This section explores the various options available for onshore waste treatment and disposal.