With the continuous improvement of environmental protection laws and regulations, people’s awareness of environmental protection has been gradually enhanced. Drilling mud treatment and disposal during drilling has become the focus problem in the drilling industry. The purpose of drilling mud treatment and disposal is to reduce environmental pollution and to find a economically and environmentally methods.
There are many existing drilling mud treatment and disposal methods, but each method has its scope of application. It should be selected according to the geologic environment, hydrology, soil, drilling fluid composition and economy of the oil and gas field. Throughout the processing methods at home and abroad, drilling mud treatment and disposal methods including the following categories:
(1) Direct discharge method
Direct discharge method mainly applied to conventional freshwater drilling fluid.
(2) Landfill method
This is a more primitive approach and is mainly suitable for general freshwater-based drilling fluids.
(3) Dehydration method
This method used the chemical flocculation, sedimentation and mechanical separation and other strengthening measures to make the waste drilling fluid in the solid-liquid two-phase separation.
(4) Pit seal
This method is a special landfill method. It is recommended for toxic waste drilling fluid treatment and disposal.
(5) Annular space treatment method
The waste drilling fluid is injected through the borehole into the formation or safety formation of the oil and gas.
(6) Soil biodegradation method
Sprinkle the waste drilling fluid directly onto the soil surface and mix it into the soil with a soil tillage machine. This method is mainly applicable to the processing of freshwater drilling fluids and some oil-based drilling fluids that are easily biodegradable.
(7) Land cultivation method
Land cultivation practices require an open and relatively flat land and it should have surface conditions that prevent erosion.
(8) Closed loop system
The system is equipped with high-efficiency solid-control equipment that uses rigorous management tools to reduce the amount of fluid-borne waste discharged while drilling and emit only a certain amount of wet solids for land, sea and virtually all non-gaseous Dispersed phase drilling fluid system. Effluent wet-solid phase can be buried in-situ, diluted in land, paved, filled or centralized, and the liquid phase recycled and reused, which not only reduces the cost of mud treatment but also saves water resources.
(9) Solid-liquid separation method
Solid-liquid separation technology is the solid-liquid waste drilling fluid separation, the discharge of liquid standards, solid-phase buried or reprocessing.
(10) Curing method
This method is add curing agent to the waste drilling fluid to make it solidified into soil-like solid material, and then landfill or used as building materials. (Editor:Kosun Lily.Wang)
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