- Source of waste drilling mud
The main source of waste drilling mud is the production during the process of oil and gas excavation, mining, and well repair. Drilling fluid is the blood of oil and gas drilling and an important component to ensure the smooth progress of the entire mining work.
Drilling mud can carry the cuttings produced during the drilling process, cool and lubricate the drill bit and drilling tools, protect the well wall, balance the downhole air pressure, prevent blowouts, drive power drilling tools, and use nest pressure jetting to break rocks.
Since the location of oil and gas mining is mainly in the wilderness, after the operation is finally completed, a large amount of waste drilling mud will be left in the storage pit at the operation site.
- Composition of waste drilling mud
The composition of waste drilling mud produced in the process of oil and gas mining is very complex. According to its source, it can be divided into three main components: drilling fluid, cuttings, and waste liquid generated by various operations.
Drilling fluid accounts for about 70% of the total waste, mainly from waste liquid discharged during drilling, ground circulation system, drilling fluid reserved for complex situations, and drilling fluid replaced during cementing. To ensure its performance, drilling fluid usually adds a certain amount of chemical treatment agents and activators, resulting in a variety of components, generally containing oil substances, bentonite, alkali, etc.
Due to increasingly stringent environmental protection requirements, it is rare to see drilling fluid containing heavy metal additives. Drill cuttings are waste that is broken by the drill bit during drilling and brought to the ground with mud. They are mostly solid particles with complex composition, high alkalinity and small particles.
Waste liquid is generated during the exploration and development of oil and gas fields. It is composed of cleaning fluids of various operating equipment, liquids for flushing oil and gas wells, and muddy and oily liquids generated by rainwater flushing the well site. 3. Classification of drilling mud
With the continuous development of the oil and gas industry, the technical level of drilling mud has been continuously improved, and the types of drilling mud have also increased. Among them, the more common classifications are as follows:
(1) According to the strength of the inhibition of clay hydration: inhibitory drilling mud and non-inhibitory drilling mud.
(2) According to density: non-weighted drilling mud and weighted drilling mud.
(3) According to the mud preparation system: salt-treated mud, polymer mud, sulfonated mud, etc.
(4) According to the solid content: high solid fine dispersion drilling mud, low solid non-dispersed drilling mud, solid-free drilling mud.
(5) According to the fluid medium: water-based drilling mud, oil-based drilling mud, gas-type drilling mud, synthetic-based drilling mud.