The composition of drilling waste is complex, generally alkaline, with a pH value of 8. 5-12, and the solid particle size is generally 0.01 to 0.3 μm. The appearance is generally viscous fluid or semi-fluid, with fine particles and grades. Various chemical treatment agents are added to it, generally containing heavy metals, oils, bentonite, alkalis and compounds (including organics), etc., such as iron chromium salt, sulfonated pitch, sulfonated tannin extract, sulfonated lignite, etc. Livestock and environmentally harmful substances. Waste fluids are produced in the process of oilfield exploration and development, such as cleaning fluids, drilling fluids, and sewage (formed by rainwater washing the well site with some mud and oily substances). The harmful substances are mainly oily substances, and there are also a small amount of them. Organic treatment agents, heavy metals and alkali substances have higher CODCr values. During the drilling process, the mud circulates in the drill bit to lubricate the drill bit while also carrying the drill cuttings to the ground. Most of the drill cuttings are solid particles, and a small part is mixed in the drilling fluid in the form of mud sand, accounting for about 20% of the total waste. Contaminants are mainly drilling fluid.
At present, domestic and foreign drilling waste treatment methods mainly include chemical and physical methods such as chemical flocculation, solidification, washing, incineration, destabilization, and landfill. After chemical flocculation treatment, it can be directly discharged in accordance with environmental protection requirements, or be recycled to prepare mud, or injected into wells, but it lacks efficient and economical flocculants, and the harmful substances after chemical solidification are no longer diffused and migrated to the environment. The solidification treatment requires a certain cost, and the amount of one-time treatment is large. The landfill method has an adverse effect on the surface water and its irradiated soil. The incineration method has a high treatment cost and will cause secondary pollution to the air. Although these methods have processed the drilling waste mud to a certain extent, the organic pollutants in the drilling waste mud have not been decomposed and may still pollute the environment.
KOSUN- China Solids Control Leader&Drilling Waste Management Expert
Contact person: Lily Wang