The Application of Oily Sludge in Chinese Oilfield

Using industry wastes for conformance control has recently attracted significant interest-in particular, when using oily sludge for in-depth fluid diversion. About 500 tons of oily sludge is generated from oil production, transportation, and refining each year. Oily sludge is mainly composed of oil, water, o/w emulsions, and solids and is quite difficult to separate and reuse. The accumulation of oily sludge has posed a serious environmental problem. Additives such as suspension agents, dispersion agents, and viscosity thickeners are often added into oil sludge as conformance control agents to extend particle suspension time, increase plugging efficiency, disperse oily drop, and increase penetration depth. The advantages of oily sludge as conformance control agents include: (1) good compatibility with formation; (2) high temperature resistance; (3) high salinity resistance; (4) low costs; and (5) environmental protections. This method has been used by most oilfields in China, with better results.