Application of Comprehensive Harmless Waste Treatment Technology to Treat Drilling Cuttings in the Tian Mountain Front Block in Tarim Basin

Abstract Due to high temperature, high pressure, and gypsum-salt formation, the stability and rheology of conventional polymer drilling fluids are difficult to maintain, so sulfonated drilling fluids (SDF) or oil-based mud (OBM) are recommended to drill deep formations or ultra-deep formations. However, a large number of sulfonated drilling cuttings or oily cuttings are generated in the process of drilling operation. These drilling cuttings contain a large number of harmful substances, including petroleum hydrocarbon, sulfonated additives, heavy metals, and so on, which are toxic and difficult to be biodegradable, so the discharge of drilling cuttings into environment will lead to serious contamination of soil and groundwater. Therefore, the environmental impact of the use of SDF or OBM is one of the main challenges facing petroleum industry. One of the most difficult environmental problems to resolve at the well site is the disposal of drilling cuttings, which is often physically unstable and unsuitable for landfill. High temperature deep pyrolysis technology (HDPT) is developed to treat sulfonated drilling cuttings from deep formations. The field results indicate that the content of petroleum hydrocarbon of treated drilling cuttings is less than 16 ppm, and various indexes of treated cuttings could meet the requirement of environmental protection. HDPT technology is characterized by high treatment efficiency and no secondary pollution, and it is very suitable for harmless treatment of sulfonated drilling cuttings. Leaching and resource utilization technology (LRET) is currently applied to treat oily drilling cuttings from ultradeep complex formations. The results indicate that the oil content of treated drilling cuttings is less than 0.6%, and the recovery rate of OBM is over 20%. LRET technology can not only recycle and reuse OBM resources, but also guard against environmental pollution from drilling operation, and thus produce great economic and environmental benefits. Comprehensive harmless waste treatment station for drilling cuttings is built in this Block. HDPT and LRET technology can provide a powerful technical support for achieving safety drilling in this Block, and they have been successfully applied to treat drilling cuttings from dozens of wells in this Block. This paper presents field data to illustrate the application of this comprehensive harmless waste technology and evaluate the potential technical and economic benefits that it might provide to petroleum development and production in Tarim Basin.