Application of Innovative High Temperature Deep Pyrolysis Technology to Treat Drilling Cuttings Harmlessly in Tarim Basim
Authors: Long Li , Da Yin , Fengbao Liu , Zihang Yan , Cha Ma , Xiao Liu 
Published: January 2018

Due to high temperature, high pressure, and gypsum-salt formations in the Tian Mountain Front Block in Tarim Basin, the stability and rheology of traditional polymer drilling fluids are difficult to maintain, so sulfonated drilling fluids (SDF) are recommended to drill deep formations. The sulfonated drilling fluids can provide a powerful technical support for achieving high quality drilling, and it has been run for above 200 wells in the past year.

However, a large number of sulfonated drilling cuttings are generated in the drilling operation. These drilling cuttings contain a large number of harmful substances, including petroleum hydrocarbon, sulfonated additives, soluble salts, 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. Conventional drilling cuttings treatment methods, include reinjection method, solidification with cement method, and chemical desorption method, have several disadvantages such as low efficiency, high cost, or recontamination, and they could not recycle any useful resource, so they are not applicable for large-scale treatment of sulfonated drilling cuttings.

Innovative high temperature deep pyrolysis technology (HDPT) is currently developed to treat sulfonated drilling cuttings. HDPT consists of cuttings drying system, high temperature pyrolysis system and waste gas treatment system. By using of high temperature pyrolysis system, harmful organic compounds in drilling cuttings could be completely degraded. Owing to complete isolation between drilling cuttings and flames, nitrogen oxides and other harmful substances could be effectively avoided to produce. Then the obtained acidic gases, such as sulfur dioxide, hydrogen chloride, chlorine, and so on, could be rapidly eliminated by waste gas treatment system.

The drilling cuttings, barite agent and waste gas could be obtained. The field results indicate that the content of petroleum hydrocarbon of obtained drilling cuttings is less than 16 ppm, and various indexes of obtained drilling cuttings could meet the requirement of environmental protection, so these drilling cuttings can be used to pave the road. The recyclable barite agent could be reused to prepare mud. The waste gas could be directly released into the atmosphere. HDPT technology is characterized by high treatment efficiency and no secondary pollution, and it is very suitable for harmless treatment of sulfonated drilling cuttings.

HDPT technology can not only guard against environmental pollution from sulfonated drilling fluids, but also recycle and reuse useful resources, and thus produce great environmental and economic benefits. HDPT treatment plant has been built in this Block, and its handling capacity can be up to 1000 kiloliters per day. HDPT technology has been successfully run for treating sulfonated drilling cuttings from dozens of wells, and provides a strong technical support for cleaning production of drilling operation. This paper presents field data to illustrate the application of this technology and evaluate the potential technical and economic benefits that it might provide to petroleum development and production.