Application of Innovative High Density High-Performance Water-Based Drilling Fluid Technology in the Efficient Development and Production of Ultra-Deep Complicated Formations in the Tian Mountain Front Block in China

Abstract

Abstract Tarim Basin is the biggest oil and gas bearing basin in China. The ultra-deep formations in the Tian Mountain Front Block in North Border of Tarim Basin is characterized by ultra-high temperature, high pressure, ultra-thick composite salt-gypsum formations, and high collapse stress formations are widely distributed, so it will bring great challenge to drilling operation. To solve significant non-productive time (NPT) and low rate of penetration (ROP) encountered in dealing with borehole instability, stuck pipe, and high pressured brine influx in the process of drilling operation in salt-gypsum formations, high-density oil-based drilling fluids have been successfully run to drill more than 70 wells in the past three years. Oil-based drilling fluid system has excellent comprehensive properties, and it could solve the contradiction between safety drilling of ultra-deep wells and formation complexity. But a great number of oily cuttings are generated in the process of drilling operation. These oily cuttings contain a large number of harmful substances, such as petroleum hydrocarbons, heavy metals, surfactants, and so on, which are toxic and difficult to be biodegradable, so the discharge of oily cuttings into the environment without any treatment will lead to serious contamination of soil and ground water. An innovative high density water-based mud (WBM) is formulated. The results show that the high performance mud can provide good rheology and fluid stability under HTHP conditions, withstand high solids loading and deliver a high tolerance to brine or salt contamination, so the high-performance drilling fluid is recommended to drill the gypsum-salt formations and the reservoirs with natural fractures and inter-bedded shale. Above all, this high-performance WBM (HPWBM) is a type of nontoxic drilling fluids. The discharge of new fluid system or obtained cuttings into the environment without any treatment could meet the discharge standard. As a result, HPWBM technology can provide a powerful technical support for achieving safety and high quality drilling in this Block. 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 in Tarim Basin.