Challenges of formation damage control technology for ultra-deep tight gas reservoirs: A case study from Tarim Basin

Abstract

Formation damage mechanisms and the corresponding control technology for the tight gas reservoirs have been reported, whereas few studies have discussed ultra-deep fractured tight gas reservoirs. Ultra-deep fractured tight gas reservoirs were susceptible to be damaged owing to geological conditions and engineering status. Taking the ultra-deep fractured tight gas reservoirs located in the Tarim Basin as an example, ultra-tight, high-pressure, high temperature (HPHT), and high-salinity formation water, ultra-low water saturation and fracture networks were identified as special geological characteristics. High-density oil-based drill-in fluids and serious lost circulation were the special engineering status. Challenges in laboratory experiments to evaluate formation damage include rigorous experimental conditions and unsuitable experimental methods. In addition, improving the formation protection ability of working fluids and minimizing the formation damage induced by the sequential use of different types of working fluids were the main challenges associated with using working fluids. Challenges in lost circulation control include the failure of plugging zone due to the degradation of lost circulation materials and repeated lost circulation due to the strength reduction of the plugging zone soaked in diesel oil. Recommendations for key technologies to improve targeted formation damage control technology have been proposed. The comprehensive analysis of these issues provides a road-map for researching formation damage control technologies.