Application of Digital Core Technology in Selecting Stimulation Processes for Anyue Fractured Gas Reservoir

Abstract

Wells in Anyue carbonate gas reservoir vary greatly in yield because of uneven distribution of pores and fractures. A digital core technology has been used to optimize stimulation processes to improve well performance. The 3D micro-pore-throat structure model can be built by digital core techniques, such as ESEM and CT scanning. The reservoirs were divided into three different classes by distribution of vugs and natural fractures from digital core results. Stimulation process was optimized for each type of reservoir. For the first-class reservoir with abundant karst vugs and natural fractures in good connectivity with each other, the acid can get into the core easily and form long wormholes. For the third-class reservoir with isolated solution vugs in poor connectivity with fractures, acidizing hardly works. Matrix acidizing was selected for the first-class reservoir and achieved good results in 15 wells. Multi-stage acid-fracturing technique was applied to the third-class reservoirs in more than eight wells, and only half of the wells got industrial production.