Well Interference and Fracture Geometry Investigation Using Production and Low-Frequency Distributed Acoustic Sensing Data in an Unconventional Reservoir

Abstract

Summary Well interference directly impacts well spacing optimization and well economics, thus it has received significant attention. Observed in many unconventional reservoirs, well interference is mainly attributed to connection of hydraulic fractures. Few studies have compared the hydraulic fracture connection during stimulation with that during the production period. This study connects these two aspects by leveraging the low-frequency distributed acoustic sensing (LF-DAS) signals acquired during the stimulation and the daily production data of 23 horizontal wells in the Denver-Julesburg (DJ) Basin. Strong cross-formation communication between Niobrara and Codell has been identified from both LF-DAS and production data. Interwell fracture connection could divert up to 80% of a shut-in well’s production to the offset well in the adjacent formation, revealing that well interference can be evaluated through random shut-ins of wells during production. Further, fracture connection in LF-DAS data is observed between Codell wells but rarely between Niobrara wells. Given the average Codell well spacing of 1,270 ft and Niobrara well spacing of 650 ft, we observe that the half-length of the stimulated hydraulic fractures in Codell wells is significantly longer than that of Niobrara wells. This study also confirms that stronger well interference during production correlates with strong fracture connection identified from LF-DAS.