The Slow Slip Analysis During Hydraulic Fracturing Stimulation of Shale Gas Reservoirs

Abstract

AbstractMark D. Zoback, et al. found and verified slow slip phenomenon during hydraulic fracturing stimulation of shale gas reservoirs. Meanwhile, they explained that the shear deformation associated with slow slip is expected to create a network of multiple permeable planes surrounding the induced hydraulic fractures, which contributes largely to the production of shale gas wells. Two shale gas wells in Sichuan used the same volume fracturing technology, fracturing scale, fracturing fluid and microseismic monitoring technology, but the production gap after fracturing between two wells was very large. This paper does production matching of two wells using gas reservoir numerical simulation method, based on the basic physical parameters and combined with microseismic monitoring and interpreting results. And production matching results indicate that stimulated reservoir volume (SRV) provides all the production of well A after fracturing, but only a small part of production of well B after fracturing comes from the microseismic monitoring SRV. Therefore, it is evident that there is other SRV created by slow slip on natural fractures or faults which cannot be detected by microseismic monitoring. Meanwhile, we compare the pressure of two wells, do net pressure matching, and results indicate that natural fracture development degree in well B is higher than that in well A which leads to more leak-off in well B during fracturing, SRV of well B is bigger and the fracture network of well B is more complicated, which is different from microseismic interpreting results. This shows that there is slow slip during fracturing of well B which cannot be detected by microseimic monitoring. So how to improve the description accuracy of natural fractures in shale gas reservoirs, how to monitor the seismic signals of slow slip, and how to quantitatively characterize the fracture network created by slow slip are one of our research direction of in the future.KeywordsShale gasFracturingSlow slipMicroseismicReservoir numerical simulationNet pressure matching