Gas shale hydraulic fracturing: a numerical investigation of the fracturing network evolution in the Silurian Longmaxi formation in the southeast of Sichuan Basin, China, using a coupled FSD approach

摘要

This paper presents state-of-the-art modeling of complex hydraulic fracture network evolution in a naturally fractured formation with pre-existing bedding and cross joints, in the Silurian Longmaxi formation, southeast of Sichuan Basin, China. A flow-stress-damage coupling approach has been used in an initial attempt toward how reservoir responds to perforation angle, injection rate, in situ stress, cohesive and frictional strength of natural fractures. A detailed sensitivity study reveals a number of interesting observations resulting from these parameters on the fracturing network evolution in naturally fractured system. When the perforation angle is 60 degrees, it gets to the maximum stimulated reservoir area (SRA). Injection rate as an operator parameter, it strongly impacts the interaction between hydraulic fractures and natural fractures, and associated SRA. In addition, in isotropic in situ stress field, fracturing effectiveness is not the best, complexity of SRA is enhanced when pre-existing fractures are oriented at an angle to the maximum stress. Moreover, the morphology of fracturing network and SRA is closely related to the frictional and cohesive strength of natural fractures. This work strongly links the production technology, geomechanical evaluation and aids in the understanding and optimization of hydraulic fracturing simulations in naturally fractured reservoirs.