Propagation area evaluation of hydraulic fracture networks in shale gas reservoirs

Based on hydraulic fracturing experiments in laboratory, the hydraulic fracture propagation in shale was analyzed, a method for evaluating the fracture propagation extent was proposed, and the effects of geological factors and engineering factors on fracture propagation were studied. Stimulated Rock Area (SRA) was proposed as an evaluation index for the hydraulic fracturing results. By analyzing the experiment results, it is found that hydraulic fracturing in shale reservoirs can generate a complex fracture network; a lower stress difference in brittle shale formation and a shorter distance between hydraulic fracture and bedding plane lead to a larger SRA and more complex fracture morphology; a fracture network is more likely to generate in the case that the angle between horizontal maximum stress and bedding plane is 90° or large enough, or the approaching angle between hydraulic fracture and well-opened natural fracture is close to 90°; a higher brittle mineral content leads to better fracturing ability; a lower fluid viscosity and higher flow rate leads to a larger SRA; a variable flow rate increases the possibility that the hydraulic fracture communicates bedding planes and natural fractures. ©, 2014, Science Press. All right reserved.