Numerical simulation of brittleness effect on propagation behavior of glutenite hydraulic fractures
Zhichao Li, Shuren Wang, Lianchong Li, Jiyun Zhang, Tianjiao Li
Abstract
For hydrocarbon exploitation in tight glutenite, glutenite brittleness plays an important role in fracturing efficiency, but the detailed effect is not entirely clear. In this study, considering rock heterogeneity, RFPA (Rock Failure Process Analysis) was applied to establish the three-dimension computational model. An improved rock brittleness index considering post-peak properties in rock uniaxial compression test was proposed to quantify the glutenite brittleness. Results show that brittle glutenite can generate multiple failure surfaces under the exterior loadings, which can be a mirror to reveal the denser development of natural fractures in the brittle reservoir, while the ductile glutenite is prone to generate a simple shear failure. Hydraulic fractures propagate faster in more brittle glutenite and can generate short branches, which is beneficial to connect the reservoir natural fractures and form complex hydraulic fractures. Brittle glutenite requires a lower treatment pressure than the ductile glutenite, which can provide convenience for ground pumping operation. Hydraulic fractures prefer to propagate in brittle glutenite, rather than the ductile glutenite. The obtained conclusions can provide a reference for the similar practice.