关键词: 流固耦合, 水力压裂, 裂缝形态, 动态造缝, 渗透率, 渗流速度, 有限元模拟, 数学模型

Abstract: A finite element simulation model for dynamic fracture creation was established on the basis of the fluidsolid coupling theory for porous media. The creation of dynamic fractures with different geometry was simulated with finite element method. The research results demonstrated that a tight zone as elliptic distribution was developed around the wellbore during the creation of dynamic fracture. For the wedge fracture and elliptic fracture, the dimension of influence region by fracture creation increased with the fracture width increasing near the fracture tip, and the distribution of the influence zone was similar to ellipse. The permeability in the region less than 5m away from the wellbore axis was influenced dramatically. The more adjacent to the wellbore axis, the more sensitive the permeability alteration would be observed. At the same time, the Darcy velocity decreases noticeably in the tight zone near wellbore. The fracture with shorter length would result in the more sensitive for the productivity alteration of fractured wells. The formation of tight zone by dynamic fracture creation is an important factor for inducing the declination of productivity of fractured wells.

Key words: fluidsolid coupling, hydraulic fracturing, fracture geometry, dynamic fracture creation, permeability, Darcy velocity, finite element simulation, mathematical model