SEGJ Technical Conference

Stress distribution and fracture propagation around borehole due to injection pressure changes

Abstract It is well known that the hydraulic fracturing is a tool commonly used for stimulating hydrocarbon reservoirs, and in-situ stress measurement. It is, however, difficult to predict the behavior of fracture propagation from boreholes due to the difficulty to estimate stress distribution in the subsurface. We have developed a program to simulate fracture propagation from a borehole due to increasing fluid pressure. We employed an extended finite element method (X-FEM), which deals with any fractures independent from the location of grid or mesh in the numerical simulation. We first found that our program could simulate that the local stress field near the borehole showed some deviated orientation from the regional stress field. We then confirmed that the tendency of fracture propagations to be a function of fluid pressure to induce the extension of fracture. The orientation of the fracture propagation converges to that of the principal stress. However, the higher the fluid pressure is, the smaller the curvature of fracture trace becomes. We would like to conclude that the orientation of maximum in-situ principal stress and the fluid pressure for fracturing is two major parameters to control the propagation of fractures due to increasing fluid pressure.