Interaction of pore pressures in double-porosity medium: Fluid injection in borehole

Abstract

Fluid injection in a borehole into the natural geological formation often encounters the contrasting pore pressures in the matrix and fractures, which can be described by the double-porosity model. However, the fluid-fluid interactions, in terms of the volume change of fluid caused by pore pressures in two porosities reciprocally, were usually neglected. The present solution showed that such simplifications resulted in a pronounced negative pore pressure in the matrix and an overestimation of the stability of borehole. Then, the volume and permeability of fractures and the mass communication between two porosities were analyzed for the interactions of pore pressures.