THE FULLY COUPLED FLUID-SOLID ANALYSIS FOR THE RESERVOIR ROCK DEFORMATIONS DUE TO OIL WITHDRAWAL

The effective normal stress in a hydrocarbon reservoir will increase as a result of the decline in pore fluid pressure associated with the withdrawal of fluids,thus leading to a compaction or deformation of the reservoir rocks,with a consequent decrease in permeability and production,and a failure of the oil wells and the casings,and sometimes subsidence of the ground surface.The reservoir rock deformation due to fluid tapping can be described by a general 3-D deformation field coupled with a 3-D fluid flow field.A finite element numerical model for a fluid flow in a deforming porous medium is here presented to simulate the response of an oil reservoir subject to fluid withdrawal wherein axisymmetric flow and deformation occur simultaneously.A few useful conclusions are obtained and can be used to explain the practical problems encountered during oil production.