Testing study on the law of permeability variation in process of rock deformation and damage

Reservoir rock which are saturated by fluid is acted by overburden pressure, tectonic stress and fluid pressure. In the process of drilling, completion, welltest and oil production, the stress state of rock will be changed to bring about stress concentration around borehole or shot hole. The effective stress of rock frame increases with the depletion of fluid pressure. Based on the tests of core permeability under different stress state, the correlation among rock permeability, rock stress state, and rock mechanics parameter is analyzed, and correspondingly a correlation model is set up between permeability and stress state. The obtained results would provide scientific foundation to determine reasonable pressure drop to prevent reservoir damage in the process of drilling and production test.