Poro-acoustoelasticity with compliant pores for fluid-saturated rocks

What is it about?

we incorporate the dual-porosity model into the conventional poro-acoustoelasticity theory to account for both linear and nonlinear elastic deformations through the strain energy transformation of rock grains, stiff pores, and compliant pores. We demonstrate that the work of the loading stress is transformed into two parts: the strain energy for the linear elastic deformation of rock grains and stiff pores and the nonlinear elastic deformation of compliant pores.

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Why is it important?

Pore pressure and tectonic-stress variations are assumed to play important roles in triggering earthquakes and enabling safe drilling and efficient reservoir exploitation. Elastic wave velocities and elastic moduli are strongly affected by pore pressure and tectonic stresses, which, in turn, are used to monitor changes in the subsurface pore pressure and tectonic stresses. Stress-induced velocity variations for tectonic-stress and pore-pressure prediction have been studied since a long time now. Despite some prediction successes via classical algorithms, the problem still lacks a solution owing to the uncertain dependence of velocity variations on effective stress. The uncertain dependence is probably related to the nonlinear elastic deformation of compliant pores and cannot be predicted by the conventional poro-acoustoelasticity theory. This dependence is the key issue addressed in this study.