Sandstone Stress Sensitivity Experiment and Stress Sensitivity Evaluation

Abstract

Change confining pressure experiment or pore pressure experiment is one of the commonly used method to evaluate the reservoir core stress sensitivity. However, a large number of studies have shown that core net stress is not equal to the effective stress,the drawdown pore pressure experiment are consistent with the characteristics of oil and gas field real development process. The pressure stability of drawdown pore pressure experiment is bad, so, a reliable modified method of change confining pressure stress sensitivity experiment is eagerly expected. On the basis of the differential method principle, effective stress coefficient can be determined through core experiments,and with the use of effective stress coefficient , change confining pressure experiment is modified. Main conclusions are as follows:For sandstone core,at reservoir original stress condition with the pore pressure from 15MPa to 11MPa effective stress coefficient from 0.436 to 0.415;Based on Terzaghi effective stress exaggerate stress sensitivity, ontology effective stress can weaken the stress sensitive; Based on effective stress coefficient in this paper correction stress sensitivity is medium weak,impacts on production results almost coincident with the drawdown pore pressure test results.