Integrated Permeability Stress Sensitivity Studies of Multi-cycle Injection and Production for Underground Gas Storage

Abstract This paper details the design of multi-cycle injection and production stress simulation experiments, aimed at quantitatively characterizing the permeability stress sensitivity in underground gas storage(UGS) during multiple operation cycles. Derived from the reservoir sensitivity evaluation method and the stress sensitivity coefficient method, a suite of stress sensitivity evaluation index was introduced to discuss the effect of stress variation paths on the stress sensitivity characteristics. It is found out that the stress sensitivity is common in sampled gas storage cores. Meanwhile, there is a significant stress sensitivity hysteresis effect in multi-cycle injection and withdrawal experiments. After multiple cycles, the rock stress sensitivity is less dependent on the stress path. However, due to the superposition of multiple cycle stress sensitive hysteresis effect, the multi-cycle permeability damage ratio and irreversible damage ratio increased. The phenomenon of stress sensitivity hysteresis is especially pronounced in cores with low permeability. This study offers a theoretical foundation for predicting gas storage operation schemes and formulating technical policies.