Abstract: In order to further study the gas-water seepage pattern of gas storage in bottom-water gas reservoir during multi-cycle injection and production, the reservoir core in S6 gas storage, Liaohe Oilfield was sampled to evaluate the stress sensitivity of permeability in multiple cycles of pressure boosting and relief, test the gas-water seepage characteristics in multiple cycles of injection and production simulation, and analyze the microstructure in combination with observation by scanning electron microscope. According to the results, the stress sensitivity of permeability in the study area was low, and the permeability was decreased to a low extent after multiple cycles of pressure boosting and relief; after gas-water mutual flooding was conducted for many times, the irreducible water saturation was decreased while the residual gas saturation increased, and then both gradually reached a balance; the multi-cycle injection and product caused micro-cracks and particle migration, the micro-cracks played a dominant role in enhancing seepage capacity, the gas saturation and gas permeability were gradually increased and tended to balance, which was consistent with the law of storage expansion at the early stage and gradual balancing in the later stage in the actual operation. The results of the study provide technical guidance for the reasonable configuration of injection and production parameters and the construction of new gas storage in the area.

Key words: gas storage, multi-cycle injection and production, gas-water mutual flooding, seepage pattern, bottom-water gas reservoir