Abstract: To effectively guide the design of the upper limit pressure for the operation of gas storage reservoirs in complex fault-block oilfields and ensure their safe and efficient operation, it is imperative to conduct a comprehensive evaluation of the sealing performance of the geological body. By introducing a multi-scale geomechanical model for simulation, we took the Nanpu 1 Gas Storage Reservoir as an example, on the basis of the single-reservoir geomechanical model, and establish a large-scale multi-reservoir interaction in-situ stress model for the first time. The four-dimensional stress field distribution under different pore pressures was simulated, and the stress changes and stability of faults and cap rocks were analyzed. On the basis of the traditional geomechanical model, a quantitative characterization method for the stress interference effect of multi-reservoir interaction was constructed, to reveal the superimposed influence mechanism of multi-gas storage reservoirs' coordinated injection and production on the regional stress field. A multi-dimensional and multi-index evaluation method for the integrity of geological bodies was proposed, achieving quantitative evaluation of cap rock tensile failure, shear failure and fault slip, and then a full-system monitoring system was deployed. The research results show that the deformation of the Guantao Cap Rock during the operation of the gas storage reservoir is small; there is no risk of fault activation in the early operation of the gas storage reservoir for hydrocarbon-controlling fault F2; the critical pressure for simulating fault slip activation is 34.5 MPa, and there is a risk of instability in the integrity of the gas storage reservoir geological body. The upper limit pressure for operation was determined to be 27.2 MPa based on the combined critical pressures for cap rock tensile failure, cap rock shear failure, and fault slip activation obtained from models of different scales. The research results provide a fine and quantitative assessment of the operational safety of gas storage reservoirs under the influence of dynamic stress fields and scientifically guide the optimization design of the upper limit pressure and monitoring system.

Key words: three-dimensional mechanical model, large-scale in-situ stress model, four-dimensional mechanical simulation, multi-dimensional ultimate pressure bearing, full-system monitoring