水侵型储气库多周期注采气水互驱在线核磁驱替实验OA

Due to the complex gas-water mutual displacement flow mechanisms and insufficient understanding of the evolution of effective storage space during multi-cycle injection-production in water-invaded gas reservoirs,this study selected the core from Well 5 of Wen 96 Gas Storage as research object and carried out online nuclear magnet-ic resonance(NMR)displacement experiments under multi-cycle gas-water mutual displacement.By real-time mo-nitoring of T2 spectra and signal distribution characteristics,the effects of reservoir physical properties,displacement pressure,and injection-production rates on gas-water mutual displacement efficiency were systematically ana-lyzed.The results indicate that reservoir properties have a significant impact:in low-permeability reservoirs with permeability below 5.00 mD,the recoverable gas pore volume decreases by about 15%after multi-cycle injection-production,whereas in high-permeability reservoirs with permeability above 80.00 mD,it decreases by only about 2%,with most of the pore volume reduction occurring in the first three cycles.Displacement pressure correlates loga-rithmically with recoverable space,and a critical pressure of around 17 MPa is identified.Below this threshold,dis-placement efficiency declines significantly,while above it,fluid distribution tends to become homogeneous.When the injection-production rate is increased to 2.0 mL/min,the movable space increases by about 7%,indicating that high-rate injection-production can reduce fluid entrapment by enhancing drive forces.The cumulative seepage hys-teresis effect induced by multi-cycle injection-production continues to reduce effective storage space,a phenome-non calling for special attention in long-term operation.This study provides theoretical guidance and technical sup-port for site selection optimization,injection-production parameter optimization,and operational efficiency improve-ment in water-invaded gas storage reservoirs.