Study on Seepage Mechanism and Productivity Evaluation of Low Permeability Gas Reservoir in East China Sea
Low permeability gas reservoirs have the characteristics of low porosity and permeability,high irreducible water saturation,etc.Due to the influence of slippage,high-speed non-Darcy effect and other factors,the gas-water two-phase seepage law is complex,and the conventional productivity evaluation method has limitations.Aiming at this problem,taking the low permeability gas reservoir Y in the East China Sea as the target area,the gas-water two-phase seepage law under different water saturations and different pressures is studied,and the relationship chart between gas permeability and water saturation is formed.The change law of gas-water two-phase relative permeability with formation pressure depletion is analyzed.On this basis,the dynamic productivity evaluation method of low permeability gas reservoir is established,and the reliability of the method is tested by practical application.The results show that there is a critical value of water saturation in low permeability gas reservoirs to accelerate the decline of gas-phase permeability,and the critical value decreases with the decrease of core permeability.In the process of gas reservoir depletion development,the gas-water two-phase seepage capacity decreases with the decrease of formation pressure.The established dynamic productivity evaluation method of gas-water two-phase seepage has good field application effect,which has important guiding significance for productivity evaluation and dynamic prediction of low permeability gas reservoirs.
low permeability gas reservoirgas-water two-phase flowgas-phase permeabilityproductivity evaluation
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维普
