水驱凝析气藏地层压力计算方法

凝析气藏地层压力是计算气藏储量、评价气井产能、进行动态分析及反凝析评价等必不可少的重要参数。水驱凝析气藏的开发是气藏开发中最复杂的类型之一，在开发过程中，地层压力不断下降，凝析油析出，凝析气中水蒸汽含量增多，边、底水不断侵入，准确计算及预测地层压力就显得尤为困难及重要。通过计算考虑多孔介质吸附及毛管力影响的反凝析油，实验测试不同压力下凝析气中水蒸汽含量，根据物质平衡原理，建立了考虑多孔介质吸附、毛管力及水蒸汽影响的水驱凝析气藏物质平衡新方程，并迭代求解得到任意生产时刻地层压力。应用结果表明，考虑多孔介质吸附、毛管力及水蒸汽影响计算的地层压力，更接近实测地层压力，从而减轻了现场测试工作量。

A computational method for reservoir pressure of water-drive condensate gas reservoir

Reservoir pressure of condensate gas reservoir is an indispensable parameter for calculation of gas reserves,evaluation of gas-well productivity,dynamic analysis and assessment of retrograde condensation.The development of water-drive condensate gas reservoir is ranked among the most complex types of gas reservoir development.During the process of development,an accurate calculation and prediction of reservoir pressure is particularly difficult but important because reservoir pressure declines ceaselessly,condensate oil drops out continuously with an increase of the water-vapor content in condensate gas,and the edge water invades constantly.We tested the water-vapor content in condensate gas under different pressures by calculating the retrograde gas condensate,which is influenced by adsorption of porous media and capillary pressure.According to material balance principles,a novel material-balance equation for water-drive condensate gas reservoir was established in consideration of porous-medium absorption,capillary pressure and water vapor as well,and finally reservoir pressure at any time during production could be computed by iteration.Application results show that the reservoir pressure calculated with this method gets much closer to actual reservoir pressure,which virtually reduce the workload in field testing.