边水凝析气藏型储气库多周期注采水侵量计算模型

Multi-cycle water influx calculation model of reconstructing gas storage in condensate gas reservoirs with edge water

关键词:  地下储气库  边水凝析气藏  物质平衡  反凝析  水侵量

Key words:  underground gas storage  condensate gas reservoir with edge water  material balance  retrograde condensation  water influx

摘要:

针对边水凝析气藏型储气库相态变化复杂而导致水侵量计算较为困难的问题，基于物质守恒原理，鉴于储气库注采气体差异，考虑注入烃类气体与凝析气混合、凝析气反凝析、边水侵入和岩石束缚水压缩性等因素，推导边水凝析气藏型储气库物质平衡通式，建立水侵量和相关参数计算方法，结合中国某边水凝析气藏改建的储气库运行动态数据，计算和评价储气库多周期注采水侵量变化。结果表明：水侵量的计算结果符合储气库注采地层压力的升降特征；随着储气库多周期扩容和库存量增加，总体水侵量逐渐减小；与考虑反凝析因素相比，不考虑反凝析因素计算的水侵量值偏大；由于注入的烃类气体对凝析气的抽提作用，反凝析对水侵量的影响程度逐渐减弱；新模型计算的水侵量与数值模拟方法结果吻合较好。

Abstract:

At present, there is difficulty for calculating the water influx caused by the complicated phase changes in reconstructing gas storage in condensate gas reservoirs with edge water. In view of the differences between the injection gas and the producing gas, considering the mixture of dry gas and condensate gas, retrograde condensation, edge water influx, the compressibility of rock and bound water and so on, the material balance formula was deduced based on the principle of mass conservation. Subsequently, the calculation model of water influx and the calculation method of parameters were established. Combining with the production data of underground gas storage in China, the water influx was calculated and its influence factors and characteristics were analyzed. The results show that the calculation results of water influx accord with the variation of formation pressure in the period of injection and production conditions, and the cumulative water influx decreases with the amount of inventory increasing. With the injection of dry gas and the extraction of condensate gas by dry gas,the impact of retrograde condensation on the water influx of gas storage is minimized. The water influx obtained by the new model is in good agreement with the numerical simulation results.