多参数回归物质平衡法在水驱气藏气井生产动态预测中的应用

Application of multi-parameters regression material balance method in production performance prediction of gas wells in water drive gas reservoirs

物质平衡法在水驱气藏气井生产动态指标预测中面临2项难题,即产能方程的建立和水侵量计算,影响指标预测精度。针对存在的问题,通过理论推导及经验回归,研究产能方程系数和气层压力、水侵量和气层总压差、产水量与产气量之间的变化规律。建立一种新的多参数回归物质平衡法:包括3个基础方程(水驱气藏物质平衡方程、二项式产能方程、井筒管流方程)和4个经验关系式(二项式产能方程系数A与气层压力、二项式产能方程系数B与气层压力、累计水侵量与气层总压差、累计产水量与累计产气量)。结果表明,多参数回归物质平衡法立足气井的生产动态数据,简化了产能方程建立和水侵量计算过程。经过实践检验,平均误差在5%以内,该方法满足现场实际要求。

Material balance method faces 2 challenges in predicting production performance indexes of gas wells in water drive gas reservoirs,including productivity equation establishment and water influx calculation,which affect the accuracy of index prediction.In view of the existing problems,variation law of productivity equation coefficients vs.gas layer pressure,water influx vs.total pressure difference of gas layer and water production vs.gas production are studied through theoretical derivation and empirical regression.A new multi-parameters regression material bal-ance method of water drive is established,including 3 basic equations(material balance equation of water drive gas reservoirs,binomial productivity equation and wellbore flow equation)and 4 empirical relationship formulas(coeffi-cient A of binomial productivity equation vs.gas reservoir pressure,coefficient B of binomial productivity equation vs.gas reservoir pressure,water influx vs.total pressure difference of gas reservoir and cumulative water production vs.cumulative gas production).The results show that multi-parameters regression material balance method based on pro-duction performance data of gas wells simplifies the process of productivity equation establishment and water influx calculation.Practical verification indicates average error of<5%,and this method meets the actual field requirements.