异常高压气藏井间连通气井动态储量计算新方法

A new method for calculating dynamic reserves of interconnected gas wells in abnormally high pressure gas reservoirs

当气藏存在井间干扰时,常规方法无法准确计算出每口井的动态储量。针对异常高压有水气藏岩石压缩系数随地层压力衰竭变化,动态储量计算过程涉及参数复杂这一客观现象,运用气藏工程理论,通过优选偏差因子和井底压力折算方法,参考岩心实验数据,分析了岩石累计压缩系数变化规律,提出了无量纲的压力和产量的物质平衡方程,形成了评价干扰井组总动态储量的新方法。结果表明:1)高压气藏产水气井的井底压力折算应使用基于Gray模型的计算方法,计算结果的误差小于2%;2)相较于有量纲形式的常规物质平衡方程,提出的无量纲压力与无量纲累产气量方程考虑了变岩石压缩系数,描述了不同水侵程度下的理论气井生产动态,拟合实际数据确定目标异常高压气藏参数水侵特征值为0.7;3)运用新方法计算的动态储量相较于常规方法计算结果精度提升了14%。新的储量计算方法成功应用于异常高压有水气藏干扰井组,能够指导气藏进一步高效开发。

The conventional method can not accurately calculate the dynamic reserves of each well,when there is interwell interference in gas reservoir.In view of the objective phenomenon that rock compressibility changes with formation pressure exhaustion and dynamic reserve calculation process involves complex parameters,this paper analyzes the variation law of rock cumulative compressibility by using gas reservoir engineering theory,optimization deviation factor and bottom hole pressure conversion method,and reference to core experimental data.The dimensionless mass balance equation of pressure and production is presented,and a new method for evaluating the total dynamic reserves of interference well groups is formed.The results show that:1)The calculation method based on Gray model should be used to calculate the bottom hole pressure of water-producing gas wells in high-pressure gas reservoirs,and the error of the calculation result is less than 2%;2)Compared with the conventional mass balance equation in dimensional form,the dimensionless pressure and dimensionless cumulative gas production equation proposed takes into account the compression coefficient of variable rock and describes the theoretical gas well production dynamics under different water invasion degrees.The water invasion characteristic value of the target abnormal high-pressure gas reservoir parameter is determined to be 0.7 by fitting the actual data;3)Compared with the conventional method,the accuracy of dynamic reserves calculated by the new method is improved by 14%.The new reserve calculation method has been successfully applied to interference well groups of gas reservoirs with abnormal high pressure and water,which can guide the further efficient development of gas reservoirs.