高含硫水驱气藏物质平衡方程推导及应用

Derivation and application of the material balance equation of high H_2S water-driven gas reservoir

针对高含硫水驱气藏与常规气藏相比存在很大差异,如开发过程中出现硫元素的沉积仍把常规水驱气藏物质平衡方程应用于高含硫水驱气藏产生较大偏差,考虑硫沉积、存在微量液烃等实际情况,根据气藏孔隙体积守恒原理,推导高含硫水驱气藏物质平衡方程通式,得到高含硫水驱气藏生产指示曲线,即直角坐标系中p/Z*—Gp的线性关系曲线.经验证,假设气藏不含硫,方程形式与常规水驱气藏物质平衡方程具有一致性,说明推导的正确性.应用生产指示曲线可以确定气藏的原始地质储量、预测气藏压力、预测气藏产量等,为高含硫水驱气藏开发动态分析及预测提供一种方法.应用结果表明,高含硫水驱气藏不考虑硫沉积,物质平衡计算结果将产生较大偏差,考虑硫沉积,其计算值与实际值相对误差为3.48%.

Because there exits a great differences between the conventional and high H2S water-driven gas reservoir,i.e.,sulfur deposition in the process of exploitation,application of the MBE of conventional gas reservoir to the high H2S water-drive gas reservoir results in wider margin of variation.Based on some actual cases,i.e.,sulfur deposition and little liquid hydrocarbon in reservoir,the generalized MBE of high H2S gas reservoir with water influx is derived from the principle of the volumetric balance,rigorously,and production index curve which is a Cartesian plot of p/Z vs.Gp should depict a straight line through derivation.By testing,the fact that the MBE has a similar form to conventional volumetric gas in the condition that the reservoir does not possess sulfur element demonstrates that derivation is correct.Application of production index curves can estimate Original-Gas-In-Place(G),predict future reservoir pressure and performance and so on,so an accurate and effect method is presented for dynamic evaluation and prediction in development of high H2S water-drive gas reservoir.The application indicates that the results of MBE calculation have greater deviation if we don't take sulfur deposition into account in high H2S gas reservoir,that the relative error between calculation result and actual data is 3.48% if we consider the sulfur deposition.