边水气藏型储气库运行动态参数计算方法及应用

Calculation method and application of operational dynamic parameters of the edge-water gas reservoir gas storage

基于“罐式”概念的传统物质平衡方法无法定量计算储气库采气阶段的水侵区残余气量,也无法定量分析边水非稳态水侵过程中的工作井运行动态参数变化规律。为了解决该问题,文中首先建立了考虑水侵区残余气量的改进物质平衡方程,并在此基础上根据气水非稳态渗流理论推导了工作井采气阶段关键运行动态参数解析模型;然后采用某边水气藏型储气库工作井的基础资料,定量分析了其在采气阶段运行动态参数的变化规律,并对计算结果进行了对比验证;最后讨论了该计算方法的特点和适用性。研究表明:该方法能够定量分析边水气藏型储气库非稳态水侵过程中时变井控参数变化规律,掌握不同区域压力变化特征,量化计算水侵区残余气量,明确工作井有效井控库容量。运行动态参数计算结果表明,随着生产时间的增加,时变井控半径逐渐减小,水侵区残余气量逐渐增大;在相同水侵量下,相较于采气末期,采气初始阶段的时变井控参数与残余气损失的增加量较小,体现了储气库采气能量由早期主要依靠弹性能驱动向晚期依靠边水补能的转变过程。研究成果对同类边水气藏型储气库运行规律探究、库容参数及运行动态分析、工作井合理工作制度制定具有明确的现实意义与实用价值。

The traditional material balance method based on the"tank"concept cannot quantitatively calculate the residual gas loss volume during gas production stage in the water invasion zone in the gas storage,nor can it quantitatively analyze the change laws of operational dynamic parameters of working wells during the edge-water unsteady water intrusion process.In order to solve this problem,this research firstly establishes an improved material balance equation considering the residual gas volume in the water intrusion zone,and based on this equation,an analytical model of the key operational dynamic parameters of the working well during gas production is derived according to the gas-water unsteady seepage theory.Then,using the base data of a working well in a certain edge-water gas reservoir gas storage,the variation pattern of the operational dynamic parameters during gas production stage is quantitatively analyzed and the calculated results are compared and verified.Finally,the characteristics and applicability of the calculation method are discussed.The research shows that this method can quantitatively analyze the variation pattern of time-varying well control parameters during unsteady water intrusion in the edge-water gas reservoir gas storage,grasp the pressure variation characteristics of different zones,quantify the residual gas volume in the water intrusion zone,and specify the effective well control storage capacity of working wells.The results of the operational dynamic parameter calculation show that as the production time increases,the time-varying well control radius gradually decreases and the residual gas volume in the water intrusion zone gradually increases.Under the same water intrusion volume,compared to the late stage of gas production,the increase of time-varying well control parameters and the residual gas loss are smaller in the initial stage of gas production,reflecting the transformation process of gas production energy in the gas storage from being mainly driven by elastic energy in the early stage to relying on the supplementary energy of the edge-water to produce gas in the late stage.The research results have clear practical significance and value for the investigation of the operation rules of similar edge-water gas reservoir gas storage,the analysis of storage capacity parameters and operation dynamics,and the formulation of a reasonable working system for working wells.