水驱气藏生产数据分析方法研究及应用

水驱气藏动态储量核算和水体大小的研究一直是此类气藏动态分析的重要内容。常规生产数据分析技术主要针对定容封闭气藏，而对于水驱气藏适应性差。为此，以气藏不稳定渗流理论为基础，考虑气藏水侵特征建立了水驱气藏渗流模型，利用Laplace变换法推导获得了水驱气藏不稳定产量响应解，计算并绘制了现代产量递减典型曲线。根据曲线特征将产量递减过程划分成4个典型流动阶段，讨论了无因次水侵量和无因次水侵时间对产量递减典型曲线的影响。结合现代生产数据分析技术，利用气井产量与压力的相互关系，提出了定量评价水侵强度和水侵开始时间，求取动储量、渗透率等气藏参数的方法。现场实际生产数据分析结果表明，该方法满足水驱气藏动态分析的工程实际要求，对于指导此类气藏的开发具有重要意义。

Analysis Method for the Production Data of Water Drive Gas Reservoirs and Its Application

Conventional production data analysis techniques are primarily applied to closed gas reservoirs having constant volume, but are not applicable to water drive gas reservoirs. Based on the unstable seepage theory, a seepage model for water drive gas reservoirs was established considering the water encroachment characteristics of gas reservoirs. Subsequently, the response solution of the unstable production of water drive gas reservoirs was derived using Laplace transform, and the typical curves of modern production-decline analysis were computed and plotted. From the results, four typical flow stages were categorized according to the characteristics of the curves. In addition, the effects of dimensionless water encroachment influx and time on a typical production-decline curve were discussed. Combined with modern production data analysis technology, a quantification method exploiting the relationship between the production and the pressure of gas wells was proposed for the quantitative evaluation of the intensity and starting time of water encroachment, as well as calculation of the dynamic reserve, permeability and other parameters of the gas reservoir. The results of the field production data analysis showed that this method was able to meet the engineering requirements of the dynamic analysis for water drive gas reservoir.