碳酸盐岩气藏的渗流模型和产量递减分析方法

Percolation model and production decline analysis method for carbonate gas reservoirs

为明确应力敏感性和高速非达西效应对双重介质气藏不稳定渗流的影响,建立了同时考虑二者影响的碳酸盐岩气藏渗流模型;引入摄动原理,在拉氏空间下对模型进行求解,获得拉普拉斯空间解析解,利用Stehfest数值反演算法将拉普拉斯空间解转换为实空间的解,根据求解结果绘制产量递减分析图版,结合产量递减分析图版进行了参数敏感性分析。结果表明,应力敏感性和非达西效应都会显著降低气藏产量。应力敏感系数越大,应力敏感性越强,气藏产量递减越快;非达西系数越小,非达西效应越强,气藏初期产量递减越快。建立的渗流模型和产量递减分析方法提高了对碳酸盐岩气藏渗流规律的认识,为分析该类气藏的产量规律提供了理论支持。

In order to clarify the effect of stress sensitivity and non-Darcy effect on unstable seepage in dual-media gas reservoirs,a seepage model of carbonate gas reservoirs considering both effects was established.The perturbation principle was introduced to solve the model in Laplace space,and the analytical solution in Laplace space was obtained.The solution in Laplace is transformed into real space solution by using Stehfest numerical inversion algorithm.Based on the solution result,the production decline analysis chart was drawn,and the sensitivity of parameters was analyzed using the production decline analysis chart.The results show that both stress sensitivity and non-Darcy effect can significantly reduce gas reservoir production.The larger the stress sensitivity coefficient is,the stronger the stress sensitivity is,and the faster the decline of gas reservoir production is.The smaller the non-Darcy coefficient is,the stronger the non-Darcy effect is,and the faster the decline of gas reservoir initial production is.The established seepage model and production decline analysis method can improve the understanding of the percolation law of carbonate gas reservoirs,which provides a theoretical support for the analysis of the production law of such gas reservoirs.