页岩气水两相物质平衡方程及其生产预测

Shale gas and water two-phase material balance equation and its production prediction

为了得到一种便于矿场应用的页岩生产动态预测分析方法,通过积分水相和气相连续性方程,得到平均含水饱和度方程和气水两相物质平衡方程,结合有限差分法,给出了计算步骤,依次分析了无量纲导流能力、裂缝半长、Langmuir体积和Langmuir常数对垂直裂缝井日产气量的影响,与数值模拟结果对比,验证了该方法的正确性.研究结果表明,无量纲导流能力和裂缝半长只影响产量最大值,而Langmuir体积和Langmuir常数对产量最大值和递减开始时间都有影响.研究结果提供了建立页岩气物质平衡方程的新思路,为页岩气藏生产潜力和压裂施工方案的评价奠定了基础.

In order to obtain a prediction and analysis method for shale production performance,the average water saturation equation and gas-water two phase material balance equation are obtained by integrating the water and gas phase continuity equations.Combined with the finite difference method,the calculation steps are given,and the effect of the dimensionless conductivity,fracture half-length,Langmuir volume and Langmuir constant on daily production of vertical fracture wells are analyzed.Compared with the numerical simulation results,the correctness of the method is verified.The results show that the dimensionless conductivity and fracture half-length only affect the maximum production,while the Langmuir volume and Langmuir constant affect both the maximum production and the start time of decline.The results provide a new way to establish the material balance equation of shale gas,which also can be used for the production potential and the evaluation of fracturing construction scheme.