煤储层压裂液滤失计算模型

为揭示煤储层天然裂缝开启后的动态滤失过程,将裂缝的动态渗透率和煤储层裂缝-孔隙型双重介质的特性结合,建立煤储层压裂液的滤失模型,模型的拟合结果表明裂缝渗透率的动态变化导致天然裂缝中的滤失量几十倍的增加,而由于弹性储容比的影响,天然裂缝向基质中的窜流量反而减少。通过对比不同模型下的滤失量,可以得出动态滤失量是PKN和CGD模型下滤失量的4.5倍左右。为验证滤失模型的准确性,利用压裂酸化动态滤失仪进行实验,实验结果表明模型的数值拟合曲线与实验曲线有较一致的变化趋势,模型能较好地模拟煤储层天然裂缝中随时间变化的滤失过程。

Leak-off model of fracturing fluid in coal seam

To reveal the dynamic filtration process after natural fractures opening in coal reservoirs，the fracturing fluid filtration model，which combines the dynamic permeability of fractures with fracture-pore dual medium of coal reservoirs，was established.The modeling results show that the dynamic change of fracture permeability leads to the increase of dozens of times of filter loss in natural fractures，while because of the influence of elastic storage ratio，the filter loss from natural fractures to matrix is reduced reversely.The dynamic filter loss is about 4.5 times of that with PKN and CGD models.To verify the accuracy of the filtration model，the fracturing and acidizing dynamic filtration apparatus was used to conduct experiments，and the experimental results show that the numerical model fitting curve has the same variation trend with the measured curve，which demonstrates that the time-dependent filtration process in natural fractures of coal reservoirs can be simulated well using the model.