【摘要】 大部分压裂水平井产能模型以单相气体流动为主,忽略气井早期返排阶段压裂液和气体共存现象。基于线性双重孔隙模型,建立致密气藏气水两相早期返排计算模型,将储层改造区域(SRV)分为天然裂缝与基岩系统,其中天然裂缝系统为气水两相流动,基岩系统为单相气体解吸;根据实际返排液体积拟合,分析天然裂缝系统动态相对渗透率与时间的关系,采用Laplace变换方法对模型进行求解,研究有效孔隙体积和初始返排率对模型气井产能的影响。致密气藏x1井的应用结果表明:初始返排率越高,气井产能越高,气水两相早期返排分析模型产能拟合效果较好;结合产水量无量纲压力与平衡时间的关系,计算裂缝总体积为22.191×10~3 m~3,基岩—裂缝接触面积为2.456×10~5 m~2,平均裂缝开度为45.2 mm。该结果对致密气井压裂效果评价和产能预测具有指导意义。更多还原

【Abstract】 Most productivity models for fractured horizontal well are based on single-phase gas flow,ignoring the coexistence of gas and fracturing fluid during early fracturing fluid flowback.In this paper,a gas-water two phased mathematical model of tight gas reservoir was established based on the linear dualporosity model,SRV region was divided into matrix and natural fracture system,in which natural fracture system was considered as gas-water two phased flow,the matrix system was single phased gas desorption.In order to avoid the calculation of saturation,the relationship between dynamic relative permeability of natural fracture system and time was obtained based on volume of field flowback fluid,the model was solved by Laplace transforms.The influence of effective pore volume of hydraulic fracture and initial flowback ratio on gas production were analyzed,and the results show that the higher the initial flowback rate,the higher the gas production.Finally,the well x1 was used for field application,the accuracy of the method was illustrated by the good productivity fitting effect,and the fracture parameters were calculated based on the relationship between dimensionless pressure and material balance time,the total fracture volume was calculated to be 22.191×10~3 m~3,the matrix-fracture contact area was2.456×10~5m~2,and the average fracture aperture was 45.2 mm.The results can be used to evaluate the fracturing performance and predict the production of tight gas reservoirs.更多还原