低渗透油藏压裂井产能评价及裂缝参数优化研究

Productivity evaluation and fracture parameter optimization of fractured wells in low permeability reservoir

低渗透率油藏因储层渗透率低,其生产受到启动压力梯度和孔隙介质变形的影响。实践表明压裂改造是提高低渗透率油藏单井产量的有效手段。为了评价低渗透油藏压裂井产能和优化裂缝参数,在分析低渗透油藏渗流机理的基础上,综合考虑启动压力梯度和介质变形系数的影响,建立了低渗透油藏流动数学模型,推导并求解得到了油井产量与井底压力的关系表达式。通过计算分析讨论了启动压力梯度与介质变形系数等地层参数以及裂缝参数对低渗透油藏油井产能的影响。研究结果表明:启动压力梯度与介质变形系数一定时,油井产量随着裂缝宽度和裂缝渗透率的增大而增大,但是增加的幅度越来越小;当裂缝参数一定时,地层启动压力梯度或介质变形系数越大,油井产能越小;裂缝长度越长,最佳裂缝宽度值和裂缝渗透率值越大;裂缝宽度越大,最佳裂缝渗透率值越小;裂缝渗透率越大,最佳裂缝宽度值越小。该研究结果为低渗透油藏提高油井产能和优化裂缝参数提供技术支持与保障,具有指导意义。

Due to low permeability, the production of low permeability reservoir is affected by threshold pressure gradient（TPG） and porous medium deformation. Research shows that fracturing transformation is an efficient measure to improve per well production. In order to evaluate productivity and optimize fracture parameters, based on the analysis of filtration theory, and by comprehensive consideration of TPG and media deformation coefficient, a mathematical model of low permeability reservoir was established, fur- thermore, the expression of well yield and bottom hole pressure（BHP） was deduced. Through calculation and analysis, the impacts of formation parameters on well productivity of low permeability reservoir was discussed, such as TPG and media deformation coeffi- cient and fracture parameters. The research shows that when TPG and media deformation coefficient are determined, the production increases with the increasement of fracture width and permeability, but the increase rate is smaller and smaller, however, when frac- ture parameters are determined, the production decreases with the increasement of TPG and media deformation coefficient, in addi- tion, the longer the fracture length is, the bigger the best fracture width and fracture permeability values are, the bigger the fracture width is, the smaller the best fracture permeability value is, and the bigger the fracture permeability is, the smaller the best fracture width value is. The research has significant guidance to provide technical supports and protection for production inereasement and fracture parameter optimization of low permeability reservoir.