低渗透油藏垂直裂缝井产能预测及分析

压裂改造技术在低渗透油藏开发中应用广泛，不同的压裂方案所产生的增产效果也不同。为了达到所预期的增产效果，研究压裂后的产能对优化压裂设计有着重要的意义。为此，根据垂直裂缝井周围地层的渗透特征，建立径向流与双线性流复合的低渗透油藏垂直裂缝井渗流模型，考虑低渗透油藏存在启动压力梯度的影响，推导出了低渗透油藏无限导流裂缝和有限导流裂缝的产能公式，有限导流裂缝产能公式计算的结果与现场数据对比误差小于7%。依据准噶尔盆地某区块的特低渗透巨厚砾岩油藏的基础参数数据，绘制了不同影响因素下的产能曲线，并对曲线进行分析得出:裂缝的导流能力达到一定值后，才能近似为无限导流，否则会产生较大的误差；压裂的各项参数必须与储层条件相匹配，才能在现有的经济条件下达到所预期的增产效果。

Prediction and analysis on productivity of vertically fractured wells in low-permeability oil reservoirs

Fracturing stimulation technology is widely applied in the development of low-permeability oil reservoirs, and the stimulation effect of different fracturing plans is different.To realize the expected stimulation effect, it is of great significance to optimize fracturing design by researching the postfrac productivity.In this paper, a seepage model combining radial flow with bilinear flow was established for vertically fractured wells in low-permeability oil reservoirs according to the permeability characteristics of formations around vertically fractured wells.Then, the productivity formulas of infinite-conductivity and finite-conductivity fractures in low permeability oil reservoirs were derived to deal with the starting pressure gradient of low-permeability oil reservoirs.The error between the calculation result of finite-conductivity fracture productivity formula and the field data is lower than 7%.Productivity curves for different influential factors were plotted on the basis of the basic parameters of thick conglomerate oil reservoir with extra low permeability in a certain block of the Junggar Basin, and then they were analyzed.It is shown that the fracture conductivity can't be approximated as the infinite conductivity until it reaches a certain value, or the error will be higher.In order to realize the expected stimulation effect in the current economic conditions, all fracturing parameters shall match reservoir conditions.