缝洞型油藏垂直裂缝井压力动态分析

Dynamic Analysis on Pressure from Vertical Fracture Well in Vugular Reservoirs

针对缝洞型油藏进行水力压裂后形成的有限导流垂直裂缝,结合沃伦-鲁特提出的双重介质模型,利用质量守恒和椭圆流法建立了缝洞型油藏椭圆流数学模型,并在此基础上,应用拉普拉斯变换,求得了在拉普拉斯空间的缝洞型油藏有限导流垂直裂缝井井底压力表达式。运用Stefest数值反演,绘制了无因次压力及压力导数对时间的双对数特征曲线图,对影响缝洞型油藏有限导流垂直裂缝井井底压力动态的诸多影响因素进行了分析。结果表明,最显著的影响因素是裂缝储集系数、裂缝表皮系数和无因次导流能力,其它参数对井底压力动态的影响与其对普通直井油藏的影响类似。

According to finite conductivity vertical fracture conducted by hydraulic fractured in vugular reservoir, based on the Warant-Root model in double porosity, an elliptical flow model for finite conductivity fracture was built by using mass conservation equation and elliptical flow method. Furthermore, based on the model, Laplace transform was used to obtain the formula of down hole pressure in Laplace space to finite conductivity vertical fracture model in vugular reservoir. By using Stefest numerical inversion of Laplace transform, the curves of pressure and its derivative to time was drawn and the dynamic and influence factors were discussed. The result indicates that fracture storage, skin and flow conductivity are the obvious affecting factors to pressure performance. However, other factors influencing on fractured wells are similar to ordinary vertical wells.