延长油田超低渗透油藏水平井分段压裂产量计算模型研究

A NEW PRODUCTION CALCULATION MODEL FOR STAGE-FRACTURED HORIZONTAL WELLS IN ULTRA-LOW PERMEABILITY RESERVOIR AT YANCHANG OILFIELD

目前国内外关于水平井压裂产量的计算主要是基于储层基质中的达西流动模型,而油田矿场生产实践和室内实验结果表明,超低渗储层基质渗流不符合经典达西定律,存在较强的非线性渗流特征。因此,建立基于非线性渗流规律的产量评价模型对于超低渗透致密油藏的开发显得尤为重要。文章针对超低渗透储层的渗流规律,考虑分段压裂水平井基质中的非线性流动、裂缝中的达西流动、水平井井筒内的水力压降流动,提出一种耦合数值求解水平井产量的计算新模型,并应用该模型对延长油田W区块水平井产量进行计算,符合率达85.21%~95.79%。结果表明,应用推导的水平井产量计算模型可得到相对可靠的计算结果,验证了模型的准确性,这对于超低渗透储层分段压裂水平井技术具有重要的实践意义。

The existing production calculation methods for fractured horizontal wells at home and abroad is mainly based on Darcy Flow Model for the reservoir matrix,but the oilfield production practice and the indoor experiment results show that the seepage in ultra-low permeability reservoir matrix does not follow the classic Darcy's law,the seepage is featured with strong nonlinearity. Therefore to establish the well productivity evaluation model based on nonlinear seepage law for ultra-low permeability tight oil reservoirs is particularly important. Considering the nonlinear seepage in reservoir,nonlinear flow in stage fractured horizontal well matrix,the Darcy flow in the fractures,and the hydraulic pressure drop produced flow in the borehole of horizontal wells,a new model using coupling values to calculate the horizontal well productivity is proposed,it has been applied at W block of Yanchang oilfield,the calculation consistency reaches at 85. 21% ~ 95. 79%. The feasibility and accuracy of the new horizontal well productivity calculation model has got verified,it has a practical significance for stage fracturing in horizontal wells in ultra-low permeability reservoirs.