【摘要】 针对致密油藏水平井体积压裂存在不同缝网改造模式的特点,考虑具有基质-天然裂缝双重孔隙和基于离散裂缝模型的缝网改造系统流动特征,建立了致密油藏体积压裂水平井不稳定渗流数学模型,利用Galerkin加权余量有限元方法对模型进行了数值求解,并与Zerzar解析模型对比验证了该算法的正确性,指出了双孔双渗与双孔单渗模型流动形态的差异,揭示了致密油藏体积压裂水平井不稳定压力及产能特征。研究结果表明:双孔双渗情况下水平井井底压降明显变缓,地层线性流不再出现,且压力较快传播至油藏边界;体积压裂水平井初期产量较高,但递减较快,不同改造模式下水平井中期渗流阶段压力及产量的差异明显,各压裂段无间隙无重叠的缝网改造模式对提高单井产量较为有利。更多还原

【Abstract】 Aiming at the different fissure network stimulated patterns for stimulated reservoir volume(SRV)-fractured horizontal wells in tight oil reservoirs;a mathematic unsteady well flow model was established in consideration of the dual porosity property of matrix natural fissures and flowing characteristics of the fissure network stimulation system based on discrete-fracture mode.Galerkin weighted residual finite element method was used for numerical solution of the model,and the accuracy of this algorithm was verified by comparison with Zerzar analytical model.Then this study points out the difference in flowing patterns between dual porositydual permeability model and dual porosity-single permeability model,and reveals the unsteady pressure and productivity features of SRV-fractured horizontal wells in tight oil reservoirs.The research results show that in case of dual porosity and dual permeability,the horizontal-well bottom hole pressure drop changes slowly;the formation linear flow no longer appears;the pressure propagates to reservoir boundary quickly.The initial production of SRV-fractured horizontal well is large but declined quickly.Under different stimulated patterns,significant differences existed in the pressure and production of horizontal wells at the middle flow stage.The fissure network stimulated pattern with no spacing and overlapping in each fracturing segment is advantageous to increase single-well production.更多还原