超前注水区块非线性渗流数值模拟及经济评价

流体在超低渗透油藏中渗流偏离达西定律,符合非线性渗流规律,据此研制了超低渗透非线性渗流数值模拟软件.建立了考虑非线性弯曲段影响的渗流数学模型,并结合矿场实际和室内岩心数据建立了大45超前注水区块地质模型.然后根据此模型进行了数值模拟.结果表明,超前注水区块开发过程中压力梯度大部分位于非线性弯曲段,非线性渗流区域占据主导地位.现有井网条件下,超前注水区块剩余油饱和度高,储层大部分区域水驱未能波及,储层动用效果较差,没有建立有效的驱动压力体系.对现有井网的预测表明,现有井网适应性较差,需要通过井网调整或加密措施进一步完善井网系统.通过对不同开发方案的经济评价和优选,认为角井直接转注为最优方案.

Numerical Simulation and Economical Evaluation of Nonlinear Seepage in Advance Water-flooding Block

Fluid seepage in the ultra-low permeability reservoirs deviates from the Darcy’s law,conforming to the law of nonlinear seepage.And according to this characteristic,the non-linear seepage numerical simulation software has been developed.Unlike most mature commercial numerical simulation software at the present stage,the influence caused by the nonlinear seepage is considered and thus a nonlinear seepage mathematical model is proposed.In addition,on the basis of practical field and laboratory experiment data,the geological model of Da 45 advanced water-flooding block is established and the numerical simulation is carried on in line with the model.The result shows that: during the development of the advanced water-flooding block,most pressure gradient belongs to the nonlinear types and the nonlinear seepage dominates in a large scale of formation.Under the conditions of present well pattern,the residual oil saturation is high and water flooding fails to spread to most regions which induce bad development effect and ineffective driving pressure system.Existing well pattern predictions show that present well pattern adaptability is bad and adjustment or further improvement is needed.According to the economical evaluation and optimization of different development plans,changing the corner oil wells to injection wells is considered to be the best scheme.