致密砂岩气藏压裂直井气水两相产能评价新方法

A new method for evaluating the gas-water two-phase productivity of fractured straight wells in tight sandstone gas reservoirs

为研究气井产水对致密气藏产能的影响,以A气田为例,针对当前致密气藏产能方程因只考虑单一气相多因素或者气水两相单因素导致模拟准确性不高的问题,基于渗流力学原理,建立了考虑多因素的致密气藏气水两相压裂直井产能模型。研究结果表明:1)通过实例计算,新模型计算的无阻流量与实际产能测试的无阻流量结果相比误差较小,仅为2%,说明新模型具有一定的准确性。2)敏感性分析表明,裂缝参数对产能影响较为明显,滑脱效应和启动压力梯度对产能影响较小。3)水气比对产能影响较大,气井产水导致气井启动压力梯度增大,应力敏感性增强,渗流阻力增大,气井产能减小,在实际生产过程中应尽量避免气井见水。该模型实现了产能的准确预测,对致密砂岩气藏高效开采具有一定的指导意义。

In order to study the influence of gas well water production on the productivity of tight gas reservoirs,tak-ing gas field A as an example,aiming at the problem that the current tight gas reservoir productivity equation only considers the influence of single gas-phase multi-factor or gas-water two-phases single-factor leading to low the simu-lation accuracy,establishing a gas-water two-phase fractured straight well productivity model for tight gas reservoirs considering multi-factor base on the principle of seepage mechanics.The results of the study show that:1)Through example calculations,there is only 2%of a minor error between the unrestrained flow results calculated by the new model and the actual productivity testing indicating that the new model has a certain accuracy.2)Sensitivity analysis shows fracture parameters have more obvious impacts on productivity,slippage effect and starting pressure gradient have less impact on productivity.3)The water-gas ratio has a great influence on productivity.The water production of gas wells leads to the increase of starting pressure gradient,enhancement of stress sensitivity,and increase of seepage resistance of gas wells,with the productivity of gas wells decreasing.In the actual production process,it is advisable to avoid gas wells encountering water.The model achieves accurate productivity prediction,which has a certain guiding significance for the efficient exploitation of tight sandstone gas reservoirs.