弹性驱低渗透油气藏的分区物质平衡方法

Domain Material Balance Method for Low Permeability Gas-Oil Reservoir by Depletion Drive Process

研究表明,流体在低渗透介质中的渗流需要启动压力梯度,即只有当流体的驱动压力大于低渗透介质的门槛压力,流体才能流动。这种渗流特性致使低渗透油气藏中与井底距离不同的地方,其地层压力降往往差异较大,因而不能近似地认为地层的各处压力降相同。然而在传统物质平衡方法应用过程中,却将地层压力降处理成同一个值。针对上述问题,提出了分区物质平衡方法用于确定低渗透油气藏的弹性驱采收率。介绍了该方法的基本原理、具体实现过程和矿场应用实例。该方法的计算结果更符合低渗透油气藏的实际情况。

Researches show that the fluid flow in low permeability media needs a start-up pressure gradient.That is,the drive pressure must be greater than a certain threshold pressure if the fluid is to flow.Such a flow feature cause that the pressure drops at the locations with different distances from the well are obviously different from each other.Therefore,the pressure drops for different locations can not be approximately thought as the same.However,these pressure drops are treated as the same one by using the conventional material balance method.The domain material balance method is presented for this case,and used to determine the elastic drive recovery of low permeability reservoir.The principle,usage and case study of this method are introduced in this paper.The calculated result by the method is more accordant with real conditions of low permeability reservoirs.