特低渗油藏生产井初始含水率高的微观机理

特低渗油藏的生产井初始含水率要比中高渗油藏的高,而且生产井开井生产后含水率有一段时间的下降。对流体流动的微观机理进行了分析。结果表明,在特低渗油藏,钻井和压裂过程造成的水锁效应使地层原油难以流动;贾敏效应的存在阻塞了油流的通道;地层微裂缝的开启与闭合、启动压力梯度的存在导致生产井初始含水率较高;岩石物性特征决定了油藏的初始含水饱和度高,进而使初始含水率比较高。

Microscopic seepage mechanism of initial high water cut of production wells in ultra-low permeability reservoir

The initial water cut of production wells in uhra-low permeability reservoirs is higher than that of in high permeabili- ty reservoirs, and the dropping trend of water cut will last for days in developing period. The analysis results of microscopic seepage mechanism show that oil flowes with difficulty because of the water lock effect resulted from drilling and fracturing. Jamin effect, the open and close of microfracture, starting pressure gradient in reservoir result in high initial water cut. Because of thin throat of rocks, the initial water saturation is high, which results in the high initial water cut of production wells.