不同含水饱和度对页岩渗流能力影响实验研究

Experimental Study on Influence of Different Degrees of Water Saturation on Seepage Capacity of Shale

通过物理模拟实验建立了不同含水饱和度的页岩岩心,测量其流态曲线,探讨了页岩含水饱和度对页岩气流动的影响。结果表明:当页岩岩心含水饱和度低于"束缚水饱和度"时,流体被基质吸收成为不可动水,不会随气体的产出而流动,也不会严重影响气体的主要产出通道;当页岩岩心含水饱和度高于"束缚水饱和度"时,部分流体滞留在裂缝表面和孔道,堵塞主流通道,从而严重影响气体渗流;当页岩储层含水饱和度高于基质"束缚水饱和度"时,应当采取措施提高压裂液返排率;反之,压裂液返排率高低对气井产能无明显不利影响。

In order to study the effect of shale water saturation on shale seepage capacity after fracturing, the shale cores with different degrees of water saturation were established by physical simulation experiment, and the flow curves were measured. The experimental results show when the water saturation of the shale core is lower than that of the ＂irreducible water saturation＂, the fluid is absorbed into the immovable water by the matrix and does not flow with the gas output, nor does it seriously affect the main output of the gas channel; when the shale core water saturation is higher than the ＂irreducible water saturation＂, part of the fluid is trapped in the cracks in the surface and the channel, blocking the mainstream channel, which seriously affects the gas seepage. This study can guide the formulation of shale fracturing fluid return flow： When the water saturation of shale reservoir is higher than the ＂irreducible water saturation＂ of the matrix, measures should be taken to improve the fracturing fluid flow rate; on the contrary, the rate of fracturing fluid back to the gas well productivity no significant adverse effects.