基于启动压力梯度的低渗含水气藏渗流规律研究

Seepage Law of Low Permeability Water-Bearing Gas Reservoir Based on Threshold Pressure Gradient

以苏里格气田某低渗致密气藏储层岩样为例,通过室内气驱水两相渗流物理模拟实验研究,发现高含水饱和度的低渗储层启动压力梯度效应明显,流体呈非达西渗流,气井开采中后期容易出现水锁现象;根据气相启动压力梯度变化规律,建立其考虑渗透率和含水饱和度影响的数学表征预测模型,这对于相邻区块或岩性及孔隙结构接近的储层均具有较好的适用性。

Taking a rock sample of a low permeability tight gas reservoir in the Sulige gas field as an example, a physical simulation experiment of gas flooding two-phase seepage is carried out. The results indicate that threshold pressure gradient effect which water saturation is high in low permeability reservoirs with is very obvious, the fluid is non-Darcy seepage, and the water lock phenomenon is easy to occur in the middle and late stages of gas well mining. According to the change law of gas phase threshold pressure gradient, a gas threshold pressure gradient prediction model with math expression based on permeability and water saturation is established, which has good applicability to adjacent areas or reservoirs with similar lithology and pore structure.