低渗砂岩气藏气体特殊渗流机理实验研究与分析

Experimental study and analysis of the special percolation mechanism in low permeability sandstone gas reservoir

针对渗透率低于10-3μm2天然低渗透砂岩岩心,在改造的气体渗透率测定仪上进行含水岩样中气体渗流规律的室内实验。实验中运用微波法建立含水饱和度模型,通过在不同孔渗范围内的低渗岩样中进行气体渗流实验以达到研究气体特殊渗流机理的目的。研究发现,气体渗流受渗透率和含水饱和度的控制。在干燥和低含水饱和度状态下,气体渗流曲线呈上凸型,渗透率越小,受滑脱效应的影响越明显。随含水饱和度增大,渗流曲线由上凸型向下凹型转变,滑脱动力影响变小,毛细管力影响变大。复合型渗流曲线则完整反映了气体渗流的整个过程。本研究对制定低渗透气藏相关开发技术对策具有重要的指导意义。

Gas percolation in sandstone cores with permeability lower than 10-3μm2 has been studied with water-bearing samples and modified gas permeability analyzer.A water saturation model has been established in the experiment by using microwave method.And gas percolation mechanism has been studied through experiments in rock samples with different porosity and permeability.The study indicates that gas percolation is controlled by permeability and water saturation.Under dry and low water saturation condition,gas percolation curve shows as convex shape,the permeability becomes lower,and the slippage effect is more evident.As water saturation increases,the percolation curve changes from convex to concave shape,the slippage effect becomes smaller,and the effect of capillary force becomes larger.Compound percolation curve can reflect the whole process of gas percolation.This study is of important guiding significance to constituting relevant development program for low permeability gas reservoirs.