新场气田须家河组致密砂岩气藏非线性渗流特征实验研究

为研究致密砂岩气藏储层特殊渗流机理及压裂后储层渗流特征,运用岩心流动实验装置,测定新场气田须家河组气藏基质及造缝岩心样品在不同驱替压力下的可动水饱和度及渗透率,并依据实验结果,分析不同束缚水饱和度下渗透率随压力平方梯度变化规律,分析了基质及造缝岩心样品气体低速渗流特征.基质岩心渗流特征曲线表明,高束缚水饱和度条件下,气体渗流曲线表现为以启动压力梯度效应为主过渡到以滑脱效应为主,最后达到拟线性渗流状态的复合型渗流特征；低束缚水饱和度条件下,启动压力梯度效应不明显,表现出一定的气体滑脱现象；渗透率对启动压力有明显影响,随渗透率的增加,启动压力梯度急剧降低,对致密砂岩气藏,滑脱效应和启动压力梯度效应共同作用,且二者作用程度的变化导致气体渗流的复杂化和流态的多变性,气体渗流具有复合型渗流规律,而造缝岩心在不同含水饱和度条件下基本上未出现启动压力现象.

Experimental Study on the Non-linear Filtering Flow Feature of Tight Sand Gas Reservoir of Xujiahe Formation in Xinchang Gas Field

In order to study the special filtering flow mechanism and features of reservoirs after fractured in tight sand gas reservoir,core flow experimental apparatus is applied to test the mobile water saturation and permeability of the base rocks and the fractured core samples under various displacement pressure in Xujiahe gas reservoir,Xinchang gas field.Alternation regularity of permeability with square pressure gradient under the different bound water saturation is analyzed based on the test results.And filtering flow features of the gas in based rocks and the fractured core samples are analyzed too.The feature curve of base rock core indicates that the filtering flow curve of the gas is characterized as actuating pressure gradient effect initially and then slippage effect,and quasi-linear flow at last under the condition of high bound water saturation.Under the condition of low bound water saturation,slippage effect mainly presents with unobvious actuating pressure gradient effect.The permeability influences the actuating pressure intensely,and the actuating pressure gradient decreases roughly with the increasing of permeability.The alternation of actuating pressure gradient effect and slippage effect caused the complication and polytrope of gas filtering flow,which indicates the complex filtering flow feature,however,the actuating pressure gradient effect did not appear under the various water saturation for the fractured cores in the tight sand gas reservoir.