对致密砂岩气藏含水饱和度的认识直接影响气藏储量评价及开发决策。密闭取心和测井解释表明鄂尔多斯盆地北部上古生界致密砂岩气藏存在超低含水饱和度现象,气藏初始含水饱和度值范围低于束缚水饱和度范围。认为致密砂岩气藏超低含水饱和度形成于其独特的成藏过程,成藏过程中的生烃排液作用对超低含水饱和度的形成具有决定性影响,并通过室内对比实验作了验证。泥岩盖层的封隔作用、致密砂岩气藏气水过渡带内相对渗透率变化及持续生烃增压作用使得致密砂岩气藏超低含水饱和度最终得以保存。

Recognizing the water saturation in tight gas reservoirs directly affects reserv es evaluation and development measurement of the gas reservoirs. Sealed coring a nd log interpretation show there is an ultra-low water saturation in tight gas  reservoirs in northern Ordos basin, the initial water saturation in tight gas re servoirs is between 20% and 30%, which is far below the irreducible water satura tion. This article believe that the mechanism of forming ultra-low water satura tion in tight gas reservoirs is the result of the process of removing water duri ng hydrocarbon generating, then proving the conclusion by an experiment. The eff ects of isolation of mudstone, the variation of relative permeability between wa ter and gas in gas and water transitional zone, the continual gas accumulation i ncreasing the pressure in tight gas reservoirs are main issues for sustaining ul tra-low water saturation.