泥岩盖层对各种相态天然气封闭能力综合评价方法

Comprehensive evaluation method for sealing ability of mudstone caprock to gas in each phase

为了研究泥岩盖层对各种相态天然气封闭能力综合评价方法,在研究其对各种相态天然气封闭机理的基础上,利用游离相、水溶相和扩散相天然气在外加压力和浓度作用下通过泥岩盖层的渗滤和扩散速度,分别建立了泥岩盖层对游离相、水溶相和扩散相天然气封闭能力评价参数Vs,Vw,Vd。以此为基础,通过Vs,Vw,Vd的加权平均建立了泥岩盖层对各种相态天然气封闭能力的综合评价方法,并将其应用于滨北地区青山口组泥岩盖层对各种相态天然气封闭能力的综合评价中,结果认为青山口组泥岩盖层主要为中等能力封闭区,仅在盆地北部讷河和东部绥棱以东局部地区为差封闭区,其对各种相态天然气封闭能力差是造成该区扶余和杨大城子油层天然气显示差的重要原因之一。

Based on the study on sealing mechanisms of mudstone caprock to gas in each phase, the percolation and diffusion velocity of gas in free phase, water-dissolving phase and diffusive phase through mudstone caprock under the action of imposed pressure and gas-beating concentration are applied to establish the evaluation parameters （Vs, Vw and Vd） for sealing ability of mudstone caprock to gas in free phase, in water-dissolving phase and in diffusive phase respectively. And then, a comprehensive evaluation method for sealing ability of mudstone caprock to gas in each phase is established by weighted average value. This method is applied to evaluate the sealing ability of mudstone caprock to gas in each phase of Qingshankou Formation in Binbei area. The result shows that the mudstone caprock of Qingshankou Formation is of middle sealing ability, and poor sealing ability in Nehe and eastern Suileng. Poor sealing ability is one of the main factors which caused the poor gas shows in this area.