天然气封盖层的突破压力

BREAKING PRESSURE OF GAS CAP ROCKS

突破压力的模拟实验方法是利用已取得的盖层岩芯样品 ,模拟到地下赋存状态 ,用气体排驱直至气体突破 ,求得的近似排替压力值即为突破压力。通过模拟实验研究发现 ,突破压力主要受控于渗透率 ,随渗透率的减小而增大 ;而介质、孔隙度等也都影响着突破压力。渗透率相同 ,饱含介质由气→油→水突破压力逐次成倍增加。孔隙度与突破压力则呈反向相关关系 ,孔隙度越大 ,突破压力越小。利用以突破压力为主的相关参数 ,将盖层封闭性能划分为 6个等级 ,建立了适合我国特点的天然气封盖层封闭能力的综合分级评价标准。

According to a modeling experiment,breaking pressure is apprioximatly calculated by the alternate drive force of gas drived into the core samples of cap strata,the samples were set in a status similar to its real geological status quo anter.It is found that the breaking pressure increases with the decreasing of permeability.Under the same permeability,the breaking pressure in gas ,oil and water bearing stata double one by one;the relation between breaking pressure and porosity is in reverse correlation.According to the parameters of the pressure,the sealing abilities of the cap rocks could be divided into six grades,and the complex grading evaluation criteria of gas cap rock sealing ability that is suitable for China is established.