The equivalently absolute permeability obtained by laboratory rock analysis is usually based on the correction of linear relationship between gas measurement permeability and average pressure recip. Study on gas measurement permeability experiment shows that for the rock with permeability lower than 0. 1 × 10-3μm2, the relationship between gas measurement permeability and average pressure recip is nonlinear, and the equivalently absolute permeability obtained by correction could be slightly smaller, even negative. The reasons for this are the extremely small radius of pore channel in the rock with super-low-permeability, the greatly increasing scale of the thickness of wall-slippage molecular layer to the radius of pore channel, and the strengthening contribution of slippage effect to flowing. Finally, according to the rarefied aerodynamics, the method of increasing the gas pressure at delivery end is proposed to effectively decrease the thickness of wall-slippage molecular layer, so as to decrease the contribution of slippage effect to flowing. The result shows that after increasing the gas pressure at delivery end, the relationship between gas measurement penneability and average pressure recip is linear, and the accurately absolute permeability could be obtained after correction.%室内岩心分析通常依据气测渗透率值与平均压力倒数之间的线性关系校正得到岩石的等效绝对渗透率.由气测渗透率实验研究发现:对于渗透率小于0.1×10<'-3>μm<'2>量级的超低渗岩石,气测渗透率值与平均压力倒数成非线性关系,校正得到的等效绝对渗透率值会偏小甚至为负值.产生这种现象的本质原因在于超低渗岩石孔道半径极小,壁面滑移分子层厚度占孔道半径的比例大大增加,滑脱作用对流动的贡献增强.为此,依据稀薄空气动力学理论,提出增加出口端气体压力的方法能有效降低壁面滑移分子层厚度,从而减小滑脱作用对流动的贡献.结果表明增加出口端压力后,超低渗岩石的气测渗透率值与平均压力倒数成线性关系,校正后可以得到准确的绝对渗透率.
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