用气测渗透率法评价川东南龙马溪组页岩流体敏感性

孔喉致密、黏土矿物含量高使得川东南龙马溪组页岩气层具有严重的潜在流体敏感性损害特征。在目前的页岩液体敏感性评价中,研究人员还只是简单地沿用行业标准法,而没有形成系统地针对页岩液体敏感性的评价方法。提出气测渗透率法来评价页岩流体敏感性,并在川东南地区下志留统龙马溪组页岩储层应用,评价结果表明该区块水敏性强、盐敏性强、碱敏性强、酸敏性中等偏强,为合理开发该区块页岩气藏提供了理论基础。与常规方法相比,气测渗透率法不需计量岩心出口端流量,而是测量液体处理后的岩心烘干后的气体渗透率来评价损害程度,从而解决了因页岩液体渗透率极低而引起的测试时间长、实验误差大等问题。此外,气测渗透率法采用气体为实验介质,更符合气井生产实际。

Using Gas Permeability to Evaluate Fluid Damage of Shales from Longmaxi Formation at Southeast Sichuan Basin

Dense pore throats and high content of clay minerals cause serious potential fluid sensitivity damage to shale gas reservoirs in Longmaxi formation at southeast Sichuan Basin. At present, the industrial standard method is usually used to evaluate fluid sensitivity of shales without emerging a systematic method for shales. A new way based on gas permeability to evaluate fluid damage of shales was put forward in this article and was employed in evaluating fluid damage of shales from Longmaxi formation at southeast Sichuan Basin. Results indicate stong water damage, strong salt damage, strong lye damage and medium to strong acid damage, which lays reasonable suggestions to develop gas reservoirs. In comparison with the industrial standard method, the fluid flow rate at the outlet of the core holder need not to be measured; instead, the gas permeability of the core dried after displaced by liquid is measured to evaluate fluid damage. Therefore, the gas permeability method shares shorter test time and smaller experimental error. What`s more, gas is employed during gas permeability method, which conforms to reality in gas field.