Abstract In order to evaluate shale gas content more accurately, a novel method for estimation of shale gas content in place is proposed based on the Polanyi adsorption potential and the London dispersion potential energy (P-L method). A series of integrated analyses were conducted on one shale core sample from the 7th member of Yanchang Formation (Chang 7 Member) in Ordos Basin, NW China, including on-site canister desorption tests, high-pressure methane adsorption isotherms, helium-based porosimetry, and gas composition analysis. On the basis of our experimental results, the P-L method and the commonly used ‘direct’ (based on measurement of desorbed gas) and ‘indirect’ (based on measurement of pore volume and state of equation) methods were used, respectively, to model the in-situ shale gas content. The results show that the shale gas content under the same experimental conditions predicted by the P-L method was 4.398 cm3/g and that by the direct method was 1.668 cm3/g, which is significantly lower. Meanwhile, those under the same lab conditions by the P-L method and the indirect method are 3.954 cm3/g and 3.820 cm3/g, respectively. Direct methods are more sensitive to human errors than the indirect methods, remove the impact of arbitrary factors by operators, and can shed light on the actual shale gas content in place based on the measured properties of samples. The P-L method is supported by well-developed theoretical basis. Through comparison between all these three methods, the results by the P-L method can be reasonable and practicable, and could be used to recover shale gas content in-situ during the shale gas resource potential assessment.

中文翻译：

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一种估算地下页岩气容量的新方法

摘要 为更准确地评价页岩气含量，提出了一种基于Polanyi吸附势和伦敦弥散势能的地层页岩气含量估算新方法（PL法）。对鄂尔多斯盆地延长组七段（长七段）一个页岩岩心样品进行了一系列综合分析，包括现场罐体解吸试验、高压甲烷吸附等温线、氦基孔隙度测定, 和气体成分分析。在我们的实验结果的基础上，分别使用PL方法和常用的“直接”（基于解吸气体的测量）和“间接”（基于孔体积和方程状态的测量）方法来建模原位页岩气含量。结果表明，在相同实验条件下，PL法预测的页岩气含量为4.398 cm3/g，直接法预测的页岩气含量为1.668 cm3/g，明显偏低。同时，在相同实验室条件下，PL法和间接法分别为3.954 cm3/g和3.820 cm3/g。直接方法比间接方法对人为误差更敏感，消除了操作人员任意因素的影响，并且可以根据样品的测量特性揭示实际的页岩气含量。PL 方法得到了完善的理论基础的支持。通过比较这三种方法，PL方法得到的结果是合理可行的，