彭水地区龙马溪组页岩甲烷等温吸附模型对比研究

Comparative studies on methane isothermal adsorption models of shale of Longmaxi formation in Pengshui area

为了研究不同等温吸附模型对等温吸附实验的模拟效果,更好地描述页岩甲烷吸附规律,对川东南PY1井的7块岩心样品开展了等温吸附实验。结果表明,最大过剩吸附量与有机质含量呈现明显正相关,相关系数最大为0.859 4,而与黏土矿物呈现负相关。分别采用不同模型对实验结果进行了模拟分析,不同模型所得到的模拟结果差异较大,其中以Lang?muir模型拟合相关系数表现最好,而SDR模型所得到的最大过剩吸附量最大,其次为定密度修正的Langmuir模型。SDR模型和修正的Langmuir模型均对实验结果进行了过剩吸附量的修正,但修正结果表明,SDR模型所得到的吸附相密度最为合理。最后综合考虑认为定密度修正的Langmuir模型和SDR模型对页岩中甲烷的吸附规律描述更为精确,能够更好地指导页岩吸附气含量的计算。

In order to study the simulation effects of different isothermal adsorption models on isothermal adsorption experiments and better describe the adsorption rule of shale methane,isothermal adsorption experiments were carried out on seven core samples from well PY1 in southeast of Sichuan Basin.The experimental results showed that the maximum excess adsorption amount was positively correlated with the organic matter content,and the maximum correlation coefficient was 0.859 4,while it was negatively correlated with clay minerals.The experimental results were simulated by different models.The simulation results of different models were quite different.Among them,the correlation coefficient fitted by the Langmuir model was the best,while the maximum excess adsorption amount obtained by the SDR model was the largest.Followed by that was the fixed Langmuir model.Both the SDR model and the modified Langmuir model had corrected the excess adsorption amount of the experimental results,but from the correction results,the adsorption phase density obtained by the SDR model was the most reasonable.Finally,the fixed density correction Langmuir model and the SDR model were considered to describe the adsorption of methane in the shale more accurately,which could guide the calculation of the shale adsorption gas content better.