Supercritical Methane Sorption on Organic-Rich Shales over a Wide Temperature Range
Supercritical Methane Sorption on Organic-Rich Shales over a Wide Temperature Range
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宽温度范围内富含有机质页岩的超临界甲烷吸附
DOI：
10.1021/acs.energyfuels.7b02628
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发表时间：
2017
期刊：
影响因子：
5.3
通讯作者：
Bernhard M Krooss
中科院分区：
文献类型：
--
作者：
Feng Yang;Congjiao Xie;Shang Xu;Zhengfu Ning;Bernhard M Krooss
通过孔隙填充/势理论分析了甲烷在宽温度和压力范围（30-120 °C，高达25 MPa）内在富含有机物的页岩上的吸附。将用密度项代替拟饱和蒸汽项的超临界Dubininin-Astakhov（SDA）吸附模型推广到页岩甲烷吸附等温线，获得了较高的精度。提出了一种改进的吸附势方法来分析页岩超临界甲烷吸附的温度依赖性。用改进的吸附势法得到了温度不变的特性曲线。从SDA模型推导出的特征曲线方程，可以用一条等温线预测其它温度下的吸附等温线。讨论了特征曲线的物理意义，它综合反映了甲烷吸附的有效孔隙空间和甲烷分子与有机质的亲和力。根据页岩和粘土矿物的甲烷特征曲线，页岩在气窗口表现出更高的亲和力比页岩在油窗口和粘土矿物，虽然粘土矿物可以提供相当的吸附体积。吸附特征能呈抛物线状，最小值约为Req = 1.1%，这与页岩孔隙度的演化有关。该研究对页岩吸附甲烷的动力学过程有了进一步的认识。
Methane sorption on organic-rich shales over wide temperature and pressure ranges (30–120 °C, up to 25 MPa) is analyzed by the pore filling/potential theory. The supercritical Dubinin–Astakhov (SDA) sorption model using a density term instead of the pseudosaturation vapor term is extended to methane sorption isotherms of shales with high accuracy. A modified adsorption potential approach is suggested to analyze the temperature dependence of supercritical methane sorption on shales. The temperature-invariant characteristic curves are obtained using the modified adsorption potential approach. A characteristic curve equation derived from the SDA model is provided to predict sorption isotherms at other temperatures using one isotherm. The physical meaning of the characteristic curve has been discussed, and it comprehensively reflects the available pore space for methane sorption and the affinity between methane molecules and organic matter. According to methane characteristic curves of shales and clay minerals, shales in the gas window show higher affinity than shales in the oil window and clay minerals, though the clay minerals may provide comparable adsorbed volume. The adsorption characteristic energy shows a parabola-like shape with a minimum of approximatelyReq= 1.1%, which is related to the evolution of the porosity of the shales. This study advanced the fundamental understanding of the dynamic process of methane sorption on shales.