Adsorption of methane onto mudstones under supercritical conditions: Mechanisms, physical properties and thermodynamic parameters  

作　　者：Yang Wang Hong-Fei Cheng Qin-Hong Hu Lang-Bo Jia Xi-Meng Wang Sha-Sha Gao Luo-Fu Liu 

机构地区：[1]School of Earth Science and Resources,Chang'an University,Xi'an,Shaanxi,710054,China [2]Key Laboratory of West Mineral Resources and Geological Engineering of Ministry of Education,Chang'an University,Xi'an,Shaanxi,710054,China [3]Department of Earth and Environmental Sciences,The University of Texas at Arlington,Arlington,TX,76019,USA [4]Exploration and Development Research Institute,Changqing Oil Field,PetroChina,Xi'an,Shaanxi,710000,China [5]Department of Geology and Geophysics,Texas A&M University,College Station,TX,77843,USA [6]State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum(Beijing),Beijing,102249,China

出　　处：《Petroleum Science》2023年第1期34-47,共14页石油科学（英文版）

基　　金：This work was supported by the Natural Science Basic Research Program of Shaanxi[No.2022JQ-291;2021JQ-234];the China Postdoctoral Science Foundation[No.2021M692735];the Fundamental Research Funds for the Central Universities,Chang'an University[No.300102271305].

摘　　要：Since the mechanisms of methane-mudstone interactions are important for estimating shale gas reserves,methane adsorption under supercritical conditions of 30 MPa pressure and 303.15,333.15,363.15 K temperatures was studied to measure the excess methane adsorption in two mudstone samples from Yanchang Formation,Ordos Basin.Excess adsorption features inflection points where the amount of adsorbed gas changes from increasing to decreasing concentrations.Three methods(fixed,slope,and freely fitted density)were applied to calculate the adsorbed-phase density(rad),which was then used to fit the measured excess adsorption.Two criteria,the goodness-of-fit and whether the fitting can obtain reasonable absolute adsorption,were applied to determine the most accurate model.Results indicated that the supercritical Dubinin-Radushkevich(SDR)model with freely fitted rad was the most reasonable model.The volume of adsorbed methane at 363.15 K is close to the micropore(d<2 nm)volume of the corresponding mudstone.Considering the actual geological conditions,the adsorbed gas should be predominantly stored in micropores.Thermodynamic parameters reveal that the methane adsorption on mudstone is a physisorption process that is jointly controlled by the heterogeneity of,and interaction forces between the methane molecule and,the rock surface.

关 键 词：Supercritical methane adsorption Excess adsorption Adsorbed-phase density Adsorption model Thermodynamic feature 

分 类 号：TE348[石油与天然气工程—油气田开发工程]