温度压力耦合作用下的页岩气吸附分子模拟——以鄂西地区下寒武统为例  

Molecular simulation of shale gas adsorption under temperature and pressure coupling:Case study of the Lower Cambrian in western Hubei Province

作　　者：方镕慧 刘晓强 张聪[1] 李美俊 夏响华[1] 黄志龙 杨程宇[3] 韩秋雅[3] 汤韩琴 FANG Ronghui;LIU Xiaoqiang;ZHANG Cong;LI Meijun;XIA Xianghua;HUANG Zhilong;YANG Chengyu;HAN Qiuya;TANG Hanqin(The key Laboratory of Unconventional Petroleum Geology,Oil&Gas Survey,China Geological Survey,Beijing 100083,China;Colliege of Chemistry and Environmental Engineering,Sichuan University of Science and Engineering,Zigong 643000,China;State Key Laboratory of Petroleum Resources and Prospecting,College of Geosciences,China University of Petroleum,Beijing 102249,China)

机构地区：[1]中国地质调查局油气资源调查中心/非常规油气地质重点实验室,北京100083 [2]四川轻化工大学化学与环境工程学院,四川自贡643000 [3]中国石油大学(北京)油气资源与探测国家重点实验室/地球科学学院,北京102249

出　　处：《天然气地球科学》2022年第1期138-152,共15页Natural Gas Geoscience

基　　金：中国地质调查局“油气地质调查钻井岩心保存参数采集与应用”项目(编号:DD20201114)资助。

摘　　要：为考察随地层温度和压力变化,页岩气吸附性质变化规律,采用分子模拟技术,构建黏土矿物—干酪根复合分子模型,揭示在温度压力耦合作用下页岩气吸附特征及微观机理。研究结果显示,页岩气在干酪根、干酪根—伊利石复合模型、伊利石狭缝孔吸附能力依次降低,且均为较弱的物理吸附;页岩气在狭缝孔中的吸附量随着地质埋深的增加而增加,但当狭缝孔道被水分子占据后页岩气吸附量不再呈现出明显的增加趋势;在压力较低的情况下,气体的吸附能力由压力决定,在压力较高的情况下,气体的吸附能力由温度控制,在超高压且含水率较高的条件下,页岩气会以溶解气的方式赋存于含水页岩之中。模拟结果进一步表明,页岩气在干酪根—伊利石复合模型中的吸附主要以游离气为主,吸附气次之,其中吸附气含量占比达20.55%~38.82%。研究结果对分析随地层演化页岩气吸附性质变化规律及含气性预测具有一定的实践意义。In order to investigate the change of shale gas adsorption properties with the change of formation tem-perature and pressure,a clay mineral-kerogen composite molecular model was constructed by molecular simulation technology to reveal the adsorption characteristics and microscopic mechanism of shale gas under the coupling effect of temperature and pressure. The results show that the absorption capacity of shale gas decreases from kerogen,kerogen-illite and illte slit,and they are all weak physical absorption. The absorption capacity of shale gas increases with increasing burial depth. But it does not display evident increasing trend when the slits were occupied by water. The absorption capacity was mainly determined by pressure under lower pressure conditions,while it depends on the temperature under higher pressure environment. The gas may dissolve in pore water when the moisture content and pressure is higher. The simulation results further show that the shale gas adsorption in kerogen-illite composite model is dominated by free gas,followed by adsorbed gas,in which the adsorbed gas content accounts for 20.55%-38.82%. The results may have practical significance to analyze the absorption behavior of shale gas and predict the gas content of shale.

关 键 词：页岩气 吸附 温度和压力 扬子区 下寒武统 

分 类 号：TE132.2[石油与天然气工程—油气勘探]