不同有效应力下泥岩盖层二氧化碳突破压力演化特征的试验研究  

Experimental study on evolutionary characteristics of CO_(2)breakthrough pressure for mudstone caprock under different effective stresses

作　　者：陈博文 李琦[1,2] 谭永胜 余涛 高文彬 李霞颖 申筛成 CHEN Bo-wen;LI Qi;TAN Yong-sheng;YU Tao;GAO Wen-bin;LI Xia-ying;SHEN Shai-cheng(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071 [2]中国科学院大学,北京100049

出　　处：《岩土力学》2024年第12期3681-3693,共13页Rock and Soil Mechanics

基　　金：国家重点研发计划(No.2022YFE0115800);内蒙古自治区科技重大专项(No.2021ZD0034);山西省重点研发计划(No.202102090301009)。

摘　　要：针对不同有效应力下泥岩盖层二氧化碳(CO_(2))突破压力演化机制不清的问题,以中国渤海湾盆地粉砂质泥岩盖层为研究对象,开展了不同有效应力下突破压力和渗透率试验,研究了泥岩盖层CO_(2)突破压力演化过程,讨论了孔隙水膜对突破压力的影响机制。研究结果表明:CO_(2)注入时,盖层有效应力由27 MPa减小至7 MPa,盖层渗透率由从1.46×10^(-6)μm^(2)增加至1.81×10^(-6)μm^(2)。当有效应力为5.2 MPa时,盖层突破压力的最小值为3 MPa,其值高于盖层最小封闭界限值2 MPa,表明盖层具有CO_(2)有效封闭能力。孔隙水膜的分离压力和分布特征是影响突破压力的主要因素,CO_(2)运移阻力随水膜分离压力增加而增大,导致CO_(2)突破压力大。渤海湾盆地泥岩小孔径范围为0.1~2.5 nm,对应的水膜分离压力为5.2~50 MPa,水膜对CO_(2)运移的束缚能力较强。The primary objective of this study is to investigate the evolution mechanism of CO_(2) breakthrough pressure in mudstone caprock under different effective stresses.This study specifically investigates the silty mudstone caprock in the Bohai Bay Basin,China,and conducted a series of experiments on breakthrough pressure and permeability under different effective stresses.Whereas,the evolution process of CO_(2) breakthrough pressure in mudstone caprock was investigated,and the mechanism of pore water film affecting the breakthrough pressure was discussed.The results of this study illustrate that during the CO_(2) injection process(reduction in effective stress on the caprock),the effective stress decreases from 27 MPa to 7 MPa,while the caprock permeability increases from 1.46×10^(-6)μm^(2) to 1.81×10^(-6)μm^(2).When the effective stress is 5.2 MPa,the minimum breakthrough pressure of caprock is 3 MPa,which exceeds the minimum sealing threshold of 2 MPa.The results of breakthrough pressure tests indicate that the caprock possesses effective sealing capability.The disjoining pressure and distribution characteristics of the pore water films are the main factors influencing the breakthrough pressure.The resistance of CO_(2) transport increases with increasing the separation pressure of the water films,leading to high CO_(2) breakthrough pressure.The pore throat radius of mudstone samples range from 0.1 nm to 2.5 nm in the Bohai Bay Basin,and the corresponding disjoining pressures of water films range from 5.2 MPa to 50 MPa.The water films has strong constraint ability on CO_(2) migration.

关 键 词：CO_(2)地质封存 粉砂质泥岩 有效应力 突破压力 水膜分离压力 盖层密闭性 

分 类 号：X701[环境科学与工程—环境工程]