摘要
煤基CO_(2)地质封存是温室气体减排的重要方式,但也存在地下CO_(2)泄露的安全风险。为了评估煤基CO_(2)地质封存的安全性,采集沁水盆地南部胡底矿3号煤顶板泥质粉砂岩样品,模拟实验研究"CO_(2)-H_(2)O-岩"反应中柱状试样人工裂缝形貌、全岩矿物组成与CO_(2)导流能力变化。结果表明:方解石脉溶蚀、次生矿物充填与外部有效应力共同影响试样裂缝导流能力。原始渗透率为0.016×10^(-3)μm^(2)的低渗试样,方解石脉溶蚀导致实验前期渗透率升高;随着反应进行,有效应力主导下裂缝闭合,渗透率呈"先升后降"变化趋势;原始渗透率为3.785×10^(-3)μm^(2)的高渗试样,H_(2)CO_(3)不断溶蚀裂缝壁面长石等矿物,并产生高岭石等次生矿物混合充填于裂缝中,使渗透率持续降低。煤基CO_(2)地质封存过程中,较高的注入压力导致顶板产生人工裂缝;CO_(2)注入施工结束后,次生矿物充填及有效应力增大使裂缝导流能力快速下降,因此,煤中封存CO_(2)沿顶板裂缝长期泄露的风险较低。
Coal-based CO_(2) geological storage is an important way to reduce greenhouse gas emissions,but there is also a safety risk of underground CO_(2) leakage.In order to evaluate the safety of coal-based CO_(2) geological storage,the roof samples of No.3 coal seam in Hudi Coal Mine,southern Qinshui Basin were collected,and the changes of artificial fracture morphology,whole rock mineral composition and CO_(2) conductivity of columnar samples in"CO_(2)-H_(2)O-Rock"reaction were studied by simulation experiments.The results show that calcite vein dissolution,secondary mineral filling and external effective stress jointly affect the fracture conductivity.For the low permeability samples with original permeability of 0.016×10^(-3)μm^(2),calcite vein dissolution leads to the increase of permeability in the early stage of the experiment.As the reaction proceeds,the fracture is closed under the guidance of effective stress,and the permeability increases first and then decreases.For the high permeability samples with original permeability of 3.785×10^(-3)μm^(2),H_(2)CO_(3) continuously dissolves feldspar and other minerals on the fracture wall,producing kaolinite and other secondary minerals to fill the fracture,so that the permeability continuous to decrease.In the process of CO_(2) geological storage,high injection pressure leads to artificial roof fracture.After the completion of CO_(2) injection construction,the fracture conductivity decreases rapidly due to the filling of secondary minerals and the increase of effective stress,therefore,the risk of long-term leakage of CO_(2) in coal along the roof fracture is relatively low.
作者
朱世良
邵丽伟
周效志
曹煜彤
张琨
王建东
ZHU Shiliang;SHAO Liwei;ZHOU Xiaozhi;CAO Yutong;ZHANG Kun;WANG Jiandong(School of Resources and Geosciences,China University of Mining and Technology,Xuzhou 221116,China)
出处
《煤田地质与勘探》
CAS
CSCD
北大核心
2021年第3期128-132,139,共6页
Coal Geology & Exploration
基金
江苏省大学生创新训练计划项目(201910290286X)
贵州省地勘基金项目(208-9912-JBN-UTS0)
国家重点研发计划项目(2018YFB0605602-02)。
