多场耦合作用下钙芒硝三维孔隙结构及渗流模拟研究

3D Pore Structure and Seepage Simulation of Glauberite Under Multi-field Coupling

钙芒硝溶浸开采是一个多场耦合的过程,每个因素都会改变其连通性,从而影响其渗透特性。以钙芒硝为研究对象,利用显微CT技术和AVIZO三维重构软件,建立了不同温度淡水溶液作用后的钙芒硝细观孔隙结构三维模型,定量表征了其内部连通性的变化,并在此基础上,进行了细观尺度的渗流模拟,研究了不同温度淡水溶液作用后钙芒硝的渗透特性。研究结果表明:钙芒硝的连通度和渗透率均与温度呈正相关关系。35℃和65℃时钙芒硝内部的孔隙空间多以小孔吼、短吼道为主,连通性较差,渗流通道较为狭小;95℃时孔隙空间多以大孔吼、长吼道为主,连通性较好,渗流通道较为宽广;35℃到65℃渗透率增幅较小,仅为0.23μm2;65℃到95℃钙芒硝渗透率急剧增加,增幅为2.75μm^2。该研究结果对提高钙芒硝矿床的开采效率及层状盐岩溶腔储库的稳定性具有一定的指导意义。

The glauberite leaching mining is a multi-field coupling process,each factor will change its connectivity,thereby affecting its permeability.Taking the glauberite as the research object,the Micro-CT technology and AVIZO 3 Dreconstruction software were used to establish 3 D model of meso-pore structure of glauberite under the action of fresh water solution at different temperatures,and the change of internal connectivity was quantitatively characterized.On this basis,the seepage simulation of meso-scale was carried out to study the permeability characteristics of glauberite under the action of fresh water solution at different temperatures.The results show that the connectivity and permeability of glauberite are positively correlated with temperature.At 35℃and 65℃,the pore space of glauberite is mainly composed of small pore throat and short throat,and the connectivity is poor,and the seepage channel is narrow.At 95℃,the pore space is dominated by large pore throats and long throats,with good connectivity and wide seepage channels.The increase of permeability from 35℃to 65℃is small,only0.23μm2.The permeability of glauberite increases sharply from 65℃to 95℃with an increase of 2.75μm2.The research results have certain guiding significance for improving the mining efficiency of glauberite deposit and the stability of layered salt karst cavity reservoir.