摘要
为了探究超临界二氧化碳注入咸水层后储层岩石的化学损伤规律,利用自制的恒温恒压超临界CO_(2)-水-岩石热流固化耦合试验系统,测试反应前后储层岩心矿物组分、微观结构、矿物元素及氧化物的变化,分析反应溶液pH值和钙、钾、镁离子浓度的变化规律,研究反应前后储层岩心试样质量、单轴抗压强度、弹性模量、泊松比等物理力学参数演化规律,揭示超临界二氧化碳注入咸水层后储层岩石的化学损伤特征和力学性质劣化规律。研究结果表明:随着反应时间延长,方解石和钾长石的质量分数逐渐减少,钙元素、钾元素及其氧化物的质量分数也随之减少,试样表面粗糙度增大,产生了溶蚀孔;反应溶液的pH值从7.19降至5.68,方解石溶解速率最快,其次是钾长石,最后是伊利石;反应时间内,试样的质量溶蚀率、泊松比逐渐增大,单轴抗压强度和弹性模量逐渐减小。此外,试样的单轴抗压强度与化学作用时间呈指数函数关系,弹性模量、泊松比与化学作用时间呈三次多项式函数关系,据此建立了化学损伤作用下储层岩石的强度预测模型。以弹性模量为损伤变量,得到了岩心的单轴抗压强度和损伤变量之间的关系,揭示了储层岩石的化学损伤机制。
To investigate the chemical damage mechanism of reservoir rocks following the injection of the supercritical CO_(2)into a saline aquifer,a self-made thermal-hydrological-mechanical-chemical coupled experimental system of the supercritical CO_(2)-water-rock at constant temperature and pressure is established,which is used to test the changes of mineral components,microstructure,mineral elements and oxides of reservoir rocks before and after the reaction.And the changes of pH value and concentrations of Ca^(2+),K^(+),Mg^(2+)ions of the reaction solution are analyzed.Furthermore,this study focuses on elucidating the evolutionary patterns of physical and mechanical parameters,including mass,uniaxial compressive strength,elastic modulus,and Poisson’s ratio.The experimental study reveals the chemical damage characteristics and mechanical property degradation of reservoir rocks after the supercritical CO_(2)injected into a saline aquifer.The results show that the mass fractions of calcite and K-feldspar decrease gradually as the reaction time increases,and those of calcium,potassium and their oxides also decrease,resulting in the presence of corrosion cavities.The pH value of the reaction solution decreases from 7.19 to 5.68,and the corrosion rate of calcite is the fastest,followed by that of K-feldspar,and finally that of illite.During the reaction time,the mass corrosion rate and Poisson's ratio of reservoir rocks gradually increase,and the uniaxial compressive strength and elastic modulus gradually decrease.The uniaxial compressive strength of reservoir rocks shows an exponential function relationship with reaction time.The elastic modulus and Poisson's ratio show a cubic polynomial function relationship with reaction time.The strength prediction model for the reservoir rocks under chemical reaction is established.Taking the elastic modulus as the damage variable,the relationship between the uniaxial compressive strength and the damage variable of reservoir rocks is obtained,which reveals the chemical damage mechanism of reservoir rocks.
作者
梁冰
李磊磊
郝建峰
孙维吉
秦冰
刘强
郭春雨
LIANG Bing;LI Leilei;HAO Jianfeng;SUN Weiji;QIN Bing;LIU Qiang;GUO Chunyu(School of Mechanics and Engineering,Liaoning Technical University,Fuxin 123000,China;College of Mining,Liaoning Technical University,Fuxin 123000,China)
出处
《岩土工程学报》
北大核心
2025年第6期1123-1131,共9页
Chinese Journal of Geotechnical Engineering
基金
内蒙古自治区科研项目(2021ZD0034-2)
国家自然科学基金面上项目(52074143)
国家自然科学基金青年基金项目(52304029)
辽宁工程技术大学学科创新团队资助项目(LNTU20TD-11)。
关键词
超临界二氧化碳
地质封存
矿物组分
化学损伤
力学参数
损伤变量
supercritical CO_(2)
geological storage
mineral component
chemical damage
mechanical parameter
damage variable
