二氧化碳羽流地热系统水-岩-气相互作用:以松辽盆地泉头组为例

Water-Rock-Gas Interaction of CO_2-Plume Geothermal System in Quantou Formation of Songliao Basin

二氧化碳羽流地热系统(CPGS)是利用CO2地质储存场地进行地热能开发的一种工程技术,也是整合CO2减排与开发深部地热资源的理想方式。但伴随着对深部地热的提取,注入储层的超临界CO2使深部咸水的pH值降低,导致周围岩体产生溶解和沉淀,从而引起孔隙度、渗透率等地层物性的变化,最终改变系统的生产能力和净热提取效率。以松辽盆地泉头组为目标储层,采用室内实验、数值模拟等技术手段,通过实验和数值计算结果的对比,揭示系统水-岩-气相互作用对热储矿物组分的改变。研究结果显示:实验过程中矿物溶解对温度和盐度变化较为敏感,而受压力影响较小;在实验和模拟时间内发生溶解的矿物主要是长石类矿物,方解石在反应后全部溶解;石英、伊利石和高岭石的矿物组分体积分数有所增加,并有少量菱铁矿生成。

CO2 plume geothermal systems （CPGS ）is an engineering technology for integrating carbon geological storage with geothermal energy development.When the supercritical CO2 is injected into a deep reservoir,the pH of reservoir water will be decreased.The surrounding rock will be dissolved or precipitated,so the porosity and permeability of the formation will also be changed.Basedon a potential geothermal reservoir of Quantou Formation of Songliao basin,experiment and numerical simulation are used to investigate water-rock-gas chemical interaction.The research results show that the experimental process is more sensitive to temperature change,and less affected by pressure.This study will provide a theoretical basis and technical support to future CPGS project in China.