地质封存条件下残余气形成过程的岩心驱替模拟实验研究
发布时间：2019-04-01 08:15
【摘要】：全球气候变暖已经严重威胁到了人类的生命财产安全,CO_2作为导致全球气候变暖的罪魁祸首之一,如何减少大气中的CO_2含量已经是人类亟需解决的科学问题。目前,进行CO_2地质封存已经是很多科学家认可的方法之一,而其中深部咸水含水层的CO_2封存是其重要的组成部分之一。深部咸水含水层的CO_2封存包括地层构造封存、水动力封存、束缚气封存、溶解封存、矿化封存等多种不同的封存机理。而束缚气封存的形成需经历两个过程:首先,在CO_2注入阶段在岩石孔隙中形成残余水;其次,当CO_2停注后,地层水回流,在岩石孔隙中会残留部分超临界CO_2,这部分残余气就形成了束缚气封存。本研究用去离子水及人工配置的17.5g/L和35g/LNaCl溶液、17.5g/LCaCl_2溶液在40℃8MPa条件下进行驱替实验模拟残余气的形成过程。残余气的形成过程模拟是在用上述4种溶液模拟形成残余水的基础上进行的。本实验使用的是均质、各项同性的人造亲水性岩心,该岩心为长柱状,规格80×50mm,孔隙度为0.139,渗透率为1.33mD。经过6h的气驱水实验,得到上面4种溶液的残余水饱和度随时间变化曲线及最终的残余水饱和度。对比各排驱实验得到的残余水饱和度曲线,我们发现,在一定的浓度范围内,岩心的残余水饱和度有随NaCl浓度增大而增大的趋势,但是当其浓度超过某值时,岩心的残余水饱和度反而会随NaCl浓度增大而减小;CaCl_2的存在对残余水形成过程的影响很小,其最终的残余水饱和度与去离子水很接近,而NaCl的存在对残余水形成过程有明显的影响。这表明,在地下深部咸水含水层中,以Na?Cl型水为主的咸水含水层相比于Ca?Cl型水为主的地下含水层,在CO_2注入阶段会形成更多的残余水,相应地,可注入的CO_2量更少。水驱气实验结果表明,NaCl的存在对残余气的形成过程有明显影响,并且残余气饱和度随着NaCl浓度增大而增大,CaCl2的存在也对残余气形成过程都有明显的影响,且NaCl溶液驱替实验的残余气饱和度大于CaCl_2溶液实验的残余气饱和度。这也表明,地下深部咸水含水层中的Na~+、Ca~(2+)、Cl~-的水含水层的束缚气封存量,以Na?Cl型水为主的含水层束缚气封存潜力比以Ca?Cl型水为主的含水层束缚气封存潜力大。
[Abstract]:Global warming has seriously threatened the safety of human life and property. As one of the leading culprits of global warming, how to reduce the content of CO_2 in the atmosphere has become a scientific problem urgently needed to be solved by human beings. At present, CO_2 geological storage is one of the methods approved by many scientists, and the CO_2 storage of deep salt water aquifers is one of its important components. The CO_2 storage of deep salt water aquifer includes formation structure storage, hydrodynamics storage, bound gas storage, dissolution storage, mineralization storage and so on. The formation of trapped gas seal needs to go through two processes: first, the formation of residual water in rock pores at the stage of CO_2 injection; Secondly, when the CO_2 is stopped, the formation water refluxes, and the residual gas of supercritical CO_2, will be retained in the rock pores, which leads to the formation of the trapped gas seal. In this study, deionized water and artificial 17.5g/L and 35g/LNaCl solutions, 17.5g/LCaCl_2 solution at 40 鈩，
本文编号：2451398
[Abstract]:Global warming has seriously threatened the safety of human life and property. As one of the leading culprits of global warming, how to reduce the content of CO_2 in the atmosphere has become a scientific problem urgently needed to be solved by human beings. At present, CO_2 geological storage is one of the methods approved by many scientists, and the CO_2 storage of deep salt water aquifers is one of its important components. The CO_2 storage of deep salt water aquifer includes formation structure storage, hydrodynamics storage, bound gas storage, dissolution storage, mineralization storage and so on. The formation of trapped gas seal needs to go through two processes: first, the formation of residual water in rock pores at the stage of CO_2 injection; Secondly, when the CO_2 is stopped, the formation water refluxes, and the residual gas of supercritical CO_2, will be retained in the rock pores, which leads to the formation of the trapped gas seal. In this study, deionized water and artificial 17.5g/L and 35g/LNaCl solutions, 17.5g/LCaCl_2 solution at 40 鈩，
本文编号：2451398
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