【摘要】：全球氣候變暖已經(jīng)嚴(yán)重威脅到了人類的生命財產(chǎn)安全,CO_2作為導(dǎo)致全球氣候變暖的罪魁禍?zhǔn)字?如何減少大氣中的CO_2含量已經(jīng)是人類亟需解決的科學(xué)問題。目前,進(jìn)行CO_2地質(zhì)封存已經(jīng)是很多科學(xué)家認(rèn)可的方法之一,而其中深部咸水含水層的CO_2封存是其重要的組成部分之一。深部咸水含水層的CO_2封存包括地層構(gòu)造封存、水動力封存、束縛氣封存、溶解封存、礦化封存等多種不同的封存機(jī)理。而束縛氣封存的形成需經(jīng)歷兩個過程:首先,在CO_2注入階段在巖石孔隙中形成殘余水;其次,當(dāng)CO_2停注后,地層水回流,在巖石孔隙中會殘留部分超臨界CO_2,這部分殘余氣就形成了束縛氣封存。本研究用去離子水及人工配置的17.5g/L和35g/LNaCl溶液、17.5g/LCaCl_2溶液在40℃8MPa條件下進(jìn)行驅(qū)替實驗?zāi)M殘余氣的形成過程。殘余氣的形成過程模擬是在用上述4種溶液模擬形成殘余水的基礎(chǔ)上進(jìn)行的。本實驗使用的是均質(zhì)、各項同性的人造親水性巖心,該巖心為長柱狀,規(guī)格80×50mm,孔隙度為0.139,滲透率為1.33mD。經(jīng)過6h的氣驅(qū)水實驗,得到上面4種溶液的殘余水飽和度隨時間變化曲線及最終的殘余水飽和度。對比各排驅(qū)實驗得到的殘余水飽和度曲線,我們發(fā)現(xiàn),在一定的濃度范圍內(nèi),巖心的殘余水飽和度有隨NaCl濃度增大而增大的趨勢,但是當(dāng)其濃度超過某值時,巖心的殘余水飽和度反而會隨NaCl濃度增大而減小;CaCl_2的存在對殘余水形成過程的影響很小,其最終的殘余水飽和度與去離子水很接近,而NaCl的存在對殘余水形成過程有明顯的影響。這表明,在地下深部咸水含水層中,以Na?Cl型水為主的咸水含水層相比于Ca?Cl型水為主的地下含水層,在CO_2注入階段會形成更多的殘余水,相應(yīng)地,可注入的CO_2量更少。水驅(qū)氣實驗結(jié)果表明,NaCl的存在對殘余氣的形成過程有明顯影響,并且殘余氣飽和度隨著NaCl濃度增大而增大,CaCl2的存在也對殘余氣形成過程都有明顯的影響,且NaCl溶液驅(qū)替實驗的殘余氣飽和度大于CaCl_2溶液實驗的殘余氣飽和度。這也表明,地下深部咸水含水層中的Na~+、Ca~(2+)、Cl~-的水含水層的束縛氣封存量,以Na?Cl型水為主的含水層束縛氣封存潛力比以Ca?Cl型水為主的含水層束縛氣封存潛力大。
[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，

本文編號：2451398