不同成分盐水驱CO2的残余气饱和度

CO₂在地下深部咸水含水层地质封存的多种封存机理中,束缚气封存的潜力很大,可占封存总量的30%左右。残余气饱和度是评价束缚气封存量的一个十分重要的参数。通过测定不同成分盐水驱CO₂的残余CO₂饱和度,对不同咸水含水层的束缚气封存潜力进行定性的评价,进一步为深部咸水含水层的CO₂封存量的评估提供了参数依据。同时也对深部咸水含水层CO₂地质封存的工程选址和目标含水层的选择具有一定的指导和借鉴意义。实验使用饱和CO₂的蒸馏水、NaCl溶液、CaCl₂溶液以及NaCl和CaCl₂的混合溶液(质量比1∶1),溶液质量浓度都为10%,驱替饱和CO₂的岩心,最后计算残余CO₂饱和度。饱和CO₂的溶液驱替CO₂的过程可以分为两个阶段：活塞式驱替和携带式驱替。实验结果显示,4种液体驱替实验的残余CO₂饱和度由小到大依次为：蒸馏水、混合溶液、NaCl溶液、CaCl₂溶液。结果表明：在界面张力和流体粘性共同作用下,界面张力对岩心中CO₂驱替效果的影响起主导作用;这3种类型盐水中,Cl-Ca型水束缚气封存潜力最大,其次是Cl-Na型水,Cl-Na·Ca型水最差。     

CO2强化煤层气产出与其同步封存实验研究

长期以来针对CO₂-ECBM已做了大量研究工作,然而有限的工业试验没能达到预期目的,使得这一煤层气强化技术推广应用欠缺。近些年随着各国碳中和路线的制定,CO₂封存逐渐受到重视,煤储层可否作为CO₂的封存空间、可否实现CO₂驱替CH₄和封存同步进行,又重新回归人们的视野。为此,以新疆准南区块目标煤层样为研究对象,采用不同CO₂与CH₄混合比例气体进行煤的吸附/解吸实验,探索混合气体比例对CO₂-ECBM和CO₂吸附封存潜力的影响。结果表明,随着混合气体CO₂比例减少,CH₄驱替效果降低,其中40%CH₄+60%CO₂混合气体的CO₂残余量最多,在解吸至0.7 MPa时已有83.05%的CH₄产出,而83.62%的CO₂吸附残余在煤中,表明其C...     

基于核磁共振和磁共振成像的低渗透岩芯CO2-H2O两相驱替特征研究

致密岩石的孔隙结构特征对CO₂和水之间的驱替行为以及CO₂相的流动特征具有重要影响,且残余水饱和度最终将影响碳封存的效率和安全性,因此,深入探究致密岩芯CO₂-H₂O两相驱替特征具有重要意义。利用取自鄂尔多斯盆地深部储层的天然低渗透岩芯,利用核磁共振(NMR)及磁共振成像(MRI)技术对其内部的气液两相驱替特征及其影响因素进行了可视化研究。在将岩芯孔隙结构进行定性和定量化表征后,可知不同的驱替模式与岩芯孔隙结构密切相关：具有较强非均质性和各向异性的岩芯更有利于指进现象的发生,具有较大孔隙度和较高渗透率的岩芯则呈现活塞式驱替模式。指进现象有助于气相的运移,会造成气相的提前突破,导致较高的残余水饱和度及较低的驱替效率。     

热力耦合条件下超临界CO2驱替煤层CH4实验

为提高煤层CH₄抽采效率,利用自主研发的实验系统,模拟超临界CO₂在深部煤层中驱替CH₄的过程,开展了不同温度和注入压力条件下原煤试样中超临界CO₂渗流、吸附及驱替CH₄实验。结果表明:在恒定温度条件下,随着超临界CO₂注入压力逐渐增大,煤体渗透率提高,CO₂吸附量增加。超临界CO₂注入压力和温度对驱替效果影响显著。不同温度条件下,当超临界CO₂注入压力从8 MPa增至12 MPa,CH₄驱替量平均增长了0.076 cm3/g,CH₄驱替效率增加了17%~23%,超临界CO₂置换体积比呈线性递减趋势;相同注入压力条件下,温度每升高10℃,驱替效率平均增加8%,置换体积比平均下降0.5。研究结果为高效抽采煤层CH₄和实现CO₂封存提供理论依据。      

CO2地质封存与利用示范工程进展及典型案例分析

CO₂地质封存与利用工程实施具有十分可观的CO₂减排效果,推行CO₂地质封存与利用项目对于缓解全球气候变暖、践行我国可持续发展战略具有重要意义。梳理了目前主要的CO₂地质封存与利用方式,统计了全球范围内的CO₂地质封存与利用示范工程,重点介绍了我国典型CO₂地质封存与利用示范工程案例,并对CO₂地质封存与利用技术发展趋势进行了展望。目前,CO₂地质封存与利用方式主要包括CO₂驱油封存、CO₂驱替煤层气封存、CO₂咸水层封存、CO₂枯竭油气藏封存、CO₂驱替页岩气封存、CO₂深部咸水层封存与采水、CO₂封存与增强型地热发电、CO₂封存与铀矿地浸开采等;国内外在CO₂驱油封存、CO₂咸水层封存以及CO...     

不同含水性无烟煤CO2吸附行为及其对地质封存的启示

深部煤层CO₂地质封存是助力“碳达峰碳中和”战略的重要途径,煤层含水性对以CO₂吸附封存为主的深部煤层CO₂地质封存能力影响显著。以无烟煤为例,开展了45℃下干燥、平衡水、饱和水煤样高压CO₂等温吸附实验,校正了饱和水煤样过剩吸附曲线,利用改进的D-R吸附模型拟合得到三者吸附能力与吸附热,对比了不同含水条件下CO₂绝对吸附曲线,阐释了饱和水增强无烟煤吸附能力的微观作用机理。结果表明:(1)干燥、平衡水、饱和水煤样CO₂吸附能力分别为56.72、45.19和48.36 cm3/g,吸附热分别为29.42、26.23和27.24 kJ/mol。(2) CO₂密度小于0.16 g/cm3(6.48 MPa)时,无烟煤CO₂绝对吸附量大小顺序为干燥煤样、饱和水煤样和平衡水煤样,而CO₂进入超临界状态后,顺序变为饱和水煤样、干燥煤样和平衡水煤样。(3)水分子优先占据高能吸附位是平衡水煤样吸附能力减弱的主要原因,而煤?水体系与CO₂相互作用强于CO₂与H₂O竞争吸附下的煤?CO₂相互作用是饱和水煤样在CO₂超临界阶段吸附能力高于干燥煤样的根本原因。(4)吸附封存是煤层CO₂地质封存的主要形式,深部煤储层条件下,煤层饱和水对超临界CO₂增储作用更为明显,高压注水是提高深部煤层CO₂地质封存潜力,改善煤储层渗透性的有效手段。      

沁水盆地柿庄北深部煤层水平井CO2注入参数研究

基于CO₂的吸附能力大于CH₄的原理,向深部煤层中注入并封存CO₂同时置换驱替CH₄增加煤层气井产量,具有环境和经济双重效益。研究深部煤储层特征,通过气、水两相多组分,单孔和双孔模型的三维储层数值模拟技术,模拟不同井底压力下,完成注入量所需要的时间。优化后的注入施工参数为井口注入压力低于10MPa,注入速率低于47 L/min。根据数值模拟结果选定注入压力,注入结果与模拟连续注入时间一致,说明该方法可以有效地模拟注入压力和注入量之间的关系,保障CO₂注入施工安全有效。      

咸水层CO2地质封存地下利用空间评估方法研究

咸水层CO₂地质封存技术是我国实现碳中和目标的重要支撑技术,也是一项深部地下空间开发利用技术。咸水层CO₂地质封存工程利用的深部地下空间,需要在确定CO₂羽流、扰动边界和经济因素“三级边界”的基础上进行综合评估。以我国唯一的深部咸水层CO₂地质封存项目——国家能源集团鄂尔多斯碳捕集与封存(Carbon Capture and Storage, CCS)示范工程为实例,基于封存场地储层CO₂羽流监测以及扰动边界的推断预测结果综合评估,认为示范工程平面上4个1'×1'经纬度范围可作为地下利用空间平面边界,垂向上以纸坊组顶界(深度约958 m)为地下封存体顶部边界,以深度2 800 m为底板封隔层底界。提出的咸水层CO₂地质封存地下利用空间评估方法,能够为未来封存工程地下利用空间审批与监管提供一定参考,但也需要进一步结合已有法律法规及规模化封存工程实践完善提升。     

CO2注气压力对瓦斯扩散系数影响规律实验研究

煤层CH₄解吸效率低、扩散慢的特点严重制约着煤层瓦斯抽采的效率,为解决低透气性煤层瓦斯抽采困难的问题,选取晋城赵庄煤矿煤样,研究不同注气压力对驱替CH₄过程的影响以及驱替过程中CH₄扩散系数的变化规律,利用自主研发的CO₂驱替CH₄试验平台,在0.6、0.8、1.0 MPa等不同注气压力条件下分别进行CO₂驱替CH₄实验。结果表明:驱替压力越大,达到最大CH₄排放量的时间越短,CO₂突破时间越快,置换效率越大,驱替效果越好;CH₄气体驱替过程分为3个阶段,先急剧增加再缓慢增加最后保持平稳;在同一注气压力下,瓦斯扩散系数随时间呈先增大后减小的变化规律,注气压力为0.6、0.8、1.0 MPa时,瓦斯扩散系数的最大值分别为2.27×10-5、3.36×10-5、4.62×10-5 cm2/s。从实验结果可知,不同注气压力下,CO₂对CH₄主要起到驱替作用、置换吸附-解吸作用及稀释驱替作用;每个阶段的CH₄气体运移情况不同,根据实验阶段合理调整注气流量、压力等参数,使注驱技术搭配更高效。研究结果对CO₂深埋与瓦斯（煤层气）高效抽采具有理论指导意义。      

塔里木盆地奥陶系礁灰岩CO2地层构造封存能力参数实验研究

在所能实施CO2地质封存的场所中,含水层的封存潜力最大。而在影响封存量的各种机理中,地层构造封存是最基本的机制。本文提出了一种测定影响地层构造封存量的关键参数——残余水饱和度的实验方法,并将该方法实际应用于富含油气资源的塔里木盆地奥陶系礁灰岩。首先根据饱和称重法和渗透实验测得样品有效孔隙度和渗透系数分别为00283,556×10-9m/s。残余水饱和度的值是在40℃,8Mpa条件下,通过超临界CO2驱替饱水岩心实验得到,测定结果为0451。同时,还得到了超临界CO2驱替饱水岩心压力、流量变化特性。     

强边底水油藏特高含水期CO2吞吐差异挖潜技术研究

冀东油田浅层强边底水油藏已整体进入特高含水开发阶段,剩余油高度分散、含油饱和度不均,不同油井CO₂吞吐效果差异大,难以实现油藏整体高效开发。考虑到油藏含油饱和度不同,差异设计CO₂吞吐段塞组合及开发政策,改善CO₂吞吐开发效果是十分必要的。利用二维物理模拟及油藏数值模拟,研究不同CO₂吞吐方式控水增油机理,定量评价不同CO₂吞吐方式适应含油饱和度界限,建立不同含油饱和度下吞吐注采参数差异化设计图版。研究结果表明:剩余油饱和度介于0.47~0.50之间时,CO₂吞吐技术经济综合效果最优;剩余油饱和度介于0.43~0.47之间时,CO₂+堵剂吞吐方式最优;剩余油饱和度介于0.375~0.430之间时,CO₂+表活剂+堵剂吞吐方式最佳。上述研究成果对特高含水油藏CO₂吞吐差异设计精准挖潜剩余油,实现油藏整体高效开发具有重要意义。     

The Influence of Allogenic Water and Sulfuric Acid to Karst Carbon Sink in Karst Subterranean River in Southern Hu’nan

Evaluating the impact of allogenic water and sulfuric acid on karst carbon sink not only helps to improve the accurate calculation of soil CO₂ uptake by rock weathering, but also obtains a complete understanding of the global carbon cycle. Groundwater samples were collected from four karst subterranean rivers watershed within different lithology strata in Wushui Basin, upstream of Beijiang Basin, Hunan Province, for revealing the important impact of silicate weathering on hydrochemistry of groundwater. To estimate the contribution of soil CO₂ uptake by silicate weathering to CO₂ uptake by rock weathering, the Galy model was employed in this article. The important impact of sulfuric acid on CO₂ uptake by carbonate weathering resulting from the substitution of carbonic acid by protons from sulfuric acid was investigated. Our results showed that the concentration of Na⁺, K⁺ and SiO₂ in L01,L02 subterranean river with silicate strata in watershed were higher than that in L03,L04 subterranean river without silicate strata in watershed, which implied that the contribution of silicate weathering to Na⁺,K⁺ and SiO₂ was very important in watershed within silicate strata . The changeable equivalent ratio between (Ca²⁺+Mg²⁺) and HCO₃^- was 1.05 to 1.15, and the value of [Ca²⁺+Mg²⁺]/[HCO₃^-+SO₄^2-] was 0.99 to 1.08. The concentrations of Ca²⁺ and Mg²⁺ exceeded the equivalent concentrations of HC₃^-, and the excess of Ca²⁺ and Mg²⁺cations were compensated by SO₄^2-, which suggested that sulfuric acid has an important influence on carbonate dissolution. The contribution of soil CO₂uptake by silicate weathering to CO₂ consumption in L01 and L02 subterranean river were 3.36% and 2.22%, respectively, whereas the contribution in L03, L04 subterranean river were less than 0.50%, indicating that the contribution of soil CO₂ uptake by silicate weathering was important in the subterranean river basin within silicate strata. Due to the contributions made by sulfuric acid, the CO₂ consumption in four subterranean rivers decreased by 4.84%, 4.52%, 6.20%, 9.36%, respectively.     

松辽盆地幔源成因CO2气藏分布规律及控制因素

通过深部15s大剖面解译和典型CO₂气藏解剖,深入剖析了松辽盆地幔源成因CO₂气藏分布规律及控制因素。纵向上CO₂气主要富集在营城组火山岩和泉头组三、四段砂岩储层中。与深部热流体（热流底辟体和侵入体）直接相连的、控陷的、控制火山通道的铲式基底断裂控制着CO₂气藏呈串珠状分布的特征,断裂走向拐点、端点和侧列叠覆区控制了CO₂气出气点。深部热流体是CO₂气藏主要的气源。与之相衔接的基底断裂活动导致幔源岩浆充注盆地,同时携带的CO₂气释放进入早期喷发的火山岩中形成营城组火山岩CO₂气藏。基于控藏断裂多为断陷期和泉头组晚期-青山口组早期活动的基底断裂,推测营城组CO₂气藏主要成藏时期为泉头组晚期-青山口组早期。松辽盆地强烈的构造反转发生在明水组末期,挤压应力自南南东向北北西方向衰减的过程中,基底断裂复活形成正反转断层,CO₂气从热流底辟体中脱出上运而聚集在反转构造带上,断层式反转构造南部比北部发育,西部比东部发育,因此松辽盆地南部比北部、西部比东部CO₂气更富集。     

玄武岩CO2矿化封存潜力评估方法研究现状及展望

二氧化碳地质封存是实现减排增汇的重要技术选择,能够将CO₂长期、安全地封存在地下岩层中。常规的CO₂封存地质体包括地下深部咸水层和枯竭油气藏,玄武岩是近年来逐渐受关注的新一类CO₂封存地质体,进一步丰富和拓展了CO₂地质封存的技术手段和碳汇潜力。封存潜力评估是CO₂地质封存技术发展的重要基础工作之一,文章系统梳理国内外玄武岩矿化封存潜力的评价方法,对比分析各类方法的原理机制和应用情景,并以冰岛活动裂谷带玄武岩为例应用、对比各类方法。研究认为目前玄武岩矿化封存潜力评估方法一般包括三类：(1)单位矿化法：基于玄武岩单位体积或单位反应面积的固碳量开展潜力评估;(2)矿物置换法：基于玄武岩中可固碳矿物的总量开展封存潜力评估;(3)孔隙充填法：基于CO₂矿化后产生次生矿物所占岩石孔隙体积比例的上限值开展封存潜力评估。单位矿化法的评估数据需进行系统的实验分析,增加了潜力评估的难度。当玄武岩储层孔隙度较大、可固碳矿物含量相对较小时,矿物置换法较为合适;反之,孔隙充填法更...     

页岩储层物性参数对CO2不同封存机制及封存量的影响

CO₂增强页岩气开采技术(CO₂-ESGR)一方面可提高CH4产量,另一方面又可实现CO₂地质封存。为了分析页岩储层物性参数对CO₂封存机制的影响,文章以鄂尔多斯盆地延长组页岩为研究对象,采用CMG-GEM软件建立双孔双渗均质模型,分析了CO₂-ESGR中页岩储层垂直渗透率与水平渗透率之比(Kv/Kh)、含水饱和度和孔隙度对不同CO₂封存机制封存量的影响;并设计了27组正交试验采用极差分析法比较了三种因素的影响程度。研究表明,Kv/Kh在0.1～1范围增大会增加不同CO₂封存机制的封存量,封存总量最大可增加69.96%,其中吸附封存量最大可增加97.96%,受到影响最大;含水饱和度在0～0.9范围增大引起CO₂封存总量先增加后减小,封存总量最大可减少67.12%,其中溶解封存量最大可减少83.35%,范围波动最大;页岩储层孔隙度在0.1～0.99范围增大会导致CO₂封存总量减少,封存总量最大...     

Chemical Weathering and CO2 Consumption of Chishuihe River Basin,Guizhou Province

Carbon sink produced during rock weathering is critical to global carbon cycles. In this work, we analyzed the major ion chemistry of the Chishuihe River Basin, and the major ion composition of the Chishuihe River system and the principal component analysis was applied for estimating the weathering rate and atmospheric CO₂ consumption via the rock chemical weathering. The results demonstrated that the chemical composition of the river was dominated by Ca²⁺, Mg²⁺, HC and S. The average concentration(317.88 mg/L) of the total dissolved solids within the Chishuihe River was higher than the average value (65 mg/L) of world rivers. The Gibbs graph combining major ion element ratio analysis indicated that the catchment major ion composition mainly originated from rock weathering, primarily from carbonate weathering, sparsely from silicate weathering. Carbonate and silicate weathering contributed 70.77% and 5.03% separately to the dissolved loads. The anthropogenic and precipitation impact was limited. According to calculation based on principal component and the ion composition characteristics, the chemical weathering rate was 126.716 t/(km²·a), significantly higher than that of the Yellow River and Yangtze River, and also higher than the average rate of the global major rivers. The CO₂ consumption flux based on annual average runoff was 10.96×10⁹ mol/a, and the CO₂ consumption rate by chemical weathering was 5.79×10⁵ mol/(km²·a).     

世界气候变暖及二氧化碳埋存现状与展望*

由于CO₂大量排放而引起的全球气候变暖问题日趋严峻。21世纪环境保护受到国际社会高度关注,全球气温上升控制目标比工业革命前水平高2 ℃以内,因此必须采取积极有效措施。捕获和埋存废气中的CO₂是避免气候变化的有效途径之一,同时要求CO₂须埋存几百或几千年。埋存对环境产生的影响最小、成本较低且遵守国际法规。CO₂地下埋存的主要场所是枯竭的油气藏、深部的盐水储集层、不能开采的煤层和深海等。CO₂地下埋存可应对因能源需求增长和CO₂排放量增加带来的挑战,必将为全球资源及环境的高水平、高效益开发和可持续发展提供理论及实践依据。     

Effects of volcanic eruptions on the CO2 content of the atmosphere and the oceans: the 1996 eruption and flood within the Vatnajökull Glacier, Iceland

The October 1996 eruption within the Vatnajökull Glacier, Iceland, provides a unique opportunity to study the net effect of volcanic eruptions on atmospheric and oceanic CO₂. Volatile elements dissolved in the meltwater that enclosed the eruption site were eventually discharged into the ocean in a dramatic flood 35 days after the beginning of the eruption, enabling measurement of 50 dissolved element fluxes. The minimum concentration of exsolved CO₂ in the 1×10¹² kg of erupted magma was 516 mg/kg, S was 98 mg/kg, Cl was 14 mg/kg, and F was 2 mg/kg. The pH of the meltwater at the eruption site ranged from about 3 to 8. Volatile and dissolved element release to the meltwater in less than 35 days amounted to more than one million tonnes, equal to 0.1% of the mass of erupted magma. The total dissolved solid concentration in the floodwater was close to 500 mg/kg, pH ranged from 6.88 to 7.95, and suspended solid concentration ranged from 1% to 10%. According to H, O, C and S isotopes, most of the water was meteoric whereas the C and S were of magmatic origin. Both C and S went through isotopic fractionation due to precipitation at the eruption site, creating “short cuts” in their global cycles. The dissolved fluxes of C, Ca, Na, Si, S and Mg were greatest ranging from 1.4×10¹⁰ to 1.4×10⁹ mol. The dissolved C flux equaled 0.6 million tonnes of CO₂. The heavy metals Ni, Mn, Cu, Pb and Zn were relatively mobile during condensation and water–rock interactions at the eruption site. About half of the measured total carbon flood flux from the 1996 Vatnajökull eruption will be added to the long-term CO₂ budget of the oceans and the atmosphere. The other half will eventually precipitate with the Ca and Mg released. Thus, for eruptions on the ocean floor, one can expect a net long-term C release to the ocean of less than half that of the exsolved gas. This is a considerably higher net C release than suggested for the oceanic crust by Staudigel et al. [Geochim. Cosmochim. Acta, 53 (1989) 3091]. In fact, they suggested a net loss of C. Therefore, magma degassed at the ocean floor contributes more C to the oceans and the atmosphere than magma degassed deep in the oceanic crust. The results of this study show that subglacial eruptions affecting the surface layer of the ocean where either Mn, Fe, Si or Cu are rate-determining for the growth of oceanic biomass have a potential for a transient net CO₂ removal from the ocean and the atmosphere. For eruptions at high latitudes, timing is crucial for the effect of oceanic biota. Eruptions occurring in the wintertime when light is rate-determining for the growth of biota have much less potential for bringing about a transient net negative CO₂ flux from the ocean atmosphere reservoir.