【作者】 房琦；

【导师】 李义连；

【作者基本信息】 中国地质大学 ， 地下水科学与工程， 2014， 博士

【摘要】 由于大气中温室气体浓度的持续增长,导致全球气候变化,引发极端气候发生、极地冰川融化、海平面上升、海洋酸化和生物物种灭绝等,对生态系统和人类活动产生严重影响。应对全球气候变化、减少温室气体排放已成为全球人类共同面对且急需解决的生存问题。CO2作为最主要的温室气体,主要来源于化石燃料的燃烧,但目前问题在于中国能源结构仍以煤为主,且在未来四五十年内不会发生大的改变,短时期内完全舍弃化石燃料的使用是不现实的。面对CO2排放量大且持续增长现状,中国政府面临着严峻的碳减排压力。碳捕集、利用与封存技术(CCUS)作为一项短时期内有望实现化石能源大规模利用且实现低碳经济发展的新兴技术,将可能成为未来中国减少CO2排放和保障能源安全的重要战略技术选择。中国的沉积盆地以陆相沉积为主,陆相储层因其沉积和成岩过程的特殊性,绝大多数陆相沉积盆地中储层的孔隙度和渗透率,特别是渗透率值均偏低。研究CO2在中国普遍存在的陆相沉积低渗储层中的封存机理与注入能力以及可行的资源化利用方式,对于CCUS在中国的推广与应用具有重要意义。本论文以江汉盆地江陵凹陷高盐低渗卤水层和富钾卤水开发利用为背景,采用数值模拟的方法利用TOUGH2和TOUGHREACT模拟工具开展CO2的灌注储存与资源化利用研究,重点关注高盐低渗卤水层中CO2注入性问题及封存机理、高盐低渗地层CO2灌注能力评估与提高方法、卤水枯竭开采与CO2完整灌注储存耦合方案等方面的研究,采用的研究方法和得到的主要结论如下：对于高盐度卤水层中的CO2灌注储存,注入井周围发生的盐沉淀对注入性产生显著影响。通过对咸水流速曲线分段解析研究了盐度和注入速率耦合毛细压力对盐沉淀量的影响,研究结果表明：(1)低毛细压力作用下,盐固体饱和度发生明显增加,仍与咸水盐度存在着显著的线性关系。盐固体饱和度在距井孔径向和垂向距离上的分布呈现显著的不均一性,持续的咸水回流带入的盐分是导致盐沉淀量变化的主要原因。(2)高毛细压力作用下,初始的残余液体饱和度和咸水的盐度不再是控制岩盐沉淀量的主导因素,即使是低盐度的咸水层,盐沉淀固体也可完全堵塞岩石孔隙。通过液体流速曲线分段解析,发现较高的毛细压力虽会提高咸水滞留作用,但持续的咸水回流带入的盐分对注入性严重受损起着致命作用。(3)盐沉淀量还受到注入速率的控制,随注入速率的升高而降低。即便是在低毛细压力作用下,较低的CO2注入速率也会造成严重的盐沉淀效应,原因在于较低的注入速率延长了咸水回流的时间,显著增加了毛细压力作用下的咸水回流量。因此,高盐度卤水层中以较高的速率注入可以减轻盐沉淀的影响。矿物捕集作为最安全有效的CO2封存机制,研究和评价特定和不同地质背景下不同岩石类型的CO2矿物封存潜力对于丰富CO2地质封存捕集机理和评估V地质储存中长期储存风险与安全性具有重要意义。以江汉盆地江陵凹陷富石英类砂岩类型为例,通过批量地球化学数值模拟的方法,以Na+、Al3+、Ca2+、Mg2+、Fe2+等关键离子的来龙去脉为主线,开展关键性矿物敏感分析,揭示石英类砂岩矿物捕集模式,评估长期储存风险及安全性,并设置不同卤水盐度,对比卤水盐度对矿物封存潜力的影响,得到结论如下：(1)针对含方解石(和/或石膏)、绿泥石、钾长石、钠长石的石英砂岩中CO2的矿物捕集,绿泥石溶解提供的Fe2+、Mg2+与方解石、硬石膏溶解提供的Ca2+反应形成铁白云石,富Mg2+条件下铁白云石可长期稳定存在,否则发生溶解转化为方解石和菱铁矿,提供的Mg2+支援伊利石沉淀。Mg2+富足条件下可生成菱镁矿,但菱镁矿的沉淀量比较有限,主要是因为Mg2+是伊利石和蒙脱石形成的必要组分。酸性条件下对Mg2+的优先消耗级别为伊利石>蒙脱石>铁白云石>菱镁矿。富铁镁条件下铁白云石和菱镁矿是主要的碳酸盐矿物捕集形式,富铁贫Mg条件下则为菱铁矿、方解石。尽管绿泥石、钾长石和钠长石溶解会产生大量的AlO2-,但大部分AlO2-会被粘土矿物如伊利石、蒙脱石、高岭石的生成消耗掉,即便是富Na+环境,早先沉淀的片钠铝石也会因水溶液中AlO2-供应不足而发生溶解,酸性条件下对AlO2-的优先消耗级别分别为伊利石>蒙脱石>高岭石>片钠铝石。然而当粘土矿物的溶解沉淀达到平衡时,钠长石向片钠铝石的稳定交替将成为主要的CO2矿物捕集形式。有Mg2+稳定供应的环境中,钾长石完全转化为伊利石,基本不具备矿化捕集CO2的潜力,另外富K+、Mg2+地层水,也将有利于伊利石的生成,消耗大量的Mg2+和AlO2-,从而不利于铁白云石、菱镁矿和片钠铝石等碳封存矿物的稳定存在。(2)盐度对CO2矿物捕集的能力主要取决于钾长石的初始含量,水溶液中较高的Na+浓度会抑制早期钠长石的溶解,形成较低的pH缓冲环境,然而酸性环境并不易于蒙脱石的生成,但不会对伊利石产生影响,如矿物组成中钾长石含量较高时,较低的pH环境可促进钾长石的溶解,提供更多的K+支援伊利石沉淀,当K+不再是限制伊利石沉淀的离子时,CO2矿物捕集的能力便随着盐度的升高而降低；如矿物组成中钾长石含量较低,伊利石沉淀量受到限制,便会促进钠长石向片钠铝石的转化,CO2矿物捕集的能力便随着盐度的升高而升高。针对江汉盆地江陵凹陷该类高盐分、低渗透且富碳酸盐岩的砂岩储层特点,我们采用数值模拟的方法考察了预注入淡水、微咸水、CO2饱和溶液和稀盐酸溶液以及水力压裂等不同方案对盐沉淀的沉降机率以及对CO2注入性的提升效果,得到结论如下：(1)注入淡水、不同盐度的微咸水溶液均可不同程度地缓解CO2注入过程中井孔周围的盐沉淀问题,淡水或微咸水的注入量越大,效果自然越好,但涉及经济成本,需权衡两者的利益关系,寻找最佳的注入量。(2)注入CO2饱和溶液或稀盐酸溶液,不仅可有效缓解盐沉淀问题,而且使得注入井附近的方解石和石膏发生溶解,明显提高注入井周围的孔渗值,从而提高CO2的注入性,但由于储层本身的低渗透性,酸性溶液的迁移影响距离毕竟有限,短时间内较难实现CO2注入速率的大幅度提高。(3)通过水力压裂工程措施可有效提高低渗储层中CO2的注入性,主要取决于压裂的裂缝长度和压裂程度。裂缝越长,注入速率越高,两者服从非常显著的指数增长关系；压裂程度越高,地层渗透率越大,注入速率也越高,但提升幅度不是很高。增加注入井周围压裂的裂缝数目,也可提高CO2的注入性,但其提升效果不如相同裂缝长度的单条裂缝的提升效果,考虑是受到注入井井壁和储层的有效接触而积重叠效应的影响。(4)对于单个垂直井,通过水力压裂或注酸压裂等工程措施对储层加以改造,并采取多层注入的方式,在低渗储层中实现数十万吨CO2的年注入量是可能的。对于多级砂泥岩互层系统中的CO2注入性与封闭性研究,我们建立了五种不同的砂泥岩互层(A[(S100+M100)×1]、B[(S50+M50)x2]、C [(S20+M20)x5]、D [(S10+M10)×10]、E[(Es-6钻孔)×7])模型,研究结果表明：CO2的注入能力与封闭性能明显受到不同砂泥岩互层的影响,随着砂泥岩互层的增多变薄而降低,砂泥岩互层中厚度较薄的泥隔层不能担当独立的封闭盖层；对于多层砂泥岩互层地层,合理地布设注入井射孔长度与位置可以获取经济投入与效益产出的最大化。江陵凹陷盐盆内古近系古新统沙市组和始新统新沟咀组含盐系赋存大量高温富钾卤水资源,构成湖北荆州颇具优势的液体矿产资源。以江汉盆地江陵凹陷深层富钾卤水层为对象,采用数值模拟的方法,建立三维均质多井模型,研究单一工业化卤水开采模式下卤水开采效率以及可能诱发的环境地质问题以及CO2地质储存联合卤水开发模式下的潜在耦合优势以及耦合过程优化,得到结论如下：(1)对于单一工业化卤水开采,其单井开采效率随着开采时间大幅度降低,而且增加卤水开采井的数目并不能达到卤水开采的效率与总开采量的目的,反而会增加经济成本。大量抽取地下卤水,开采前后巨大的压力差不仅会破坏原有流体与周围介质的压力平衡,引起介质压密、体积缩小,从而诱发地面下沉,而且使得上覆水文地质单元与目标开采层之间发生不同程度地越流泄露,无论泥岩隔层的渗透性的强弱,产生不良环境影响。(2)CO2地质储存联合卤水开采技术可有效地调控区域地层压力平衡,显著增强卤水的单井开采效率和总开采量,提高CO2单井注入速率和总储存量,并可有效地防控目标开采或注入层与上覆地质单元之间越流的发生,无论泥岩隔层的渗透性的强弱,降低泄露风险。定压注入方案明显优越于定速注入方案。定压注入模式下的9口抽卤井与4口注气井的耦合方案在压力调控、卤水开采效率、CO2注入性与储存量以及降低泄露风险各方面表现最佳。(3)改变灌注压力和采用完整卤水开采井开采方案可有效提高卤水开采效率和CO2灌注能力,但应控制在井口周围压力可承受范围内；减少布井间距和采用三角布井方案对卤水开采效率和CO2灌注能力的提升效果不显著,可根据具体场地地形和项目目标进行合理布局；减少卤水开采井的数目使得卤水开采总量和CO2灌注能力产生明显降低,抽水井和注气井之间的井群环绕构成一个相对独立的隔间,即使位于封闭角落的抽水井也对整个系统的效率协调起有重要作用。更多还原

【Abstract】 The continuing growth in the concentration of greenhouse gases has leaded to global climate change which brings the side environmental effects such as extreme weather, melting polar ice, rising sea levels, ocean acidification and species extinction and has a serious impact on the ecosystems and human activities. Therefore, dealing with climate change and reducing the emission of greenhouse gas has become the survival problem global human must confront together and urgent need to be solved. CO2, as the major member of greenhouse gas, mainly comes from the burning of fossil fuels. There is a problem, however, that the energy structure in China is still dominated by coal and will have no change in the following40or50years. Therefore, it is unpractical to completely abandon the use of fossil fuels in a short time. The Chinese government is facing severe pressure on carbon emission in the face of large CO2emissions and continuing growth. Carbon capture, utilization and sequestration (CCUS) is a new emerging technology to be expected to achieve large-scale use of fossil fuels and meanwhile developing low-carbon economy in a short time. It is mostly likely to be the important strategic technology for the future development of China with the purpose of reducing CO2emissions and guaranteeing energy security at the same time.The vast majority of sedimentary basins in China belong to continental sedimentary basins, with the continental reservoir characterized by low porosity and low permeability, permeability in particular, because of the special nature of sedimentary and diagenetic processes. It will be of great significance for the promotion and application of CCUS in China to study the sequestration mechanism and injection capacity as well as feasible ways of resource utilization of CO2geological storage in the ubiquitous low-permeability reservoirs of continental sedimentary basins. In the present work, numerical simulation method was carried out to investigate the CO2injection, storage and utilization using TOUGH2and TOUGHREACT as simulation tools by choosing high-salinity and low-permeability aquifers and potassium-rich brine in Jiangling Depression of Jianghan Basin as the study area. Main research contents focus on CO2injectivity and sequestration mechanism in the high-salinity and low-permeability formations, methods to improve CO2injection rate in the high-salinity and low-permeability formations as well as potential advantages and process optimization of exhaustive brine production combined with complete CO2storage. The method and main conclusions are as follows:For the injection of CO2in high salinity formations, salt precipitation around the injection well has a significant impact on CO2injectivity. Numerical simulation was carried out to investigate the effect and mechanism of capillary pressure couple with salinity and injection rate on salt precipitation during supercritical CO2injection into the deep saline aquifer of Jiangling Depressin in Jianghan Basin. The results are shown as follows:(1) With low capillary pressure, salt precipitation is in a significant linear relationship with salinity. From the solid saturation profile of radial and vertical distance from the wellbore, we find that the imbibition of additional salt from capillary backflow is the main source of the increased salt precipitation.(2) With high capillary pressure, the initial salinity is no longer the dominant factor controlling the solid saturation. Even in the formation with low salinity, salt precipitation can continuously accumulate near the injection well until it completely blocks the pore throats which do not permit the fluid movement. After the subsection analysis of the liquid flow curve, we find that in spite of the enhanced salt precipitation under the retention, additional salt imbibition from the strong capillary backflow is fatal to severe injectivity impairment for high capillary case.(3) In addition, salt precipitation is highly controlled by injection rate. The higher injection rate, the lower salt precipitation will be. Even for the low capillary case, injection of CO2with a low rate can still lead to severe salt precipitation for the reason that low CO2flow prolongs the backflow of brine under the force of capillary pressure. Therefore, injection of CO2with high rate can effectively mitigate the effect of salt precipitation.Since mineral trapping is the most effective and safety sequestration mechanism of CO2, it is very meaningful to investigate and evaluate the CO2mineral trapping capacity of different rock types under specific and different geological conditions for the richness of CO2geological sequestering mechanisms and assessment method of the long term storage risk and safety of CO2geological sequestration. This paper takes the quartz-rich sandstone of Jiangling depression in Jianghan basin for example, through the batch geochemical simulation method, based on the cause and effect of the critical ions such as Na+, Al3+, Ca2+, Mg2+, Fe2+and so on, carries out the sensitivity analysis of critical minerals, explores the mineral capture mode of quartz sandstone, and evaluates the safety of long term storage risks, in the same time, sets up the different reservoir salinity to compare the salinity influence on mineral capturing capacity, the conclusions are as follows:(1) Mineral trapping of CO2for quartz sandstone which contains of calcite (and/or gypsum), chlorite, k-feldspar, albite, Fe2+, and Mg2+dissolved from chlorite can react with Ca2+that dissolved from calcite/gypsum to produce ankerite which can be stable for long time under the condition of rich Mg2+, otherwise dissolves into calcite and siderite and the providing Mg2+can help in the precipitation of illite. Magnesite can be generated under the condition of rich in Mg2+, but its precipitation amount is limited due to the reason that Mg2+is the necessary component for the formation of illite and smectite. The minerals order for the consumption of Mg2+in acid condition is illite>smectite>ankerite>magnesite. Ankerite and magnesite is the main form of carbonate mineral capture for the rocks rich in Mg2+and Fe2+, while it is ankerite and calcite for the rock typre rich in Fe2+but poor in Mg2+Although the dissolve of chlorite, k-feldspar and albite can provide with large amount of AlO2-, the majority of AlO2-will be consumed for the generation of clay minerals such as illite, smectite, kaolinite, even for the rock rich in Na+, the dawsonite precipitated earlier will also dissolve because of the short supply of AlO2-. The mineral order for the consumption of AlO2-in acid condition is illite>smectite>kaolinite>dawsonite. However, when clay minerals come into the equilibrium of dissolution and precipitation, the stable alternation of albite and dawsonite will be the main CO2mineral capture mechanism. K-feldspar totally transfers into illite under the environment with Mg2+stable supply and basically loses the potential of CO2mineral trapping. Moreover, the formation water rich in K+and Mg2+is also benefit for the production of illite which can consume large amounts of Mg2+and AlO2-and hinder the stable existing of CO2trapping minerals such as ankerite, magnesite and dawsonite.(2) The influence of salinity on mineral CO2trapping capacity mainly depends on the initial mineral content of albite and k-feldspar. Higher concentration of Na+in aqueous solution will inhibit the early dissolution of albite and evolve into the lower pH buffer environment. However, acid environment is not helpful for the generation of smectite, but has no impact on illite. If the rock is rich in k-feldspar, the low pH can promote the dissolution of k-feldspar and provide with much more K+to support the precipitation of illite. When illite precipitation is no longer limited to K+, CO2mineral trapping capacity will decrease with salinity. If the rock is poor in k-feldspar, illite precipitation is restricted and the transformation of dawsonite from albite will be prompted. In this case, CO2mineral capturing capacity will increase with salinity.For the specific of the sand reservoir of Jiangling Depression in Jianghan basin which has high salinity, low permeability and is rich in carbonate rocks, we conduct a series of modeling studies to examine the salt precipitation and CO2injectivity in different cases such as pre-injection of fresh water, salt water, CO2saturation solution and diluted hydrochloric acid as well as hydraulic fracturing. Findings are as follows.(1) The injection of fresh water and salt water with different salinities can mitigate the salt precipitation which occurs near the CO2injection wellbore in different degrees. Larger injection of fresh water and salt water can certainly obtain greater improvement. But the economic cost has to be considered, therefore, finding a best injection rate of fresh water and salt water is a must.(2) The injection of CO2saturated solution or diluted hydrochloric acid solution not only mitigrate the salt precipitation, but also can dissolve the calcite and gypsum near-wellbore and increase the permeability which enhances CO2injectivity. However, due to the low permeability of the reservoir, the movement of the acid solution is limited. It is difficult to achieve impressive promotion for CO2injection rate within a short time. (3) Hydraulic fracturing can enhance CO2injectivity effectively, mainly depending on the length and width of the fracture. The data shows obvious exponential growth in the length of the fracture with the injection rate. Improving fracturing permeabilitycan also increases the injection rate, but the improvement room is not so obvious. Giving more fractures near-wellbore can also improve CO2injectivity, but the increase is less than that of a single fracture with the same length. It is maybe caused by the eclipsing effect of the effective contact area between the sidewall of the injection well and the reservoirs.(4) For singe vertical well, it is possible to inject hundreds of1000t of CO2into low permeability reservoirs in one year through reservoir fracturing and several sandstone layers.For the investigation on CO2injectivity and containment in the sandstone system consisting of multiple interbedded sandstone and mudstone, we built5different models such as (A [(S100+M100)×1], B [(S50+M50)x2], C [(S20+M20)x5], D [(S10+M10)×10], E [(Es-6real drilling)x7]). The results show that the injectivity and containment of CO2is obviously affected by interbedded sandstone and mudstone, and decrease with the increase of the interbedded sandstone and mudstone. The thin interbedded mudstone cannot be able to act as independent caprock. In addition, the reasonable design in the opening of injection well and location can obtain the maximum benefit on ecology investment and beneficial output.As a salt lake rift basin, Jiangling depression is rich in large hyperthermal potassium-bearing brine in Shashi Formation and Xin Gouzui Formation of Paleocene period. This is valuable liquid mineral resource for Jinzhou city in Hubei province. Taking the potassium-bearing brine formation of the Jiangling depression in Jianghan basin as research objective, we build a3-D homogeneous model with multiple wells to study the efficiency of the only industrial-scale brine production and the environmental geological problems which may occur during the production. Then simultaneous brine extraction and CO2storage is proposed researched and optimized. Results that have been obtained are as follows.(1) For only industrial-scale production of brine, the production rate of single well declines significantly with time, and multiple wells of brine production with higher economic cost are also unable to obtain higher efficiency. In addition, the tremendous pressure difference not only breaks the balance of the fluid and the medium which may not only seduce land subsidence but also cause the leakage between the target reservoir and the overlying formation, mitigating the leakage risk regardless of the permeability of the confining bed.(2) Simultaneous brine extraction and CO2storage can not only effectively regulate the region pressure balance of the storage formation, significantly enhance the brine production capacity and CO2injectivity as well as the storage capacity, but also can effectively avoid the leakage between the target reservoir and the overlying formation, mitigating the leakage risk regardless of the permeability of the confining bed. The constant pressure injection scheme is much superior to the constant rate injection scheme. The simultaneous brine production of nine wells and CO2injection of four wells under the constant pressure injection scheme act best in all respects of pressure regulation, brine production efficiency, CO2injectivity and storage capacity as well as leakage risk mitigation. (3) Several ways to further optimize the combined strategy are investigated and the results show that increasing the injection pressure and adopting fully penetrating production wells can further significantly enhance the combined efficiency within the pressure near-wellbore under control. Meanwhile there is no obvious promoting effect by shortening the well spacing and using the triangular pattern of well placement, but on the basis of the specific site terrain and project objectives, a reasonable layout of wells can also be obtained. On the contrary, the reduction of the brine production wells decreases the brine production capacity and CO2injectivity, due to that the wells group composes a relatively independent unit so that every single production well is important for the whole system’s efficiency.更多还原