温室气体排放量的增加，对人类的可持续发展造成了严重的影响。减少CO2的排放量是人类急需解决的问题。作为有效的CO2减排途径，二氧化碳地质封存技术发展前景乐观。地下咸水层在世界各地广泛分布，而且规模大，因此咸水层二氧化碳地质封存被认为是切实可行和最具发展前景的二氧化碳减排途径之一。CO2注入率和累积注入总量是衡量咸水层中CO2注入能力的有效因素，研究注入速率和注入总量的变化规律及提高措施是很有工程价值的，在很多区域，地层的低渗透性限制了CO2的注入能力。本文从理论研究出发，分析H2O-CO2-NaCl混合系统的特性；建立假定的三维多相流理想模型，应用TOUGH2/ECO2N模拟器，利用数值模拟分析在恒定注入压力的方式下，调整储层盐度、对储层进行压裂、设置水平注入井、调整CO2流体的注入温度、改变注入井的射孔位置等措施对CO2注入能力的影响，并评估了这些措施的提高效果。其中改变储层中的盐度可通过在注入CO2前，向储层中注入一定量的水来实现。另外，利用假定的理想模型分析在给定注入速率下压裂措施对注入能力的提高效果，并以鄂尔多斯的深部咸水含水层为研究区域，建立三维模型，利用现场实际注入数据，模拟压裂方案对CO2注入能力的提高效果，验证模拟结果的准确性以及实际应用的可行性，计算确定注入压力方式下的孔口压力值，并进行相关的不确定分析，为今后咸水层二氧化碳地质封存工程提供参考。这对深入我国二氧化碳地质封存技术的研究，开展我国咸水层二氧化碳地质封存项目有着一定的指导意义。主要结论如下：（1）在经济条件允许的情况下，采用水平注入井，增加水平井段的长度；延长CO2注入前，向系统中注入水的时间，降低储层中的含盐度；对储层进行足够程度的压裂等措施都有利于提高系统CO2注入能力。对有限厚度的储层，水平井方案可有效的增加注入井井壁和储层间的接触面积，提高注入率和注入总量。水平井段越长，提高效果越好。采用水力压裂的工程措施可以同时增加绝对渗透率和接触面积。对储层的压裂改造程度越大，提高效果越好。（2）储层中注入点越深，注入厚度越大，有利于提高注入率和注入总量。对于实际二氧化碳封存场地存在较厚的储层，只考虑射开部分储层所在的井段时，射穿深度较大的位于储层下部的井段进行注入可以有效的提高注入率和注入总量。（3）不考虑经济因素，采用水力压裂的措施，或采用足够长度的水平注入井更有利于增加CO2注入能力，实际应用中可作为优先考虑的措施。（4）水平井注入方案在前期注入阶段效果明显，持续注入情况下，后期效果变弱，更适用于短时间内需大量存储CO2的情况。（5）在保证注入储层中的CO2流体温度在超临界状态的范围内，调整注入流体的温度对注入率和注入总量的影响不大，实际应用中可作为提高注入率和注入量的次要手段。（6）鄂尔多斯盆地实际封存非连续注入下的数值模拟表明，压裂改造方案可以更好的控制系统的最大积聚压力，提高注入能力，与理想模型研究结果一致。

The increasing emissions of greenhouse gases cause serious influences on human sustainable development. The emission of reducing CO2 becomes an urgent problem of human being. As an effective approach to reduce CO2 emissions, the prospects of CO2 geologic sequestration are optimistic. Deep saline aquifers is considered to be the most promising and feasible place for CO2 storage due to the characteristics of large capacity and broad distribution,. CO2 injection rate and cumulative injection quantity are critical factors to assess CO2 injectivity in saline aquifer. Besides, saline aquifers may have relatively low permeability which limits the CO2 injectivity. So the study for enhancing injection rate and cumulative injection mass are of great value.In this study, the properties of H2O-CO2-Nacl were analyzed theoretically. With the development of an ideal 3D multiphase flow model and the use of TOUGH2/ECO2N simulator, numerical simulations were carried out to evaluate the approaches for improving injectivity. The approaches include changing the fluid salinity in reservoir, introducing hydraulic fracturing for storage aquifer improvement, using horizontal well, altering temperature of the injected CO2, and adjusting the perforating position on injection well and their effectiveness of improving injectivity under constant-pressure. Changing fluid salinity can be implemented through injecting a slug of fresh water prior to commencement of CO2 injection. Moreover, an ideal model under given injection rate was used to assess the impact of hydraulic fracturing on injectivity. With data extracted from in-site testing, three-dimensional site-scale model of Erdos basin was built to investigate the effectiveness of hydraulic fracturing on injectivity improvement, demonstrate the accuracy of the ideal model and the feasibility of practical application, calculate the wellbore pressure under constant injection pressure, and analyze the uncertainties of simulation results. The findings may provide helpful hints to the CO2 geologic sequestration project in China. The key results are given as following:(1) If economically permitted, the approaches such as using horizontal well or longer injection screen, reducing the salinity of the reservoir by extending the period of injecting water and introducing hydraulic fracturing of sufficient degree for storage aquifer improvement can help to increase the CO2 injectivity. For reservoir with certain thickness, horizontal well can effectively increase the contact area between the wellbore and reservoir to improve the injection rate and accumulative injection mass. The longer the horizontal wells, the better improvement for injectivity. Hydraulic fracturing contributes the increase in the absolute permeability and the contact area between the wellbore of injection well and reservoir. The higher degree of fracturing, the better improvement for injectivity.(2) With deeper injection point and larger vertical injection range, the improvement for injection rate and accumulative injection mass will be better. For a relatively thicker reservoir, if parts of the injection well which are located in the reservoir were considered to be shot, penetrating deeper wells located at the lower part of the reservoir can effectively improve the injectivity.(3) Cases with horizontal well and hydraulic fracturing showed obvious injectivity enhancement, which can be considered as the priority methods if economically permitted.(4) Horizontal well may be preferable if the goal is to sequester a large amount of CO2 in a short period of time, but do not offer a significant advantage in terms of long-term injectivity of a potential repository.(5) Changing the temperature of the injected fluid has little impact on the injection rate and accumulative injection mass, which can be considered as a secondary means to increase the injectivity in injection practice.(6) The numerical simulation results of Erdos basin with in-site data under non-continuous injection show that fracturing measure could effectively control the pressure buildup in the reservoir and is of interest for increasing injectivity, which are consistent with the ideal model results.