【摘要】 CO2地质封存可以减少化石燃料燃烧排放的CO2量,有效减缓温室效应。储层渗透率可以决定CO2通道的形成,进而改变其在储层中的运移规律,因而是影响CO2地质封存的重要因素。根据研究区基本地质数据、三维地震勘探结果和统计规律确定了渗透率的分布情况,运用储层多相流模拟软件TOUGH2-MP分析了渗透率的非均质性对CO2地质封存的影响。结果表明:(1)渗透率的分布情况对CO2储存量和注入压力的影响很大,相比于均值模型,CO2的注入总量明显减少,到达最大允许压力积聚所需的时间要比均质模型短;(2)在保证注入速率和压力积聚不超过允许最大值的双重要求下,定压和定量两种注入方案都有待改进,建议考虑如人工压裂等工程措施;(3)渗透率的非均质性使得CO2晕呈现出不规则扩散,经过20年的注入,其最大扩散距离约800m,比均质情况下小150m,须做好相应的监测工作。更多还原

【Abstract】 Geological sequestration of CO2 helps reduce the volume of CO2 emissions from the combustion of fossil fuels, and may help reduce global warming. The distribution of permeability may determine the formation of CO2 migration paths, thereby changing the underground migration of CO2. Permeability distributions in the model area are determined based on hydrogeological conditions observed in Ordos Basin and three-dimensional seismic exploration results at the site. The numerical model is run with TOUGH2-MP software to analyze the impacts of heterogeneous permeability on CO2 storage. Model results lead to three main conclusions. Firstly, the distribution of permeability is of great importance to CO2 storage capacity and injection pressure. Compared with the homogeneous model, CO2 injection volume in the heterogeneous model decreased significantly, as did the time required to reach the maximum allowable pressure. Secondly, injection schemes may need to be improved in cases when there is a required injection rate and maximum allowable pressure build-up. As a consequence, appropriate engineering treatments, such as hydraulic fracturing, are recommended. Third, heterogeneous permeability makes CO2 plumes appear irregular and annular in shape. After 20 years of injections, the CO2 migration distance reached 800 m in the heterogeneous model, compared with only 150 m in the homogeneous model. This study highlights the needs for proper monitoring of geological CO2 sequestration.更多还原