Numerical Simulation Of Co₂Geological Sequestration Of Shanxi Formation In Yulin Area, Ordos Basin

With the rapid development of economy and society, the problem of global warming caused by large amount of emissions of greenhouse gases is increasingly widely concerned by countries around the word. As the world’s largest emitter of carbon dioxide, it is difficult to have a fundamental shift in the basic energy structure of our country in the short term. So the situation of reducing carbon dioxide emissions faced by our country is very serious. As one of the largest regional energy and chemical base of China, the problem of carbon dioxide emission has become one of the biggest bottleneck constraints the development of energy and chemical industry in the Ordos basin. In order to meet the urge needs for sustainable development of economic and social in the Ordos basin, effective measures must be taken to reduce large-scale emissions of carbon dioxide. As a mature and feasible technology, geological storage of carbon dioxide has become recognized as one of the best way to achieve large-scale, efficient and economic reduction in the emission of CO2.Based on the above background, the object of this article is to simulate the CO2geological sequestration of Shanxi formation in Yulin area of Ordos Basin. With system collecting and organizing relevant literature and basic data, we preliminary analysis the CO2geological storage conditions in the study area and establish the corresponding three-dimensional geological model. By means of reservoir simulation methods, the CO2geological storage characteristics of Shanxi formation has been studied from its distribution characteristics, injection rate and storage quantity, sequestration types and evolution characteristics. On the other hand, the influence of the reservoir conditions, injection process and the grid resolution on the storage process has also been discussed.Studies have shown that Shanxi formation in Yulin area has good geological storage conditions for CO2geological storage, and the sequestration of Shan2which is the main storage formation is better than Shan1. Because of low porosity and permeability of Shanxi formation, the CO2migration speed is very slow. In the injection stage, the main migration way is horizontal migration, while it will become the vertical migration after the injection stopped. The total injected CO2formed an inverted cone in the reservoir gas gathering area, finally most of the CO2were trapped in Shan2formation under the seal of Shan1, the other is gathered at the bottom of the cover layer. The research shows that the Shanxi formation of study area has strong CO2injection ability and tremendous storage potential. The majority of injected CO2is trapped as the free CO2, the other is storage as residual state and dissolved state, the mineralization is very weak. As time goes with sequestration, free storage is constantly converted to other storage types, finally the importance of mineralization is increasingly evident, and the security of geological storage is increasing.Numerous influencing factors are included in the process of CO2geological storage. The increase of the vertical and horizontal permeability ratio is in favor of improving the CO2migration ability and expanding spread wide. Relative permeability and capillary pressure bind a greater influence on the residual gas sequestration, reducing the migration ability of CO2and increasing the residual gas storage capacity. Injection rate has less effect on the CO2sequestration type and the balance between storage capacity and security must be taken into account when selecting the CO2injection rate. Choice the horizontal injection well and bottom perforation can improve the capacity of injection and sequestration and increase the security of CO2storage. Grid resolution has greater impact on the simulation results, coarse grid tend to overestimate dissolve sequestration and underestimate free storage.