Fugang Wang

Simulation and analysis of geological Sequestration environment factors change caused by CO 2 injection

Sequestration environment factors such as porosity, pressure, permeability will change after supercritical CO2 injected reservoir aquifer, and that will impact the geological storage capability and stability of sequestration. Based on quartz sand- stone reservoir, by using reactive solute transport simulation software TOUGHREACT, this paper simulated sequestration environment factors change, which was leaded by CO2 diffusion and CO2-water-rock chemical reaction after injection of CO2. The results show that the model can well describe sequestration e environment factors change. Analysis of these Sequestration environment factors change simulation will provide theoretical reference to CO2 geologic storage project in future.

Experimental Study on the Effects of Stress Variations on the Permeability of Feldspar-Quartz Sandstone

The multistage and discontinuous nature of the injection process used in the geological storage of CO2 causes reservoirs to experience repeated loading and unloading. The reservoir permeability changes caused by this phenomenon directly impact the CO2 injection process and the process of CO2 migration in the reservoirs. Through laboratory experiments, variations in the permeability of sandstone in the Liujiagou formation of the Ordos CO2 capture and storage (CCS) demonstration project were analyzed using cyclic variations in injection pressure and confining pressure and multistage loading and unloading. The variation in the micropore structure and its influence on the permeability were analyzed based on micropore structure tests. In addition, the effects of multiple stress changes on the permeability of the same type of rock with different clay minerals content were also analyzed. More attention should be devoted to the influence of pressure variations on permeability in evaluations of storage potential and studies of CO2 migration in reservoirs in CCS engineering.

Use of a CO2 Geological Storage System to Develop Geothermal Resources: A Case Study of a Sandstone Reservoir in the Songliao Basin of Northeast China

The concept of a carbon dioxide(CO2) plume geothermal (CPG) system, which uses the CO2 geological storage system to develop geothermal resources has been proposed recently. On the basis of the geological structures and geothermal conditions in the Songliao Basin in North East China, a three-dimensional model of a sandstone layer with a temperature of 120°C was developed using TOUGHREACT. Numerical simulations for operating both the geothermal system using CO2 only and that using water only were carried out, and the results compared. A number of comprehensive processes including flow (under gravity, buoyancy and injection pressure), and heat transfer have been considered. A cold fluid (20°C) injection well and a hot fluid production well were specified in the geothermal reservoir. The heat extraction rates for CO2 and water as heat transfer medium were analysed and compared. Modeling results indicate that compared to the CPG system, the variation range of temperature of the water system reduces by about 50% during the same simulation period. This phenomenon is caused by the favorable properties of CO2 such as low density and viscosity. The heat extraction rate for CO2 significantly increased by nearly 200% more than water in this sandstone reservoir under the present simulation conditions. Thus, the fundamental understanding and the scientific base for the future CPG development could be provided by this research.

The Analysis of the groundwater geothermal reserves conditions of Changchun City

Groundwater geothermal reserves is defined by Geological conditions, hydrogeological conditions, hydrodynamic conditions and hydrochemical conditions. There are three areas suitable for the development of water source heat pump in Changchun city, which are Yi tong Valley pore groundwater resources area, Jiajiawazi - Xinglonggou and Sijianfang-Xiaochengzi bedrock groundwater areas. Pore water is plentiful but with high content of iron and manganese. The cost of exploitation pore water for water source heat pump will be high because it must be treatment before application. The water quality is well and the exploitation amount is large in bedrock groundwater area. In order to obtain better social, environmental and economic benefits, to use more bedrock water for water source heat pump, the exploitation plan of the bedrock groundwater should be adjusted and the exploitation amount should be limited so as to stop exploit the bedrock groundwater for water supply.

The quantified board models of fine-grained soil layer subsidence caused by pit dewatering

Based on the ground settlement calculation method recommended by the Chinese national Standards(GB 50307-1999), according to the type of soil and soil physical properties(characteristics of porosity ratio, plastic limit, compression modulus), soil layer thickness and water drawdown, the ground settlement quantified board models are established. The established models provide a fast, direct, simple and useful method and tool for land subsidence calculation in engineering construction.