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CO2 geological storage combined with deep saline water recovery technology (CO2-EWR) is one of the most effective ways to reduce carbon emissions. Due to the complex structural features, it is difficult to use CO2-EWR technology in Huaiyin Sag, Subei basin, East China. In this study, the multi-source information superposition evaluation technology of GIS was utilized for the selection of CO2 storage sites and water displacement potential target areas in this area, which mainly focused on the sandstone reservoirs of Cretaceous Pukou Formation. Based on the results, a three-dimensional injection–extraction model was established. Various scenarios with different production/injection well ratios (PIR) were simulated. Research has shown that the suitability of the surrounding site of Huaiyin Power Plant can be divided into two levels: relatively suitable and generally suitable; the area in the generally suitable level accounts for more than 80%. At a PIR of 1, CO2 is distributed asymmetrically, whereas at PIRs of 2 or 4, CO2 is distributed symmetrically. When the number of production wells is constant, a higher injection rate results in a faster expansion rate of the CO2 plume. This means that the time taken for the CO2 plume to reach the production wells is shorter. Reservoir pressure increases rapidly after more than 60 years of CO2 injection at lower PIR values, while at higher PIRs, reservoir pressure eventually stabilizes. Higher PIR values correspond to higher gas saturation, indicating a greater capacity for CO2 sequestration with more producing wells. When PIR = 4, the total CO2 injection increased by 55.73% compared to PIR = 1. However, the extraction of saline decreases with an increase in the number of producing wells, resulting in a decrease in replacement efficiency. This study provides a theoretical basis and technical support for the implementation of large-scale CO2-EWR engineering and technology demonstration in this region. [ABSTRACT FROM AUTHOR]

Gas breakthrough pressure is a key parameter to evaluate the sealing capacity of caprock, and it also plays important roles in safety and capacity of CO2 geological storage. Based on the published experimental results, we present numerical simulations on CO2 breakthrough pressure in unsaturated low‐permeability rock under 9 multiple P‐T conditions (which can keep CO2 in gaseous, liquid and supercritical states) and thus, a numerical method which can be used to accurately predict CO2 breakthrough pressure on rock‐core scale is proposed. The simulation results show that CO2 breakthrough pressure and breakthrough time are exponential correlated with P‐T conditions. Meanwhile, pressure has stronger effects on experimental results than that of temperature. Moreover, we performed sensitivity studies on the pore distribution index λ (0.6, 0.7, 0.8, and 0.9) in van Genuchten‐Muale model. Results show that with the increase of λ, CO2 breakthrough pressure and breakthrough time both show decreasing trends. In other words, the larger the value of λ is, the better the permeability of the caprock is, and the worse the CO2 sealing capacity is. The numerical method established in this study can provide an important reference for the prediction of gas breakthrough pressure on rock‐core scale and for related numerical studies. [ABSTRACT FROM AUTHOR]

Toxoplasma gondii is a ubiquitous protozoan parasite that may cause devastating conditions in animals, including humans. Dogs are the main host of T. gondii; however, little information is available on the cytokine expression profile in T. gondii–seropositive dogs. The present study aims to evaluate the levels of certain cytokines in serum collected from T. gondii–seropositive stray dogs. With a commercial enzyme-linked immunosorbent assay kit, we investigated the presence of antibodies for T. gondii in stray dogs in Hefei, Anhui, P. R. China, and found 26 of those tested were seropositive. For proinflammatory cytokines, higher levels of interleukin (IL)-6 were detected in the sera of T. gondii–seropositive dogs compared with seronegative dogs. Additionally, the concentration of anti-inflammatory cytokine IL-10 in seropositive dogs was slightly lower. [ABSTRACT FROM AUTHOR]

CO2 geological storage in deep saline aquifers is an effective way to reduce CO2 emissions. The injection of CO2 inevitably causes a significant pressure increase in reservoirs. When there exist faults which cut through a deep reservoir and shallow aquifer system, there is a risk of the shallow aquifer being impacted by the changes in reservoir hydrodynamic fields. In this paper, a radial model and a 3D model are established by TOUGH2-ECO2N for the reservoir system in the CO2 geological storage demonstration site in the Junggar Basin to analyze the impact of the CO2 injection on the deep reservoir pressure field and the possible influence on the surrounding shallow groundwater sources. According to the results, the influence of CO2 injection on the reservoir pressure field in different periods and different numbers of well is analyzed. The result shows that the number of injection wells has a significant impact on the reservoir pressure field changes. The greater the number of injection wells is, the greater the pressure field changes. However, after the cessation of CO2 injection, the number of injection wells has little impact on the reservoir pressure recovery time. Under the geological conditions of the site and the constant injection pressure, although the CO2 injection has a significant influence on the pressure field in the deep reservoir, the impact on the shallow groundwater source area is minimal and can be neglected and the existing shallow groundwater sources are safe in the given project scenarios. [ABSTRACT FROM AUTHOR]

CO2 geological storage (CGS) proved to be an effective way to mitigate greenhouse gas emissions, and CO2-enhanced water recovery (CO2-EWR) technology may improve the efficiency of CO2 injection and saline water production with potential economic value as a means of storing CO2 and supplying cooling water to power plants. Moreover, the continuous injection of CO2 may cause a sharp increase for pressure in the reservoir system, so it is important to determine reasonable reservoir pressure control strategies to ensure the safety of the CGS project. Based upon the typical formation parameters of the China Geological Survey CO2-EWR test site in the eastern Junggar Basin, a series of three-dimensional (3D) injection-extraction models with fully coupled wellbores and reservoirs were established to evaluate the effect of the number of production wells and the well spacing on the enhanced efficiency of CO2 storage and saline production. The optimal key parameters that control reservoir pressure evolution over time are determined. The numerical results show that a smaller spacing between injection and production wells and a larger number of production wells can enhance not only the CO2 injection capacity but also the saline water production capacity. The effect of the number of production wells on the injection capacity and production capacity is more significant than that of well spacing, and the simulation scenario with 2 production wells, one injection well, and a well spacing of 2 km is more reasonable in the demonstration project of Junggar Basin. CO2-EWR technology can effectively control the evolution of the reservoir pressure and offset the sharp increase in reservoir pressure caused by CO2 injection and the sharp decrease of reservoir pressure caused by saline production. The main controlling factors of pressure evolution at a certain spatial point in a reservoir change with time. The monitoring pressure drops at the beginning and is controlled by the extraction of water. Subsequently, the injection of CO2 plays a dominant role in the increase of reservoir pressure. Overall, the results of analysis provide a guide and reference for the CO2-EWR site selection, as well as the practical placement of wells. [ABSTRACT FROM AUTHOR]

Although CO geological storage has been recognized as an effective strategy to lower carbon emissions directly, there are no suitable guidelines for safety risk assessment of CO geological storage projects in deep saline aquifers in China and elsewhere. When CO is injected into deep saline aquifers, stratigraphic and structural trapping is the major basic mechanism controlling CO storage capacity and migration in reservoirs. Therefore, a safety risk assessment method is proposed in this paper using perspectives from hydrogeological and environmental geology. The uncertainties and risks consist of CO leakage, ground deformation, and induced earthquakes. Identifying and assessing potential risks are the first and most important step in the process of risk assessment. Based on the identification of risks of CO geological storage projects, we built an elementary risk evaluation index system in an analytic hierarchy process framework. Meanwhile, the possibility of occurrence and damage to the environment and public caused by CO leakage, ground deformation, and induced earthquakes was analyzed in detail, and current risk criteria were also summarized. Furthermore, using the Shenhua CO Capture and Storage Demonstration Project as a case study, we performed a risk identification and evaluation by using qualitative or semi-quantitative methods in sequence, as well as developing the related preliminary risk management measures. This method and case study for short-term safety risk assessment could provide a guideline for site selection, injection design, and monitoring of CO geological storage projects in deep saline aquifers. [ABSTRACT FROM AUTHOR]