Significant aspects of carbon capture and storage – A review

Excessive emission of greenhouse gases into the atmosphere has resulted in a progressive climate change and global warming in the past decades. There have been many approaches developed to reduce the emission of Carbon Dioxide (CO2) into the atmosphere, among which Carbon Capture and Storage (CCS) techniques has been recognized as the most promising method. This paper provides a deeper insight about the CCS technology where CO2 is captured and stored in deep geological formations for stabilization of the earth's temperature. Principles of capturing and storage for a long-term sequestration are also discussed together with the processes, mechanisms and interactions induced by supercritical CO2 upon injection into subsurface geological sites

Social resistance drives persistent transmission of Ebola virus disease in Eastern Democratic Republic of Congo: A mixed-methods study.

BACKGROUND:The second largest Ebola virus disease (EVD) epidemic in history is currently raging in Eastern Democratic Republic of Congo (DRC). Stubbornly persistent EVD transmission has been associated with social resistance, ranging from passive non-compliance to overt acts of aggression toward EVD reponse teams. METHODS:We explored community resistance using focus group discussions and assessed the prevalence of resistant views using standardized questionnaires. RESULTS:Despite being generally cooperative and appreciative of the EVD response (led by the government of DRC with support from the international community), focus group participants provided eyewitness accounts of aggressive resistance to control efforts, consistent with recent media reports. Mistrust of EVD response teams was fueled by perceived inadequacies of the response effort ("herd medicine"), suspicion of mercenary motives, and violation of cultural burial mores ("makeshift plastic morgue"). Survey questionnaires found that the majority of respondents had compliant attitudes with respect to EVD control. Nonetheless, 78/630 (12%) respondents believed that EVD was fabricated and did not exist in the area, 482/630 (72%) were dissatisfied with or mistrustful of the EVD response, and 60/630 (9%) sympathized with perpetrators of overt hostility. Furthermore, 102/630 (15%) expressed non-compliant intentions in the case of EVD illness or death in a family member, including hiding from the health authorities, touching the body, or refusing to welcome an official burial team. Denial of the biomedical discourse and dissatisfaction/mistrust of the EVD response were statistically significantly associated with indicators of social resistance. CONCLUSIONS:We concluded that social resistance to EVD control efforts was prevalent among focus group and survey participants. Mistrust, with deep political and historical roots in this area besieged by chronic violence and neglected by the outside world, may fuel social resistance. Resistant attitudes may be refractory to short-lived community engagement efforts targeting the epidemic but not the broader humanitarian crisis in Eastern DRC

Carbon capture and storage

22 juillet 18961896/07/22 (A8,N29)-1896/07/22

Multi-tracer and hydrogeophysical investigation of the hydraulic connectivity between coal seam gas formations, shallow groundwater and stream network in a faulted sedimentary basin

Characterization of geological fault networks in sedimentary basins targeted for coal seam gas development typically use deep-penetrating seismic data. Such methods can reveal the presence of numerous fault zones at depths greater than 100 m but not necessarily show if these extend to the surface or provide a significant degree of hydraulic connectivity between deep and shallower geological formations. Our combined multi-tracer and hydrogeophysical study used transient electromagnetic surveys to image the subsurface in a sedimentary coal seam gas basin (Gloucester Basin, NSW, Australia) and indicated that deep faults (greater than 200 m) from seismic analysis may extend to within metres of the ground surface. Analysis of environmental tracers in surface water and groundwater samples near fault traces showed the presence of hotspots of deeper groundwater from the coal seams discharging into the stream network via the alluvial aquifer. The isotopic composition of methane was extremely variable in groundwater (δC-CH from –81.6 to –29.2‰ V-PDB) and surface water (δ C-CH from –56.0 to –19.9‰ V-PDB), suggesting several sources of methane being recycled in the connected alluvial aquifer and stream network. A He hotspot (1.67 × 10 cm STP g) in the alluvial aquifer close to a fault line showed high methane (463 µg L) with a thermogenic signature (δ C-CH of −62.4‰ and δH-CH of −174.7‰). The Gloucester Basin, which has experienced multiple episodes of complex restructuring, displays high dilation tendency of fractures close to fault damage zones with fracture orientations parallel to the orientation of maximum horizontal stress. As a result, there is increased permeability for wells close to the fault damage zone and with increasing depth. These findings resulted in a robust hydrogeological conceptual model of a faulted basin, which can be used in a monitoring and modelling framework for improved evaluation of risk associated with unconventional gas developments

Pressure distribution in a reservoir affected by capillarity and hydrodynamic drive: Griffin Field, North West Shelf, Australia

The effects of capillarity in a multilayered reservoir with flow in the aquifer beneath have characteristic signatures on pressure-elevation plots. Such signatures are observed for the Griffin and Scindian/Chinook fields of the Carnarvon Basin North West Shelf of Australia. The Griffin and Scindian/Chinook fields have a highly permeable lower part to the reservoir, a less permeable upper part, and a low permeability top seal. In the Griffin Field there is a systematic tilt of the free-water level in the direction of groundwater flow. Where the oil-water contact occurs in the less permeable part of the reservoir, it lies above the free-water level due to capillarity. In addition to these observable hydrodynamic and capillary effects on hydrocarbon distribution, the multi-well pressure analysis shows that the gas-oil contacts in the Scindian/Chinook fields occur at different elevations. For both the Griffin and Scindian/Chinook fields the oil pressure gradients from each well are non-coincident despite continuous oil saturation, and the difference is not attributable to data error. Furthermore, the shift in oil pressure gradient has a geographical pattern seemingly linked to the hydrodynamics of the aquifer. The simplest explanation for all the observed pressure trends is an oil leg that is still in the process of equilibrating with the prevailing hydrodynamic regime