For the past decade, the communes of Abidjan have been increasingly affected by natural hazards, causing considerable damage. One of the most dreaded of these is flooding, which haunts the population during the rainy seasons. The State of Côte d’Ivoire has shown its commitment to eradicating flooding by taking preventive measures (evacuation, cleaning out gutters, etc.) in the city, particularly in the areas most affected by the damage. Despite the efforts that have been made, the municipality of Abobo, which is located in a basin and on a steep slope with inadequate development, still suffers from flooding, with more than 15% of victims. The aim of this study is to elucidate the reasons that amplify this hazard. The study was made possible by field surveys involving observation and interviews, documentary research, and photographs taken using our GPS-enabled mobile phone based on a topographical map of the Abobo commune. In short, morpho-structural conditions and man-made factors, the consumption of space in all its forms by urbanisation, the fundamental role of rainfall and the occupation of pavements and drainage networks are the basic reasons for flooding in Abobo.
China boasts abundant heavy oil resources,which is vital for its energy security.However,its heavy oil typically exhibits high viscosity,which severely hinders its flow and extraction.Enhancing heavy oil flowability is vital for its effective exploitation.This study independently developed a visualization experimental system and explored the mechanisms through which combined thermal flooding(a combination of heat,chemical agents and gas)enhances heavy oil flowability.Results indicate that combined thermal flooding,that is,synergistically integrating heat,chemical agents,and gas,can effectively enhance the recovery of heavy oil by improving its flowability.Its working mechanisms were explored from the aspects of thermal effects,emulsification,precursor film,profile control capacity,and CO_(2) solution and extraction effects.The emulsification was observed using a confocal laser scanning fluorescence microscope(CLSFM).Findings reveal that steam flooding can boost crude oil flowability by augmenting temperature,while a chemical system tends to produce low-viscosity oil-in-water emul-sions,thus further aiding the flow of crude oil.During CO_(2) flooding,the solvent initially reduced crude oil viscosity and formed foamy oil,followed by the pronounced component separation of the produced fluids in the later stage.This demonstrates the effectiveness of CO_(2) in viscosity reduction and component extraction.Additionally,the results of interfacial tension experiments indicate that surfactants can reduce the heavy oil's interfacial tension,fostering the formation of nano-scale precursor films.They can also thicken these films and diminish their spreading resistance,thus accelerating residual oil removal and promoting heavy oil production.This study further elaborated the mechanisms behind the combined thermal flooding's efficiency in enhancing heavy oil recovery,offering a theoretical foundation for its broader application.
Yongqiang TangHaitao WangQiaoyu GeSuobing ZhangZengmin LunXia ZhouTao Ma Petroleum
To address the water sensitivity of conglomerate reservoirs,a series of core sensitivity tests were conducted to evaluate the effects of varying ionic content.These findings serve as a foundation for improving reservoir fluid dynamics and optimizing the concentration of anti-swelling agents in water flooding operations.The experiments revealed a marked disparity in response between cores with differing permeabilities.In Core No.5,characterized by low permeability,a 0.5% anti-swelling agent achieved only a modest 7.47% reduction in water sensitivity.Conversely,in the higher-permeability Core No.8,a 5%anti-swelling agent significantly reduced the water sensitivity index by 44.84% while enhancing permeability.Further,two displacement strategies-gas flooding following water flooding and water flooding after gas injection-were tested to assess the potential of CO_(2)water-alternating-gas(WAG)displacement.CO_(2)injection after water flooding in Core No.5 increased oil recovery by 9.24%,though gas channeling,evidenced by a sharp rise in the gas-liquid ratio,emerged as a critical concern.In Core No.8,water flooding following gas injection failed to improve recovery,likely due to pronounced water sensitivity,reduced permeability,and the formation of dominant flow channels under high displacement pressure,which limited sweep efficiency.
Haishui HanJian TanJunshi LiChanghong ZhaoRuoyu LiuQun ZhangZemin JiHao Kang
Rice varieties tolerant to submergence regulate shoot elongation during short-term submergence by expressing the SUB1A gene.In contrast,the deep-rooted DRO1 is effectively expressed under drought conditions to enhance water and nutrient uptake.This study investigates the growth and yield of rice with both SUB1A and DRO1 in the background of IR64,under early-season flooding,and mid-season drought.The study used a randomized complete design with two factors:soil moisture treatments(submergence,drought,and their combination)and genotypes.The genotypes included IR64,and three near-isogenic lines(NILs):NIL-SUB1DRO1,NIL-SUB1,and NIL-DRO1.Complete submergence was imposed for 7 days on 14-day-old seedlings,while drought was imposed on control and submerged plants following a 21-day recovery period from submergence,using 42-day-old plants.Variables were measured before and after treatments(submergence and drought),and at harvest or grain maturity.The stresses negatively affected the genotypes.At harvest,IR64 and NIL-SUB1DRO1 under both stresses showed a significant reduction in tiller numbers,shoot dry weights,and yields compared to their control plants.IR64 exhibited a significant delay in reaching flowering under all stresses.The rice introgression lines showed significant improvements in tolerance to the stresses.The study showed no negative consequences of combining drought and submergence tolerance in rice.
Ibrahim SoeEmmanuel OdamaAlex TamuAquilino Lado Legge WaniTaiichiro OokawaAbdelbagi M.IsmailJun-Ichi Sakagami
