Synthesis and mechanism of environmentally friendly high temperature and high salt resistant lubricants

With the exploration and development of deep and ultra-deep oil and gas,high torque and high friction during the drilling of deep and ultra-deep wells become one of the key issues affecting drilling safety and drilling speed.Meanwhile,the high temperature and high salt problem in deep formations is prominent,which poses a major challenge to the lubricity of drilling fluids under high temperature and high salt.This paper reports an organic borate ester SOP as an environmentally friendly drilling fluid lubricant.The performance evaluation results show that when 1%lubricant SOP is added to the fresh water-based mud,the lubrication coefficient decreases from 0.631 to 0.046,and the reduction rate of lubrication coefficient is 92.7%.Under the conditions of 210℃ and 30%NaCl,the reduction rate of lubricating coefficient of the base slurry with 1%SOP was still remain 81.5%.After adding 1%SOP,the wear volume decreased by 94.11%compared with the base slurry.The contact resistance experiment during the friction process shows that SOP can form a thick adsorption film on the friction surface under high temperature and high salt conditions,thus effectively reducing the friction resistance.Molecular dynamics simulation shows that lubricant SOP can be physically adsorbed on the surface of drilling tool and borehole wall through hydrogen bond and van der Waals force.XPS analysis further shows that SOP adsorbs on the friction surface and reacts with metal atoms on the friction surface to form a chemically reactive film.Therefore,under high temperature and high salt conditions,the synergistic effect of physical adsorption film and chemical reaction film effectively reduces the frictional resistance and wear of the friction surface.In addition,SOP is non-toxic and easy to degrade.Therefore,SOP is a highly effective and environmentally friendly lubricant in high temperature and high salt drilling fluid.

Environment-friendly Insulating Gases for HVDC Gas-insulated Transmission Lines

Environment-friendly gas insulating mediums adapted to a DC gas-insulated transmission line(GIL)electric field condition is the key to the next generation of Environment-friendly HVDC GILs.In this paper,we review the literature on sulfur hexafluoride(SF6)alternatives including the scientific understanding,control,and implementation of gas-solid systems in this type of power transmission.First,the structure-activity relationship between the molecular structure and physico-chemical properties of Environment-friendly insulating gases is presented.Then,the search and prediction of important physicochemical properties of gases are summarized.Subsequently,in view of the potential of environmental friendly insulating gases,the swarm parameters of gas discharge and breakdown properties in a quasi-uniform field,inhomogeneous field,and at the gas-solid interface,that need to be taken into account with industrialized DC GILs are discussed.The latest research progress on insulation characteristics,especially the polarity effect in DC gas-solid insulation systems,the sensitivity to the electrode surface state,and the non-uniformity of the electric field,and the influence of metal particles and their variation with air pressure,is highlighted.In addition,the heat transfer characteristics of insulating gases,related to DC GIL transmission with a large current-carrying capacity and the influence of alternative gases on the heat transfer characteristics are described.Finally,aiming at solving the contradiction of low environmental impact,high dielectric strength and low liquefaction temperatures in the selection of alternative gases,an coordinated regulation model for Environment-friendly gases in DC GILs is established.Considerations for future work on this topic are also presented.

Development of Mixed Insulation Oil as Alternative Liquid Dielectric:A Review

Use of traditional mineral oil(MO)as a liquid insulation in transformers has spanned more than 130 years.However,MO has poor heat resistance,a low ignition point,and is a non-renewable resource,which does not meet development requirements for high-performance and environmentally friendly insulation oil.Consequently,researchers have explored alternatives such as natural ester(NE)and synthetic ester(SE)oils,as well as mixed insulation oils.Mixed insulating oil is a blend of diverse insulating oil types,with optimal performance achieved by adjusting proportions of base oils.This article summarizes the innovative achievements and development of mixed insulation oil in terms of development of mixed ratio,basic physical chemical properties,electrical properties,thermal stability,and application including operation and maintenance technology.Through these efforts,this article aims to provide recommendations for future development of mixed insulating oils to advance liquid dielectric research based on enhancement mechanisms.

Environmental risks of shale gas exploitation and solutions for clean shale gas production in China

Shale gas is a relatively clean-burning fossil fuel,produced by hydraulic fracturing.This technology may be harmful to the environment;therefore,environmentally friendly methods to extract shale gas have attracted considerable attention from researchers.Unlike previous studies,this study is a comprehensive investigation that uses systematic analyses and detailed field data.The environmental challenges associated with shale gas extraction,as well as measures to mitigate environmental impacts from the source to end point are detailed,using data and experience from China’s shale gas production sites.Environmental concerns are among the biggest challenges in practice,mainly including seasonal water shortages,requisition of primary farmland,leakage of drilling fluid and infiltration of flowback fluid,oil-based drill cuttings getting buried underground,and induced seismicity.China’s shale gas companies have attempted to improve methods,as well as invent new materials and devices to implement cleaner processes for the sake of protecting the environment.Through more than 10-year summary,China’s clean production model for shale gas focuses on source pollution prevention,process control,and end treatment,which yield significant results in terms of resource as well as environmental protection,and can have practical implications for shale gas production in other countries,that can be duplicated elsewhere.