This paper focused on the corrosion resistance of cold spray Al–Al_2O_3composite coatings used on carbon steel pipe surfaces under thermal insulation. Al–Al_2O_3coatings were produced on the carbon steel pipe surfac...This paper focused on the corrosion resistance of cold spray Al–Al_2O_3composite coatings used on carbon steel pipe surfaces under thermal insulation. Al–Al_2O_3coatings were produced on the carbon steel pipe surface by cold spray(CS) technology. Experimental apparatus was built to test the corrosion resistance of coatings beneath mineral wool insulation under isothermal, thermal cycling and wet/dry conditions. The results showed that when α-Al_2O_3 was added in spraying powder, the coating could obtain higher hardness and a denser microstructure. From corrosionunder-insulation(CUI) tests, Al–Al_2O_3CS coatings were proven to be efficient in protecting carbon steel pipe from CUI mainly owning to lamellar microstructures of coatings. There was no evidence to show that α-Al_2O_3 might bring any negative effect on corrosion resistance. Al–Al_2O_3CS coatings were sensitive to the chloride ion concentration. When these coatings were exposed to higher concentrations of NaC l, the coating's exhibited faster degradation.展开更多
The exploitation of oil resources has now extended to ultra-deep formations,with depths even exceeding 10,000 m.During drilling operations,the bottomhole temperature(BHT)can surpass 240℃.Under such high-temperature c...The exploitation of oil resources has now extended to ultra-deep formations,with depths even exceeding 10,000 m.During drilling operations,the bottomhole temperature(BHT)can surpass 240℃.Under such high-temperature conditions,measurement while drilling(MWD)instruments are highly likely to malfunction due to the inadequate temperature resistance of their electronic components.As a wellbore temperature control approach,the application of thermal insulated drill pipe(TIDP)has been proposed to manage the wellbore temperature in ultra-deep wells.This paper developed a temperature field model for ultra-deep wells by coupling the interactions of multiple factors on the wellbore temperature.For the first time,five distinct TIDP deployment methods were proposed,and their corresponding wellbo re temperature variation characte ristics were investigated,and the heat transfer laws of the ultra-deep wellbore-formation system were quantitatively elucidated.The results revealed that TIDP can effectively restrain the rapid rise in the temperature of the drilling fluid inside the drill string by reducing the heat flux of the drill string.Among the five deployment methods,the method of deploying TIDP from the bottomhole upwards exhibits the best performance.For a 12,000 m simulated well,when6000 m of TIDP are deployed from the bottomhole upwards,the BHT decreases by 52℃,while the outlet temperature increases by merely 1℃.This not only achieves the objective of wellbore temperature control but also keeps the temperature of the drilling fluid at the outlet of annulus at a relatively low level,thereby reducing the requirements for the heat exchange equipment on the ground.The novel findings of this study provide significant guidance for wellbore temperature control in ultra-deep and ultra-high-temperature wells.展开更多
基金Supported by innovation program for graduate students in Jiangsu Province of China(CXLX12_0434)
文摘This paper focused on the corrosion resistance of cold spray Al–Al_2O_3composite coatings used on carbon steel pipe surfaces under thermal insulation. Al–Al_2O_3coatings were produced on the carbon steel pipe surface by cold spray(CS) technology. Experimental apparatus was built to test the corrosion resistance of coatings beneath mineral wool insulation under isothermal, thermal cycling and wet/dry conditions. The results showed that when α-Al_2O_3 was added in spraying powder, the coating could obtain higher hardness and a denser microstructure. From corrosionunder-insulation(CUI) tests, Al–Al_2O_3CS coatings were proven to be efficient in protecting carbon steel pipe from CUI mainly owning to lamellar microstructures of coatings. There was no evidence to show that α-Al_2O_3 might bring any negative effect on corrosion resistance. Al–Al_2O_3CS coatings were sensitive to the chloride ion concentration. When these coatings were exposed to higher concentrations of NaC l, the coating's exhibited faster degradation.
基金supported by the National Natural Science Foundation of China(Grant No.U22B2072)Research Project of China Petroleum Science and Technology Innovation Fund(Grant No.2025DQ02-0144)。
文摘The exploitation of oil resources has now extended to ultra-deep formations,with depths even exceeding 10,000 m.During drilling operations,the bottomhole temperature(BHT)can surpass 240℃.Under such high-temperature conditions,measurement while drilling(MWD)instruments are highly likely to malfunction due to the inadequate temperature resistance of their electronic components.As a wellbore temperature control approach,the application of thermal insulated drill pipe(TIDP)has been proposed to manage the wellbore temperature in ultra-deep wells.This paper developed a temperature field model for ultra-deep wells by coupling the interactions of multiple factors on the wellbore temperature.For the first time,five distinct TIDP deployment methods were proposed,and their corresponding wellbo re temperature variation characte ristics were investigated,and the heat transfer laws of the ultra-deep wellbore-formation system were quantitatively elucidated.The results revealed that TIDP can effectively restrain the rapid rise in the temperature of the drilling fluid inside the drill string by reducing the heat flux of the drill string.Among the five deployment methods,the method of deploying TIDP from the bottomhole upwards exhibits the best performance.For a 12,000 m simulated well,when6000 m of TIDP are deployed from the bottomhole upwards,the BHT decreases by 52℃,while the outlet temperature increases by merely 1℃.This not only achieves the objective of wellbore temperature control but also keeps the temperature of the drilling fluid at the outlet of annulus at a relatively low level,thereby reducing the requirements for the heat exchange equipment on the ground.The novel findings of this study provide significant guidance for wellbore temperature control in ultra-deep and ultra-high-temperature wells.
