The corrosion behavior of C100 steel in simulated environments with high H2S and CO2 content was studied through high-temperature and high-pressure autoclave, and the HaS stress corrosion cracking （SSC） resistance o...The corrosion behavior of C100 steel in simulated environments with high H2S and CO2 content was studied through high-temperature and high-pressure autoclave, and the HaS stress corrosion cracking （SSC） resistance of C100 steel was evaluated by SSC tests. Scanning electron microscopy （SEM）, transmission electron microscope （TEM） and X-ray diffraction （XRD） technique were employed to characterize the corrosion products and the metal matrix. The results indicate that all of the corrosion products in this investigation are mainly composed of different types of iron sulfide such as Fe0.95S, FeS0.9, F0.985S, Fe7S8 and FeS, and the absence of iron carbonate in the corrosion scales suggests that the corrosion process is governed by H2S corrosion. The corrosion rate decreases in the initial stage and then increases with the enhancement of the temperature. There exists a minimum corrosion rate at about 110 ℃. Under the partial pressure of H2S lower than 9 MPa, the corrosion rate decreases with the increase of P112S While over 9 MPa, a higher P112S will result in a faster corrosion process. When the applied stress is 72%, 80% and 85% of actual yield strength （AYS）, all tested specimens show no crack, which reveals a superior SSC resistance.展开更多
Based on an analysis of the existing models of CO 2 corrosion in literatures and the autoclave simulative experiments, a predictive model of corrosion rate (r corr) in CO 2/H 2S corrosion for oil tubes has been ...Based on an analysis of the existing models of CO 2 corrosion in literatures and the autoclave simulative experiments, a predictive model of corrosion rate (r corr) in CO 2/H 2S corrosion for oil tubes has been established, in which r corr is expressed as a function of pH, temperature (T), pressure of CO 2 (P CO 2) and pressure of H 2S (P H 2S). The model has been verified by experimental data obtained on N80 steel. The improved features of the predictive model include the following aspects: (1) The influence of temperature on the protectiveness of corrosion film is taken into consideration for establishment of predictive model of the r corr in CO 2/H 2S corrosion. The Equations of scale temperature and scale factor are put forward, and they fit the experimental result very well. (2) The linear relationship still exists between ln r corr and ln P CO 2 in CO 2/H 2S corrosion (as same as that in CO 2 corrosion). Therefore, a correction factor as a function of P H 2S has been introduced into the predictive model in CO 2/H 2S corrosion. (3) The model is compatible with the main existing models.展开更多
Sulfate rocks and organic sulfur from sedimentary organic matter are conventionally assumed as the original sulfur sources for hydrogen sulfide （H2S） in oil and gas reservoirs. However, a few recent experiments prel...Sulfate rocks and organic sulfur from sedimentary organic matter are conventionally assumed as the original sulfur sources for hydrogen sulfide （H2S） in oil and gas reservoirs. However, a few recent experiments preliminarily indicate that the association of pyrite and hydrocarbons may also have implications for H2S generation, in which water effects and natural controls on the evolution of pyrite sulfur into OSCs and H2S have not been evaluated. In this study, laboratory experiments were conducted from 200 to 450°C to investigate chemical interactions between pyrite and hydrocarbons under hydrothermal conditions. Based on the experimental results, preliminary mechanism and geochemical implications were tentatively discussed. Results of the experiments showed that decomposition of pyrite produced H2S and thiophenes at as low as 330°C in the presence of water and n-pentane. High concentrations of H2S were generated above 450°C under closed pyrolysis conditions no matter whether there is water in the designed experiments. However, much more organic sulfur compounds （OSCs） were formed in the hydrous pyrolysis than in anhydrous pyrolysis. Generally, most of sulfur liberated from pyrite at elevated temperatures was converted to H2S. Water was beneficial to breakdown of pyrite and to decomposition of alkanes into olefins but not essential to formation of large amounts of H2S, given the main hydrogen source derived from hydrocarbons. In addition, cracking of pyrite in the presence of 1-octene under hydrous conditions was found to proceed at 200°C, producing thiols and alkyl sulfides. Unsaturated hydrocarbons would be more reactive intermediates involved in the breakdown of pyrite than alkanes. The geochemistry of OSCs is actually controlled by various geochemical factors such as thermal maturity and the carbon chain length of the alkanes. This study indicates that the scale of H2S gas generated in deep buried carbonate reservoirs via interactions between pyrite and natural gas should be much smaller than that of thermochemical sulfate reduction （TSR） due to the scarcity of pyrite in carbonate reservoirs and the limited amount of long-chained hydrocarbons in natural gas. Nevertheless, in some cases, OSCs and/or low contents of H2S found in deep buried reservoirs may be associated with the deposited pyrite-bearing rock and organic matters （hydrocarbons）, which still needs further investigation.展开更多
基金Funded by Key National Science&Technology Specific Projects(No.2008ZX05017-002)
文摘The corrosion behavior of C100 steel in simulated environments with high H2S and CO2 content was studied through high-temperature and high-pressure autoclave, and the HaS stress corrosion cracking （SSC） resistance of C100 steel was evaluated by SSC tests. Scanning electron microscopy （SEM）, transmission electron microscope （TEM） and X-ray diffraction （XRD） technique were employed to characterize the corrosion products and the metal matrix. The results indicate that all of the corrosion products in this investigation are mainly composed of different types of iron sulfide such as Fe0.95S, FeS0.9, F0.985S, Fe7S8 and FeS, and the absence of iron carbonate in the corrosion scales suggests that the corrosion process is governed by H2S corrosion. The corrosion rate decreases in the initial stage and then increases with the enhancement of the temperature. There exists a minimum corrosion rate at about 110 ℃. Under the partial pressure of H2S lower than 9 MPa, the corrosion rate decreases with the increase of P112S While over 9 MPa, a higher P112S will result in a faster corrosion process. When the applied stress is 72%, 80% and 85% of actual yield strength （AYS）, all tested specimens show no crack, which reveals a superior SSC resistance.
基金TheResearchProjectofTubularGoodsRe searchCenterofChinaNationalPetroleumCorporation (No .2 3 5 2 4)andtheResearchProjectofHenanUniversityofScienceandTechnology (No .2 0 0 10 1)
文摘Based on an analysis of the existing models of CO 2 corrosion in literatures and the autoclave simulative experiments, a predictive model of corrosion rate (r corr) in CO 2/H 2S corrosion for oil tubes has been established, in which r corr is expressed as a function of pH, temperature (T), pressure of CO 2 (P CO 2) and pressure of H 2S (P H 2S). The model has been verified by experimental data obtained on N80 steel. The improved features of the predictive model include the following aspects: (1) The influence of temperature on the protectiveness of corrosion film is taken into consideration for establishment of predictive model of the r corr in CO 2/H 2S corrosion. The Equations of scale temperature and scale factor are put forward, and they fit the experimental result very well. (2) The linear relationship still exists between ln r corr and ln P CO 2 in CO 2/H 2S corrosion (as same as that in CO 2 corrosion). Therefore, a correction factor as a function of P H 2S has been introduced into the predictive model in CO 2/H 2S corrosion. (3) The model is compatible with the main existing models.
基金the National Natural Science Foundations of China(No.41472095 and No.40902034)the Foundation of State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing(No.PRP/open-1508)PetroChina Innovation Foundation(No.2012D-5006-0104)
文摘Sulfate rocks and organic sulfur from sedimentary organic matter are conventionally assumed as the original sulfur sources for hydrogen sulfide （H2S） in oil and gas reservoirs. However, a few recent experiments preliminarily indicate that the association of pyrite and hydrocarbons may also have implications for H2S generation, in which water effects and natural controls on the evolution of pyrite sulfur into OSCs and H2S have not been evaluated. In this study, laboratory experiments were conducted from 200 to 450°C to investigate chemical interactions between pyrite and hydrocarbons under hydrothermal conditions. Based on the experimental results, preliminary mechanism and geochemical implications were tentatively discussed. Results of the experiments showed that decomposition of pyrite produced H2S and thiophenes at as low as 330°C in the presence of water and n-pentane. High concentrations of H2S were generated above 450°C under closed pyrolysis conditions no matter whether there is water in the designed experiments. However, much more organic sulfur compounds （OSCs） were formed in the hydrous pyrolysis than in anhydrous pyrolysis. Generally, most of sulfur liberated from pyrite at elevated temperatures was converted to H2S. Water was beneficial to breakdown of pyrite and to decomposition of alkanes into olefins but not essential to formation of large amounts of H2S, given the main hydrogen source derived from hydrocarbons. In addition, cracking of pyrite in the presence of 1-octene under hydrous conditions was found to proceed at 200°C, producing thiols and alkyl sulfides. Unsaturated hydrocarbons would be more reactive intermediates involved in the breakdown of pyrite than alkanes. The geochemistry of OSCs is actually controlled by various geochemical factors such as thermal maturity and the carbon chain length of the alkanes. This study indicates that the scale of H2S gas generated in deep buried carbonate reservoirs via interactions between pyrite and natural gas should be much smaller than that of thermochemical sulfate reduction （TSR） due to the scarcity of pyrite in carbonate reservoirs and the limited amount of long-chained hydrocarbons in natural gas. Nevertheless, in some cases, OSCs and/or low contents of H2S found in deep buried reservoirs may be associated with the deposited pyrite-bearing rock and organic matters （hydrocarbons）, which still needs further investigation.
