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
Initial corrosion kinetics of X52 anti-H2S pipeline steel exposed to 90 ℃/1.61 MPa H2S solutions was investigated through high temperature and high pressure immersion tests. Corrosion rates were obtained based on wei...Initial corrosion kinetics of X52 anti-H2S pipeline steel exposed to 90 ℃/1.61 MPa H2S solutions was investigated through high temperature and high pressure immersion tests. Corrosion rates were obtained based on weight loss calculation. The corrosion products were analyzed by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD） and electron probe micro-analysis （EPMA）. The initial corrosion kinetics was found to obey the exponential law. With increasing immersion time, the main corrosion products changed from iron-rich mackinawite to sulfur-rich pyrrhotite. The corrosion films had two layers： an inner fine-grained layer rich in iron and an outer columnar-grained layer rich in sulfur. The corrosion film formed through the combination of outward diffusion of Fe2＋ ions and inward diffusion of HS^- ions. The variation of the corrosion products and compaction of the corrosion layer resulted in a decrease in the diffusion coefficient with increasing immersion time. The double-layered corrosion film formed after long time immersion acted as an effective barrier against diffusion.展开更多
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
The corrosion behavior of the 110S tube steel in the environments of high H2 S and CO2 content was inves- tigated by using a high-temperature and high-pressure autoclave, and the corrosion products were characterized ...The corrosion behavior of the 110S tube steel in the environments of high H2 S and CO2 content was inves- tigated by using a high-temperature and high-pressure autoclave, and the corrosion products were characterized by scanning electron microscopy and X ray diffraction technique. The results showed that all of the corrosion products under the test conditions mainly consisted of different types of iron sulfides such as pyrrhotite of Fe0.95 S, mackinaw- ite of FeS0.9, Fe0. 985 S and FeS, and the absence of iron carbonate in the corrosion scales indicated that the corrosion process was controlled by H2S corrosion. The corrosion rate of the 110S steel decreased firstly and then increased with the rising of temperature. The minimum corrosion rate occurred at 110 ℃. When the H2 S partial pressure PH2s below 9 MPa, the corrosion rate declined with the increase of PH2s. While over 9 MPa, a higher PH2s resulted in a faster corrosion process. With the increasing of the CO2 partial pressure, the corrosion rate had an increasing trend. The morphologies of the corrosion scales had a good accordance with the corrosion rates.展开更多
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supported by the National Natural Science Foundation of China(No.51025104)
文摘Initial corrosion kinetics of X52 anti-H2S pipeline steel exposed to 90 ℃/1.61 MPa H2S solutions was investigated through high temperature and high pressure immersion tests. Corrosion rates were obtained based on weight loss calculation. The corrosion products were analyzed by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, X-ray diffraction （XRD） and electron probe micro-analysis （EPMA）. The initial corrosion kinetics was found to obey the exponential law. With increasing immersion time, the main corrosion products changed from iron-rich mackinawite to sulfur-rich pyrrhotite. The corrosion films had two layers： an inner fine-grained layer rich in iron and an outer columnar-grained layer rich in sulfur. The corrosion film formed through the combination of outward diffusion of Fe2＋ ions and inward diffusion of HS^- ions. The variation of the corrosion products and compaction of the corrosion layer resulted in a decrease in the diffusion coefficient with increasing immersion time. The double-layered corrosion film formed after long time immersion acted as an effective barrier against diffusion.
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Sponsored by Key National Science and Technology Specific Projects of China(2008ZX05017-002)
文摘The corrosion behavior of the 110S tube steel in the environments of high H2 S and CO2 content was inves- tigated by using a high-temperature and high-pressure autoclave, and the corrosion products were characterized by scanning electron microscopy and X ray diffraction technique. The results showed that all of the corrosion products under the test conditions mainly consisted of different types of iron sulfides such as pyrrhotite of Fe0.95 S, mackinaw- ite of FeS0.9, Fe0. 985 S and FeS, and the absence of iron carbonate in the corrosion scales indicated that the corrosion process was controlled by H2S corrosion. The corrosion rate of the 110S steel decreased firstly and then increased with the rising of temperature. The minimum corrosion rate occurred at 110 ℃. When the H2 S partial pressure PH2s below 9 MPa, the corrosion rate declined with the increase of PH2s. While over 9 MPa, a higher PH2s resulted in a faster corrosion process. With the increasing of the CO2 partial pressure, the corrosion rate had an increasing trend. The morphologies of the corrosion scales had a good accordance with the corrosion rates.
