The corrosion behavior of expandable tubular materials was investigated in simulated downhole formation water environments using a series of electrochemical techniques. The corrosion morphologies in the real downhole ...The corrosion behavior of expandable tubular materials was investigated in simulated downhole formation water environments using a series of electrochemical techniques. The corrosion morphologies in the real downhole environment after three months of application were also observed by stereology microscopy and scanning electron microscopy （SEM）. The results show that, compared with the unex- panded sample, the area of ferfite increases dramatically after a 7.09% expansion. The expanded material shows a higher corrosion current in the polarization curve and a lower corrosion resistance in the electrochemical impedance spectroscopy （EIS） plot at every studied tempera- ture. The determined critical pitting temperatures （CPT） before and after expansion are 87.5℃and 79.2℃, respectively. SEM observations demonstrate stress corrosion cracks, and CO2 corrosion and H2S corrosion also occur in the downhole environment. Due to additional defects generated during the plastic deformation, the corrosion performance of the expanded tubing deteriorates.展开更多
BACKGROUND Emergency surgical resection is a standard treatment for right-sided malignant colonic obstruction; however, the procedure is associated with high rates of mortality and morbidity. Although a bridge to surg...BACKGROUND Emergency surgical resection is a standard treatment for right-sided malignant colonic obstruction; however, the procedure is associated with high rates of mortality and morbidity. Although a bridge to surgery can be created to obviate the need for emergency surgery, its effects on long-term outcomes and the most practical management strategies for right-sided malignant colonic obstruction remain unclear.AIM To determine the appropriate management approach for right-sided malignant colonic obstruction.METHODS Forty patients with right-sided malignant colonic obstruction who underwent curative resection from January 2007 to April 2017 were included in the study.We compared the perioperative and long-term outcomes of patients who received bridges to surgery established using decompression tubes and those created using self-expandable metallic stents(SEMS). The primary outcome was the overall survival duration(OS) and the secondary endpoints were the diseasefree survival(DFS) duration and the preoperative and postoperative morbidity rates. Analysis was performed on an intention-to-treat basis.RESULTS There were 21 patients in the decompression tube group and 19 in the SEMS group. There were no significant differences in the perioperative morbidity rates of the two groups. The OS rate was significantly higher in the decompression tube group than in the SEMS group(5-year OS rate; decompression tube 79.5%,SEMS 32%, P = 0.043). Multivariate analysis revealed that the bridge to surgery using a decompression tube was significantly associated with the OS(hazard ratio, 17.41; P = 0.004). The 3-year DFS rate was significantly higher in thedecompression tube group than in the SEMS group(68.9% vs 45.9%; log-rank test,P = 0.032). A propensity score–adjusted analysis also demonstrated that the prognosis was significantly better in the decompression tube group than in the SEMS group.CONCLUSION The bridge to surgery using trans-nasal and trans-anal decompression tubes for right-sided malignant colonic obstruction is safe and may improve long-term outcomes.展开更多
This paper studies the effect of expansion ratio on the corrosion rate of the expanded tubes exposed to sea water as well as the microstructure changes caused by the expansion of Cr-Mo steel tubes to large permanent d...This paper studies the effect of expansion ratio on the corrosion rate of the expanded tubes exposed to sea water as well as the microstructure changes caused by the expansion of Cr-Mo steel tubes to large permanent deformations. 2.25 Cr-1.0 Mo steel (schedule 40 and schedule 80) tubes were subjected to various expansion ratios of 10%, 15%, 20%, and 25% by pushing conical mandrels through them using a piston. The microstructure was also studied to determine the effect of the expansion on the grain structure of the material. Microscopic examination of the expanded tubes revealed that grains elongate along the direction of the hoop stress and this elongation increases with an increase of expansion ratio. Moreover, it was found that corrosion rate and hardness increase with an increase in expansion ratio.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51222106)the Fundamental Research Funds for the Central Universities of China(No.FRF-TP-14-011C1)
文摘The corrosion behavior of expandable tubular materials was investigated in simulated downhole formation water environments using a series of electrochemical techniques. The corrosion morphologies in the real downhole environment after three months of application were also observed by stereology microscopy and scanning electron microscopy （SEM）. The results show that, compared with the unex- panded sample, the area of ferfite increases dramatically after a 7.09% expansion. The expanded material shows a higher corrosion current in the polarization curve and a lower corrosion resistance in the electrochemical impedance spectroscopy （EIS） plot at every studied tempera- ture. The determined critical pitting temperatures （CPT） before and after expansion are 87.5℃and 79.2℃, respectively. SEM observations demonstrate stress corrosion cracks, and CO2 corrosion and H2S corrosion also occur in the downhole environment. Due to additional defects generated during the plastic deformation, the corrosion performance of the expanded tubing deteriorates.
文摘BACKGROUND Emergency surgical resection is a standard treatment for right-sided malignant colonic obstruction; however, the procedure is associated with high rates of mortality and morbidity. Although a bridge to surgery can be created to obviate the need for emergency surgery, its effects on long-term outcomes and the most practical management strategies for right-sided malignant colonic obstruction remain unclear.AIM To determine the appropriate management approach for right-sided malignant colonic obstruction.METHODS Forty patients with right-sided malignant colonic obstruction who underwent curative resection from January 2007 to April 2017 were included in the study.We compared the perioperative and long-term outcomes of patients who received bridges to surgery established using decompression tubes and those created using self-expandable metallic stents(SEMS). The primary outcome was the overall survival duration(OS) and the secondary endpoints were the diseasefree survival(DFS) duration and the preoperative and postoperative morbidity rates. Analysis was performed on an intention-to-treat basis.RESULTS There were 21 patients in the decompression tube group and 19 in the SEMS group. There were no significant differences in the perioperative morbidity rates of the two groups. The OS rate was significantly higher in the decompression tube group than in the SEMS group(5-year OS rate; decompression tube 79.5%,SEMS 32%, P = 0.043). Multivariate analysis revealed that the bridge to surgery using a decompression tube was significantly associated with the OS(hazard ratio, 17.41; P = 0.004). The 3-year DFS rate was significantly higher in thedecompression tube group than in the SEMS group(68.9% vs 45.9%; log-rank test,P = 0.032). A propensity score–adjusted analysis also demonstrated that the prognosis was significantly better in the decompression tube group than in the SEMS group.CONCLUSION The bridge to surgery using trans-nasal and trans-anal decompression tubes for right-sided malignant colonic obstruction is safe and may improve long-term outcomes.
文摘This paper studies the effect of expansion ratio on the corrosion rate of the expanded tubes exposed to sea water as well as the microstructure changes caused by the expansion of Cr-Mo steel tubes to large permanent deformations. 2.25 Cr-1.0 Mo steel (schedule 40 and schedule 80) tubes were subjected to various expansion ratios of 10%, 15%, 20%, and 25% by pushing conical mandrels through them using a piston. The microstructure was also studied to determine the effect of the expansion on the grain structure of the material. Microscopic examination of the expanded tubes revealed that grains elongate along the direction of the hoop stress and this elongation increases with an increase of expansion ratio. Moreover, it was found that corrosion rate and hardness increase with an increase in expansion ratio.
