Materials Performance

SEP 2018

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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Page 98 of 128

40 SEPTEMBER 2018 W W W.MATERIALSPERFORMANCE.COM MATERIALS SELECTION & DESIGN T An investigation and testing were performed following a fracture event of a S13Cr-110 premium joint tubing string in a high-pressure, high-tem- perature well. Based on fracture anal- ysis, fractography, and metallogra- phy, it was determined that the tubing failures were caused by stress corro- sion cracking and corrosion fatigue. Analysis of the well depths of the failed tubes indicated that the load borne by the tubing string produced bending that resulted in tubing fail- ure. Based on an analysis of the tub- ing string assembly process and the tubing structure, the failure occurred where the tubing string was weakest, which was the location of greatest flexibility. Tubing made of S13Cr-110 (UNS S41426) stainless steel is sensitive to the environ- ment, and stress corrosion cracking (SCC) easily occurs. Cause analysis for the failure of S13Cr-110 single tubing has been studied by many authors; 1-4 however, there are few papers addressing fracture-cause analysis of multiple S13Cr-110 tubes in one high- pressure, high-temperature (HPHT) well that consider well depth, stress condition, environment caused by the medium, and failure position of the tubing. FAILURE ANALYSIS Fracture Investigation of a S13Cr-110 Tubing String with Premium Joints Xiang-tong Yang, Jun-feng Xie, Hua Wang, Mi-feng Z H ao, Yan Li, Lei Ma, and Mao- X ian Xiong, Tarim Oil Field, Xinjiang, China S H uan- L u Lv, Tarim Oil Field, Xinjiang, China; and Material Science and Engineering Department, China University of Petroleum, Beijing, China Yong Han and Ji- J un Xue, Xi'an Maurer Petroleum Engineering Laboratory, Xi'an, China Two lengths of 89-mm diameter and 6.5- mm thick, S13Cr-110 tubing with premium joints fractured, and nine lengths of 89-mm diameter S13Cr-110 tubing cracked in one HPHT well after acidification and spray as part of production. Here, premium joints refer to box and tube joints that exceed API Spec 5B. 5 This article discusses the tests and analysis that were carried out to determine the cause of the multiple tubing failures. Test Results and Analysis Tubing Fracture Position and Nondestructive Testing Results Segment No. 418 of the 89-mm diame- ter tubing with premium joints broke at the pin vanish point—where the tube's pin threads are no longer visible on the tube connection made up in the mill. The well depth of that fracture location was 4,146 m. Segment No. 432 of the 89-mm diameter tubing, with premium joints and coupling made by the mill, also fractured at the pin vanish point (Figure 1) of the connection made up in the mill, but at a well depth of 4,285 m. The total depth of the well is 6,815 m and the packer position depth is 6,714 m. Nondestructive testing (NDT) identi- fied transverse cracks on eight lengths of tubing at the pin thread vanish point of the connection made up in the mill. The loca- tion of the cracks and the fracture positions of the tubing were coincident. NDT also showed there was a longitudinal crack on

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