Failure Analysis of Well-Logging Steel Wire in a Gas Injection Well
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TECHNICAL ARTICLE—PEER-REVIEWED
Failure Analysis of Well-Logging Steel Wire in a Gas Injection Well Yan Long . Mifeng Zhao . Junfeng Xie . Anqing Fu . Zhenquan Bai
Submitted: 20 May 2018 Ó ASM International 2018
Abstract The fracturing of well-logging steel wire occurred during downhole operation in a gas injection well in China. The failed well-logging steel wire material was austenitic stainless steel manufactured by cold drawing. In this study, the failure cause was investigated based on visual inspection, chemical composition analysis, metallographic observation, mechanical performance testing, SEM and EDS analysis. The results showed that the failure reason was primarily Cl-induced stress corrosion cracking which made the steel wire unable to bear the normal load of well-logging operation. The steel wire had experienced SCC during previous operation in a production well where downhole mediums contained high Cl concentration, and then cracks-containing steel wire was used for this operation. Most of the cracks initiated within surface scratches caused by cold drawing where corrosion pits were present. In addition, cold drawing process of steel wire had a significant influence on SCC propagation mode, and the secondary cracks mainly extend along deformed austenitic grain boundaries in cold drawing direction.
Y. Long (&) A. Fu Z. Bai Tubular Goods Research Institute, China National Petroleum Corporation, Xi’an 710077, China e-mail: [email protected] Y. Long A. Fu Z. Bai State Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials, Xi’an 710077, China M. Zhao J. Xie Tarim Oilfield Company, PetroChina Company Limited, Korla 841000, China
Keywords Well-logging steel wire Austenitic stainless steel Stress corrosion cracking Cold drawing
Introduction During oil and gas production, well logging is a necessary operation for downhole data acquisition by using logging tools suspended by a steel wire [1]. Austenitic stainless steels are extensively used as well-logging steel wire materials in oilfields, because of their excellent corrosion resistance in high-temperature and high-CO2/H2S environments [2, 3]. However, austenitic stainless steels are susceptible to transgranular stress corrosion cracking (TGSCC) [4]. The TGSCC mechanism of austenitic stainless steel is directly related to aggressive Cl ions which rapidly transfer the passive film on metal surface and then induce local corrosion and cracking [5–7]. However, through the addition of Cr and Mo alloying elements, especially Mo, austenitic stainless steels have been proved to have satisfying performances in corrosion resistance [8, 9]. For material selection of well-logging steel wire, 2– 4% Mo austenitic stainless steels could provide adequate pitting corrosion and TGSCC resistance in high-Cl well environment [10]. Due to several kilometers working depth and just 1.69– 3.18 mm diameter range, these steel wires also require extreme strength to withstand high gravity loads of logging tool
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