TS-90连续油管断裂失效分析  

Fracture Failure Analysis of TS-90 Coiled Tubing

作　　者：赵金兰 程佩 王彬[3] 仝珂 ZHAO Jinlan;CHENG Pei;WANG Bin;TONG Ke(CNPC Tubular Goods Research Institute,Xi’an 710077,China;Petrochina Changqing OilfeildCompany,Xi’an 710021,China;PetroChina Qinghai Oilfield Company,Dunhuang 736202,Gansu,China)

机构地区：[1]中国石油集团工程材料研究院有限公司,西安710077 [2]中国石油天然气股份有限公司长庆油田分公司,西安710021 [3]中国石油天然气股份有限公司青海油田分公司,甘肃敦煌736202

出　　处：《焊管》2022年第6期39-44,共6页Welded Pipe and Tube

摘　　要：为了分析某井气举作业用TS-90连续油管断裂失效原因,通过宏观分析、无损检测、几何尺寸测量、化学成分分析、力学性能测试、金相检测、扫描电镜(SEM)等手段,对该失效连续油管进行了试验研究。试验结果显示,该失效连续油管的管体壁厚、外径、化学成分、显微硬度、晶粒度均符合API SPEC 5ST—2010要求;油管表面整体布满台阶状横向裂纹,裂纹沿油管周向扩展;原始裂纹断口表面大量腐蚀产物覆盖,且从裂纹源区到裂纹尖端部位,始终存在少量导致应力腐蚀开裂的S元素;原始裂纹萌生于腐蚀坑底,裂纹尖端呈局部沿晶脆性断裂,且断口外表面附近呈解理形貌。综合分析结果表明,该连续油管断裂的根本原因是应力腐蚀开裂,其在井下作业时受腐蚀因素和应力载荷的共同作用,管体外表面萌生应力腐蚀裂纹,裂纹扩展并最终导致管体断裂失效。In order to analyze the fracture failure causes of TS-90 coiled tubing for gas lift operation in a well, the failed coiled tubing was tested and studied by means of macro analysis, nondestructive testing, geometric dimension measurement, chemical composition analysis, mechanical property test, metallographic examination and scanning electron microscope(SEM) testing.The results showed that the wall thickness, outer diameter, chemical composition, microhardness and grain size of the failed coiled tubing meet the requirements of API SPEC 5ST—2010. The overall surface of the oil pipe is covered with stepped transverse cracks, which extend along the circumference of the oil pipe. The surface of the original crack fracture is covered by a large number of corrosion products, and there is always a small amount of S element leading to stress corrosion cracking from the crack source area to the crack tip. The original crack originated at the bottom of the corrosion pit, the crack tip showed local intergranular brittle fracture, and there was cleavage near the outer surface of the fracture. The comprehensive analysis results show that the root cause of the coiled tubing fracture is stress corrosion cracking. Under the combined action of corrosion factors and stress during downhole operation, stress corrosion cracks are initiated on the outer surface of the pipe, the cracks expand and eventually lead to the fracture failure of the pipe body.

关 键 词：连续油管 裂纹 应力腐蚀开裂 失效 

分 类 号：TG115[金属学及工艺—物理冶金]