Φ139.7 mm×9.17 mm N80 LC套管螺紋黏結(jié)原因分析

Analysis of Causes for Thread Gulling Failure of Φ139.7 mm×9.17 mm N80 LC Casing

摘要: 為找出下套管時Φ139.7 mm×9.17 mm N80 LC套管接頭發(fā)生螺紋黏結(jié)的原因，分析該套管的化學(xué)成分、力學(xué)性能、金相組織，檢測3對全新套管的螺紋參數(shù)，并進行上卸扣試驗，最后分析螺紋黏結(jié)形貌。試驗結(jié)果表明：該套管的材料理化性能及螺紋參數(shù)符合API Spec 5CT—2011、API Spec 5B—2008及Q/SY 1572.1—2013標準要求；現(xiàn)場螺紋清洗不當及作業(yè)不規(guī)范是套管螺紋發(fā)生黏結(jié)的根本原因。

Abstract: In order to find out the causes for the thread gulling failure of the Φ139.7 mm×9.17 mm N80 LC casing connection as occurred during the casing in hole operation, relevant analysis are conducted involving chemical composition, mechanical properties, and metallographic structure of the failed casing.And the thread parameters of three completely-new casings as coupled are checked, and screw-down test is also made.Finally the thread gulling morphology is analyzed.The test results show that the material physiochemical properties and thread parameters of the casing are up to API Spec 5CT-2011, API Spec 5B-2008 and Q/SY 1572.1-2013.It is identified that the root causes for the thread gulling failure are improper thread cleaning and irregular operation as conducted at site.