某油井在固井过程中套管断裂原因分析

Cause Analysis of Casing Fracture in the Process of Cementing in an Oil Well

YM21-2X井在固井过程中发生了套管断裂事故。为了确定套管断裂原因,对套管的使用工况及所受载荷等进行了调查分析。通过对井下返出的铁屑残片进行化学成分分析,确定套管发生了断裂。通过测井检查,确定了套管断裂位置和断裂井深。通过对套管底部预留的“口袋”井深结构进行分析,确定套管底部不预留“口袋”会使套管柱承受异常弯曲载荷,容易发生套管断裂事故。最后提出了预防套管断裂的建议。

This paper gives an investigation on working conditions and loads against a casing fracture accident during well cementation in well YM21-2X.It was confirmed that the casing broke per analyzing results of the chemical composition of the remains from well bottom.The casing fracture position and well depth were determined by well logging.It was considered that unusual bend load would be introduced on casing string because there was no distance between well bottom and cement casing shoe,so that casing failure accident would take place easily.The measure to prevent from casing fracture was suggested.