长井段大尺寸井眼钻具疲劳失效分析模型建立与应用

Development and application of an analysis model for BHA fatigue failures in long and large-diameter hole sections

塔河油田开发井均为深井,二开444.5 mm钻头须钻至3 000 m左右,平均钻速8 m/h左右,钻井过程中易出现钻具失效事故,导致该油田万米进尺故障率居高不下。为了有效缩短钻井周期、安全实施快速钻进,分析了长井段大尺寸井眼钻具失效原因,在刚杆模型的基础上,建立了长井段大尺寸井眼钻具疲劳失效分析模型。塔河油田TH1井实例分析表明:扶正器的存在是导致钻具疲劳失效的主要因素,钻井参数不合理也易导致钻具的疲劳损坏;实施钻具组合和钻井参数的优化设计能有效降低钻具疲劳失效的风险。本文研究成果可为长井段大尺寸井眼的钻具组合和钻井参数的优化设计提供技术支持。

All of the development wells in Tahe oilfield are deep,making it necessary for the 0444. 5 mm hole interval to be drilled to about 3000 m, with an average rate of penetration （ROP） being about 8 m/h. Bottom hole assembly （BHA） fatigue failures occur easily during the drilling operation, which results in a persistently high failure rate for each ten thousand meters footage. In order to achieve safe and fast drilling and shorten the rig time, BHA？s failure mechanism was analyzed. Meanwhile, a model for researching the failure mechanisms was established on the basis of the stiff string model. Cases study results of TH-1 well showed that the existence of the stabilizer is probably the main factor which leads to fatigue failure of BHA,and unreasonable drilling parameters could also result in the failure. Therefore, optimization of BHA and drilling parameters can effectively reduce the risk of BHA failures. The findings of this work will provide theoretical foundation for design optimization of both BHA and drilling parameters in long and large-diameter hole sections.