大邑构造浅部井段钻具失效与预防

Drilling-tool Failure and Its Prevention at Shallow Well Section of Dayi Structure

大邑构造浅部地层砂岩和泥岩交错,局部夹杂砾石层,可钻性差。2005～2008年该地区13口深井在浅部地层井段共发生了42次钻具失效事故,造成了极大的经济损失。为此,统计了钻具失效的相关数据,并结合室内实验研究查明了钻具失效主要是由于地层软硬交错引起的交变应力疲劳破坏,以及忽视对钻井参数的控制和钻具无损探伤所致。在此基础上提出了合理控制钻井参数,保证转速不致过高,认真做好钻具的无损探伤等预防钻具失效的措施,并经现场应用取得了良好效果。

Sandstone and shale are interbedded at the shallow well section of Dayi Structure,partially mixed with gravel and having poor drillability.In 2005~2008,there happened 42 drilling-tool failures for 13 deep wells in this section resulting in seriously economic loss.Therefore,according to the relevant data of the failures and combing with experiments,we find out that these failure may be mainly caused by the damage from alternating stress induced by staggered hard-soft formations and the neglect of drilling-parameter control and nondestructive detection ford rilling tools.On that basis,some prevention for the failures,including to reasonably control drilling parameters,to guarantee a drilling speed,to have a nondestructive detection,has been put forward and better results have also been achieved.