475型静态推靠式旋转导向钻具组合的弯曲应力分布规律

Bending stress distribution rules of the 475 static push-the-bit Rotary Steerable Bottom-Hole Assembly(RSBHA)

旋转导向钻井系统(RSS)是定向钻井的核心装备.经过多年攻关,中海油田服务股份有限公司(简称中海油服)研制出了475型旋转导向钻井系统.为了降低该系统在高造斜率井段的疲劳失效风险,本文采用纵横弯曲梁理论建立了475型静态推靠式旋转导向钻具组合(RSBHA)力学分析模型,模拟分析了RSBHA的弯曲应力总体分布规律、最大弯曲应力影响因素及变化规律.研究表明,限定导向头结构参数条件下,适当加长挠性短节并合理调控钻压和导向合力有助于获得较高造斜率并降低BHA(Bottom-Hole Assembly,底部钻具组合)最大曲率和弯曲应力,最终降低挠性短节疲劳失效风险.研究成果能够为提升该系统的工作能力和安全可靠性提供支持.

Rotary Steerable drilling System(RSS)is the core equipment of directional drilling.After years of efforts,China Oilfield Services Limited took the lead in developing 475 static push-the-bit rotary steering drilling system.In order to reduce the fatigue failure risk of the system in high build-up section,a mechanical analysis model of 475 static push-the-bit Rotary Steerable Bottom-Hole Assembly(RSBHA)was established by using the theory of vertical and horizontal bending beams,and the overall distribution law of bending stress,the influencing factors of maximum bending stress and the variation law of RSBHA were simulated.The research show that under the condition of given steering unit structural parameters,appropriately lengthening the flexible sub and properly regulating the weight on bit and steering force can help to obtain higher build-up rate and reduce the maximum curvature and bending stress of the BHA(Bottom-Hole Assembly).The research results can provide support for improving the working capacity and safety reliability of the system.