自动垂直钻井工具纠斜能力影响因素分析

Factors Influencing Deviation Correction Capability of Automatic Vertical Drilling Tool

自动垂直钻井系统可解决传统被动防斜效果不佳的问题。为使自动垂直钻井工具高效防斜纠斜,研究了其纠斜能力影响因素。通过分析钻头钻进趋势的方法来研究工具纠斜能力,基于纵横弯曲连续梁法,建立了考虑变截面处理的自动垂直钻井系统BHA力学模型,推导钻头侧向力和转角计算公式,结合钻头与地层相互作用模型,推导钻进趋势预测模型,并对模型进行了验证。在此基础上,以井斜趋势角为评价指标,结合钻头侧向力和转角,对工具纠斜能力影响因素进行了分析。分析结果表明,钻压、推靠力、翼肋位置、第一稳定器位置、柔性短节参数、钻头各向异性以及地层各向异性对工具纠斜能力影响显著,并对钻具组合进行了优化。研究结果可为钻具组合结构设计、钻井参数优选以及井眼轨迹预测和控制提供理论依据。

Automatic vertical drilling system can solve the poor effect of traditional passive deviation control system.In order to realize effective deviation control and correction of automatic vertical drilling system,the factors influencing the deviation correction capability are studied in this paper.The deviation correction capability is studied based on the analysis of bit drilling trend.By use of beam-column method,the BHA mechanical model of automatic vertical drilling system considering variable cross-section processing is established,and the calculation formulas of bit lateral force and rotation angle are derived.Combined with the bit-formation interaction model,the drilling trend prediction model is derived and proved.On this basis,taking the deviation trend angle as the evaluation index,combining with the bit lateral force and rotation angle,the factors influencing the deviation correction capability are analyzed.The results show that,WOB,thrust force,rib position,first stabilizer position,flexible joint parameters,bit anisotropy and formation anisotropy have significant effects on the deviation correction capability of the automatic vertical drilling system.Thereby the BHA was optimized.These conclusions could provide a theoretical basis for BHA structure design,drilling parameter optimization,well trajectory prediction and control.