PDC钻头对推靠式旋转导向工具的适配性

Adaptability of PDC drill bit with push-the-bit rotary steerable tools for inclined drilling

针对使用推靠式旋转导向工具配套PDC钻头钻井过程中出现造斜率不达标的问题,进行PDC钻头切削结构对推靠式旋转导向工具适配性研究。基于纵横弯曲连续梁理论,考虑井径扩大率对工具的影响,建立推靠式旋转导向工具BHA力学分析模型,再结合PDC钻头与地层相互作用模型,提出以井斜趋势角作为评价推靠式旋转导向工具与PDC钻头适配性的指标,定量分析钻头结构参数对推靠式旋转导向工具造斜能力的影响,并进行相关试验。结果表明:随着PDC钻头内锥深度变浅、冠部高度变短,旋转导向工具造斜能力越强;PDC钻头切削齿后倾角越大、摩擦角越大,工具造斜性能越强;PDC钻头保径对工具造斜能力影响较大,钻头主动保径和被动保径面积越小,工具造斜能力越强;钻头被动保径刀翼越窄,工具造斜能力越强;当钻头保径总长一定时,随着主动保径与被动保径面积比值变小,工具造斜能力呈先增加后减小,存在最佳主动保径与被动保径比例使推靠式旋转导向工具造斜能力达到最大;模型井斜趋势角的预测值与试验值基本一致,最大误差仅为6.71%,验证了本文所建立模型的准确性。

In the drilling process of using PDC bits with the push-the-bit rotary steerable tools,there is a problem that the well inclination drilling rate cannot meet the required standard,in which the adaptability of the cutting structure of the PDC bit to the push-the-bit rotary steerable tools needs to investigated.In this paper,a BHA mechanical analysis model of the push-the-bit rotary steerable tool was established based on the continuous beam-column theory considering the influence of well expansion during the drilling process.In combination with the interaction models of PDC bit and rock formation,it was proposed to use the inclination angle as an index to evaluate the adaptability of the push-the-bit rotary steerable tool and the PDC bit.The influence of the bit structure parameters on the inclined drilling ability of the push-the-bit rotary steerable tool was quantitatively analyzed.The modeling results show that,the shallower inner cone depth and shorter crown height of the PDC bit,the better inclined drilling ability of the rotary steerable tool,and the greater the back rake angle and the larger friction angle of the PDC bit,the stronger the tool̍s inclined drilling ability.The PDC bit gauge has a great influence on the inclined drilling ability of the tools,the smaller the active gauge and passive gauge area of the bit,the stronger the inclined drilling ability,and the narrower the passive gauge blade of the drill bit,the stronger the inclined drilling ability.When the total length of the drill bit gauge is constant,as the ratio of the active gauge to passive gauge area becomes smaller,the inclined drilling ability first increases and then decreases,and there is the best active gauge and passive gauge ratio to maximize the inclined drilling ability of the push-the-bit rotary steerable tool.Relevant experiments were also conducted and compared with the modeling results.The predicted value of the model̍s inclination drilling angle is basically the same as that of the experiments,with a maximum error of only 6.71%,which can verify the accuracy of the model.