摘要
为提高特殊赋存条件下的油气井定向钻进过程钻头的造斜可控性,提出一种新型的PDC钻头设计方案。综合考虑钻头心部锥角、冠部形状、过渡圆弧半径和中心线位置等因素,研究其造斜易控特性。进行了钻头的线型轮廓设计,建立了造斜段钻头的力学分析模型,并在此基础上分析了钻头破岩过程的造斜特性;根据实验测试结果,分析轮廓设计参数对钻头破岩特性的影响。研究结果表明:心部锥角和过渡圆弧半径对PDC钻头的造斜能力及造斜曲率影响较大;心部锥角太深,使钻头偏转能力下降,进而导致其造斜曲率过大;心部锥角太浅,钻头稳斜能力显著下降,使实际稳斜阶段曲线较设计曲线偏离较大;在定向井实际钻进过程中,增强造斜易控性的新型PDC钻头能较好地解决现有常规PDC钻头偏转能力弱、造斜曲率过大的缺点。建立的分析模型综合考虑了钻头在定向钻进时的复杂工况,并对相关研究进行了修正和完善;同时,通过相关参数的调整,可将分析模型应用于其他情况下的分析研究,研究结论对定向井技术的发展及钻井工具的研制具有重要参考意义。
A new PDC bit has been presented to improve the deflecting controllability of drill bit during the process of directional drilling under new occurrence conditions.The characteristics of deflecting controllability were studied in consideration of such factors as bit-core taper angle,crown shape,transition arc radius and centerline position.The design of linear bit profile was carried out to establish the mechanical analysis model of deflecting bit,based on which the deflecting characteristics of bit during the rock-cutting process were analyzed.According to experimental results,the influences of contour design parameters on the rock-cutting characteristics of bit were also investigated.The results show that core taper angle and transition arc radius have a great impact on deflecting ability and curvature of PDC bit.Due to deep core taper angle,the deflecting ability is reduced,thus leading to excessively large deflecting curvature;in case of shallow core taper angle,the angle holding ability of bit is decreased significantly,resulting in a great deviation of the real stabilized curve from design curve.In the actual drilling process of directional wells,the new PDC bit with enhanced deflecting controllability can better surmount the deficiencies of conventional PDC bit,such as weak deflecting ability and excessively large deflecting curvature.The mechanical analysis model considers all complex working conditions of the bit during directional drilling,and has amended and improved the relevant studies.Meanwhile,this analysis model can be applied in the researches of other cases by adjusting relevant parameters.These results are of important reference significance to the development of directional drilling technology and the design of drilling tools.
出处
《石油学报》
EI
CAS
CSCD
北大核心
2015年第7期882-889,共8页
Acta Petrolei Sinica
基金
国家自然科学基金项目(No.51074202
No.11102173)
西南石油大学石油天然气装备教育部重点实验室开放课题(OGE201403-05)
四川省教育厅成果转化重大培育项目(12ZZ003)资助
关键词
PDC钻头
定向井
造斜
破岩
力学模型
PDC drill bit
directional well
whipstocking
rock breaking
mechanical model
