多齿重载冲击下花岗岩裂纹萌生—扩展机理及布齿建议OA
Mechanisms of crack initiation and propagation in granite under multi-tooth heavy-load impact and recommendations for tooth layout
冲击钻进是当前提高硬岩机械钻速最有效的方法之一,其钻头布齿是研究的重点方向,但在重载冲击条件下齿间参数对岩石内部裂隙的激发、扩展贯通及破岩效率的影响规律尚不明确.为此,开展了有/无围压条件下的室内双齿冲击实验并结合数值模拟,系统研究了齿径、齿距、围压、冲击功及齿分布形式对岩石裂纹萌生、扩展与贯通的影响.研究结果表明:①合理的齿距对激活冲击坑间裂纹并促进其扩展与贯通具有关键作用,在无围压条件下,单齿冲击功为 50 J和 75 J时,裂纹贯通的临界齿距分别为 20.46 mm和 28.40 mm;②围压增强了冲击坑间的独立性,显著抑制了裂纹的扩展与贯通,在齿距为 20.46 mm、单齿冲击功为 75 J的条件下,围压超过 30 MPa后裂纹无法贯通;③随着单齿冲击功的增加,齿径与冲击功交替成为影响裂纹贯通临界齿距的主导因素,随着齿径增大,影响破岩比功变化趋势的主控因素逐渐由齿距转向齿径;④在冲击齿的不同分布形式中,正四边形布齿下岩石裂纹的扩展与贯通效果最佳,其次为正三角形、正五边形和正六边形.结论认为,该研究对于深入认识冲击齿相互作用机理及岩石裂纹扩展贯通机制具有重要意义,可为重载冲击条件下冲击钻头的优化布齿提供理论依据与设计参考,对深地钻井提速具有理论指导价值.
Impact drilling is currently one of the most effective methods for improving the rate of penetration(ROP)in hard rock formations.The bit tooth layout is an important research direction,while no clear understanding has been obtained on the effects of tooth parameters on the initiation,propagation and coalescence of internal rock fractures and rock-breaking efficiency under heavy-load impact.This paper systematically investigates the effects of tooth diameter,tooth spacing,confining pressure,impact energy and tooth distribution pattern on rock crack initiation,propagation and coalescence through laboratory dual-tooth impact experiments and numerical simulations under conditions with/without confining pressure.The following results are obtained.First,a reasonable tooth spacing plays a key role in exciting the cracks between impact craters and promoting their propagation and coalescence.Under the condition without confining pressure,the critical tooth spacings for crack coalescence at single-tooth impact energies of 50 J and 75 J are 20.46 mm and 28.40 mm,respectively.Second,confining pressure enhances the independence between adjacent impact craters,significantly inhibiting the crack propagation and coalescence.At a tooth spacing of 20.46 mm and a single-tooth impact energy of 75 J,crack coalescence becomes unattainable under the confining pressures exceeding 30 MPa.Third,as the single-tooth impact energy increases,tooth diameter and impact energy alternately serve as the dominant factor influencing the critical tooth spacing for crack coalescence.With increasing tooth diameter,the primary factor controlling the variation trend of rock-breaking specific energy gradually shifts from tooth spacing to tooth diameter.Fourth,among different impact tooth distribution patterns,regular quadrilateral pattern yields the optimal rock crack propagation and coalescence effect,followed by regular triangular,regular pentagonal,and regular hexagonal patterns.In conclusion,this research is of important significance to deeply understanding the interaction mechanisms between impact teeth and the mechanisms of rock crack propagation and coalescence,provides a theoretical basis and design references for optimal tooth layout of impact drill bits under heavy-load impact,and offers theoretical guidance value for ROP improvement in deep strata.
祝效华;程飞龙;石昌帅;刘伟吉
西南石油大学机电工程学院||石油天然气装备教育部重点实验室||西南石油大学地热能研究中心西南石油大学机电工程学院西南石油大学机电工程学院||石油天然气装备教育部重点实验室||西南石油大学地热能研究中心西南石油大学机电工程学院||石油天然气装备教育部重点实验室||西南石油大学地热能研究中心
能源科技
重载冲击冲击破岩花岗岩多齿冲击裂纹贯通裂纹扩展临界齿距钻头布齿
Heavy-load impactImpact rock-breakingGraniteMulti-tooth impactCrack coalescenceCrack propagationCritical tooth spacingBit tooth layout
《天然气工业》 2026 (1)
105-115,11
国家自然科学基金杰出青年基金项目"钻井提速理论与方法"(编号:52225401).
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