冲击回转钻进参数对PDC钻头钻进效果的影响研究OA

To investigate the influence of percussive-rotary drilling parameters on rock cutting efficiency and drilling stability of PDC bits in complex formations,this study employed Tiangangbai(medium hard rock)and Zhimahei(hard rock)granites as test specimens.Systematic laboratory drilling tests were conducted under varying conditions of drill pressure,rotation speed,impact frequency and impact load with orthogonal test method.Rock cutting mechanisms of rotary drilling and percussive-rotary drilling were also compared and studied with cuttings screening analysis.The test results indicate that percussive-rotary drilling significantly enhances mechanical drilling rates in different rock types,particularly in hard rock.Under optimal drill pressure-rotation speed combination,the mechanical drilling speed can increase by 40.6%when drilling in Zhimahei,much higher than 14.5%in Tiangangbai.Drilling pressure is the key factor influencing cuttings size distribution and rock fragmentation patterns.Under low drilling pressure,rocks are mainly ground and broken,while under high drilling pressure,the proportion of large-sized rock cuttings increases significantly,and volume crushing becomes dominant,resulting in a significant improvement in drilling efficiency.Finally,optimal drilling parameters for both rock types were determined,providing experimental evidence and theoretical support for optimizing percussion-rotary drilling parameters with PDC bits in deep and complex formations.