Numerical Simulation and Field Test Research on Vibration Reduction of PDC Cutting of Pebbled Sandstone under Composite Impact Load

Downhole vibrations caused by rock breaking when drilling through pebbled sandstone formations negatively affect the rate of penetration (ROP) and safety downhole tools. Therefore, it is great significance to study cutting characteristics find a method reducing formations. Based on DEM (discrete element method), simulation model considering random filling high-strength gravels was established using polygon distribution method. The influence gravel content strength parameters state samples analyzed. Additionally, PDC rocks loaded spring–mass system established, Stribeck effect contact friction between cutter periodic vibration stick–slip phenomenon during process were presented this model. employed simulate explore composite impact load sandstone. results showed that had more obvious mitigating under condition higher horizontal amplitude coefficient (qh = 40%). results, impactor with large angle α 70° selected conduct field tests in formation Well T1. that, compared conventional drilling, average WOB (weight bit) section drilled decreased 57.13%, standard deviation 57.29%, ROP increased 98.31%. employing impactors can significantly reduce vibration, improve ROP, protect bits instruments.