Optimization of PDC Cutter for Percussive Drilling in Deep Highly-Abrasive Strata in the East China Sea Basin
The problems of low rate of penetration(ROP),easy wear of PDC cutters and small single-bit footage are becoming increasingly prominent in the deep strata of the East China Sea Basin.The rock drillability,hardness and plasticity coefficient,strength,abrasiveness and component detection tests were performed to clarify the main controlling factors for low ROP in the deep strata of the study area,and the results were verified by the changes in ROP.Then,a rock breaking test device for special-shaped cutters of PDC bit under impact load was designed for rock breaking test of single cutter.The 3D scanning technique was used to quantify the penetration depth and rock breaking volume of triangular and axe-shaped cutters at different impact speeds,the energy absorp-tion efficiency and rock-breaking specific energy during the percussive rock breaking process were calculated,and the special-shaped cutters of PDC bit were optimized.Finally,field tests were conducted based on the optimization results.The results show that the high abrasiveness and strength of rocks are the main controlling factors for low ROP in the East China Sea Basin.When the impact speed of the hammer is less than 7.1 m/s,the penetration depth and rock breaking volume of the triangular cutter are greater,and the ROP improving effect is more obvious.When the impact speed of the hammer is greater than 7.1 m/s,the rock breaking specific energy of the axe-shaped cutter is lower than that of the triangular cutter,and the energy absorption efficiency is better;when it is used for drilling in highly-abrasive strata,the wear is smaller,and the service life of PDC bit can be better prolonged.The field tests also verify these conclusions.The research results provide effective references for the determination of per-cussive drilling parameters and the optimization of cutters of PDC bit in deep formations of the East China Sea Basin.
highly-abrasive strataPDC bitROPcutter optimizationtriangular cutteraxe-shaped cut-terpercussive rock breaking
万方数据
维普
