Optimized Design And Experimental Study On Plow-crushing PDC Bit

Nowadays,PDC bit is mainly used in soft to medium hard formations,but in hard rock drilling effect of PDC bit is not ideal,its penetration rate and bit life is low,the drilling cycle is long.The development of conical PDC cutter provides a kind of theory in drilling hard rocks,its rock breaking methods is ploughing rocks,which has been experimented at home and abroad,and achieved good effect of drilling.However,the research on conical cutter mixed with PDC teeth is still blank,especially the key parameters of tapered PDC tooth cutting angle and cutting tooth on the influence law of rock breaking efficiency is still unclear,which greatly restrict the application of cone gear PDC.This paper aims to explore the key tooth arrangement parameters of plough type PDC bit on the rock breaking efficiency of influence and the selection of cutter parameters of high rock breaking efficiency,and then improve the mechanical of PDC bit in hard rock drilling speed and long service life.In this paper,we analysis the relationship between rock-breaking efficiency and cutting angle and cone angle and WOB through the single rock-breaking experiment,and the highest optimized cutting angle is 25 °;by PDC experiment we study the relationship between rock breaking efficiency and wear degree,and compare the rock breaking efficiency of conical cutter and PDC cutter,the cutter depth of conical cutter is less than PDC,but cutting force of conical cutter is less than the PDC cutter;we design and make three kinds of plowing type of PDC bits,which are staggered tooth arrangement,PDC and conical cutter exposed in the same track at the same height,and PDC and conical cutter exposed in the same track at the different height.Through bench test we study how the cutter arrangement influence the ROP,we get the PDC and conical cutter exposed in the same track at the different height help bit improve ROP.Lastly we design and develope a 8-1/2 " PDC bit,the average ROP of 10.72m/h,total footage of 1533 m,compared with the offshore wells,drilling speed increase 7.4%,the total footage increase 41.4%.