Study On Impregnated Diamond Bit's Optimal Design For Hard Formation

In view of that the problem of the impregnated diamond bit is low efficiency, short endurance in drilling hard formation of strong or weak abrasiveness, this article has studied a series of parameters that impact on the efficiency and endurance of the impregnated diamond bit through the theoretical analysis and the laboratory experiment, such as diamond grade, particle size, concentration and other parameters as well as the matrix formulation of the drill. The results of study showed that:(1) The diamond grade selection has some relationships with the diamond size, if diamond bit uses the large granular diamond in 46 mesh rough or more, the grade requirements is above JR4; If uses the small diamond in 60 mesh tenuity or less ,the grade of diamond may choose JR2 or JR3. (2)When drilling in strong abrasive hard rocks (such as quartz sandstone, granite, etc.), diamond is 80% concentration and 80 mesh granular size, drilling rate is highest; when drilling in abrasive (hard limestone) and the weak abrasive (flint) strata, diamond is 70% concentration and 46 mesh granular size, drilling rate is highest.(3) Life expectancy is inversely proportional with the drilling rate, generally speaking, the drilling rate quickly short bit life, through the optimization of diamond particle size, concentration and carcass performance, we can have little effect on the drilling rate and give consideration to life, get the best formation results of drilling formation. (4)When drilling quartz sandstone, matrix hardness is HRC45 or more, we can get a higher drilling rate and longer bit life;drilling the granite, matrix hardness is about HRC40,effect is better; drilling in abrasive rock, the better condition is that matrix hardness is about HRC30; to the weak abrasive formation, matrix hardness is not to exceed HRC20.(5) The requirements of Diamond sintered impregnated block are that framework structure and bonding metal has fine granular size as far as possible, the bit wear resistance sintered by Cu powder with 400 mesh tenuity or less is improved than 200 mesh tenuity or less by 20%.(6) In view of Sichuan Xujiahe quartz sandstone formation,the use of blade contour diaborit is more conducive to drilling;Impregnated chunk using artificial diamond and natural diamond mixed fillet increases both bit offensive and abrasion resistance of drill bits.Research of this paper has some advising significance to improve drilling efficiency and lifetime of diamond drill bits in different nature rock formations.