Diamond drilling

(Рисунок) Типы алмазных коронок / (Figure) The types of the diamond drill crownsDIAMOND DRILLING (EN: diamond drilling, diamond boring; DE: Diamantbohren; FR: forage au diamant; ES: sondeo con corona de diamantes; RU: алмазное бурение) is the mechanical rotary drilling by the rock-destructing tool, which is reinforced by the diamonds.

The diamond drilling has been proposed in 1862 by the Swiss watchmaker J. Lesho for the drilling during the heading of the tunnels, and later it has found the usage for the exploration and operation of the deposits of the minerals. The downhole drilling tool for the diamond drilling comprises the diamond drill crown (Figure) or bit, the diamond reamer, which preserves the diameter of the borehole during the wear of the crown, the kern-tearing device, the core barrel, and the drill string.The types of the diamond drill crowns

They use during the prospecting and exploration of the deposits of the minerals the diamond drill crowns and partially the diamond drill bits (the diameters are 36, 46, 59, 76, 93, 112 millimetres); they use during the drilling of the deep operational drilled wells for the extraction of the oil and gas mainly the drill bits (the diameters are 140, 159, 188, 212, 242 millimetres). They place the diamonds within the matrix of the drill crown into the layers (from 1 to 3), or they uniformly mix the diamonds with the material of the matrix (so called impregnated drill crowns). Taking into account the character of the rocks, which are traversed, the hardness of the matrix ranges from 10 to 50 HRC (the harder and more abrasive is the rock, the harder is the matrix). They use for the reinforcement of the drill crowns the technical diamonds (mostly the bort diamonds).

They use the diamonds with the size of 20-100 grains per 1 carat for the manufacturing of the single-layered and multi-layered drill crowns; they use the diamonds with the size from 120 to 1,200 grains and more per 1 carat for the impregnated drill crowns, which are used during the drilling of the very hard, abrasive, fractured rocks. They distinguish by the location in the tool the bulk diamonds for the end of the drill crown, and the larger cutting ones, which are placed on the side surface. For example, they insert into the single-layered drill crown with the diameter of 46 millimetres 6-8 carats of the diamonds, into the drill crown with the diameter of 59 millimetres 10-12 carats of the diamonds (of which 60% are the bulk diamonds, and 40% are the cutting diamonds).

The method for the manufacturing of the matrices of the diamond drill bits is the same, as the method for the diamond drill crowns, but they use the larger diamonds with the size of 0.05-0.34 carats (for example, there are consumed for the drill bit with the diameter of 188 millimetres 400-650 carats, or 2000-2500 grains of the diamonds). The durability resource of the diamond rock-destructing tools is by 8-10 times more in comparison with other tools. The high productivity of the diamond drilling (the heading of the diamond drill bit is by 19 times more than the heading of the roller-cone drill bit) is achieved on the account of the usage of the high frequencies of the rotation of the drilling tool (up to 2,000 revolutions per minute or more).

The diamond drilling yields the greatest effect during the usage of the drill crowns with the small diameters (49-76 millimetres), at the high speeds of the rotation, and with the specific load of 5-15 megapascals on the working end of the drill crown. They use the diamond drilling usually in the special conditions, which are characterized by the low mechanical speed, for the drilling of the drilled wells of the small diameter, and during the usage of the downhole motors with the high speed of the rotation. The volume of the diamond drilling constituted 1% at the midddle of the 1970s (10% in the regions of the active drilling) of the total volume of the drilling in the world (3.9% in the USSR).