The choice of the diamond bit used in the formation phase is a key factor affecting the drilling, and the quality and efficiency of the drilling directly affect the quality of the geological report and the exploration cost. When choosing a diamond drill bit, people often expect it to have high timeliness, fragile rock, and long life, that is to say, it is easy to use and durable, that is, efficient and cost-effective.

First, the choice of diamond size, strength and concentration

When choosing diamonds, the drilling rate is usually considered first, and then the durability of the bit is considered. If the rock is hard, brittle or broken, we first consider the life span; If it's hard. In dense formations, drilling rate and life should be considered.

1, structural integrity, medium hard and lower rock drilling

The wear of the rock to the diamond is weak, and the pressure exerted on the single particle diamond does not need to be very large to break the rock by volume crushing, so the diamond should be selected with coarser grain size. Because the compressive strength of the rock is not high, the higher drilling rate can be achieved with a smaller bit weight, so the choice of lower strength diamond can be; The diamond concentration should not be too large.

2, hard dense, hard brittle, broken rock drilling

Diamond not only to withstand the larger axial force and shear force, the good drug to withstand the larger impact force, must choose finer granularity, high strength diamond.

Second, the choice of fetal performance

The wear resistance of the matrix is one of the important factors affecting the bit life. The wear resistance of the matrix should be adapted to the abrasive property of the drilled rock, that is, the rock and abrasive particles at the bottom of the hole should produce moderate wear on the matrix metal while the footage is fed, so that the diamond can maintain a good cutting edge state. Generally, the wear resistance of a drill bit is only suitable for certain formations. There are many factors affecting the wear resistance of the matrix: 1, the composition of the matrix alloy and its hardness; 2, the concentration of diamond in the carcass; 3, the wear state of the bottom of the drilling hole.

The drill bit adapted to the complete formation below the medium hard, when drilling in the strong abrasive and broken formation, it shows that the wear resistance of the matrix is insufficient and the wear is too fast, and the diamond is broken and threshed. The broken diamond and the highly abrasive rock powder speed up the wear of the matrix under the rotary pressure holding of the bit, and aggravate the diamond threshing, and the service life of the bit is greatly reduced.

The drill bit with high hardness has poor self-sharpness and low drilling efficiency in the formation below medium hardness. Encounter hard and weak abrasive formation, if the hardness of the matrix is too high, the diamond concentration is too large, the particle size is too fine, the matrix is not easy to wear, the diamond is not easy to edge, under rotary pressure holding, the drill is easy to slip. If the hardness of the matrix is too soft, the diamond falls off too fast, so choosing the right hardness of the matrix can shorten the interval of lifting drilling, effectively improve efficiency and reduce costs.

Third, the choice of diamond drill nozzle

When drilling in soft, broken and erosion-prone strata, it is advisable to choose bottom-jet or side-jet bit to ensure the adoption of rock core.

In the medium hard and lower rock drilling, because the strength of the rock is not high, the drilling rate and life mainly depend on the discharge of powder and cooling conditions, so choose multi-nozzle or large nozzle concentric bit;

While drilling in hard and dense rock formations with good powder discharge conditions and too large bottom lip contact area will lead to slipping, a hot-pressed flat-bottomed pulling groove with a bottom lip contact area of 18-20cm² should be selected to swing a single-step pulling groove bit, which can locally enrich rock powder at the bottom of the hole, enhance the wear of rock powder on the matrix, and make the diamond continuous cutting edge.

Four, the use of drill

The choice of diamond bits is important, but the correct use and operation should also pay attention to give full play to the technical characteristics and structural characteristics of various bits themselves. In order to prevent hole deviation and improve drilling efficiency, the drill bit should be stratified and used alternately regularly.