What we should notice when piling with roller bits ?

Specifications for the use of rollers

1. When using the roller cone bit, make sure that the diameters of the drilling bucket and the core barrel are matched. 
2. The order of use of the roller cone bit is to use the sand drill to open the hole until it can't be drilled, then change the pick barrel and drill until the barrel drill can't be drilled. 
It is necessary to slowly sweep the rock surface by hanging and then carry out normal operation.

Precautions for the use of rollers

1.When the roller bit is drilling, the drill bit is affected by the axial pressure and reverse force of the WOB and rotational speed. The cutting teeth are worn, dulled or damaged in the process of pressing and shearing the rock,
which will definitely affect the drilling speed. With the increase of drilling pressure, the tooth feeding efficiency will continue to improve, and the parts such as the bearings and cutting teeth of the drill bit will also wear faster, 
which will affect the tooth feeding efficiency and the service life of the cone.When the roller is drilling on the rock surface, since the WOB and rotational speed are controlled within the minimum range, when the WOB is less 
than the hardness of the rock, the cutting teeth cannot cut into the rock, and can only break the rock by friction on the surface of the rock. , the cutting teeth wear is relatively large, although the tooth feeding efficiency also increases
proportionally with the increase of the drilling pressure, but the tooth feeding efficiency is very low; at this stage, the drill bit should be lifted up from time to time and rinsed with clean water.



2.When the roller cone is drilled into medium-hard and hard-finished rock formations, the cutting teeth are continuously blunted during drilling, the contact area between the teeth and the rock is also increasing, the difficulty increases, 
the tooth feeding efficiency becomes slower, and the demand is greater. In order to prevent the cutting teeth from wearing quickly, the speed should not be increased excessively when drilling in medium-hard and hard formations.

3. If you encounter complex formations, if the drill bit is not used properly, the wear of the cone will also increase. For example, in broken rock formations, it is better to drill with a core barrel with bullet teeth first, and the use of the cone 
will easily cause alloys smashed, thus affecting the using life.

In the stratum with a large sand content, the alloy of the cone and the slag guide bar wear faster, and the slag guide bar needs to be added in time. It can only be drilled on the rock nitrate by friction method, which causes the alloy to be annealed
 and causes the hardness to decrease, which affects the service life of the cone.
 
 The service life and benefit of the roller bits are related with the operator's technical level and the complexity of the formation. Not all formations are suitable for the use of roller bits, which requires the operator's experience to judge.