R/C or Core drilling?
Core drilling(Diamond Drilling)
A type of fast rotation drilling.
The implementation of which results in the destruction of the rock within a ring pattern but not over the entire bottom hole in this mode of drilling the interior of the rock in the form of core.
A rock pile with an undisturbed structure is fully preserved for this purpose the core is periodically get locked and isolated from the bottom and lifted up to the surface using a core receiver suspended a rope from which the core is removed and distribute to core boxes.
코어 시추(다이아몬드 드릴 시추)는 고속으로 회전하는 드릴로 코어를 시추하는 방식이다.
드릴 내부의 단면으로 채취되는 코어의 단면을 통해 암석의 형태를 확인할 수 있다.
RC drilling(Reverse Circulation drilling)
Carried out using the air supplied through the rods with the reciprocating piston a so-called air hammer used as the drilling mechanism rotating the drilling bit made of tungsten steel when pressure is applied to the rod and aerodynamic lift is generated by means of which the water rises up the annular space with the sludge rising within the inner tube which is located inside each rod. Ideally in the course of RC drilling we obtain dry drill cuttings since the compressed air from the compressor dries rock in front of the drilling bit.
The cuttings reach the reflector on the rig mast move through the sampling hose and into the cyclone followed by processing within the cyclone until released through the opening at the bottom(the sampling bag) whereupon collected in a sampling bag.
For comparison during the drilling method with direct blowing which is mainly used for the blast hole drilling cuttings reach the Earth’s surface using the same air pressure but through the annulus where the sample is naturally contaminated.
The most commonly used drilling bits for RC drilling have a diameter of 124-130mm with protruding round metal buttons or pins.
If we use in diamond drilling the average size of 95 mm the core diameter is about 63 mm.
Thus comparing RC drilling and Core drilling by the sample amount,
RC drilling is characterized by the obvious superiority.
It is also worth noting that, unlike air-hammer drilling, core drilling provides geologists with the opportunity to visually analyze samples since an undisturbed core structure provides a complete picture of the structure and rock occurrence.
When exploring at shallow depths RC drilling can be used independently without the aid of core drilling. When exploring to a greater depth RC method is used as a cost-saving method of drilling in order to reach mineralization.
After that geologist may decide whether to continue RC drilling to extract cuttings or go shift to core drilling for the extraction of the core. In this case RC drilling becomes a great addition to the normal core drilling.
(Core - a rock sample extracted from the well by core drilling. It is a cylindrical column strong enough to maintain the solidity.)
Due to a number of the factors mentioned above, RC drilling method is cheaper than core drilling and therefore it is preferred in the exploration of mineral resources.
Confidence/(time&cost) = Profit
The choice of method used in the exploration and assessment depends on whether drilling is performed from the surface or from mines on the geological features of the deposit all depth the complexity and the category of drill ability of rocks as well as preferences of the geologists.
Modern core rig allow for fast and efficient coring to a sufficient depth from holes of different diameters.
At the same time RC drilling has become so progressive and advanced but more and more geologists believe that to determine the mineral composition of rocks.
Taking all the forces into consideration, we should say that drill from the surface offers a choice of cuttings core or a combination thereof underground RC drilling is certainly technically possible but until now has been used to a very limited extent.
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