The correct selection of core barrels in geomechanical drilling is only one of the keys to get well drilled core sample. Currently are in use single tube, double tube and triple tube core barrels. Beacuse of need to pull out all the drill rods of borehole to get sample are now slowly replaced with newer and more advanced methods of core sampling. Two of the more advanced methods are; the »wire line« method of sampling and sonic sampling. These two methods can provide core in less time than other previously mentioned methods. The »wire line« method was developed mainly beacuse of saving time due to pull in and out core samppler. In the sonic method of samppling, high frequency resonance energy is used to drill in formations. During drilling, energy is transported trough drill rods to a drill head with different sonic frequences. In first part of diploma thesis work i described different characteristics, advantages and disadvantages of core barrels. In continuation i was describing influential parameters on the quality and quantity obtained core. The selection of the drill bit with which we are drilling is important, beacuse it is the first component on the whole drill assembly. Usually, diamond crowns and crowns of carbide materials are in use. For faster progression in formations, the drilling fluids are in use. The main task of fluid, which circulate through the drill rods and then back to the surface is to collect and amount the cuttings from the working face.
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