The procedure for determining pressure losses in washing fluid flow in hydraulic system of the core barrel

Purpose.Development of calculation procedure and analysis of pressure losses in the flow of washing fluid circulating through a hydraulic system of the core barrel. Methods. Theoretical analysis based on the methods of hydraulic calculation. Findings. An approach to computation of hydraulics processes is proposed herein. Design ratios have been developed in order to determine the pressure losses in the inner area of the core barrel and in the annular space, taking into account changes of the hydraulic system geometry by height of the barrel. The regularities of pressure loss change in the flow depending on the depth of the discharge ports are obtained. The influence of the core bit's wear on pressure loss was studied. The efficiency of the hydraulic systems of core bits 01А3-76 and БС33-76 was analysed. Originality. It is proved that the existing recommendations for determining the pressure losses in the hydraulic system of the core barrel give conservative values of this parameter. The proposed method of determining the pressure losses, as distinct from the known, is sensitive to the design features of the barrel and core bits. For the in first time, the developed procedure takes into account pressure changes in the hydraulic system during the run due to the core bit wear. It is shown that the loss of pressure during the run can be used as an indicator of the core bits' wear. Practical implications. The proposed method allows to determine more precisely the necessary pump rate in developing borehole drilling technology. The suggested calculation procedure can be used to design the flushing system of new core bit concepts as well.