Abstract:

This paper deals with our experiments on the measurement of the hydranlic energy imposed on the rock surface of the hole bottom (denoted by “RSHB”). We have established two new theories of the hydraulic programs in design concerning the maximum hydraulic horsepower and impact force on the RSHB. The “black box” theory, which can be effectively used to solve modern engineering problems, has now been primarily introduced in the research of the flow field of the jet bit above the hole bottom. An unique full-scale experiment (i.e. the experiment measuring the hydraulic energy on the RSHB ) has been done to measure directly the hydraulic horsepower and the impact force of the jets beneath a tricone bit striking on the RSHB. Empirical formulae have been developed for calculating the hydraulic horsepower and the impact force on the RSHB. Two new hydraulic programs have been provided which take the maximum hydraulic horsepower and impact force on the RSHB as the design criteria for the optimized hydraulic programs.
Under the experimental conditions in this paper, critical values have been obtained, such as the ratio (Rn) of the horsepower distribution for the maximum hydraulic energy on the RSHB and the range of the hydraulic energy decline factor at the standoff distance (135mm, from the nozzle exit to the RSHB). Under the same condition, the optimum flow rate for the maximum hdraulic energy on the RSHB is about 7.5 per cent more than that for the maximum hydraulic energy on the bit nozzle. From the theory and drilling practice, it has been proved that properly increasing the flow rate and pump-horsepower seems to be quite necessary.