Performance analysis and optimization of self-excited pulsed jet suck-in annulus fluids

Key words:  jet drilling  self-excited pulse  large eddy simulation  rock breaking  orthogonal experiment  structure optimi-

Abstract:

The pulsed water jet drilling technology suck-in annulus fluids was proposed to take full use of the bottom-hole hydraulic power and promote the rock breaking efficiency. The large eddy simulation numerical analysis method was adopted together with laboratory experiments to analyze the modulation mechanism of self-excited pulsed jet suck-in annulus fluids and the effect of structural parameters change on the jet performance of the modulator. The multi-factor orthogonal simulation experiments were done and the pulsed structure was optimized according to the fluctuating velocity. The results show that the structural parameters significantly influence the jet performance，and the suck-in modulator with a rational structure is superior to non-suck-in one. In addition, the bigger the outlet fluctuating velocity of the modulator, the better the rock-breaking effect, and there is a good linear correlation between them. The simulation results agree well with the laboratory experimental data, which indicates the feasibility of the structure optimization of the self-excited pulsed water jet.