Abstract

This laboratory investigation involved evaluating the potential to enhance drilling Rate of Penetration (ROP) and drilling efficiency by applying axial vibrations on the bit using a pulse cavitation drilling tool in combination with varying levels of axial compliance. The pulse cavitation tool generates cavitation bubbles in the drilling fluid by flowing through a venturi. When the cavitation bubbles produced within the tool are collapsed, pressure pulses are generated which produce pressure pulsations and oscillatory forces on the bit. Drilling results were evaluated on the basis of ROP, Mechanical Specific Energy (MSE), bit loads and bit displacements. The tool was tested both with and without compliance to evaluate the effects of the compliant element. Experimental results show that the pulse cavitation tool starts to cavitate and produce vibrations when a critical flow rate is reached. When the drilling system was rigid (i.e. no compliance was used), the vibration produced did not have any significant effect on the ROP. However, when the drilling system was compliant the vibrations produced by the tool intensified the natural displacement vibration of the compliant element and the ROP was increased and MSE was decreased.

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