Enhancing rate of penetration in a tight formation with high-pressure water jet (HPWJ) via a downhole pressurized drilling tool

In this study, a robust and pragmatic technique has been developed to experimentally and theoretically evaluate the performance of high-pressure water jet (HPWJ) dynamics in tight formations by use of a new downhole pressurized drilling tool (DPDT). Experimentally, principles and structure of the new DPDT are described, while well-designed tests are conducted to examine the effects of water jet velocity, dwell time, incident angle, and rock type on the rock-breaking volume at pressures higher than 100 MPa. Numerically, the smoothed particle hydrodynamics coupled with the finite element method has been used to quantify the rock-breaking volume as a function of the 1st principal stress under various conditions. The experimentally measured and numerically simulated rock-breaking volumes are in good agreement under the same conditions. As for a marble specimen, there is a rapid increase in rock-breaking volume at nozzle pressures higher than 150 MPa and dwell times shorter than 40 s. The optimal incident angle for the rock-breaking efficiency is found to be 77 degrees. With the same nozzle pressure and dwell time, the rock types can be ranked in terms of rock-breaking volume in the order of marble < sandstone < concrete < shale. Also, field tests of the DPDT have been successfully performed to enhance the rate of penetration (ROP) by 32.9-80.5% for different rock types compared with the traditional drilling methods.