The Design and Research of a New Cavitation-Jet Blockage-Removal Tool

Wellbore plugging has become the primary constraint on gas production for numerous oil, gas, and geothermal wells in China. To enhance productivity in mature wells, a novel straight-swirling integrated jet (SSIJ) deplugging tool was designed, incorporating a converging-diverging jet (CDJ) nozzle. A combined approach of numerical simulation and experiments was employed to optimize the tool structure and evaluate the effects of different operational parameters on its blockage-removal performance. Structural optimization identified an impeller spinning angle of 540° and an impeller thickness of 12 mm as the optimal parameters, which significantly improve the three-dimensional velocity peaks and cavitation generation capability. Compared with the CDJ nozzle, the SSIJ tool produces substantially higher tangential and radial velocity components, with peak tangential and radial velocities reaching 22 m/s and 45 m/s, respectively, under the optimized conditions. The numerical results show that the peak impact pressure reaches 2.7 MPa at a standoff distance of 12 mm, while the optimal standoff distance, considering both impact magnitude and effective coverage area, is determined to be 16 mm (4 times the outlet diameter). Furthermore, indoor validation experiments under a pump pressure of 20 MPa demonstrate that the tool completely removes the artificial scale layer from the tubing inner wall within 2 min of continuous flushing, leaving no visible residue. This study provides a quantitative reference for the design and process optimization of jet blockage-removal tools.