Multiscale Physical Destruction Mechanisms of Rotating Water Jets for Wellbore Cleanout and Field Verification

Summary

During the extraction of oil and gas resources, the near-wellbore region is highly susceptible to severe composite blockages, which form dense barriers that dramatically restrict well productivity. To address the limited circumferential coverage and shallow stripping effect of conventional cleanout methods, we propose a coiled-tubing-conveyed self-rotating hydraulic jetting technology tailored to the Mahu conglomerate reservoir. The tool integrates an innovative multivector nozzle configuration—axial penetration, inclined coverage, and tangential shearing—with an internal axial flow turbine to convert hydraulic energy into mechanical rotation and multidirectional jet action. We performed full-flow-path steady-state computational fluid dynamics (CFD) simulations to clarify internal pressure/velocity evolution, energy transfer behaviors, and outlet jet-velocity formation, providing a theoretical basis for hydraulic parameter optimization rather than directly resolving transient water hammer processes. During field application in Well HW16, solid returns were characterized using particle-size distribution (PSD), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Results demonstrate that the high-velocity rotating jets induced strong brittle fracture and pulverization of carbonate scale, overcoming the superficial stripping limits of conventional hydraulic scouring. At 600 L/min, the effective nozzle pressure drop was approximately 5 MPa, producing outlet jet velocities exceeding 100 m/s. Compared with naturally detached materials, the jet-fragmented products showed a decrease in D[4,3] from 602.84 μm to 111.92 μm and an approximately 13-fold increase in specific surface area, indicating enhanced pulverization, transport, and flowback of solids. Furthermore, the high-energy jets successfully penetrated superficial carbonate-scale barriers to break deeper dense composite blockages cemented by aluminosilicate minerals, as supported by silicon (Si) and aluminum (Al) detected by EDS, 0.29% lattice microstrain from XRD, and impact craters and brittle cleavage steps observed by SEM. After treatment, daily oil production increased from 0.5 metric t/d to 3.5 metric t/d, while the skin factor decreased from +24.9 to −1.7, indicating substantial removal of near-wellbore damage and restoration of flow capacity. These results demonstrate the technology’s capability to efficiently remove composite blockages in strongly heterogeneous horizontal wells, supporting its application for production restoration in damaged mature wells.