Structural design and optimization of hydraulic sandblasting perforator

The re-perforation and production enhancement of offshore gas wells are confronted with challenges such as limitations in wellbore structure and insufficient adaptability of tools. The existing sandblasting perforators are unable to meet the demands of high-temperature and high-pressure, highly deviated wells, and large-diameter differences operations. Therefore, this paper proposes a novel eccentric hydraulic sandblasting perforator design, which can penetrate 7" casing through a 2.562" production tubing without moving the tubing string. Based on the abrasive jet theory, the acceleration process and erosion characteristics of high-speed abrasive jets in the nozzle were studied and analyzed, and multiphase flow simulations of different nozzle structures were conducted using Fluent software. The results show that the conical-straight type nozzle performs best in terms of jet velocity (increased by approximately 25%), jetting effect, and erosion resistance (life extended by 40%), with the optimal parameters being a total length of 20 mm, an inlet contraction angle of 40°, and a contraction section length of 10 mm, which can form a stable and uniform core. Through outdoor experiments of the same size, it was verified that the perforator has good directivity, with well-connected and regular-shaped perforation channels (average hole diameter of 12.5 mm, circularity deviation < 5%), providing an effective technical solution for the re-perforation and production enhancement of offshore gas wells.