# A Review of Failures and Malfunctions in Hydraulic Sandblasting Perforation Guns
## 2 Erosion Wear of the Perforation Gun
### Erosion Wear Mechanisms on the Gun Surface
[PERSON] reported that micro-cutting, stress fatigue, and brittle fracture are the main erosion forms in perforation guns [14]. In high-pressure environments, commonly used wear-resistant materials include tungsten carbide, nickel-based alloys, and ceramic coatings, all capable of sustaining high-velocity impacts while reducing surface spalling. Moreover, nozzle shape optimization and protective coating designs (e.g., gradient coatings) have become key strategies to mitigate erosion. [PERSON] et al. further revealed through numerical studies that fluid viscosity and particle characteristics affect erosion rates and proposed using higher-viscosity fluids to effectively reduce erosion [8]. However, since erosion  
Figure 2: Impact forging and surface cutting in erosion wear. behavior is inherently nonlinear under varying conditions, research on the multi-factor interactions influencing erosion remains insufficient. Beyond the fundamental properties of erosion, understanding the erosion location within the perforation gun is crucial for guiding structural optimization. During hydraulic sandblasting perforation, the target shape evolves over time, and as perforation continues, a macroscopically visible depression on the target surface emerges. This morphological change alters the particle impact angle and can cause rebounding particles to cut the perforation hole's sidewalls, gradually enlarging the hole's radial dimensions. Over time, as particle rebound angles decrease and the rebound erosion zone narrows and intensifies, erosion becomes more concentrated near the nozzle [15] (Figure 3). In addition, the arrangement of multiple, closely spaced nozzles and the interactions among them significantly influence erosion distribution patterns. Research shows that jet interference occurs between nozzles oriented at the same azimuth, leading to particle collisions in the flow and concentrated erosion in the upper portion of the upper nozzle and the lower portion of the lower nozzle [11]. This jet interference effect is particularly pronounced in multi-nozzle configurations, severely impacting nozzle lifespan and perforation efficiency. By comparing field erosion wear conditions with numerical simulations of the internal flow field, one study found that the most severe erosion zones on the gun's inner wall occur at the lower portion of the lower nozzle inlet and the upper portion of the upper nozzle inlet (Figure 4). This localized erosion primarily results from the impact of the jet and secondary reflections of the sand-laden fluid [10]. Moreover, on the gun's outer wall, the rebound erosion near the lower nozzle outlet is more severe than that near the upper nozzle outlet, reflecting a stronger turbulent disturbance in the sand-laden flow outside the gun [16]. In summary, the erosion behavior of perforation guns under different operating conditions exhibits significant multi-factor coupling. Consideration of fluid parameters, particle properties, gun materials, and jet interference effects is essential. Although considerable progress has been made, further exploration in material optimization, complex condition simulation, and multi-objective optimization is needed. Figure 3: Wear erosion issues near the nozzle caused by target shape changing.