# 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  
Erosion wear of the perforation gun surface is a pressing issue in hydraulic sandblasting perforation, as it directly affects tool longevity and operational efficiency. Fundamentally, erosion wear arises from the continuous impact and shear action of high-velocity sand-laden fluids on the gun's inner surface. Its severity is influenced by multiple factors, including pressure, fluid velocity, particle size, sand concentration, and jet angle. Studies have shown that increasing inlet pressure and flow velocity leads to a nonlinear escalation in erosion rates, with high-pressure conditions intensifying the impact forces on nozzle materials [8]. Moreover, temperature variations and fluid composition can significantly alter erosion mechanisms. Elevated temperatures may reduce the viscosity of the fluid phase, intensifying particle impact velocity, while reactive fluid compositions--containing corrosive ions or acidic components--could accelerate material loss by combining mechanical erosion with chemical corrosion. Particle characteristics, such as shape (angular vs. rounded) and mineral hardness, further dictate how erosive the abrasive media will be under dynamic flow conditions. In addition, particle diameter, hardness, and mass concentration significantly affect erosion behavior; larger or harder particles typically induce deeper cutting-type erosion, while smaller particles tend to cause more superficial abrasive wear [9]. Notably, there is a positive correlation between erosion severity and abrasive particle concentration. In addition to the influences of nozzle geometry and flow velocity, the quantification of erosion severity often relies on specific erosion models. For instance, the Finnie model focuses on ductile materials and assesses wear based on particle impact angle and velocity, whereas the Oka model incorporates material hardness and fracture toughness, enabling more accurate predictions of erosion rates under varying flow conditions. By embedding  
Figure 1: Key issues of hydraulic sandblasting perforation guns. these models into CFD simulations, researchers can more precisely identify high-risk zones for erosion, thereby guiding targeted structural optimizations. Under varying operating conditions, erosion patterns exhibit complex nonlinear characteristics. Experimental investigations and numerical simulations are the primary tools for examining erosion behavior. Experimentally, high-pressure test rigs are employed to simulate erosion by sand-laden jets, while high-speed imaging and scanning electron microscopy (SEM) reveal erosion morphologies and wear characteristics on nozzle surfaces [10]. Findings indicate that when the jet angle approaches 90\({}^{\circ}\), impact energy concentrates on the surface, resulting in a maximum erosion rate characterized by impact forging-type damage. At smaller angles (<45\({}^{\circ}\)), shear effects dominate, producing scratch-like surface wear, as illustrated in Figure 2. Additionally, [PERSON] et al. developed a sand-laden jet test apparatus and, through macroscopic observation combined with SEM analyses, found that higher sand concentrations increased shallow pits and brittle cracks, whereas lower concentrations produced predominantly cutting and plowing wear patterns [10]. On the numerical side, computational fluid dynamics (CFD) methods are widely used to predict nozzle erosion. By establishing flow models for sand-laden fluids and analyzing particle trajectories, researchers can quantitatively assess erosion distributions and their interplay with material properties [11; 12]. [PERSON] et al. integrated ANSYS-FLUENT simulations with different sand flow rates and concentrations and validated the model's reliability against downhole perforation field data [13]. The research also confirms that material selection significantly influences erosion resistance.