# A Review of Failures and Malfunctions in Hydraulic Sandblasting Perforation Guns
## 3 High-Pressure Leakage in Perforation Guns  
### Causes of High-Pressure Leakage  
High-pressure leakage is a critical issue affecting the performance and service life of hydraulic sandblasting perforation guns. Its underlying causes are multifaceted, involving seal failure, structural deformation, material fatigue, high-pressure fluid erosion, and thermal effects. Under high-pressure conditions, sealing materials are subject to aging and wear due to prolonged exposure to intense loading. Creep, fatigue, and thermal aging of seal components markedly reduce sealing effectiveness [29; 30; 31]. For example, dynamic seals such as O-rings and lip seals deteriorate through prolonged compression and friction, ultimately failing to maintain a proper seal. Moreover, materials like polytetrafluoroethylene (PTFE) and rubber-based composites can undergo elastic fatigue in high-pressure environments; once the operating pressure surpasses the material's yield strength, permanent deformation ensues, weakening the seal [32]. Concurrently, microscopic deformation and roughness changes at the sealing interface reduce the effective contact area, thereby increasing leakage potential [33]. In high-temperature wells or operations involving steam injection, seal materials may degrade faster due to thermal expansion mismatches or reduced elastomer resilience. Likewise, aggressive fluid compositions--high salinity, acidic brines, or solvents--can \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Study** & **Material** & **Flow Velocity (m/s)** & **Particle Size (\(\mu\)m)** & **Erosion Rate (mg/kg)** & **Key Findings** \\ \hline \multirow{3}{*}{[25]} & \multirow{3}{*}{\(13\)Cr Steel} & \multirow{3}{*}{\(35\)–\(60\)} & \multirow{3}{*}{\(150\)–\(250\)} & \multirow{3}{*}{\(0.8\)–\(2.5\)} & Higher velocity leads to near-exponential rise in erosion; synergy with corrosion observed. \\ \cline{3-6}  & & & & & More stable erosion rate under \\ \hline \multirow{3}{*}{[26]} & \multirow{3}{*}{Inconel} & \multirow{3}{*}{\(25\)–\(45\)} & \multirow{3}{*}{\(100\)–\(200\)} & \multirow{3}{*}{\(0.3\)–\(1.2\)} & 300\({}^{\circ}\)C; micro-cracks formed along grain boundaries. \\ \cline{3-6}  & & & & Exhibits superior resistance \\ \cline{1-1} \cline{3-6}  & & & & & due to harder coating; minor \\ \cline{1-1} \cline{3-6}  & & & & & spallation at edges. \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Representative Erosion Data from Selected Studies. chemically attack polymeric seals, making them prone to micro-cracks and increased permeability. Consequently, operational parameters such as downhole temperature profiles and fluid chemical composition should be carefully considered when selecting and designing seal systems. Structural deformation and fracture of the perforation gun itself constitute another major cause of high-pressure leakage. Complex stress distributions--axial, hoop, and tangential--arise in the gun's inner walls under high-pressure fluid conditions. When localized stresses exceed the material's yield limit, the gun wall may undergo elastic or plastic deformation and potentially irreversible geometric changes [34]. Stress concentration points, such as nozzle interfaces and seal grooves, are prone to crack initiation. Under cyclical high-pressure pulses, these areas are highly susceptible to fatigue crack propagation, ultimately causing localized gun failure [35; 36; 37; 38]. Moreover, stress corrosion under high-pressure conditions can accelerate crack formation and propagation [39; 40]. Inadequ wall thickness design and insufficient machining precision may also lead to localized stress concentrations, exacerbating leakage and fracture risks [41]. Abrasive particles (e.g., sand) carried by high-pressure fluid streams induce high-frequency impact and cutting on the gun's inner walls and sealing surfaces. This erosion diminishes surface strength and leads to the formation of pits or microcracks [42; 43]. For instance, sand particles impinging on sealing surfaces intensify material wear, further compromising seal integrity [44; 45].