## 4 Field Case Analysis  
### Case 1: XX-1 Well in the Southwest Region  
Considering example A in southwest China, the safety analysis of a pipe string under shock loading has been carried out. The key parameters required for the analysis of pipe string safety under shock loading include perforation charge parameters, perforation parameters, casing parameters of the perforating section, tubing parameters of the perforating section, packer parameters, construction parameters, reservoir parameters and formation parameters, as shown in Table 1. Figure 8 is a schematic diagram of the pipe string structure of example well A in southwest China.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Category** & **Parameter** & **Value** \\ \hline \multirow{3}{*}{Perforation charge parameters} & Type of explosives & HMX \\  & Bursting charge amount & 45 g/piece \\  & Loading density & 1.6 g/m\({}^{3}\) \\ \hline \multirow{6}{*}{Perforation parameters} & Hole density of the perforation & 16 holes/m \\  & Phase angle & 60\({}^{\circ}\) \\  & Hole diameter & 12 mm \\  & Perforating gun model & 127 mm \\  & Top perforation boundary & 4307 m \\  & Bottom perforation boundary & 4354 m \\ \hline \multirow{3}{*}{Casing parameters of the perforating section} & Outer diameter & 177.8 mm \\  & Wall thickness & 12.65 mm \\  & Steel type & 140 V \\ \hline \multirow{3}{*}{Tubing parameters of the perforating section} & Outer diameter & 88.9 mm \\  & Wall thickness & 6.45 mm \\  & Steel type & CB110 SS \\ \hline \multirow{3}{*}{Packer parameters} & Packer type & 7\({}^{\prime\prime}\) RTTS \\  & Setting position & 4200 m \\ \hline \multirow{6}{*}{Construction parameters} & Artificial well bottom & 4400 m \\  & Screen tube top boundary & 4305 m \\ \cline{1-1}  & Screen tube bottom boundary & 4306 m \\ \cline{1-1}  & Shock absorber location & 4303–4305 m \\ \cline{1-1}  & Perforating fluid density & 1.0 g/cm\({}^{3}\) \\ \hline \multirow{3}{*}{Reservoir parameters} & Poisson’s ratio & 0.33 \\  & Reservoir porosity & 2.0–7.1\% \\ \hline \multirow{3}{*}{Formation parameters} & Well bottom depth & \multirow{2}{*}{6398.00 m/5395.28 m} \\  & (inclined/vertical) & \\ \cline{1-1}  & Logging temperature & 152 \({}^{\circ}\)C \\ \hline \hline \end{tabular}
\end{table}
Table 1: Key parameters for pipe string safety analysis in example well A.  
Using the peak pressure calculation model of pipe string under shock loading in this paper, the relevant parameters of the example well are substituted into Equation (10) for analyzing and calculating, and the resulting peak pressure calculation of pipe string under shock loading is 69.52 MPa.  
A commercial software for analyzing wellbore dynamics was used to analyze the dynamic strength safety of the string under the shock loading of the well in this example. The peak value of the maximum shock load in clear water is about 70.43 MPa, as shown in Figure 9.  
The calculation results of the peak pressure model under shock loading have been compared with those predicted by the commercial software. The calculation results are as follows:  
\[\delta=\frac{70.43-69.52}{70.43}\times 100\%=1.30\% \tag{20}\]  
The error between the peak pressure calculated by the model and the result calculated by the commercial software is less than 10%, and the error is within the allowable range. According to the established flexion mechanical check model and tensile strength mechanical check model, the safety of the pipe string under shock loading is checked. The calculated maximum tensile force of the pipe string is 244.45 kN, the tensile safety factor is  
Figure 8: Pipe string structure diagram of example well A in southwest China.  
Figure 9: Simulation result of shock load.  
5.11 and no pulling phenomenon will occur. The maximum impact pressure of the string is 103.97 kN, the buckling safety factor is 1.62 and the buckling phenomenon will not occur.