# Study on Explosive Fracturing Mechanism of Qianjiang Shale Oil
## 3 Results and Discussion
### Blasting Damage Simulation Process  
The circumferential stress distribution within the reservoir prior to blasting can be determined through static analysis. As illustrated in Figure 5, ten monitoring points (A through J) are sequentially arranged along the \(x\)-axis of the borehole to evaluate effective stress and analyze the stress distribution on both sides of the borehole as well as its variation with respect to the borehole. To comprehensively capture the monitoring results, the points are strategically positioned as follows: Point A is located at the leftmost position on the central axis of the borehole; Point B is placed at the midpoint on the left side of the central axis; Point C is situated 4 times the borehole radius from the central axis on the left side; Point D is positioned 2 times the borehole radius from the central axis on the left side; Point E marks the starting point on the left side of the central axis. On the right side of the central axis, Point F is placed at the starting position; Point G is located 2 times the borehole radius from the central axis; Point H is situated 4 times the borehole radius from the central axis; Point I is placed at the midpoint on the right side of the central axis; and Point J is positioned at the far-right end of the central axis. Based on the position of the measurement point illustrated in Figure 5, the theta-stress curve at this point is extracted as shown in Figure 6, where negative values denote compressive stress. It is observed that during the static analysis under in-situ stress conditions, the formation pressure at the measurement point increases over time and eventually stabilizes. By examining the stress change curve at the stabilization point, it becomes evident that the theta compressive stress at equidistant points is largely consistent, with higher pressures closer to the borehole. This phenomenon is attributed to the stress \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & \(A\)/MPa & \(B\)/MPa & \(R_{1}\) & \(R_{2}\) & \(\omega\) & \(E\)/J\(\cdot\)m\({}^{-3}\) & \(V\) \\ \hline NTNMT & \(9.3223\times 10^{5}\) & \(8.689\times 10^{3}\) & 4.42 & 1.193 & 0.33 & \(9.644\times 10^{9}\) & 1 \\ DEGDN & \(3.8518\times 10^{5}\) & \(7.751\times 10^{3}\) & 4.65 & 1.256 & 0.33 & \(6.77\times 10^{9}\) & 1 \\ TNT & \(4.365\times 10^{5}\) & \(3.241\times 10^{3}\) & 4.34 & 1.172 & 0.33 & \(6.418\times 10^{9}\) & 1 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Dynamic JWL equation of state parameters. Figure 5: Schematic diagram of measuring point locations (Unit: cm). A–J indicates the monitoring points. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \(R_{0}\)/kg\(\cdot\)m\({}^{-3}\) & \(D\)/m\(\cdot\)s\({}^{-1}\) & \(P_{\textit{off}}\)/MPa & \(K\) & \(G\) & \(SIGY\) \\ \hline NTNMT & \(1940\) & \(8983\) & \(3.9034\times 10^{4}\) & 0 & 0 & 0 \\ DEGDN & \(1380\) & \(6911\) & \(1.7499\times 10^{4}\) & 0 & 0 & 0 \\ TNT & \(1680\) & \(6881\) & \(2.033\times 10^{4}\) & 0 & 0 & 0 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: HIGH_EXPLOSIVE_BURN parameters. concentration around the borehole, which diminishes with increasing distance from the borehole, while the far end remains unaffected by the perforation. To analyze the stress state of the reservoir region post-blasting, measurement points were strategically selected based on Figure 5 for dynamic blasting analysis. Figure 7 illustrates the temporal variation curves of Y-stress and effective stress at each measurement point following explosive detonation. As shown in the Figure 7, during the initial 0-800 us, the shock wave generated by the explosion impacts the reservoir rock, causing it to fracture and leading to a sudden increase in effective stress. Under the influence of theta-stress, the initial stress values vary among different measurement points, with Y-stress values aligning with those under static loading conditions (Figure 6). The response time of each measurement point to the explosive stress wave increases proportionally with its distance from the blast source.