## 4 Discussion
### Influence of Temperature on Fracturing Effect  
For hydraulic fracturing of high-temperature granite, the role of temperature primarily lies in changing the mechanical properties of the rock. Elevated temperatures induce thermal cracks within the rock [40], subsequently reducing the tensile strength of the rock samples. Both laboratory experiments [16; 41] and numerical simulations [42] have demonstrated that as the temperature increases up to 600 \({}^{\circ}\)C, the tensile strength of the rock decreases significantly. Using the previously mentioned 3 DEC numerical model for recalculation but with the tensile strength of the fracture reduced to \(1\times 10^{3}\) Pa, the fluid pressure variation during the water injection process is illustrated in Figure 12. It can be observed that crack propagation initiates before the fluid pressure reaches its maximum  
Figure 11: Three-dimensional visualization model of fractures induced by two different fracturing methods: (**a**) for hydraulic fracturing, these subfigures correspond, from left to right, to H1–H4; (**b**) for deflagration fracturing, these subfigures correspond, from left to right, to D1–D4.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Fracturing Methods** & **a/cm\({}^{2}\)** & **b/cm\({}^{2}\)** & **c/cm\({}^{2}\)** & **d/cm\({}^{2}\)** & **Average Area/cm\({}^{2}\)** & **Total Fracture Crack/mm** & **Space/cm\({}^{3}\)** \\ \hline Hydraulic fracturing & 5620 & 2936 & 1677 & 4989 & 3805.5 & 1.5 & 570.8 \\ Deflagration fracturing & 630 & 207 & 1061 & 973 & 717.75 & 0.05 & 3.6 \\ \hline \hline \end{tabular}
\end{table}
Table 3: A rough statistical estimation of fracture area and space generated by different fracturing methods.  
value. Following the peak, the fluid pressure no longer experiences a sharp drop but rather a more gradual decline, which aligns well with the experimental results for H2 and H3 shown in Figure 7. This phenomenon is also referred to as a reduction in the brittleness of granite [40, 43]. Furthermore, the growth of microcracks at high temperatures leads to the formation of more localized damage zones within the sample, known as \"cloud-like fractures\" [28]. Therefore, based on the impact of high temperatures on the tensile strength of rocks, the injection parameters of fracturing fluid can be adjusted to accommodate changes in the rock mechanical properties in high-temperature environments and enhance the fracturing effectiveness. For instance, adopting a low-temperature injection method can promote crack propagation through increasing the thermal stress generated from the temperature difference, thereby creating larger fracture spaces.  
In the process of deflagration fracturing, the fracture morphology is directly correlated with the peak pressure and duration of its action within the wellbore, which, in turn, are influenced by factors such as explosive parameters [44] and wellbore structure [35]. Under high-temperature conditions, the increase in microcracks within the rock reduces the pressure and the duration of the high-energy gas generated inside the wellbore, thereby resulting in a paradoxical decrease in the number of cracks generated during fracturing.