## 4 Results
### Diagenetic Events
#### 4.6.1 Compaction and Cementation
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{\begin{tabular}{c} **Sample** \\ **No.** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Well** \\ **Name** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Depth** \\ **(m)** \\ \end{tabular} } & \multicolumn{6}{c}{**Pre-Combustion**} & \multicolumn{6}{c}{**Post-Combustion**} \\ \cline{3-14}  & & & & \multicolumn{2}{c}{**Pore Volume (10\({}^{-2}\) cm\({}^{3}\)/g)**} & \multicolumn{2}{c}{**Surface Area (m\({}^{2}\)/g)**} & \multicolumn{2}{c}{**Pore Volume (10\({}^{-2}\) cm\({}^{3}\)/g)**} & \multicolumn{2}{c}{**Surface Area (m\({}^{2}\)/g)**} \\ \cline{3-14}  & & & & & & & & & & & & & & \\ \hline DB1 & DB & 3743.3 & 0.25 & 0.88 & 0.23 & _7.69_ & 5.7 & 0.09 & 0.1 & 0.78 & 0.32 & 3.5 & 3.47 & 0.13 \\ \hline DB6 & DB & 3754.04 & 0.31 & 0.92 & 0.3 & _9.67_ & 5.57 & 0.12 & 0.09 & 0.8 & 0.32 & 3.26 & 3.5 & 0.13 \\ \hline DB17 & DB & 3783.9 & 0.24 & 0.86 & 0.23 & 6.95 & 5.5 & 0.09 & 0.09 & 0.84 & 0.32 & 3.19 & 3.87 & 0.13 \\ \hline DB15 & DB & 3776.11 & 0.29 & 0.93 & 0.21 & 8.69 & 6.07 & 0.08 & 0.1 & 0.88 & 0.42 & 3.68 & 3.63 & 0.17 \\ \hline DA21 & DA & 2247.09 & 0.36 & 1.36 & 0.42 & 11.3 & 7.48 & 0.17 & 0.12 & 1.21 & 0.45 & 4.4 & 5.11 & 0.19 \\ \hline DB20 & DB & 3799.28 & 0.43 & 1.21 & 0.32 & 13.26 & 7.34 & 0.13 & 0.12 & 1.31 & 0.54 & 4.57 & 5.63 & 0.23 \\ \hline DA23 & DA & 2262.2 & 0.43 & 1.22 & 0.31 & 13.5 & 7.32 & 0.13 & 0.13 & 1.27 & 0.59 & 4.83 & 5.05 & 0.24 \\ \hline DB23 & DB & 3809.24 & 0.57 & 1.45 & 0.31 & 18.02 & 8.47 & 0.13 & 0.09 & 1.31 & 0.87 & 3.53 & 4.84 & 0.35 \\ \hline DB25 & DB & 3812.4 & 0.57 & 1.69 & 0.23 & 17.86 & 9.63 & 0.1 & 0.09 & 0.99 & 0.66 & 3.14 & 3.86 & 0.25 \\ \hline DB27 & DB & 3817.27 & 0.7 & 1.17 & 0.19 & 22.11 & 8.78 & 0.07 & 0.09 & 1.3 & 0.74 & 3.58 & 4.78 & 0.33 \\ \hline DA25 & DA & 2267.7 & 0.64 & 1.75 & 0.25 & 20.09 & 9.96 & 0.11 & 0.1 & 1.11 & 0.67 & 3.9 & 4.36 & 0.27 \\ \hline DA27 & DA & 2269.74 & 0.65 & 1.85 & 0.22 & 20.33 & 10.82 & 0.09 & 0.1 & 1.28 & 0.56 & 3.85 & 5.39 & 0.24 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Pore volume and surface area of micropore, mesopore, and macropore between pre-combustion and after combustion samples. Abbreviation: micro = micropore, meso = mesopore, and macro = macropore. Figure 9: SEM images showing pores after combustion in the Wufeng–Longmaxi shales. (**A**) Intergranular pores between authigenic quartz aggregates, well DB, depth = 3812.4 m; (**B**) EDS map confirming the identification of quartz minerals, the same area to A; (**C**) Intraparticle pores between framboidal pyrite crystals, well DA, depth = 2267.7 m; (**D**) Intergranular pores and intraparticle pores, well DA, depth = 2267.7 m; (**E**) Intergranular pores, well DA, depth = 2267.7 m; (**F**) Intergranular pores between clay platelets, well DB, depth = 3812.4 m.  
(Figure 11D-F). As suggested by [PERSON] et al. (2016) [40], the detrital quartz displays bright luminescence and authigenic quartz is essentially non-luminescent. Figure 10: The comparison of pore volume (**A**,**B**) and surface area (**C**,**D**) between pre-combustion and after combustion samples. Pre: pre-combustion, Post: post-combustion. Carbonate cements mainly include calcite, dolomite, and iron-rich dolomite. The silt-sized calcite grains are generally distributed with the shale matrix (Figure 7D,E). The silt-sized dolomite grains are characterized by a rhombic shape (Figure 7F). The edge of dolomite grains is usually replaced by iron-rich dolomite as revealed by SEM and EDS images (Figures 7F and 11H,I). Pyrite cement was commonly observed within shale samples, which are generally characterized by granular, framboidal, and irregular shapes. The average size of granular and irregular shape pyrite is usually less than 1 \(\upmu\)m (Figures 6B and 11I). The average diameter of pyrite framboids is generally less than 5 \(\upmu\)m (Figures 6F and 11K). Figure 11: Mineral types and diagenetic modifications.