## 4 Experimental Results
### Organic Matter Maturity  
Mud shale organic matter maturity is an important indicator for evaluating the degree of thermal derivatisation of organic matter in hydrocarbon source rocks, and the most commonly used is the specular body reflectance, Ro. In this study, whole-rock specular plasma reflectance was determined for 18 of 40 samples from Permian shales in northeastern Sichuan (Tables 4 and 5). Microscopic observation shows that the abundance of vitrinite in the Permian shale samples in northeast Sichuan is generally low. The vitrinite is mainly unstructured vitrinite and detrital vitrinite, and the vitrinite is generally distributed in small granular and band-like layers. Only a very small number of samples can be found to meet the test standards ([PERSON], 2014). Figure 3: Photomicrographs of light thin section samples of the Permian Wujiaping Formation, northeast Sichuan, China. (**a**) is sample X-19, (**b**) is also sample X-22, (**c**) is sample X-20, and (**d**) is sample Y-7. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Stratum**} & \multicolumn{2}{c}{**Number of Samples/pc**} & \multirow{2}{*}{**La/Ce**} & \multirow{2}{*}{**Sc/Cr**} & \multirow{2}{*}{**Y/Ho**} & \multirow{2}{*}{**Sr/Cu**} & \multirow{2}{*}{**Sr/Ba**} & \multirow{2}{*}{**U/Th**} & \multirow{2}{*}{**Mo/U**} \\ \cline{1-1} \cline{5-10} \cline{7-10} \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multirow{2}{*}{**Sampling**} & \multirow{2}{*}{**Stratum**} & \multicolumn{5}{c}{**Whole Rock Reflectance/\%**} \\ \cline{3-6}  & & & **Minimum** & **Maximum** & **Average** & **Measured** \\  & & & **Value** & **Values** & **Value** & **Point** \\ \hline X-2 & 4216.25 & & 0.93 & 1.45 & 1.14 & 22 \\ X-4 & 4229.1 & & 1.33 & 1.84 & 1.52 & 32 \\ X-6 & 4243.1 & & 1.38 & 1.96 & 1.66 & 25 \\ X-8 & 4247.13 & & 1.76 & 2.28 & 1.98 & 24 \\ X-10 & 4253.69 & & 1.9 & 2.44 & 2.2 & 22 \\ X-12 & 4263.09 & & 2.02 & 2.69 & 2.42 & 42 \\ X-14 & 4268.47 & & 1.8 & 2.29 & 2.07 & 25 \\ \hline X-17 & 4280.78 & & 2.14 & 2.68 & 2.57 & 18 \\ X-20 & 4297.28 & & 1.61 & 2.47 & 2.01 & 22 \\ X-22 & 4310.39 & & 1.83 & 2.27 & 2 & 22 \\ \hline X-24 & 4330.48 & & 1.99 & 2.5 & 2.25 & 35 \\ X-26 & 4333.75 & & 1.25 & 1.94 & 1.46 & 44 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Whole-rock reflectivity of Permian X-well shale in northeastern Sichuan Province. Figure 4: Photomicrographs of light thin section samples from the Permian Maokou Formation, northeast Sichuan, China. (**a**) is sample Y-14, (**b**) is also sample Y-14, (**c**) is sample Y-10, and (**d**) is sample Y-7. The experimental results show that the whole-rock reflectivity of the Northeast Sichuan Permian is generally high, with the lowest value being 0.93, the highest value being 2.69, and the average value being 1.86 in the Dalong Formation, which belongs to the stage of high-mature cracked gas; the whole-rock reflectance of the Wujiaping Formation ranges from 1.25 to 2.68, with an average value of 2.14, which belongs to the overmature stage. The whole-rock reflectance of the Maokou Formation ranges from 1.25 to 2.66, with an average value of 2.03 belonging to the overmature stage. Therefore, the whole-rock albedo of the Permian shales in northeast Sichuan is generally high, with a high degree of thermal evolution, belonging to the overmature stage, and showing no fluorescence under the microscope [63]. Figure 5: Trace element relationships for X wells in the Permian of northeastern Sichuan Province.