## 4 Results
### Multivariate Statistical Results
#### 4.3.2 PCA Results  
The \(11\) geochemical parameters used for principal component analysis (PCA) are the same as those used for the HCA and are shown in Table 2. The results show that the cumulative variance contribution of the top five principal components (PCs) accounts for nearly 90% of the data. Consequently, PC1 to PC5 was selected to distinguish the geochemical relationship among the oil samples. The PCA loadings and score data used for oil-source correlation are shown in Tables 4 and 5, and Figure 11.  
The coefficient in the loadings plot shows either a positive or negative correlation between the variables and PCs, and the greater the absolute value is, the stronger the correlation would be (Table 4). For example, PC1 is mainly influenced by two source variables, \(\mathrm{C_{27}}/(\mathrm{C_{27}}+\mathrm{C_{28}}+\mathrm{C_{29}})\) regular steranes (R1) and gammacerane/\(\mathrm{C_{30}}\) propane (R10), with positive correlation coefficients of 0.815 and 0.814 (Table 4), respectively, showing a strong linkage to the sedimentary environment. The scores plot of PC1 to PC5 show that the source rock samples can be clearly separated into two distinct genetic families (Figure 11A), with higher score values in PC4 and PC5 for the Jurassic source rocks while  
Figure 10: Hierarchical cluster analysis (HCA) results identify two oil families, with oils from the J\({}_{1}\)\(a\) formation mainly derived from the Triassic source rocks, while those from the J\({}_{1}\)\(y\) Formation mainly derived from the Jurassic source rocks. Sample numbers and selected parameters are shown in Tables 1 and 3, respectively. \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Samples** & **Wells** & **Formations** & **No.** & **PC1** & **PC2** & **PC3** & **PC4** & **PC5** \\ \hline Source-1 & YN-2 & J\({}_{2}\)\(k\)z & 1 & \(-\)1.522 & \(-\)1.525 & \(-\)0.153 & 1.043 & 0.772 \\ Source-3 & YN-2 & J\({}_{2}\)\(k\)z & 3 & \(-\)0.786 & \(-\)1.827 & \(-\)0.777 & 0.573 & 0.508 \\ Source-6 & YN-2 & J\({}_{1}\)\(y\) & 6 & 0.570 & \(-\)0.978 & 1.362 & \(-\)0.244 & \(-\)1.106 \\ Source-7 & YN-2 & J\({}_{1}\)\(y\) & 7 & 0.682 & \(-\)0.720 & 1.998 & 0.723 & \(-\)1.098 \\ Oil-1 & YN-2 & T\({}_{3}\)\(t\) & 8 & \(-\)0.494 & \(-\)0.710 & \(-\)0.086 & \(-\)1.414 & 1.031 \\ Oil-2 & YN-2 & T\({}_{3}\)\(h\) & 9 & 0.213 & 0.099 & 0.974 & \(-\)0.773 & 1.072 \\ Oil-3 & YN-2 & T\({}_{3}\)\(h\) & 10 & 0.049 & \(-\)0.127 & 0.126 & \(-\)1.168 & 0.565 \\ Oil-4 & DB-104 & J\({}_{1}\)\(y\) & 11 & 0.766 & 1.498 & \(-\)0.520 & \(-\)1.161 & \(-\)0.089 \\ Oil-5 & DX-1 & J\({}_{1}\)\(y\) & 12 & \(-\)0.486 & 1.446 & 0.527 & 0.298 & 2.298 \\ Inclusion-1 & YN-2 & J\({}_{1}\)\(y\) & 13 & \(-\)1.507 & 1.294 & 0.504 & 0.081 & \(-\)1.082 \\ Inclusion-2 & YS-4 & J\({}_{1}\)\(a\) & 14 & \(-\)1.534 & 1.123 & 0.959 & 0.401 & \(-\)1.010 \\ Inclusion-3 & DB-5 & J\({}_{1}\)\(a\) & 15 & 0.349 & 0.702 & \(-\)0.942 & 1.686 & \(-\)0.098 \\ Inclusion-4 & DB-5 & J\({}_{1}\)\(y\)-B & 16 & 1.078 & \(-\)0.655 & \(-\)0.007 & \(-\)1.516 & \(-\)0.396 \\ Inclusion-5 & DB-102 & J\({}_{1}\)\(y\)-Y & 17 & 1.745 & 0.233 & \(-\)0.405 & 1.473 & 0.175 \\ Inclusion-6 & DB-102 & J\({}_{1}\)\(a\)-B & 18 & 1.423 & 0.171 & \(-\)0.168 & 0.823 & 0.529 \\ Inclusion–7 & YN\(-2\) & J\({}_{1}\)\(a\)-B & 19 & \(-\)0.148 & \(-\)0.180 & \(-\)1.710 & \(-\)0.183 & \(-\)0.835 \\ Inclusion–8 & YS\(-4\) & J\({}_{1}\)\(a\)-B & 20 & \(-\)0.400 & 0.156 & \(-\)1.682 & \(-\)0.644 & \(-\)1.236 \\ \hline \end{tabular}
\end{table} 
Table 5: The score data of the samples for PCA. there are higher score values in PC1, PC3, and PC4 for the Triassic source rocks. The reservoir oils from the J1\(y\) Formation have higher score values in PC3 and PC5, whereas the reservoir oils from J1\(a\) Formation have higher score values in PC2 and PC5 (Figure 11B). For the inclusion oils, samples from the J1\(y\) Formation have higher score values in PC2, PC3, and PC4 (Figure 11C), while the samples from the J1\(a\) Formation have higher score values in PC1 and PC4 (Figure 11D).