## 4 Results
### Fractal Dimension Features
The fractal dimension D\({}_{2}\) for relatively fine pores ranges from 2.643 to 2.702, with an average value of 2.674. In the delta front sandstone reservoirs, the fractal dimension D\({}_{1}\) for relatively coarse pores ranges from 2.997 to 2.998, with an average value of 2.998. The fractal dimension D\({}_{2}\) for relatively fine pores ranges from 2.730 to 2.808, with an average value of 2.771. In delta front sandstone reservoirs, the average values of fractal dimensions D\({}_{1}\) and D\({}_{2}\) of the Type D and Type F pore-throat combinations are both higher than those of Type A and B in turbidite sandstones, indicating a more complex pore size distribution and pronounced heterogeneity in delta front sandstones. The delta front reservoirs exhibit the highest D\({}_{1}\) value, reflecting as markedly heterogeneous for the macroscopic  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{ \begin{tabular}{c} **Sedimentary** \\ **System** \\ \end{tabular}  } & \multirow{2}{*}{ \begin{tabular}{c} **Pore–Throat** \\ **Combination Type** \\ \end{tabular}  } & \multirow{2}{*}{\ \begin{tabular}{c} **Sample** \\ **Number** \\ \end{tabular}  } & \multirow{2}{*}{**Porosity/\%**} & \multirow{2}{*}{**Permeability/mD**} & \multicolumn{2}{c}{**D\({}_{1}\)**} & \multicolumn{2}{c}{**D\({}_{2}\)**} & \multicolumn{2}{c}{**D\({}_{3}\)**} \\ \cline{6-9}  & & & & **D\({}_{1}\)** & **R\({}_{1}\)\({}^{2}\)** & **D\({}_{2}\)** & **R\({}_{2}\)\({}^{2}\)** & **D\({}_{3}\)** & **R\({}_{3}\)\({}^{2}\)** \\ \hline \multirow{6}{*}{ \begin{tabular}{c} **Turbidity** \\ **current** \\ \end{tabular}  } & Type A & TX307-1 & 12.565 & 0.837 & 2.998 & 0.9837 & 2.675 & 0.9979 & / & / \\ \cline{2-9}  & Type A & TX307-2 & 7.580 & 1.169 & 2.998 & 0.9749 & 2.643 & 0.9972 & / & / \\ \cline{2-9}  & Type B & T305-1 & 8.870 & 0.391 & 2.998 & 0.9527 & 2.678 & 0.9879 & / & /-pre-fracture network. The average value of D\({}_{2}\) of turbidite sandstones is low. Under the combined influence of compaction, cementation, and dissolution during the diagenesis processes, the pore-throat distribution of the reservoirs is uniform and the homogeneity is pronounced. 2. Three-segment fractal characteristics: These correspond to the Type C pore-throat combination in turbidite sandstones (Figure 9d) and Type E in delta front sandstone reservoirs (Figure 9g). As shown in Table 1, in turbidite reservoirs, the fractal dimension D\({}_{1}\) for relatively coarse pores is 2.997, D\({}_{2}\) is 2.927, and D\({}_{3}\) for relatively fine pores is 2.644. In delta front reservoirs, the fractal dimension D\({}_{1}\) for relatively coarse pores ranges from 2.992 to 2.995, with an average of 2.993. D\({}_{2}\) ranges from 2.726 to 2.810, with an average of 2.762. D\({}_{3}\) ranges from 2.078 to 2.283, with an average of 2.206. The average values of the fractal dimensions D\({}_{1}\) and D\({}_{2}\) segments of the Type C pore-throat combination in turbidite sandstones are both higher than those of Type E in delta fronts. The D\({}_{1}\) segment implies that the pore size distribution within the turbidite reservoirs is more complex and heterogeneous. Moreover, complex and multi-branched flow channels have been formed under the influence of sedimentation. The D\({}_{2}\) segment is predominantly controlled by diagenesis. Under the combined modification of compaction, cementation, and dissolution, the turbidite reservoirs exhibit enhanced heterogeneity and an increased complexity of fluid-flow pathways. The D\({}_{3}\) segment fractal dimension characterizing micropores in the turbidite sandstones is significantly larger than that of the delta front reservoirs, indicating that the micropore diameters in turbidite sandstones exceed those in delta fronts. The Type E pore-throat combination developed in delta front facies exhibits a relatively uniform micropore distribution and pronounced homogeneity, while the small micropore diameters limit the fluid-flow capacity.