## 6 Conclusions  
1. Quantitative pore structure analysis identifies six types: In turbidite sandstones, pores and throats range from coarse-coarse (Type A) through medium-medium (Type B) to fine-medium (Type C). In delta front sandstones, they progress from medium-coarse (Type D) via medium-fine (Type E) to fine-fine (Type F). The integration of HPMI, NMR, and SEM data reveals that turbidite reservoirs exhibit comparatively enhanced pore structure characteristics relative to those of delta front tight sandstones.
2. Sedimentation furnishes the material basis for reservoir space development. Two depositional settings are classified into six reservoir lithofacies--three turbidite (Type A: fine sandstone; Type B: siltstone; Type C: argillaceous siltstone) and three delta front (Type D: fine-silstone; Type E: calcareous siltstone; Type F: argillaceous layered siltstone)--each directly linked to a specific pore structure type. This lithofacies-pore correlation clarifies how contrasting sedimentary processes govern the structure and connectivity of reservoir pore systems.
3. Diagenesis governs reservoir pore structures: compaction and cementation diminish the porosity, whereas dissolution augments it. Accordingly, six diagenetic facies--medium compaction--medium cementation-strong dissolution; medium compaction--medium cementation-weak dissolution; medium compaction--strong cementation-weak dissolution; medium compaction--strong cementation-strong dissolution; strong compaction--strong cementation--medium dissolution; and strong compaction--strong cementation--weak dissolution--are defined, each mapping to pore structure Types A-F, respectively.  
The reservoir pore structures in the study area result from the interplay of sedimentary and diagenetic controls, with six combined lithofacies and diagenetic facies defining distinct pore structure types. An optimal coarse pore-coarse throat pore structure (Type A) develops in turbidite fine sandstone lithofacies under medium compaction-medium cementation-strong dissolution diagenetic facies. Conversely, the poorest fine-pore-fine-throat pore structure (Type F) occurs in delta front argillaceous layered siltstone lithofacies subjected to strong compaction, strong cementation, and weak dissolution. Furthermore, turbidite reservoirs generally exhibit higher oil contents than delta front counterparts, and the oil content systematically declines as the pore structures transition from Type A to Type F.  
Conceptualization, L.R. and D.C.; Methodology, L.R.; Software, F.W.; Formal analysis, J.C. and F.W.; Investigation, L.R., Y.W., W.L. and M.J.; Data curation, L.R.; Writing--original draft, L.R. and Y.W.; Writing--review & editing, D.C. and Q.W.; Visualization, L.R. and J.C.; Supervision, D.C. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Major Science and Technology Projects of China grant number 2024 ZD14001-001. And the APC was funded by 2024 AAPG Foundation Grants-in-Aid Program grant number [PERSON] & [PERSON] Named Grant.  
Not applicable.  
The raw data supporting the conclusions of this article will be made available by the authors on request.  
We appreciate the support from the Sinopec Shengli Oilfield Branch of the China Petroleum and Chemical Corporation for providing the data and tight sandstone samples used in this study and the permission to publish the results.  
The authors declare no conflict of interest.