## 6 Conclusions  
Multiple major conclusions can be drawn:  
1. Three major lithofacies were identified in the WF-LMX formations, including siliceous shales, siliceous-argillaceous mixed shales, and argillaceous shales. Compared to other lithofacies, siliceous shales have relatively high TOC and quartz contents.
2. Four types of pores can be identified in the WF-LMX shales, mainly including organic pores, interparticle pores, and intraparticle pores and fractures; the organic pore is dominant pore type. There are significant differences in pore development among different lithofacies. The pore volume and surface area of micropores, mesopores, and macropores of siliceous shales are larger than those of siliceous-argillaceous mixed and argillaceous shales. Organic matter combustion experiments showed that micropores and mesopores are largely contributed by organic pores, while macropores may be contributed by both organic and inorganic pores.
3. Early diagenesis was characterized by compaction, pyrite precipitation, and authigenic quartz cementation. Compaction was the main factor driving declined porosity. The thermal degradation of organic matter, transformation of clay minerals, and dissolution of carbonate minerals were the dominant processes in middle diagenesis. The secondary cracking of residual organic matter was the main diagenetic event in late diagenesis. They together controlled the collapse of primary pores and generation of secondary pores, leading to shale reservoir quality.
4. The siliceous shale is characterized by high TOC and biogenic silica contents. During the early and middle diagenetic stages, recrystallization of biogenic silica can form a rigid framework that is resistant to overlying mechanical compaction. The generated oil and bitumen from organic matter maturation filled into pore spaces between microcrystalline quartz crystals can produce numerous organic pores through thermal cracking at the gas window. Thus, the porosity of siliceous shale is well developed, which is also of great significance for later development. On the contrary, the argillaceous shale is characterized by low TOC and high clay content. The primary pore space of argillaceous shales is greatly reduced under mechanical compaction simply due to the plastic behavior of clays.  
Methodology, T.D.; Software, K.H.; Validation, K.H.; Formal analysis, T.D. and C.W.; Resources, Z.H. and S.L.; Data curation, T.D. and C.W.; Writing--original draft, T.D.; Writing--review & editing, T.D.; Visualization, T.D.; Supervision, T.D., Z.H., J.G. and S.L.; Project administration, Z.H., J.G. and S.L.; Funding acquisition, J.G. and S.L. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This study was financially supported by the SINOPEC Key Laboratory of Geology and Resources in Deep Stratum Foundation (No. 33550000-22-ZC0613-0252), and jointly funded by the National Natural Science Foundation (Nos. U19B6003, U20B6001 and 42002137).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.  
**Conflicts of Interest:** The authors declare that they have no known competing financial interests or personal relationships that might have influenced the work presented in this article.