## 1 The Lower Limit of Effective Reservoir Burial Depth for Clastic Rocks
This well is part of Sinopec's exploration and production activities) at 6700 m in the Triassic Kelamayi Formation and 7600 m in the Upper Wuerhe Formation in the central Junggar Basin, and Cheng-6 (Cheng-6 also owned and operated by China Sinopec) (2022) at 6530 m in the Lower Wuerhe Formation. These discoveries have promoted researchers to redefine the concept of \"deep layers\" and reassess the lower burial depth limit for effective clastic reservoirs. Recent exploration results confirmed that in the Tarim and Junggar Basins (Table 2), this limit can exceed 8000 m [32; 33; 34]. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Country**} & \multirow{2}{*}{**Basins**} & \multirow{2}{*}{**Basin Type**} & \multirow{2}{*}{**Reservoir Age**} & \multirow{2}{*}{**Lithology**} & \multirow{2}{*}{**HC Type**} & \multirow{2}{*}{**Depth**} & \multicolumn{2}{c}{**Recoverable**} & \multicolumn{2}{c}{**Recoverable**} & \multirow{2}{*}{**Gas (tc)**} & \multirow{2}{*}{**Gas (tc)**} & \multirow{2}{*}{**Total**} \\  & & & & & & & & & & (\(\times 10^{6}\) b) & & & **(bb)** \\ \hline \multirow{5}{*}{China} & Tarim Basin & Craton & Ordovician & Limestone & Oil, gas & 7300 & 6.77 & 9.7 & 49.6 & 343 & 109 \\ \cline{2-11}  & Junggar Basin & Craton & Jurassic & Conglomer sandstone & Oil, gas & 5000 & 2.84 & 2.24 & 20.8 & 79 & 34 \\ \cline{2-11}  & Sichuan Basin & Craton & Permian- Triassic & Dolomite & Gas & 6200-7000 & 0.0001613 & 38.11 & 0.001 & 1346 & 232 \\ \cline{2-11}  & Ordos Basin & Craton & Triassic & Sandstone & Gas & 5000 & - & 0.1 & - & 4 & 1 \\ \hline \multirow{2}{*}{Iraq} & West Qurna & Foreland & Greataceous & Limestone & Oil, gas & 3447 & - & - & 15-21 & - & 228,000 \\ \cline{2-11}  & Field & Basin & & & & & & & & & & \\ \hline \multirow{2}{*}{Qatar} & North and Ras & Passive & & & & & & & & & & \\ \cline{2-11}  & Lafan Field & Margin & Cretaceous & Sandstone & & & & & & & & \\ \hline \multirow{2}{*}{Russia} & Urengoy Field & Craton & Cretaceous & Sandstone & & & & & & & & \\ \cline{2-11}  & Urengoy Field & Craton & Cretaceous & Sandstone & & & & & & & & \\ \hline \multirow{2}{*}{Kuwait} & Mesopotamian & Foreland & Greataceous & Dolomite & Oil, gas & 3500-5000 & - & 1.8 & 66-72 & 63.6 & 85,000 \\ \cline{2-11}  & Foredeep Basin & Basin & & & & & & & & & & \\ \hline \hline \end{tabular}  
* Using a conversion of \(7.33\) bursts per tenure, values may vary based on oil density, Abbreviations; b = billion barreds; torn = million cubic meters = 1012 m\({}^{3}\); 1.m\({}^{3}\) = 35.3347 c/m for \(t\) d = million cubic feet; BOE = barrel of oil equivalent = 5800 m of gas or 159 L of old; MOOE = one million MOOE.  
\end{table} 
Table 1: Recoverable oil and gas reserves of major global basins. With ongoing advancements in oil and gas exploration theory and technology, along with the implementation of Deep Earth Engineering, new breakthroughs in deep-layer oil and gas will continue to reshape researchers' understanding of deep reservoirs. Simultaneously, the burial depth limit and formation mechanisms of effective sedimentary rock reservoirs are being continuously redefined. This paper aims to systematically summarize the development characteristics of effective reservoirs in deep oil-bearing basins in China, clarify their formation mechanisms, and provide reference guidance for future deep-layer sedimentary rock exploration (Figure 1).