In order to understand the hydrocarbon accumulation characteristics of the Silurian carbonates on the southeast margin of Sichuan Basin

this paper studied reef-shoal facies sedimentary features and paleo-oil reservoirs in the Lower Silurian Shiniulan Formation based on the comprehensive field and laboratory research of petrography and geochemical analysis.The Lower Silurian Shiniulan Formation is composed of upward-shallowing three cyclic deposits

of which the third cyclic deposits are bioherm-shoal facies on platform margin occurring along Lintanchang-Liangcun-Dingshan structures.The reservoirs of reef-shoal facies are rich in bitumen

indicating that they are lithologic paleo-oil reservoirs of shoal-reef type.These paleo-oil reservoirs are small in resource scale and scatter in regional distribution.Their resources are estimated to be about 6.62?10

3

t.The oil of the paleo-oil reservoir is mainly sourced from the Sinian paleo-oil reservoir

partly from the Silurian source rocks.The formation and destruction of the Shiniulan paleo-oil reservoir includes the following process:the Sinian oil reservoirs were destroyed and the escaping oil accumulated in the Shiniulan Formation to form the oil reservoir(Late Triassic to Early Jurassic).The oil of the oil reservoir was cracked to gas due to the long term deep burial

to lead to the gas reservoir(Middle Jurassic to Middle Cretaceous).Finally

the gas reservoir was destroyed by folding and quick uplifting(since 80 Ma).The exploration prospect in the Silurian in southeast Sichuan Basin is not as good as in the eastern Sichuan-eastern Chongqing.