Organic Reef in Lower Silurian. Guangyuan.Sichuan to Ninggiang. Shanxi

Key words: 
• Silurian /
• Organic Reef /
• Oil and Gas bearing fermation /

Abstract: Between Guangyuan. Sichuan to Ningqiang. Shaanxi province, Within giant-thick dead color mudstones of lower Silurian there are hundreds of reefs developed，including barrier reef, patch reef, barrier-like patch reefs, biohorm，Limemud mound and bed-rock mound. All of them are out Groped well and a great disparity in size. The reefs developed on the bases of the mudrock facies of the shallower shelf. The reef-building organism are mainly Halysites. Favorites, subalveotella,paleaofavosites, and clathrodictyon, Rosenella. The basesment rock on which reefs grooved is mainly mudbasis-knollenakalk and some are on the bioclast bank，the proximal tempestites and sumerged tidal flat stratifera limestones. Many of the reefs declimed and fell because of drove and a few of them died for drought. The reef is over 50 meters thick in the Hoshen 1 well and Ho 15 well in Guangyuan. North-west Sichuan，and a litter gas was gotten in it. Also, the reef was found in many wells in the southern Sichuan. In addition，the reefs is distributed over the eastern Sichuan，Northern Guizhou and western Hebui, the character of reef Complex is similar to that of the studied area. Bitumen filling crack and vug is often found. The organic carbon content in dead color mudstone which wraped up the reefs is high. There for. It is hope for the reef of the lower Silurian to be the exploration bojective formation in the Sichuan basin.