Geological Conditions of Shale Gas of the Upper Ordovician Wufeng Formation--Lower Silurian Gaojiabian Formation in Lower Yangtze Area

摘要

According to the outcrop, well data, geochemical and reservoir property in lower Yangtze area. This paper analyses the sedimentary environment, thickness, distribution, buried depth, organic matter content and types, maturity and reservoir characteristics of shale in Wufeng--Gaojiabian Formation of Upper Ordovician to Lower Silurian. The shale is formed in shelf sedimentary environments with large thickness and moderate depth. Wufeng--Gaojiabian Formation contains 0.5% to 1.0% of organic carbon, consistent with type I and II kerogen. The Ro in rang of 1.5%~2.5%, indication high mature to over mature stage for gas generation. It has high brittleness of mineral content in this set of shale with rich micro-fracture. The thickness of shale, buried depth, organic carbon and maturity shows that Gaoyou--Haian--Jurong of Northern Jiangsu,Jingxian--Ningguo of Southern Anhui, Linan of Western Zhejiang areas are considered favorable zones for shale gas formation.