| Based on the analysis of sedimentary lithology, sedimentary facies and palaeogeography of Quemocuo formation of lower to middle Jurassic in Qiangtang basin, it is considered that Quemocuo formation in the Northen Qiangtang basin is an offshore terrigenous fresh water lake facies, which can be further divided into lake delta, lakeshore, lake flat, saline lake and other subfacies. The lithologic combination of clastic rock, carbonate rock and evaporite formed in salt water and brackish lake sedimentary environment of Quemocuo period is beneficial to the formation and development of source rock; the sedimentary environment of gypsum salt rock and dolomite and the conversion of gypsum to anhydrite can effectively improve the reservoir properties of carbonate rock under salt; the plasticity and compactness of anhydrite can effectively protect the oil and gas resources under salt It was destroyed by neotectonic movement in Qiangtang basin. The salt lake lithologic association of Quemocuo formation in Qiangtang basin is a favorable area for oil and gas exploration, in which Baitanhu Quemocuo rift trough is a favorable area for this type of oil and gas reservoir. |