EVALUATION OF PETROLEUM POTENTIAL OF UPPER TRIASSIC SPONGE PATCH REEFS IN NORTHWESTERN SICHUAN

A sponge patch reef complex is found within the strata of Carnian Hanwang Formation.The reefs existed in the Tethysian ocean.They are not of organic skeletal reefs,but of sponge-baffled bioherms.Based on the study of geological and geochemical features of the reef complex,and physical properties of potential reservoir rock,it is proposed that the buried part of the reef group is of hydrocarbon potential,and this is a clue to search for oil and gas in northwestern Sichuan Basin.