Three hydrocarbon generation and accumulation processes of marine carbonate rocks in northeastern Sichuan Basin,China

Abstract

The solid asphalt characteristics,inclusions homogenization,and diagenesis are studied in northeastern Sichuan Basin.During Indosinian movement,the source rocks in O3w(Upper Ordovician Wufeng Formation) and S1l(Lower Silurian Longmaxi Formation) generated low-mature heavy oil,meanwhile,the reef facies of Upper Permian Changxing Formation formed reservoir space for the heavy oil.The Permian and O3w-S1l source rocks generated peak oil during early Yanshan movement.The homogenization temperature of hydrocarbon fluid inclusions formed during the aforementioned two stages ranged from 100 to 150 ℃.During late Yanshan and Himalayan movements,the early formed oil and source rocks and soluble organic matter all had reached high and post mature stages.The present natural gas reservoirs were formed by cracking.Therefore,there are three hydrocarbon generation and accumulation processes in northeast Sichuan Basin,which occurred during Indosinian movement,early Yanshan movement and late Yanshan movement,respectively.