Classification and distribution of oil in Huizhou Depression of Pearl River Mouth Basin

Abstract

Many oilfields and oil-bearing traps have been found in Huizhou Depression and its neighboring area in recent years.Oils in Huizhou Depression and its neighboring area can be classified to three types according to their biomarker characteristics.Type-I oil mainly originated from the middle-deep lacustrine source rock in Wenchang Formation and had high content of C304-methyl steranes and low content of bicadinanes.Type-Ⅱ oil was mainly derived from source rock of Enping Formation and had high content of bicadinanes and low content of C304-methyl steranes.Type-Ⅲ oil came from the middle-deep lacustrine source rocks in Wenchang and Enping formations and had relatively high content of C304-methyl steranes and bicadinanes.Regionally,type-Ⅰoil mainly distributed at the uplift area.Type-Ⅱ oil mainly distributed inside the sags that have good source rock of Enping Formation and poor source rock of Wenchang Formation.Type-Ⅲ oil mainly distributed inside the sags that have good middle-deep lacustrine source rocks of Wenchang and Enping formations.Vertically,type-Ⅰoil mainly distributed at shallow layers of Hangjiang and Zhujiang formations.Type-Ⅱoil mainly distributed at deep Enping and Zhuhai formations,and type-Ⅲ oil commonly distributed at Hangjiang,Zhujiang and Zhuhai formations.