Hydrocarbon exploration
in the deep-water area of the South China
Sea is increasingly important. However, the Eocene strata, which are
the primary source rock in the deep-water area of the Pearl River
Mouth basin (PRMB), are poorly understood. This article studied the
geological characteristics and hydrocarbon potential of the Eocene
source rocks in the Baiyun Depression, which is the biggest and most
important depression in the deep-water area of the PRMB. In the Eocene,
the Baiyun Depression was an asymmetric rift basin that was controlled
by the north-dipping detachment faults. A big freshwater lake existed
in the study area and a huge delta developed in the northern gentle
slope. The delta source rocks had higher total organic carbon and
were greatly controlled by terrigenous organic matter input. They
were type III kerogen and were likely to produce gas during maturation.
The lacustrine source rocks were widely distributed in the center
and south and had a higher hydrogen index (HI). They had both terrigenous
and aquatic organic matter inputs. The kerogen was type II to III.
They could produce both oil and gas during maturation. The Eocene
source rocks were widely distributed in the Baiyun Depression. They
had a huge thickness and high organic matter abundance. The organic
matter had enough maturity to generate hydrocarbon from 18.5 Ma to
the present. Therefore, the Eocene source rocks can provide sufficient
hydrocarbon resources for deep-water petroleum accumulations and gas
hydrate formations in the deep-water area of the PRMB.