Tracing of deeply-buried source rock: A case study of the WC9-2 petroleum pool in the Pearl River Mouth Basin, South China Sea

The identification of a deeply-buried petroleum-source rock, owing to the difficulty in sample collection, has become a difficult task for establishing its relationship with discovered petroleum pools and evaluating its exploration potential in a petroleum-bearing basin. This paper proposes an appro...

Full description

Saved in:
Bibliographic Details
Published in:Marine and petroleum geology 2009-09, Vol.26 (8), p.1365-1378
Main Authors: Xiao, X.M., Li, N.X., Gan, H.J., Jin, Y.B., Tian, H., Huang, B.J., Tang, Y.C.
Format: Article
Language:English
Subjects:
2D basin modeling
Basins
Crude oil
Deeply-buried source rock
Earth sciences
Earth, ocean, space
Exact sciences and technology
Faults
Fluid inclusion
Freshwater
Hydrocarbons
Kinetic modeling
Marine
Marine geology
Mudstone
Natural gas
Pearl River Mouth Basin
Pools
Reservoirs
Rock
Sag
Sedimentary rocks
Wenchang A sag
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The identification of a deeply-buried petroleum-source rock, owing to the difficulty in sample collection, has become a difficult task for establishing its relationship with discovered petroleum pools and evaluating its exploration potential in a petroleum-bearing basin. This paper proposes an approach to trace a deeply-buried source rock. The essential points include: determination of the petroleum-charging time of a reservoir, reconstruction of the petroleum generation history of its possible source rocks, establishment of the spatial connection between the source rocks and the reservoir over its geological history, identification of its effective source rock and the petroleum system from source to trap, and evaluation of petroleum potential from the deeply-buried source rock. A case study of the W9-2 petroleum pool in the Wenchang A sag of the Pearl River Mouth Basin, South China Sea was conducted using this approach. The W9-2 reservoir produces condensate oil and gas, sourced from deeply-buried source rocks. The reservoir consists of a few sets of sandstone in the Zhuhai Formation, and the possible source rocks include an early Oligocene Enping Formation mudstone and a late Eocene Wenchang Formation mudstone, with a current burial depth from 5000 to 9000 m. The fluid inclusion data from the reservoir rock indicate the oil and the gas charged the reservoir about 18–3.5 Ma and after 4.5 Ma, respectively. The kinetic modeling results show that the main stages of oil generation of the Wenchang mudstone and the Enping mudstone occurred during 28–20 Ma and 20–12 Ma, respectively, and that the δ 13C 1 value of the gas generated from the Enping mudstone has a better match with that of the reservoir gas than the gas from the Wenchang mudstone. Results from a 2D basin modeling further indicate that the petroleum from the Enping mudstone migrated upward along the well-developed syn-sedimentary faults in the central area of the sag into the reservoir, but that the petroleum from the Wenchang mudstone migrated laterally first toward the marginal faults of the sag and then migrated upward along the faults into shallow strata. The present results suggest that the trap structure in the central area of the sag is a favorable place for the accumulation of the Enping mudstone-derived petroleum, and that the Wenchang mudstone-derived petroleum would have a contribution to the structures along the deep faults as well as in the uplifted area around the sag.
ISSN:0264-8172
1873-4073
DOI:10.1016/j.marpetgeo.2009.02.009