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Finding the Pearl in the Pearl River Mouth Basin, Offshore China: A Deepwater Turbidite Oil Play?*
By
Janice M. Christ1, William G. Dickson2, and James W.Granath3
Search and Discovery Article #10044 (2003)
*Adapted from “extended abstract” for presentation at the AAPG Annual Meeting, Houston, Texas, March 10-13, 2002.
1J-SEA Geoscience, The Woodlands, Texas ([email protected])
2Dickson International Geosciences, Houston, Texas ([email protected])
3Granath & Associates, Houston, Texas ([email protected])
Introduction
The Pearl River Mouth Basin (PRB), offshore China, is reexamined in light of:
- advances in understanding deepwater depositional systems;
- better
data analysis and display 
tools
and techniques;
- recent experience in South Atlantic margin basins and offshore Borneo illustrating correlations between potential field data and controls on sediment distribution systems.
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uSediment distribution & gravity
uSediment distribution & gravity
uSediment distribution & gravity
uSediment distribution & gravity
uSediment distribution & gravity
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Click here to view sequence of Figures 2 and 3 (hdx and isodazi, respectively).
Geologic Framework and HistoryThe Pearl
River Mouth Basin (PRB) is a passive margin rift system composed of
three subbasins (Figure 1). The southernmost of these, the Zhu II subbasin, is significantly extended in a new The initiation of seafloor spreading is marked by the 30 Ma “breakup” or T7 unconformity, a key boundary separating the more isolated depocenters containing lacustrine source-prone rift fill from the succeeding and widespread paleo-Pearl River deltaics (Chen et al., 1994). The deltaic reservoirs in the Zhu I and Zhu III subbasins have been the target of most PRB exploration. Few wells have tested the edge of the Zhu II subbasin, where a lack of reservoir quality sands has been perceived (Letsch et al., 1994). Recent advances in understanding deepwater depositional systems (i.e., Posamentier, 2000; Dickson and Macurda, 2001) predict turbidite reservoirs well outboard of the deltaic environments explored to date.
Sediment Distribution Systems and Regional GravityRecent work on a non-exclusive study of the South Atlantic by one of the authors (Dickson) introduced the possibility of defining controls on sediment distribution systems from regional gravity data. Examples from both Brazilian and West African basins suggested the relationship was not restricted to a single basin. Offshore northwest Borneo, the authors identified feature patterns on gravity attribute images that correlate with interpreted channel/canyon systems (CCS). These CCS debouch into the known Tertiary Lingan Fan (Mohamad and Lobao, 1997) and additional speculative fans (Figures 2 and 3); their sources coincide with the locations of slump-scars and back-cutting shelf edges. Similar distinct CCS patterns appear to correlate to the Tertiary Pearl River fan system, initiating at the delta front (Chen et al., 1994), extending across the slope and terminating at the southern basin extension, raising the expectation for turbidite reservoirs.
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Figure 1.
Location map of the Pearl River Mouth Basin, South China Sea, showing
the various elements of the basins (after Moldovanyi et al., 1995).
Figure 2.
NW Borneo interpreted channel/canyon systems (CCS, in dark brown) with
Lingan Fan (yellow) and speculative fans (white) on background of
gravity horizontal derivative (hdx).
Figure 3.
NW Borneo interpreted channel/canyon systems (CCS, in brown) with Lingan
Fan (yellow) and speculative fans (cream) on background of dip-azimuth
of isostatic gravity anomaly (isodazi).
Figure 4.
Pearl River Mouth Basin (PRB) interpreted channel/canyon systems (CCS,
in brown) with interpreted fans (yellow) on background of dip-azimuth of
isostatic gravity anomaly (isodazi).
