|
Caribbean Research at UTIG
VENMAR
Towards an integrated understanding
of regional seismic stratigraphy, age of deformation,
basin subsidence, and petroleum systems of the
northern offshore margin of Venezuela
Principal Investigator: Paul
Mann
Postdoctoral fellow:
Alejandro Escalona
Funding
Agency: The Petroleum Research Fund, American Chemical
Society and the Jackson school of Geosciences at The University of
Texas at Austin
Abstract
The region of Venezuela and Trinidad
and Tobago has one of the largest hydrocarbon reserves in the
western hemisphere with 38 known giant fields whose oil reserves are
currently estimated at 77 BBO (Fig.1 ). All but one of these giants
occur in the onland foreland basins and Orinoco delta area of
Venezuela, south of the presently active Caribbean-South America
plate boundary. The northern offshore area of Venezuela on the
present-day Caribbean plate is far less mapped and explored for
hydrocarbons, although giant gas fields are being developed offshore
and oil and gas shows and rich source rocks have been reported in
offshore exploration and DSDP wells.
|
 |
|
Figure 1.
Bathymetric and topographic map of the South
America-Caribbean plate boundary zone. Heavy black line shows location of
the major fault of the plate boundary, the Bocono-San Sebastian-El
Pilar-Central Range right-lateral strike-slip fault zone.
Black areas are locations of giant oil fields.
Areas dotted in white are individual offshore basin outlines
studied by previous workers: 1 = Venezuelan; 2 = Grenada;
3 = Bonaire-Blanquilla; 4 = Tobago; 5 = Carupano-North
Trinidad; 6 = Cariaco.
Terrestrial basins studied onland or in nearshore areas include: 7
= Columbus; 8 = Maturin; 9 = Guarico; 10 = Falcon;
11 = Barinas; 12 = Maracaibo
|
|
We propose a regional, two year
study of ~40,000 km of seismic reflection data and more than 100
wells (Fig. 2) to better constrain the tectonic history and setting
of petroleum systems of more than 1,000,000 km2
area of the Venezuelan shelf, slope and its deepwater basin
(Venezuelan basin). Digital data - including more than 10,000 km of
previously uninterpreted and digital Gulfrex reflection data (Fig.
3) - will be interpreted on a workstation to improve
three-dimensional interpretation of seismic sequences and structures
in offshore basins. Interpretations will be compiled with other
basic data in the form of a Geographic Information System (GIS) data
base. |
 |
 |
|
Figure 2. Track map showing on-
and offshore seismic reflection data. |
Figure 3. Examples of Gulfrex
seismic lines not previously used showing different components of the tectonic
provinces |
|
Specific objectives include: 1)
improved mapping of offshore angular unconformities, faults and folds,
their ages, and correlation to better studied onland tectonic
features; 2) improved determination of major basinal subsidence events
and their relation to tectonic, eustatic, and paleoceanographic
events; 3) improved mapping of offshore deltaic depocenters of the
proto-Orinoco River (Fig. 4); and 4) synthesis of the above
information into a better understanding of petroleum systems now
studied at the scale of individual hydrocarbon fields or basins.
|
|
|
Figure 4. Depth to basement map
of the northern margin of South America compiled from Edgar et al.
(1971), Lugo (1991), Diaz de Gamero (1996) and Di Croce et al. (1999).
The age of the top of the basement shown varies but is generally
a late Jurassic or older surface.
Major depocenters with fills greater than 6 km (compacted) and
their ages include: 1 = Maracaibo basin (Eocene-Miocene); 2
= Barinas basin (Eocene-Miocene); 3 = Maturin basin; 4 =
South Caribbean deformed belt; 5 = Grenada basin and 6 =
Carupano-Tobago-Barbados prism.
The dotted lines represent proposed locations of the
proto-Orinoco River by Diaz de Gamero (1996).
Driscoll and Diebold (1999) has proposed that the South Caribbean
deformed belt depocenter is the distal equivalent of proto-Orinoco
deltaic deposits now found in the Maracaibo basin.
Our improved seismic and well data set will allow better
correlations between the six major depocenters shown. |
|
Publications
Alejandro Escalona
Paul Mann
|
