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The AAPG/Datapages Combined Publications Database
Houston Geological Society Bulletin
Abstract
Abstract: A Review of the Petroleum Systems of the Gulf of Mexico with Emphasis on the
Mexican Sub-
basins
: Oil Quality Distribution, Recognition of a New Petroleum System, and Remaining Petroleum Potential
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The Gulf of Mexico is a prolific basin with multiple source
rocks
that are Jurassic, Cretaceous, and Tertiary in age.
Oil quality distribution in the subsurface is controlled primarily by the characteristics of the
source
rocks
. For example, carbonate
source
rocks
contain marine, sulfur-rich organic matter and yield oils high in asphaltene compounds and sulfur. In contrast, siliciclastic
source
rocks
contain a mixture of marine and terrestrial organic matter and yield waxy, low-sulfur oils with greater gas/oil ratio. In the Gulf of Mexico, the
Mesozoic
source
rocks
are generally carbonate whereas Tertiary
source
rocks
are siliciclastic. In the northern Gulf of Mexico, petroleum generated from Jurassic and Cretaceous
source
rocks
has been recognized in the inner onshore region, whereas Tertiary sourced oils and gases are found in the onshore and continental shelf areas (Figure 1). Oils generated from
Mesozoic
sequences are pervasive in the deep Gulf of Mexico (Gross et al., 1995). On the Mexican
side of the Gulf of Mexico, sub-
basins
also contain oil and gas of different origins.
Burgos Basin
The Tertiary Burgos Basin produces gas and condensate from reservoirs
that consist of sand deposited as bars and wide, thin-bed deposits at the front of Paleocene, Eocene, Oligocene, and Miocene prograding deltaic systems.
Although the Mesozoic
sequences, such as the Kimmeridgian Tithonian La Casita Fm., Aptian La Pena Fm., and Turonian Eagle Ford Fm., are rich in organic matter, they are spent
source
rocks
, and did not contribute to the commercial accumulations in the basin. Active
source
rocks
are the Paleocene-Eocene
Midway-Wilcox Fms. and Oligocene Vicksburg Fm. that contain a gas-prone Type III kerogen (Echanove-Echanove, 1986; Gonzalez-Garcia y Holguin-Quinones, 1992).
The trapped hydrocarbons have been generated at more than 4 km depth and migrated along the listric and gro~ fault systems that affected the whole Tertiary section. Exploration in this basin is being revitalized with the search for gas in deeper traps, secondary recovery techniques, infill drilling and looking for new prospective areas offshore where there is great potential for accumulations of hydrocarbons (Yanez-Mondragon, 2001).
Tampico-Misantla Basin
The Tampico-Misantla basin produces high-sulfur oil of variable quality (e.g., 15° to 40° API gravity) and associated gas. Production comes from stratigraphic, and mixed structural-stratigraphic traps with naturally fractured carbonate reservoirs
in Upper Jurassic San Andres Fm., Cretaceous EI Abra , Tamabra and Tamaulipas Superior Fms., and clastic
reservoirs
in the Eocene Chicontepec Fm. In the central part of the basin, oil and associated gas were generated from Upper Jurassic
source
rocks
, whereas to the west, light oil, condensate, and gas were generated from the Lower Jurassic Huayacocotla Fm. (Morelos-Garcia, 1996; Roman-Ramos y Holguin-Quinones, 2001). In the Sierra Madre Oriental, an oil seep sample suggests that oil charge must have come from a carbonate
source
rock deposited in an anoxic, hypersaline, shallow water environment (platform). This new evidence suggests that within the Cretaceous Valles San Luis Potosi Platform, there are
source
rocks
that could have charged the Sierra Madre Oriental and adjacent regions. In the Sierra
End_Page 15---------------
El Abra, an exhumed reservoir contains oil in the moldic porosity of rudist build-ups of the El Abra Fm. This reservoir shows a complex hydrocarbon charging history (Pottorf et al., 1996). Petroleum activity in this basin is focused on the rehabilitation of mature oil fields, development
of the Chicontepec trend and offshore exploration (Yanez-Mondragon, 2001).
Veracruz Basin
The Veracruz Basin is divided into the Tectonic Buried Platform and Veracruz Tertiary Sedimentary Basin.
Tectonic Buried Platform
The stratigraphic section of the Tectonic Buried Platform comprises Upper Jurassic to Early Eocene sequences that were deformed and thrusted during the Middle
Eocene. This region
contains high sulfur oil and associated gas in structural traps of
Cretaceous age (Orizaba, San Felipe and Guzmantla Fms). Active
source
rocks
have been identified in the Upper Jurassic Tepexilotla Fm., Turonian Maltrata Fm. and Aptian-Albian Orizaba Fm.
Tertiary Sedimentary Basin
The stratigraphic section of the Veracruz Sedimentary Basin includes a thickness of more than 8 km of Tertiary terrigenoclastic sediments, and Cretaceous and Upper Jurassic sequences that have not been penetrated. This region produces mainly gas and minor volumes of condensate and oil from Miocene and Pliocene stratigraphic reservoirs
. Although it is inferred that
Mesozoic
source
rocks
are present, they are most likely spent and may have contributed only minor gas and some oil. Paleocene-Eocene and Miocene sedimentary
sequences contain fair to good
source
rocks
with gas-prone Type III kerogen, and are the most likely
source
of the hydrocarbons trapped locally (Roman-Ramos y HolguinQuinones, 2001).
Exploration in the Veracruz basin is concentrated in the Tertiary Sedimentary: Basin, which has great potential for gas discoveries.
Southeastern Basins
and Campeche Bay Region
The southeastern basins
include the contiguous Salina del Istmo, Chiapas- Tabasco, and Macuspana
basins
, and the Campeche Marine Platform. These
basins
have a common geological history during the
Mesozoic
, and a different structural and stratigraphic
development
since the Tertiary.
Source
rocks
have been identified in the Upper Jurassic (Tithonian),
Middle
Eocene, Oligocene and Middre Miocene sections (Sosa-Patron y Clara-Valdez, 2001)
Salina del Istmo
Several giant oil fields in the Salina del Istmo Basin produce oil of about 35° API and associated gas. The main reservoirs
are Miocene and Pliocene sequences in stratigraphic-structural traps developed by salt tectonism.
Source
of these hydrocarbons has been identified as Upper Jurassic (Guzman-Vega and Mello, 1999).
Figure 1. Geographic distribution of petroleum systems in the Gulf of Mexico.
End_Page 17---------------
Chiapas-Tabasco Basin
The Chiapas-Tabasco Basin produces oil and associated gas from
combined stratigraphic-structural traps of Upper and Lower
Cretaceous reservoirs
. These hydrocarbons were generated from
Upper Jurassic
source
rocks
. To the south, some oils correlate
with Cretaceous carbonate
source
rocks
that were deposited in a
platform environment of hypersaline conditions (Guzman-Vega
and Mello, 1999).
Macuspana Basin
The Macuspana Basin is a gas producing basin with minor
production of condensate and oil. Gases are a mixture of biogenic
and thermogenic, and the thermogenic gases are of variable
maturity. Thermogenic gases were produced from primary
cracking of Tertiary source
rocks
and probably secondary cracking
from Upper Jurassic
source
rocks
(Sosa Patron et al., 200 1).
Campeche Marine Platform
The Campeche Marine Platform is the richest oil region in
Mexico, and contains several giant oil fields, including the
Cantarell Trend. Three stratigraphic sections have been identified
as source
rocks
in this region: Oxfordian, Tithonian and
Miocene sequences (Santamaria, et al., 1998; Sosa-Patron and
Clara-Valdez, 2001). The Oxfordian
source
rock appears to be of
limited geographic extent, and is only active in the north, whereas
the potential ,Miocene
source
is more widespread. However,
the Tithonian is clearly the
source
of most of the hydrocarbons
trapped in the region (Romero-Ibarra et al., 2001).
The southern basins
have been producing oil and gas since the early
70s and this region has still great potential for new discoveries.
Offshore Mexico as well as the deep and ultradeep regions of the
Gulf of Mexico are frontier regions of oil exploration. Regional
work on the petroleum systems suggests that the Tertiary section
will be an important source
of hydrocarbons on the western side
of the Gulf of Mexico, close to the shoreline (Figure 1). Likewise,
evidence of oil from the Challenger Knoll and regional trends
suggest that the
Mesozoic
section (e.g., Upper Jurassic) will be
the most important
source
of hydrocarbons in the deep and
ultradeep regions of the Gulf of Mexico.
References
Echanove-Echanove, O. 1986, Geologia petrolera de la Cuenca de Burgos. Consideraciones geologicas-petroleras: Boletin Assoc. Mex. Geol. Petr., v. XXVIII, p. 3-74.
Gonzalez-Garcia, R., y N. Holguin Quinones, 1992, Las rocas generadoras de Mexico: Boletin Assoc. Mex. Geol. Petr., v. XLII, p. 16-30.
Gross, O. P., K. C. Hood, L. M. Wenger, and S. C. Harrison, 1995,
Seismic Imaging and analysis of source
and migration within
an integrated hydrocarbon system study: Northern Gulf
of Mexico: 1st Latin American Geophysical Conference, Rio
de Janeiro, Brazil, Extended abstract.
Guzman-Vega, M. A., and M. R. Mello, 1999, Origin of oil in the Sureste Basin, Mexico: AAPG Bulletin, v. 83, p. 1068- 1095.
Morelos-Garcia, J. A., 1996, Organic Geochemistry of southern
Tampico-Misantla basin, Mexico: Oil-oil and oil-source
rocks
correlation: Dissertation, University of Texas at
Dallas, 635 p.
Pottorf, R. J., G. G. Gray, M. G. Kozar, W. M. Fitchen, M. Richardson, R. Chuchla, and D.A. Yurewicz, 1996, Hydrocarbon generation anf migration in the Tampico-segment of the Sierra Madre Oriental Fold-Thrust Belt: Evdencc from an exhumed oil field in the Sierra de El Abra: in, M.E. Gomez-Luna and A. Martinez-Cortez, eds., Memorias del Congreso Latinoamericano de Geoquimica Organica, Cancun, Mexico, p. 100- 101.
Roman-Ramos, J.R., y N. Holguin-Quirlones, 2001, Subsistemas generadores de la region norte de Mexico: Boletin Assoc. Mex. Geol. Petr., v. XLIX, p.68-84.
Romero-Ibarra, M.A., L.Medrano-Morales, y R. Maldonado- Villalon, 2001, Subsistemas generadores del area marina de Campeche, Mexico: Boletin Assoc. Mex. Geol. Petr., v. XLIX, p.105-115.
Santamaria, O. D., R. di Primio,B. Horsfield, and D.H. Welte,
1998, Influence of maturity on sulphur-compounds in
Tithonian source
rocks
and crude oils, Sonda de Campeche,
Mexico: Org. Geochem., v. 28, p. 423-439.
Sosa-Patron, A. A., P.R. Philp, y E. Caballero-Garcia, 2001, Caracterizacion genetica de los gases de la Cuenca de Macuspana: Boletin AMGP, v. XLIX, p. 143-144. Sosa-Patron, A. A., y L. Clara-Valdez, 2001, Subsistemas gener adores del sureste de Mexico: Boletin Assoc. Mex. Geol. Petr., v. XLIX, p. 85-104.
Yanez-Mondragon, M., 2001, Mexico's northern region launches
massive development
: World Oil, November 2001, p. 69-70.
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