El Ciclo de las Cuencas

Basin Modelling and Thermal Maturation in the Rio Muni BasinEquatorial Guinea Offshore by Ricardo Veiga and Jordi Franques i Faixa

1st MAPG Conference, Marrakech, Morocco, October 28-31, 2007

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R. Veiga & J. Franques i Faixa

Highlights

1- Objectives. 2- Introduction. 3- Results 4- Conclusions


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Highlights

1- Objectives. Define the location of the main active pods on the offshore of Guinea Equatorial. Know the evolution of these pods through the time.

2- Introduction. 3- Results 4- Conclusions


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Highlights

1- Objectives. 2- Introduction. Geological framework. Petroleum System overviewPlay Concepts. Source Rocks 3- Results 4- Conclusions


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Geological framework: Main Petroleum Provinces

NIGER DELTA

DOUALA DOUALA BASIN BASIN

RIO RIO MUNI MUNI BASIN BASIN


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Geological framework: General Stratigraphy


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Geological framework: Schematic Play Concept Types


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Geological framework: Source rocks types-Summary and example Source Rock Interval

Age

Kerogene Type

Environment Occurrences

Drift Marine Transitional Rift

Albian-Turonian Aptian-Albian Neocomian to Early Aptian

II II or IIS I, II & III

marine marine lacustrine

Rio Muni wells Rio Muni wells Rio Muni wells & Coastal Gabon Basin

Log Normal Distribution

TOC mean Benito well=1.8%

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Log Normal Distribution

HI mean Benito well=168

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Geological framework: Source rocks Emplacement (generic seismic section E-W)


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Highlights

1- Objectives. 2- Introduction. 3- Results Thermal modelling Active pods for main source rock Timings and migration Overlap between pods and turbidites systems. 4- Conclusions


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Maturity Maps for Different Source Rocks= Syn Rift Source Rocks Case A: Early Syn Rift Source Rock Case B: Late Syn Rift Source Rock

Modelated wells

Oil window in the Northern

Hydrocarbons Fields

CASE A Modelated wells

Overmature in the Central Rio Muni

Hydrocarbons Fields

Early mature in the Northern

CASE B

Oil window in the Southern

Overmature in the Central Rio Muni

Oil window in the Southern

In both cases the western boundary of the Syn Rift Source Rock is the Kribi Fault Zone


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Maturity Maps for Different Source Rocks= Transitional Source Rock (major) A)

Region with high maturity coincide with the region with more overburden Niger Delta effect.

Modelated wells

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Hydrocarbons Fields

A)

Maturity Map Calculated

B)

Overburden Map Sea Bottom-Transitional Source Rock

B)

Niger Delta effect

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Maturity Maps for Different Source Rocks= Cenomanian-Turonian Source Rock (minor) A)

Region with high maturity coincide with the region with more overburden Niger Delta effect.

Modelated wells

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Hydrocarbons Fields

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Maturity Map Calculated

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Overburden Map Sea Bottom-Cenomanian Source Rock

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Niger Delta effect

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Oil & Gas Generated and Hydrocarbon expulsion interval for Okume-Oveng fetch areas 450000

Timing to Early Generation (Ro>0.5%) M.Y

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Timing to Mid Mature~Hc Expulsion (Ro>0.7-1.0%)

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Generation started in the North (Cameroon offshore) by the influence of PaleoSanaga and/or PaleoNkam rivers and it took place at Late K times. The hydrocarbons expulsion (on the Equatorial Guinea offshore) started at Paleogene times. Finally, the main gas generation occurred in the northern areas. 1st MAPG Conference, Marrakech, Morocco, October 28-31, 2007

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Active Pods for the Transitional Source Rock

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Relationship between active pods for the Transitional Source Rocks and the location of the main Hydrocarbons fields in the Rio Muni Basin-Guinea Offshore. Hc Expelled (bbl/acre)

Active Pods @Eocene

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Active Pods @Oligocene

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Active Pods@ Pliocene&Recent times

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Hydrocarbons migration lines in the Rio Muni Basin

Okume/Oveng Complex Ceiba

Note the different hc migration trends to Okume-Oveng complex fields and for the Ceiba Field 1st MAPG Conference, Marrakech, Morocco, October 28-31, 2007

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Miocene Pod and Turbidites distribution on the Equatorial Guinea Offshore. Hc Expelled bbl/acre)

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Miocene pods with Lower Tertiary turbidites

Miocene pods with Upper K turbidites


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Highlights 1- Objectives. 2- Introduction. 3- Results 4- Conclusions


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Conclusions 1.

Several source rocks have generated and expelled hydrocarbons in the Rio Muni Basin.

2.

The Syn-Rift source rocks are restricted between Kribi fault zone and the coastal area. They are overmature in the central Rio Muni, but they could be in the oil window in the southern and northern region.

3.

The Transitional and Cenomanian source rocks are overmature in the northern area by the influence of the Niger delta. In contrast, they are in the oil window in the Rio Muni Basin.

4.

For the Transitional source rock, the generation started in the northern regions at Late Cretaceous times. The hydrocarbon expulsion (on the Guinea offshore) took place between Late Cretaceous and Paleogene times. Finally, the gas generation occurred only in the northern area.

5.

During Miocene and Recent times, the active pods (for the Transitional source rock) were located close and below to the Upper Cretaceous and Lower Tertiary turbidites, so a vertical and lateral migration could be expected to charge multiples reservoirs.


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