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Petroleum System Analysis of West Africa Deepwater from Cameroon to Angola: a Systematic Approach to Identifying Exploration Targets

Ku Shafie, Ku Rafidah 1; Madon, Mazlan 1; Abu Bakar, Zainol Affendi 1; Ismail, Hasnol Hady 1; Abu Hassan, Redzuan 1; Ishak, Sarpan 1; Mohd Ali, Amita 1
1 Subsurface Technology, PETRONAS Research Sdn Bhd, Kajang, Malaysia.

A petroleum system review of West Africa deepwater, from Cameroon to Angola, was undertaken with the view of assessing the remaining potential and to determine areas for further investigation. With the wealth of exploration/production data available internally and from the public domain, a systemic approach was taken to obtain a "bird’s eye view" of the geology of the margin and its petroleum systems. The study was also a means for identifying data and knowledge gaps where future studies may be focused.

A chrono-stratigraphic chart for the entire West African margin serves as the framework for further analysis. The chart was compiled mainly from public domain data, detailing out the main source, reservoir and seal rock units in a tectono-stratigraphic context. Information such as hydrocarbon occurrences (fields and discoveries) and wells drilled are pasted on the chart (both in printed and digital forms) for easy viewing. In its digital form, tabulated data for fields and discoveries are provided as hyperlinks to worksheets.

Petroleum systems are defined by linking the reservoirs to their respective source rocks. A total of 24 petroleum systems, both proven and hypothetical are identified in all the major basins along the margin, from north to south: (Rio del Rey, Douala, Rio Muni, Gabon, Lower Congo, Kwanza, and Namibe). Each petroleum system is illustrated in folio sheets, which give details of the petroleum systems elements: source, reservoir, migration and trapping mechanism and timing, complete with a petroleum systems events chart. Besides the proven major petroleum systems such as Bucomazi-Vermelha and Pinda-Malembo, a number of hypothetical petroleum systems have been identified, which need further investigation and validation. Wells drilled to date are pasted on the charts to determine the major risk factors (post-mortem) and provide a basis for future exploration or research strategies. The chronostratigraphic charts and petroleum systems folios are used in conjunction with a comprehensive GIS database that was established to aid further analysis of the margin.

 

AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009