Print this pageAAPG ANNUAL CONFERENCE AND EXHIBITION
Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA
Cretaceous Deepwater (Base of Slope and Basinfloor) Depositional Architecture and Evolution in the Rio Muni Basin, West Africa
(1) PetroChina Hangzhou Research Institute of Geology, Hangzhou, China.
Since the discovery of the Upper Cretaceous turbidites and the commercial Ceiba field in 1999, deepwater reservoirs in the Rio Muni basin of West Africa have become the target of investigations. In 2008 and 2009, high-resolution 2-D and 3-D seismic data were analyzed to study the depositional architecture, evolution and reservoir potential of the Cretaceous interval in the Rio Muni basin.
In the study area, deepwater depositional architectural elements interpreted from seismic stratigraphy and seismic attributes in the Cretaceous (Albian- Maastrichtian) stratigraphic interval mainly include different sized channels, mouth lobes, and hemipelagic drape complexes, which range in character from base of slope facies to basinfloor facies. Slope channel complexes are absent in the study area but present in Ceiba field that lies to the east of the study area, which suggests that the sediments probably come from the east and have been supplied by channel systems.
The investigation of depositional evolution in the study area indicates that the Rio Muni basin experienced retrogradation during the Upper Albian- Turonian and gradual progradation during the Santonian- Maastrichtian. During the the Upper Albian- Turonian, deepwater architectural elements changed from channels to hemipelagic drape complexes because of transgression and retrogradation of sediments. And then, these elements gradually evolved into mouth lobes and channels during the Santonian- Maastrichtian because of progradation of sediments, which is caused by gradual regression and tectonic uplift of the basin. Controlled by the depositional evolution, the Santonian- Maastrichtian mouth lobes and channels are likely to be the best reservoir targets in the study area.