Sequence Correlation Across Major Depositional 'Cells' in NW Niger Delta

Louise Linden, Val Onyia, Adedoja Ojelabi, Joshua Adubiobi, and Unwana Nkeme
Chevron Nigeria Limited, Lagos, Nigeria

Integrated sequence analysis of seismic, well log and biostratigraphic data provides a new understanding and correlation of depositional sequences across five main depositional cells otherwise known as depobelts in the NW Niger delta. Depositional cells are geologic trends, compartmentalized by major structure-building growth faults. The depositional cells show strong progradation from early Oligocene to Pleistocene in the direction of the basin. Attempts were made to group genetically related successions of strata into depositional sequences, and place them into a sequence stratigraphic framework.

Nine regional transects were generated to establish and document correlation across the depositional cells. Time structure maps of six of the major sequence boundaries highlight aspects of key structural and stratigraphic features. Correlation across major fields and depositional cells has been established, and potential untested parasequences, which we now recognize, have been inferred or predicted. Examples of untested parasequences include the deep condensate trend below Okan - Meji - Mefa fields. The recent discovery in Okan - 76st confirms this new potential.