Sequence stratigraphic Implication to Hydrocarbon Exploration in the Niger Delta Basin

SEQUENCE STRATIGRAPHIC IMPLICATION TO HYDROCARBON

EXPLORATION IN “BETA FIELD”, NORTHERN DEPOBELT OF THE NIGER DELTA BASIN

1,2Ukpong, A. J.    and   2Anyanwu, T. C.

1. Department of Geology, Gombe State University, Gombe, Nigeria (Sabbatical),

2. Department of Geology, University of Calabar, Calabar, Nigeria

ABSTRACT

Seismic and checkshot data, geophysical data and biostratigraphic data extracted from ditch cutting samples, were used for the sequence stratigraphic analysis of Beta-24 well within the Beta field, Northern depobelt of the Niger Delta. The results revealed three Maximum Flooding surfaces and three Sequence Boundaries. System tracts; Highstand System Tract, Transgressive System Tract and Lowstand System Tract were identified within the well. Foraminiferal bioevents; LDO of Globigerina ampliapertura at 2928m, FDO of Bolivina ihuoensis at 2768m and the LDO of Bolivina imperatrix at 2648m delineated from the well were used to date the interpreted surfaces with the aid of the Niger Delta chronostratigraphic chart. The ages assigned to the Maximum Flooding Surfaces (MFS: 1, 2, 3) were 38.0Ma, 36.8Ma, 35.9Ma respectively and sequence boundaries (SB: 1, 2, 3) were 37.3Ma, 36.3Ma and 35.4Ma respectively. The depositional environment of the sediments penetrated by the well were inferred based on well log signatures and biostratigraphic information to have fluctuated from non-marine through coastal deltaic to marine. The Maximum Flooding Surfaces and Sequence Boundaries identified from the foraminiferal-well log sequence stratigraphy were tied to seismic using checkshot data. Seismic stratigraphic interpretation revealed two key bounding surfaces, two systems tracts and two major faults in the field. The faults (F2 and F3) were responsible for the structural truncations that limited the recognition of strata terminations in the vicinity of the well. An observation of the horizons within the system tracts revealed that they may have potentials to serve as excellent reservoir rock and seals.

Keywords: Sequence stratigraphy, Seismic stratigraphy, Biostratigraphy, Northern depobelt, Niger Delta.