Quantitative Palystratigraphy: A Key for Delneating Maximum Flooding Surfaces and Sequence Boundary in the Onshore Depobelt, Niger Delta of Nigeria
Adojoh, Onema C.¹; Osterloff, Peter L.²; Adejinmi, Kehinde³
¹Earth Scinces, Plymouth University, Plymouth, United Kingdom.
²Geosolution, Shell Petroleum Development Company, Warri, Nigeria.
³Geosolution, Shell Petroleum Development Company, Warri, Nigeria.
The advance use of sequence stratigraphy and the search for quantitative palynological stratigraphy related to global cycles has led to the application of new technique ‘' Salinity Index (S.I) and Tidal Limit Index (TLI) '' for the establishment of maximum flooding surfaces and sequence boundary. This research studies the linear correlation using the relative frequencies of marine and fresh water remains linked to palaeovetational trend influenced by the tidal limit of the sea level to map maximum flooding surfaces and sequence boundary between two wells: Abraka-1 Well and Effurun-1 Well, Northern depobelt, Niger Delta.
By construction, the curve inverse of the inland ecosystems and fresh water suggest the Sequence Boundary (SB), whereas the coupling of saline water and shore plants indicates Maximum Flooding Surfaces (MFS) between the two wells High salinity index values are linked to transgression and low values represent regressive phases. High tidal limit index represent increased marine influence, whereas low tidal limit index values indicates regression. Consequently, tidal limit maximum coincide with flooding surfaces, and tidal limit minimum represents sequence boundary.
These combinations (salinity index and tidal limit index) were used to establish maximum flooding surfaces and sequence boundary for the two wells. Notional application of this principle is a promising tool in the development of sequence stratigraphic studies in continental and coastal sediments where traditional biostratigraphic tools such calcerous nannofossils and foraminifera are absent.
AAPG Search and Discovery Article #90155©2012 AAPG International Conference & Exhibition, Singapore, 16-19 September 2012