Abstract:
Seismic attributes and sequence stratigraphy have been used to characterized hydrocarbon
bearing reservoir in a field, offshore Niger Delta. Hydrocarbon and non-hydrocarbon
bearing sands were identified from gamma ray and resistivity log responses. Well log
chronostratigraphic correlation was done using the principle of similarities in log responses
and time stratigraphic surfaces. Log sequence evaluation was done by the analysis of log
amplitude and stacking patterns of facies succession. Computation of petrophysical
properties of reservoir rocks was executed using well established equations. Identification
and mapping of network of faulting using seismic attributes such as amplitude and
reflection geometry was carried out. Seismic sequence analysis using reflection
terminations was used for the mapping of three depositional sequences on the basis of
reflection character analysis. The general stratigraphy is alternation of sands and shales
typical of Agbada Formation. Average petrophysical properties of the three reservoirs
mapped include: net-to-gross sand thickness of 0.78, volume of shale 15%, porosity 21%,
water saturation 43%, hydrocarbon saturation 57% and permeability 405 mD Typical
seismic facies associated with the mapped sequences include; parallel, parallel/sub-parallel,
divergent/convergent and chaotic. This arrangement of facies connote sand-shale
interbedding within a low to high energy depositional environment. The probable structure
harboring oil and gas is faulted and unfaulted anticlines. Amplitude maps analysis showed
that structural highs coincided with zones of thick sediment accumulation. The depositional
environment deduced from seismic and well logs ranges from delta plain, shelf and slope
respectively.
