SEQUENCE STRATIGRAPHY AND SEISMIC ATTRIBUTES ANALYSIS FOR HYDROCARBON POTENTIAL EVALUATION OF “JONES” FIELD, NIGER DELTA

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.