USE OF SEISMIC ATTRIBUTES IN RESERVOIR CHARACTERISATION OF “OYINKS” FIELD OFFSHORE NIGER DELTA

Abstract

Seismic attributes which are proven seismic technological tool are important qualitative and quantitative predictors of reservoir properties and geometries when correctly used in reservoir characterization studies. Seismic attributes reveal information, which are not readily apparent in the raw seismic data. The ultimate goal of reservoir characterization is to identify reservoir, delineate the pay zone and determine the distribution of their relevant properties. This project discusses the use seismic attribute for reservoir characterization analysis of Oyinks field offshore Niger Delta. The study attempts to enhance the characterization of subsurface reservoirs by improving the spatial prediction of petrophysical properties through integration of petrophysical measurements and 3D seismic data. Petro-physical analysis was done to identify pay sand from logs and estimate their parameters, the porosity of two reservoirs mapped ranges from 21% to 31% and 30% to 32% respectively. A functional relationship between porosity and seismic inversion properties (acoustic impedance) was derived at the well location, this relationship was applied to the inversion properties using regression analysis and a porosity cube is generated. The result provides a geologically realistic spatial porosity distribution which helps to understand the subsurface reservoirs heterogeneities in the study area. The instantaneous frequency volume and reflection strength attributes slice extracted close to the horizons were analyzed by a 3D visualization tool. The restriction of frequency to those of the signal gave a better geologic appearance of the sand distribution, the reflection strength were used to identify pay zones away from the wells. The result of this research has demonstrated that the integration of seismic attributes (physical and geometrical) with structural interpretation as an efficient way of characterizing a reservoir.