Integration of Petrophysical and 3D Seismic Attribute Analyses for Reservoir Characterization in Agana Field, Onshore Niger Delta, Nigeria

The study integrates petrophysical analysis, attribute studies of 3D seismic data to analyze structures, delineate reservoirs, identify prospects and estimate reserves within the Agana field. The study area is located in the coastal swamp of the Eastern Niger Delta. Four wells were used for the study. Four reservoirs A, B, C and D were identified and correlated across the wells. Volume attribute studies revealed a complexly faulted region. A total of sixty six faults were mapped and were labeled F1 to F66. The major faults were trending East-West direction, while the minor faults were trending in Northeast-Southwest direction. The trapping mechanism identified from the interpretation indicates that the field is characterized mostly by fault assisted closures. The results of the three surface attributes; RMS Amplitude, Extract value, Sum of Positive Amplitudes extracted from the subsurface structure maps identified only one prospect, B1 on horizon B. The average petrophysical parameters of reservoir B in the four wells which included thickness, net-to-gross, volume of shale, water saturation, hydrocarbon saturation and porosity, were calculated as 485.99ft, 0.58, 0.20, 0.52, 0.48, and 0.21, respectively. These average parameters were used to estimate the reserve for the identified prospect B1. The calculated results for Hydrocarbon Initially In Place (HIIP) and Hydrocarbon Pore Volume (HPV), are 303,709.43×106 STB, and 455,564.15ft3 respectively. Risk analysis based on Geologic Chance of Success showed that the prospect can be explored with 56% chance of success. The result showed integration of petrophysical and structural analysis with attribute studies to be more efficient in identifying prospect so that where structural interpretation is inefficient attribute studies compliment.