Structural Interpretation and Attribute Evaluation for Characterization of Oil Field: A Case Study of “Sowari” Field, Niger Delta, Nigeria

Abstract

Effective structural interpretation and attribute analysis using well logs, high-resolution 3D seismic data and surface attributes maps of the Sowari field Niger Delta, Nigeria have been successfully investigated. The approach includes correlation of wells using GR and SP logs to establish the lithology of the Formation, identification of reservoirs from the resistivity logs, horizon and fault mapping, generation of depth structure map and surface attribute analysis. Two horizons, H1 and H2 were mapped, and structure contour maps produced for each of the horizons. The study of faults showed a complex pattern of subsurface structures. The formation has extensive simple rollover structures bounded by growth faults trending in the NNW direction. Faulted rollover anticlines exist in the middle zone while the southern area is featured by collapsed crest structures. Structural closures considered as good hydrocarbon prospects were identified and delineated. Horizon (H1) lies at a depth of 2758m, and Horizon (H2) is at a depth 3190m across the reservoir. Average energy, Maximum Amplitude and RMS Amplitude surface attribute maps were extracted to reveal bright spot and high amplitude zones. Thus, seismic attribute analysis is a good complement to conventional structural interpretation, identification and correlation of geological structures.