The Use of Seismic Attributes to Enhance Fault Interpretation of OT Field, Niger Delta

Benard Ifeanyi Odoh,Nnaemeka Ifeanyi Okoli,Juliet Nneamaka Ilechukwu

doi:10.4236/ijg.2014.58073

Abstract

An integrated approach to the study of the fault patterns and seismic attributes was carried out on the OT field using a 3D swamp seismic data covering approximately 420 Km2 of western belt of the Niger Delta. This study aimed at improving the visualization of faults in the study area using different seismic attributes. Three major growth faults dipping south with few antithetic faults dipping in opposite direction to the growth faults and other minor faults were identified manually on the original and steered seismic cube in the inline 11669, while in the cross line only one major fault was identified manually. The seismic volume was subjected to several stages of post-stack processing to enhance discontinuities. First, a dip-steering volume was created. Several dip-steered filters were then applied to enhance faults and fractures visualization. Finally, similarity and curvature attributes were calculated on the dip-steered and fault enhanced volume. These final attributes show detailed geometry of the fault system and the numerous subtle lineaments in the study area. The integration of the attributes has increased confidence in the seismic mapping of the faults and the other numerous subtle lineaments which were difficult to identify on the input data. Similarity and curvature attributes of the seismic volume preserve subtle structural details and permit a more robust interpretation of the structures.

Highlights

Seismic attributes form an integral part of qualitative interpretative tool that facilitates structural and stratigraphic interpretation as well as offers clues to lithology type and fluid content estimation with a potential benefit of detailed reservoir characterization [1]
Identification of faults is essential in effective definition and mapping of prospects especially that exploration and production in the Niger Delta has moved to geologically complex frontier deep-water settings
The structural framework was done by picking assigned fault segments on inline 11669 sections of seismic volume and on the cross line 3045

Summary

Introduction

Seismic attributes form an integral part of qualitative interpretative tool that facilitates structural and stratigraphic interpretation as well as offers clues to lithology type and fluid content estimation with a potential benefit of detailed reservoir characterization [1]. Though the seismically resolvable faults may be interpreted using traditional diagnostic criteria (e.g. abrupt reflector cut off, kinks etc.), the subtle faults which are often of geological or exploration significance are usually not visibly imaged by the conventional seismic sections and time slices displays. This is because they have smaller throws relative to the resolution limit of the seismic survey, which is a factor dependent on the frequency content, signal to noise ratio of the dataset and the depth to the reflecting horizon. We have applied multiple seismic attributes for accurate detection and mapping of faults and fractures relevant for prediction of seismic structure of fault regions ahead of drilling costly oil and gas wells

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