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Date of Award

2016

Document Type

Campus Access Master's Thesis

Degree Name

Master of Science in Geophysics (MS)

Administrative Home Department

Department of Geological and Mining Engineering and Sciences

Advisor 1

Wayne D. Pennington

Committee Member 1

Greg Waite

Committee Member 2

Radwin Askari

Abstract

The purpose of this study is to compare different AVO approximations and support these results through pre-stack inversion. A 3D seismic survey in Penobscot area was used to conduct the study. The data quality was very poor, so the enhancement process was applied to the data to increase quality. The data were filtered by various the Parabolic Radon Transform time ranges which do not disturb real AVO characteristics while removing noise, particularly the interference from multiples. The 2-term (“Shuey”) and the 3-term (“Aki-Richards”) approximations were run on the data. Similar AVO characteristics were obtained for both approximations for the same filtering parameters of the Parabolic Radon Transform. In order to check AVO approximations results, pre-stack trace inversion was applied to one of the Parabolic Radon Transform results, solving for two parameters (acoustic impedance and shear impedance) and for three parameters (Vp, Vs, and density). In order to further investigate the nature of pre-stack data, these inversions were applied to the data to maximum angles of incidence of 30° and 45°. The inversion results show no significant differences for P-impedance or, S-impedance, regardless of the angle limitations or number of terms solved for, and no significant variations in density for angle range covered. It was found that there is a strong correlation between P-wave velocity and density. It was also observed that lack of S-wave log caused similar results for inversion.

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