A description of seismic amplitude techniques

Abstract

The acquisition of seismic data is a non-invasive technique used for determining the sub surface geology. Changes in lithology and fluid fill affect the seismic wavelet. Analysing seismic data for direct hydrocarbon indicators (DHIs), such as full stack amplitude anomalies, or amplitude variation with offset (AVO), can help a seismic interpreter relate the geophysical response to real geology and, more importantly, to distinguish the presence of hydrocarbons. Inversion is another commonly used technique that attempts to tie the seismic data back to the geology. Much has been written about these techniques, and attempting to gain an understanding on the theory and application of them by reading through various journals can be quite daunting. The purpose of this paper is to briefly outline DHI analysis, including full stack amplitude anomalies, AVO and inversion and show the relationship between all three. The equations presented have been included for completeness, but the reader can pass over the mathematical detail.

Analysing seismic data for direct hydrocarbon indicators (DHIs) and amplitude variation with offset (AVO) can be instrumental in identifying the presence of hydrocarbons. Inversion converts seismic data into acoustic impedance, which can be used to estimate geological properties. This paper reviews the literature and commonly used techniques for seismic amplitude analysis.

Key words::

• amplitude variation with offset (AVO), direct hydrocarbon indicators (DHIs), seismic inversion.

Acknowledgements

I would like to thank Bala Kunjan, Naomi Osman, Irfan Yuliandri, for their proof reading and suggestions.