Introduction

This book is about the physical interpretation of seismic amplitude principally for the purpose of finding and exploiting hydrocarbons. In appropriate geological scenarios, interpretations of seismic amplitude can have a significant impact on the ‘bottom line’. At all stages in the upstream oil and gas business techniques based on the analysis of seismic amplitude are a fundamental component of technical evaluation and decision making. For example, an understanding of seismic amplitude signatures can be critical to the recognition of direct hydrocarbon indicators (DHIs) in the exploration phase as well as the evaluation of reservoir connectivity or flood front monitoring in the field development phase. Given the importance of seismic amplitude information in prospect evaluation and risking, all technical disciplines and exploration/asset managers need to have a familiarity with the subject.

Philosophy, definitions and scope

The central philosophy is that the seismic interpreter working in exploration and appraisal needs to make physical models to aid the perception of what to look for and what to expect from seismic amplitude responses in specific geological settings. This usually involves the creation of synthetic seismic models for various rock and fluid scenarios based on available well log data. In rank exploration areas the uncertainties are generally such that only broad concepts, assumptions and analogies can be used. By contrast, in field development settings where data are readily available, physical modelling can lead to a quantification of reservoir properties from seismic (with associated error bars!).