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The AAPG/Datapages Combined Publications Database

CSPG Special Publications


Facts and Principles of World Petroleum Occurrence — Memoir 6, 1980
Pages 219-241
Petroleum Exploration and Assessment

Geophysics: Target Shooting for the Drill

A. Easton Wren


While the oil industry was totally familiar with applied geophysics in the 1930’s, it was during the 25-year span following World War II that geophysical technology and expertise underwent substantial development. Major innovations during this period included multifold acquisition, non-dynamite sources, competent marine acquisition, the transition from analog to digital recording and the corresponding emphasis on computer processing.

However, geophysical objectives did not change during the same period. Primary targets remained structural traps (including reefs) and the collective development in acquisition and processing technology represented essentially an improvement in data quality. While interpretation techniques remained virtually static, the industry became intoxicated with aesthetic seismic sections and very little attention was paid to what the sections should look like.

An elusive butterfly that taunted the industry was the idealistic possibility of using seismic data to do something more than map structure. This ability, to remote-sense hydrocarbon reservoirs from the surface, eventually materialized with the major metamorphosis which occurred in the early seventies and heralded the beginning of a new geophysical era. This was synchronous with the “Bright Spot” technology and its direct hydrocarbon-detecting capabilities. The new language is still being learned and its pitfalls as well as its potential are being more and more appreciated. The whole key to the technology is the unique relationship of the velocity-density parameters of a hydrocarbon reservoir and the ability of the seismic method to remote-sense these properties from the surface.

Other new developments include the appreciation of the seismic wavelet and the significance of its derivation and removal; detailed analysis of rock properties and reservoir parameters and the appearance of the new art of seismic stratigraphy, first introduced by Exxon. The latest techniques relate to the generation of the pseudo-acoustilog from the seismic trace and the insight thus provided into lithology and velocity.

The gradual emergence of the seismic method can be demonstrated and the expectation is that a collective impression of a mature science of remote sensing will be generated. Predicting the future for applied seismology is as difficult as predicting the future in anything else. However, if the present is any key to the future, the industry can anticipate a fine-tuning of present capabilities, resulting in better resolution of hydrocarbon reservoirs which are becoming progressively tougher to find.

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