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Stephen Creaney1, Gary H. Isaksen2

(1) ExxonMobil Exploration Company, Houston, TX
(2) ExxonMobil Upstream Research Center, Houston, TX

ABSTRACT: Evolution of Knowledge and Ideas in Petroleum Geochemistry - From "GeoAlchemy" to Petroleum Systems Analysis and Beyond

Petroleum Geochemistry as a science is relatively young and has its roots in a number of precursor disciplines. These include the sciences of geology and chemistry but also the knowledge gained in a pragmatic way over hundreds of years of exploiting petroleum from seeps and early production. The pragmatic has often pushed out beyond the science but as the science begins to catch up new understandings reveal new exploration opportunities. A good example is the understanding of source rocks - initially ignored by the pragmatic 'wildcatter' but now considered a vital part of any risk evaluation on an exploration venture. This has occurred as a result of meticulous science in both chemistry and geology.

A timeline of knowledge accrual in Petroleum Geochemistry reveals that scientific understanding began to coalesce in the 1920's (largely as a result of understandings of maturation from the coal industry) but didn't really 'gel' until the late 1940's and 1950's. This was almost a hundred years after the industry began the intensive pursuit of petroleum outside of the Far East. The timeline confirms the late 1940's as the "Birth of Petroleum Geochemistry" - in the sense of using geochemical means to not only understand composition and origin of petroleum but also to aid in the exploration of it. The 1950's and 1960's saw growth in the techniques used to identify sources, measure maturity, correlate oils to sources and understand processes that can alter petroleum composition. The 1970's were a period of analytical 'catch-up' where the chemical tools of glass capillary chromatography, mass spectrometry and pyrolysis were added to the geochemists toolbox and began to further constrain interpretations. In addition basin modeling emerged and began to play a role in further enriching our understanding of petroleum generation.

AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado