Page 6 - The Petroleum System From Source to Trap

x Preface

geochemistry. Because I was involved in the national 1987 to 1991, I developed the petroleum system
resource assessments of undiscovered oil and gas concept and presented these ideas as a poster
and because I realized how difficult it is to incorpo­ session during the 1987 AAPG Annual meeting in
rate geologic information into the assessment Los Angeles, at the 28th International Geological
process, I felt it would be worthwhile to develop a Congress in Washington, D.C., during 1989, and in
scheme that would better serve our purposes. the 1990-1991 AAPG Distinguished Lecture tour.
Because our organization was without reflection Wally Dow and I teamed up to co-convene the
seismic data that could map potential hydrocarbon successful oral session (by the same name as this
traps, we needed a method to evaluate the entire volume) for the 1991 AAPG Annual meeting in
country systematically without seismic data. In Dallas. Over this same time period, I have edited
addition, our geologic staff was much smaller and three U.S. Geological Survey Bulletins on the
less focus than in industry. Obviously, a different petroleum system. During 1992 and 1993, Wally
approach than industry used was needed to get and I have visited many oil companies to acquaint
science into the assessment process. their staffs with the petroleum system concept.
I began by reflecting on the way evaluations The help and support of many people, those
were carried out while I was with Shell and the mentioned above and others, are acknowledged.
way petroleum geology and geochemistry were Ken Bird and George Claypool have always been
being presented in the literature. Through many open and direct in their suggestions and criticisms
discussions with colleagues, it became apparent during the development of the concept. I thank
that basin studies was a catch-all phrase for any Gary Hill and Don Gautier for approving the
type of work relating to sedimentary rocks and USGS petroleum system project so that I could
petroleum and that source rock and migration develop the concept. The authors and co-authors of
studies were poorly defined. In addition, mass every chapter ensured the success of this book by
balance calculations seemed to be the best allowing the editors sufficient latitude to incorpo­
approach to determine the upper limit of rate the petroleum system concept. Zenon Valin is
petroleum available to trap, but it was unclear gratefully acknowledged for his help on proof­
which factors should be included in the mass reading each chapter and with other duties as well.
balance equation. With the problem outlined, I The editors appreciate the reviewers, Gerard
presented the solution in several ways Demaison, Miner Long, John T. Smith, and Peter
In 1986, I circulated internally a brochure about van de Kamp, who read and made valuable
the petroleum system and how it could be used to suggestions that improved the volume. We thank
set up the mass balance equation. That same year, I all those geoscientists who spoke up and criticized
presented a poster session at the Gordon Confer­ the petroleum system concept and made it more
ence on Organic Geochemistry where Wally Dow useful. Lastly, the petroleum system concept will
reminded me that he had already defined such an evolve as more case studies are published, which
"oil system" in 1972 in Denver and that he had will undoubtedly require that the concept be
published it in the AAPG Bulletin in 1974. From continually improved.