GAY, S. PARKER, Jr., Applied Geophysics, Inc., Salt Lake City, UT

ABSTRACT: Basement Control of Oil and Gas Traps: More Common Than We Thought?

Applied Geophysics, Inc., has been mapping basement structure in sedimentary basins for petroleum companies since 1982 using high resolution aeromagnetic methods and a newly developed processing technique called NewMag(R). In that time we have mapped 680,000 square kilometers in 18 petroleum basins scattered throughout the United States. Careful comparison of the basement data with hundreds of detailed subsurface and Seismic maps, coupled with studies of outcropping basement rocks, has led to the concept of the "basement fault block pattern." This is not a new concept, however, having been espoused in the 1930s and 1940s by European geologists, most notably Hans Cloos.

For this presentation we have classified oil and gas traps controlled by basement into 20 categories, and will show actual field examples of most of them. Of these 20 categories of traps, 12 result from fault movement along basement block boundaries and 8 from gravitational compaction of the sedimentary section over basement topography. Additionally, 12 of the 19 categories are considered to be "purely stratigraphic" in origin, but their relationship to basement is easily demonstrated. In another classification scheme developed by Hyne in 1984 as a wall chart, 20 of his 29 types of traps can be due to basement control under the proper geological circumstances.

Our work thus indicates that basement control of oil and gas is much more common than has heretofore been realized. Consequently, petroleum companies using basement concepts and basement mapping techniques will be more successful in finding hydrocarbons, and have lower finding costs, than those that do not.

AAPG Search and Discovery Article #90987©1993 AAPG Annual Convention, New Orleans, Louisiana, April 25-28, 1993.