Paul Mann¹, Lisa Gahagan², Mark B. Gordon³

(1) Institute for Geophysics, University of Texas at Austin, Austin, TX
(2) Institute for Geophysics, University of Texas at Austin
(3) GX Technology, Houston, TX

ABSTRACT: Classification of the Tectonic Setting of the World's Giant Oil Fields

The world's 595 giant oil fields are those with 500 million bbl of ultimately recoverable oil or gas equivalent. We present a digital compilation and classification of the tectonic setting of these fields using six classes of tectonic setting: 1) continental rifts and overlying "steer's head" sag basins (263 giants); 2) collisional margins produced by the terminal collision between two continents (141); 3) continental passive margins fronting major ocean basins (99); 4) collisional margins produced by the overthrusting on an arc onto a passive margin (44); 5) strike-slip margins (42); and 6) subduction margins not affected by major arc or continental collisions (6). For giant fields with multi-phase histories, we have attempted to identify the tectonic setting we consider to have the most profound effect on hydrocarbon formation, migration, and trapping. Continental rifts and overlying "steer's head" sag basins form the dominant tectonic setting that includes 44% of all the world's giant fields. Terminal collisional belts between two continents form a distant second setting with 24% of oil giants. Continental passive margins fronting major ocean basins are third place with 17% of giants. Other setting classes are relatively insignificant with 7% or less of the total basin population. Our result differs significantly from previous giant classifications where collisional settings form the dominant tectonic setting for oil giants. We outline several possibilities for this discrepancy and point out trends in the tectonic setting of recently discovered giant oil fields that might be useful for exploration in the 21st century.

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