Stacy A. Smith1, Chris Whitefield2
(1) Texaco Worldwide Exploration, Bellaire, TX
(2) Independent Geologist, New Braunfels, TX
ABSTRACT: Structural Restorations in the "Mensa" / "Crazyhorse" Area of Mississippi Canyon, Northern Gulf of Mexico
Three dimensional structural restoration models of a regional area in the Mississippi Canyon protraction covering the "Mensa" / "Crazy Horse" discoveries conceptually document the slope mini-basin development of different generations of turtle structures and the concurrent movement of autocthonous salt into stock piercements and partially coalesced salt tongues. An interpretation of a 1,215 square mile data set of 3-D seismic was used to generate a sequentially restored structural framework. In this region, the Jurassic Louann Salt has been initially mobilized to form primary basins and first generation allochthonous salt bodies. Later stages of Louann Salt evacuation coincides with the formation of younger turtle structures. This structural style is similar to other areas in the Lower Slope of the Northern Gulf of Mexico documented by others.
Time step models of this study area illustrate several important relationships that include: 1) current structural trends are probably related to inherited pre-salt structures and initial salt thickness; 2) northeast-southwest trending salt antiforms began developing between thickening depo-pods of upper Jurassic to lower Cretaceous source rock and sediments; 3) avulsing sequences of Oligocene-Miocene sediments spilled onto portions of the salt antiforms and initiated new turtle folding; and 4) structures in the study area have evolved subtly through time; however, until only recently (~5Ma) did some of the significant hydrocarbon-bearing structures close into trapping configuration.
Synthesizing the structural restorations into the context of basin analysis helps discern the risk associated with different turtle plays. Structural restorations help explorationists visualize the dynamics of the evolving basin architecture as well as focus on questions regarding the timing of trap, seal, hydrocarbon generation, and migration.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado