PETERSEN, KENNETH, and IAN LERCHE, Department of Geological Sciences, University of South Carolina, Columbia, SC

ABSTRACT: Delineating Salt Dome Growth and Play Development from Observed Present-Day Salt Shapes and Bed Geometries

The geometry of the sedimentary beds above and in the rim synclines of salt structures is commonly attributed to the interactive evolution of salt and sediments. The traditional type of salt structure has often developed primary and secondary rim synclines. The primary rim syncline sediments show thickening away from the salt and sediments may pinch out towards the salt structure, possibly accompanied by erosion of sediments overlying the rising salt. Upon entering the diapiric stage the depositional configuration reverses. Uplifted sediments are exposed to erosion, and sediments in the secondary rim syncline may pinch out towards the salt at the end of the diapiric stage.

The bed geometry undergoes constant deformation as the salt migrates and feeds the growing structure. The strain in the sediments reflects the deformation imposed by the evolving salt structure. Based on the observed present-day salt shape and bed geometries a self-consistent non-linear quantitative model is developed, capable of constraining the possible evolution histories. The model provides estimates of erosion episodes, growth rates, and of the evolving strain distribution in the sediments. Constraints can therefore be put on timing of development of migration pathways, traps, and reservoirs, and on the necessary timing of maturation and migration of hydrocarbons crucial for development of prospective hydrocarbon plays. Applications to salt structures from the North Sea area demo strate the model procedure.

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