Salt Tectonics, Patterns of Basin Fill, and Reservoir Distribution

Howard J. Yorston, A. E. Miles

Salt structures, which develop due to sediment loading, gravity creep, and/or buoyancy, include boundary-fault grabens and half grabens, rollers, anticlines, domes and walls, diapirs, sills, massifs, and compressional toe structures. Associated features include fault systems and turtle structures. Of these, six directly relate to basin fill and all directly influence the distribution of reservoir facies.

Salt structuring is initiated by sedimentation, which in turn is localized by salt withdrawal. Withdrawal produces individual salt structures, migrating sills, dissected massifs, and regional depocenters bordered by salt walls. Composite withdrawals dictate the patterns of basin fill.

Relative rates of structural growth and sedimentation control the distribution of reservoir facies. When growth dominates, sands are channeled into lows. When sedimentation dominates and maintains flat surfaces, facies distribution is not impacted except where faulting develops.

Turtle structures, developed by the inversion of peripheral synclines, can move sands into favorable structural position and/or serve as platforms for carbonate reservoir development.

Salt growth varies with type structure, stage of development, and rate of sedimentation. Sedimentation at a specific location depends on basin position, sediment transport system, sea level stand, and rate of salt withdrawal.

This paper presents techniques for using seismic data to determine the controls on salt structural growth and sedimentation and the patterns of basin fill and reservoir distribution.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.