Intimate relations: interaction of tectonics and sedimentation in the formation of roller-style fault families and traps in the eastern East Venezuela basin, Trinidad and Venezuela

Wood, L. J., Bureau of Economic Geology, University of Texas at Austin, Austin, Texas

Abstract

The Columbus basin situated along the obliquely converging margins of the Caribbean and South American plates forms the easternmost extension of the East Venezuelan basin and has produced more than 1 BBO of oil since exploration began in the late 1950’s. Subsequent exploration has resulted in the discovery of more than 3.27 billion barrels of oil in place and 20 + TCF of gas in place. It is estimated that an equal amount of resources may lie undiscovered in the Columbus basin, making this area one of the five largest hydrocarbon producing deltaic provinces in the world. The basin can be divided into three structurally based provinces of extensional, monoclinal, and compressional in a relative west to east direction. Each province exhibits its own unique interplay of shale diapirism, regional strike-slip and subregional normal faulting, marine processes, and sediment inputs that control locus’s of accommodation, distribution of reservoir, timing of maturation, and processes of hydrocarbon migration. Shallow marine parasequences 500-700’ thick stack into >8,000’ megasequences forming highly economic stacked-pay scenarios. High accommodation along diapir flanks and in slope-setting saddles results in stacked basin-floor fans >330 m thick having high net to gross sand content. Slope fan/leveed channel complexes >500 m thick comprise multiple stacked, 80–100-m-thick parasequences. Productive sands can be found progressively deeper toward the major growth faults. Fault geometry is strongly tied to the nature of underlying mobile shales and varies along fault strike due to changes in shale thickness, which is controlled in part by the orientation of the paleo-Cretaceous shelf edge. Faults "fan" from southeast to the northwest with each major strand forming a hydrocarbon field.