Outcrop Analogs: Adding Value to Reservoir Characterization and Modeling

Jeroen Kenter¹ and Mitch Harris^2
1Chevron ETC, Voorburg, Netherlands
²Chevron ETC, San Ramon, CA

Digital models of key outcrops of (exceptionally well exposed, continuous and structurally intact) end-member carbonate systems provide exact and quantitative information on spatial sedimentary lithofacies trends and juxtaposition rules as well as associated stratal anatomy, properties in the subsurface that are typically unknown and can only be guessed at.

Outcrop studies at Djebel Bou Dahar, Morocco, yield insight into facies and stratigraphy for the platform top and steep slopes of an isolated carbonate platform, 34 by 6 km, that serves as an analog for reservoirs in the Caspian Basin and elsewhere. Themes are the extensional tectonic setting, relatively minor role of eustatic sea level on sedimentation, a shallow platform dominated by tidal flat deposits, the evolution from ramp to flat topped platform and retrograding margin with allochtonous deposition and extensive syndepositional fracturing.

Amellago is a high-quality outcrop of an early Jurassic ramp system nearly 35 km in dip direction that is an analog for Mesozoic to Tertiary carbonate ramp reservoirs, particularly in the Middle East. Amellago is an alternating ooid (lowstand) - and mud (highstand) dominated ramp showing the interaction of both eustacy and tectonics.

Field observations combined with satellite imagery and LIDAR were used to capture lithofacies patterns and stratal architecture. Final (interpreted) products following the isolated platform and ramp studies are a digital catalog with spatial data on grand-scale and smaller (reservoir) scale, lithofacies elements and stratal anatomy of two key carbonate settings. The resulting models can be queried and contrasted/compared with subsurface carbonate reservoirs to provide solutions and/or alternatives.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery