Modeling High Resolution Sequence Stratigraphy in the Cusiana Field, Eastern Colombia; Static Builds to Dynamic Simulation

Andy Pulham, David MacDonald, and Colin Daly

The Cusiana Field (BP, Ecopetrol, Total and Triton) is located in the Llanos Foothills of Eastern Colombia. The Cusiana reservoirs range from late Cretaceous, passive margin deltaic to early Tertiary, early foreland basin estuarine-fluvial. The key reservoir is the late Eocene Mirador Formation which comprises over 50% of reserves. Currently (October 1995) the Mirador reservoir is providing nearly all of the 180,000 bopd of production from the Cusiana Field.

The Mirador reservoir comprises a stack of incised valley deposits. The fills of the valleys are sandstone-dominated and comprise the majority of the reservoir quality in the reservoir. Critical to an effective understanding of reservoir behavior has been a detailed reservoir description and reservoir modeling of the incised valley stratigraphy in the Mirador.

Models have been constructed using the deterministic information provided by extensive core (3000 feet) coupled with stochastic tools and techniques. Dynamic data, provided by extensive acquisition of production logs during early development drilling, have been integrated within the static descriptions. Important reservoir characteristics such as degree of valley connectivity, intra-valley heterogeneities and textural controls on permeability have been captured in the modeling process. Upscaling of the high resolution static model has preserved the key sequence stratigraphic facets of the reservoir and also incorporated textural controls on relative permeability. Prediction of pressure transient behavior and fluid movement is working well in the full field simulator.

Key software in the modeling and visualization process have been internal BP R&D tools, Stratamodel, Geomatic and in the full field simulator; VIP.

AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California