Understanding of Heterogeneity Effects in Fluid Flow Impacts, Cusiana Field Management

Luis Enrique Soto
BP, Bogota, Colombia

Cusiana is a large volatile oil field with a rich condensate gas cap. The oil-bearing sandstones are Tertiary and Cretaceous in a thrust folded anticline and have been developed through gas cycling and waterflood schemes.

3D Seismic, over 70 wells, 10 years of production history and outcrop studies have provided a broad set of static and dynamic data that have been integrated to understand reservoir heterogeneity at different scales enabling the reduction of the production decline by means of a new gas and water injection strategies.

The integration of petrography, sedimentology, stratigraphy, structural geology and innovative passive seismic data in Cusiana Field have allowed the development of a robust reservoir heterogeneity model from pore scale to structure scale, that satisfactorily explains the production history characterized by very high oil production rates with adverse early water and gas breakthrough.

Static and dynamic models capturing appropriate levels of heterogeneity were developed for the Cusiana Field improving dynamic model history match and helping in a better understanding of wellwork design and performance.

These new models clarified the impact of reservoir heterogeneity in sweep efficiency so that a new strategy of gas and water injection was designed and is currently being implemented. Recent observations indicate a reduction in the base production decline from 4.7% in early 2003 to 3.5 % by late 2004, and it is expected higher benefits next years.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005