Abstract: Opon Gas Renews Interest in the Hydrocarbon Prolific Middle Magdalena Basin, Colombia

Denise M. Stone, Robert Elliott, Glenn Latimer, Mark Steuer

A total of 45 fields have been discovered in the Middle Magdelena basin of Colombia since 1918. In August 1994, the Amoco-operated Opon-3 well tested significant hydrocarbons in the basin. The well flowed 45 MMCFGPD and 2000 BCPD from 1118 ft of perforations between 10,018 and 12,348 feet. A second well, Opon-4, tested 58 MMCFGPD from the same interval. Opon now appears to be a significant gas condensate field. A full assessment of commercial potential requires 3D seismic data, as well as further development drilling. Operational challenges include: drilling, coring, logging, cementing and testing in a world-record setting 23 ppg hematite-weighted mud environment involving simultaneous perforation over a 2330 ft gross pay interval and management of high production rates at >8000 ps FwHP.

The Opon structure is a surface anticline on the western edge of the Eastern Cordillera fold and thrust belt. Seismic definition of the trap, however, is complicated by multiple faults, steep dips, rugged topography and variable surface velocities. The main gas reservoirs are fluvial sandstones of the Eocene La Paz Formation sealed by the overlying upper Eocene Las Esmeraldas Formation shales. Individual producing sandstones range from 40 to 200 ft thick in a minimum gross gas column of 4200 ft. Average porosity is 6%. Tectonically induced fractures probably enhance reservoir performance.

AAPG Search and Discovery Article #90951©1996 AAPG International Conference and Exhibition, Caracas, Venezuela