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Key Exploration Uncertainties and the Petroleum Potential of the Deepwater Caribbean Offshore Colombia

Brian R. Frost
International Exploration New Ventures, Anadarko Petroleum Corporation

Abstract

The Magdalena River and its tributaries drain an area covering over 400,000 km2. From its headwaters in the south, it travels 1000 km. north and flows into the Caribbean near Cartagena. It carries mixed volcanic, basement, and reworked clastic sediments derived from mountains as high as 5,200m and deposits them into the offshore Colombia basin at a water depth in excess of 4000m below sea level. From Miocene to present, the river has built a delta and deep-water fan that covers an area of 180,000 km² and is up to 16 km thick.

Numerous onshore oil and gas seeps and mud volcanoes are present throughout the area. Offshore seabed fluid expulsion features are common and deep-water piston coring is reported to have turned up good evidence of oil and gas seepage. Numerous onshore and near shore wells have encountered oil and gas shows but to date only modest size oil and gas accumulation have been found onshore and only one sizable gas field called Chuchupa-Ballena (~5 TCF) has been found in shallow water near the coastline.

A probabilistic approach was used to assess the predicted resource range of the deep-water Western Caribbean play. Sparse 2D can be tied back to a DSDP well 200 kms offshore that shows some Cretaceous source rock potential. The wide range of uncertainty in reservoir potential and trap definition, plus unknown likely hydrocarbon type precluded using a deterministic assessment. DHIs seen on the seismic data suggest potential trap size and reservoir volumes could be huge and these data were used to determine a P01 field size for the play. A log-normal distribution for the number of potential leads was generated by looking at seismic control, existing leads and extrapolating an expected P01 number.

A total of 28 near-shore (< 50km) shallow water exploration wells and only one deep-water well in 541m wd have been drilled in offshore Caribbean Colombia over an area covering 25,000 km². A totally untested area of over 100,000 km² is present down-dip in water depths ranging from 550-4000 m. The drilling history and exploration results for the area are very similar to East Africa prior to 2009. It is our hope the Deepwater Caribbean Offshore Colombia will have similar post-2009 success. What the area needs now is more seismic coverage and wells.

AAPG Search and Discovery Article #90203 © AAPG Geoscience Technology Workshop, Trinidad and Tobago Deep Horizon and Deep Water Frontier Exploration in Latin America and the Caribbean, March 9-11, 2014, Port of Spain, Trinidad