Discovery of Cano Limon Field, Llanos Basin, Colombia

Charles N. McCollough

After 40 years of sporadic exploration that yielded negative or marginal results, the Llanos basin of eastern Colombia was thrust to the forefront of world attention by the discovery of the supergiant Cano Limon field in July 1983. This discovery culminated an intensive 3-year exploration effort by Occidental involving 4,000 km of dynamite seismic, 20 stratigraphic tests from 1,300 to 3,500 ft deep, and 13 exploratory wells. Cost prior to discovery was $45 million.

The Llanos is an oily basin with abundant excellent reservoir sands. The problem has been to define traps. The basin deep lies along the foot of the eastern Cordillera, from which a sediment thickness of 30,000 ft thins gradually to the east on a homoclinal flank terminating at the Guyana shield. Except for the very young folding along the Andean front, structural traps are generally sparse and subtle.

An exception is the Cano Limon area, which is dominated by major early Tertiary northeast-southwest strike-slip faulting. Concurrent folding and fault sealing formed Cano Limon and other smaller fields.

The Cano Limon field with its other half, the Guafita field in Venezuela, contains an estimated initial potential of 3,160 million bbl of oil, of which about 1,460 million bbl is expected to be recovered. The bulk of the oil is in deltaic sands of the Eocene Mirador with additional reservoirs in the Upper Cretaceous and the Oligocene Carbonera Formation. Average porosity of the Mirador is 24%, permeability is 5.3 darcys, and water saturation is 23%. Initial flow rates are in the 10,000 BOPD range, with some wells having produced at rates over 20,000 BOPD.

AAPG Search and Discovery Article #91030©1988 AAPG Annual Convention, Houston, Texas, 20-23 March 1988.