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Abstract: Cusiana Trend Exploration, Llanos Foothills thrustbelt Colombia - The Opening of a New Hydrocarbon Province

Anthony B. Hayward, Fergus T. Addison, German Espinosa

The Cusiana discovery in 1991 followed 30 years of exploration in the Llanos foothills. Wells drilled in the early 1960's on large surface anticlines encountered residual oil accumulations in structures that had been flushed by along strike exposure of the major reservoir horizons. A second period of exploration activity in the early 1970's failed through a consequence of drilling technology and seismic data quality.

The Cusiana 2A well completed at the end of 1991 proved the existence of a 1500' hydrocarbon column in a structure 25 km long and 5-6 k across. Reserves in Cusiana are estimated at 1.5 BN BBLS and several TCF of gas. The Cusiana discovery opened the way for a concentrated exploration effort in the Llanos foothills. The subsequent Cupiagua discovery (500 mmstb) made in 1993 and the Volcanera discovery (5TCF, 250 mmstb) in 1994 have demonstrated the continuation of the trend northwards.

Within the trend there are two discrete structural trapping geometries Cusiana and Volcanera are thick-skinned basement involved structures related to the late Miocene reactivation of pre-existing Cretaceous extensional faults. The Cupiagua structural trend is a series of thin-skinned thrust sheets that have been displaced up to 10 km from the west.

Key to successful exploration has been the effective imaging of hydrocarbon trapping geometries brought about through a significant improvement in seismic acquisition and processing technology.

AAPG Search and Discovery Article #90956©1995 AAPG International Convention and Exposition Meeting, Nice, France