--> The Sedimentology and Stratigraphy of the Early Tertiary, Cusiana Field, Colombia, by A. Pulham; #90986 (1994).

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Abstract: The Sedimentology and Stratigraphy of the Early Tertiary, Cusiana Field, Colombia

Andy Pulham

The Cusiana field (British Petroleum, Ecopetrol, Total and Triton) is located in the Llanos Foothills, Eastern Colombia and is presently in an early phase of development following an aggressive appraisal program in 1992/93. The Cusiana reservoirs span Santonian to Oligocene in age. Early Tertiary reservoirs range in age from late Palaeocene to earliest Oligocene and comprise the basal part of a foreland basin megasequence. Depositional environments within the Early Tertiary reservoirs range from alluvial to nearshore marine.

Deposition took place on the distal fringes of the evolving foreland basin remote from the mountain front. Sediment supply was dominantly extrabasinal. Under these circumstances rates of sediment input to the basin are likely to have been somewhat independent of the foreland basin tectonics and relative sea level changes are likely to have generated Type 1 rather than Type 2 sequence boundaries. The evidence from over 3000 feet of conventional core and 10 comprehensively logged wells points to a highly punctuated stratigraphy with the major productive reservoir zones linked to intervals of closely-spaced high order sequence boundaries (lowstand sequence sets) during periods of major transgression across the basin margin.

Both lithostratigraphic and sequence stratigraphic techniques have been used to describe the Lower Tertiary Cusiana reservoirs. An evaluation of the value of each method will be made and their implications to early field development.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994