Summary

The Middle Miocene Oficina Formation is the most important producing unit at Quiamare Field. The Oficina Formation consists of a succession of littoral to shallow marine deposits prograding to the north - northeast. The oil-bearing parasequences show typical coarsening- and thickening upward pattern, where foreshore, upper-, middle- and lower-shoreface facies were recognized. Continuous coal seams and associated marsh/coastal plain deposits were interpreted. Flooding surfaces are associated with ravinement surfaces marked by erosion and deposition of transgressive lag deposits. The transgressive lag is constituted by matrix to clast supported conglomerates of underlying shales, siltstones and by chert. Some parasequences display an internal facies shift, where coastal plain facies is flanked landward and basinward by shoreface deposits; this discontinuity of facies tracts is interpreted as lowstand shoreline wedge (forced regression). The mapped parasequences, facies mosaic, and the intrinsic reservoir properties are used to solve the details of reservoir heterogeneity, and the consequent reserve assessment and development plans.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah