Quantitative biostratigraphy for the Cuervos Formation (Paleocene) of the Llanos foothills, Colombia: Improving palynological resolution for oil exploration
Published:January 01, 2005
C. A. Jaramillo, F. Muñoz, M. Cogollo, F. De La Parra, 2005. "Quantitative biostratigraphy for the Cuervos Formation (Paleocene) of the Llanos foothills, Colombia: Improving palynological resolution for oil exploration", Recent Developments in Applied Biostratigraphy, A. J. Powell, J. B. Riding
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Oil exploration in Colombia has traditionally taken place in areas with relatively few structural complexities. However, in the last decade, exploration has moved to regions characterized by complex structural deformation, poor seismic resolution, and many stratigraphic problems, such as in the Llanos foothills. In this region, the major reservoirs occur in mostly continental Paleogene sequences, where palynomorphs are usually the only fossil group found. Thus, palynology has become an important tool in controlling the stratigraphic position of a well during drilling, in testing diverse seismic and structural interpretations, and correlating reservoirs. This study provides a biostratigraphic framework for the Cuervos Formation (Late Paleocene to earliest Eocene) of the Llanos and Llanos foothills, making use of graphic correlation. We used 14 sections with palynological information from outcrops, well cores, and well ditch cuttings. Five informal palynological zones are proposed. Based on the biostratigraphic model produced by this analysis, we reinterpreted a recently drilled well in the Llanos foothills upon which several previous interpretations had been made. A sidetrack of that well was subsequently drilled, validating the proposed model. This is a positive test that the biostratigraphic framework developed for the Cuervos Formation is reliable and can be successfully applied to exploration in the Llanos foothills.
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Recent Developments in Applied Biostratigraphy
In recent years the application of biostratigraphy to hydrocarbon exploration and development has become increasingly important both scientifically and economically. The demand for higher stratigraphical resolution in field development studies has resulted in the utilization of new approaches. However, in under-explored areas with little reliable primary biostratigraphical data, conventional methods using relatively coarse biozonations still have relevance. The aim of this volume is to encourage an exchange of ideas and to seed new research initiatives particularly within integrated multidisciplinary teams. The papers are divided into four main themes which cover a broad range of modern applications of biostratigraphy. The first three themes are: UK North Sea field development; outcrop analogues; and international exploration and development. The final section discusses new methodologies, such as the application of correspondence analysis and multivariate correlation of wells, and palynological processing techniques applicable to the wellsite.