Indexing
All Issues
Submission
Author Guidelines
Reviewers
Editorial Members
Publication Fee
Vol.2 , No. 3, Publication Date: Apr. 25, 2015, Page: 29-38
 in the Namorado oil field of the Campos basin, in the southeastern continental margin of Brazil. The methodology adopted makes use of an optimization program based on simplex algorithm in inverting results of gamma and density logs for determinations of radioelements and radiogenic heat production. Successful application of the method has been verified using both synthetic and real data. Test runs with synthetic data are found to provide results within 95% confidence level. Tests with real indicated agreement within the limits of experimental uncertainty. Analysis of results for Namorado oil field have allowed identification of characteristic features in the vertical and lateral distributions of radioactive elements. Most of the sand and shale sequences in this oil field area are characterized by relatively low concentrations of uranium, generally in the range of 0.5 to 5ppm. On the other hand, concentrations of thorium are found to be relatively high, with values generally in the range of 2 to 10 pm. Potassium abundances are found to fall in the normal range of 1 to 8%. Maps of the spatial distributions of radioelement abundances and radiogenic heat indicate the presence of sinuous belts that are nearly coincident with the trajectories of turbidity currents inferred in geologic studies. It is proposed that the method of the present work may be used to map migration trends of radionuclides during subsidence history of continental margins.&picture=http://www.aascit.org/aascit/decorators/img/journal/899.jpg)
| [1] | Eara de Souza Luz Oliveira, Observatório Nacional, Rio de Janeiro, Brazil. |
| [2] | Valiya M. Hamza, Observatório Nacional, Rio de Janeiro, Brazil. |
Results of natural gamma logs in 39 deep wells have been used for estimating distributions of radioelements (Uranium, Thorium and Potassium) in the Namorado oil field of the Campos basin, in the southeastern continental margin of Brazil. The methodology adopted makes use of an optimization program based on simplex algorithm in inverting results of gamma and density logs for determinations of radioelements and radiogenic heat production. Successful application of the method has been verified using both synthetic and real data. Test runs with synthetic data are found to provide results within 95% confidence level. Tests with real indicated agreement within the limits of experimental uncertainty. Analysis of results for Namorado oil field have allowed identification of characteristic features in the vertical and lateral distributions of radioactive elements. Most of the sand and shale sequences in this oil field area are characterized by relatively low concentrations of uranium, generally in the range of 0.5 to 5ppm. On the other hand, concentrations of thorium are found to be relatively high, with values generally in the range of 2 to 10 pm. Potassium abundances are found to fall in the normal range of 1 to 8%. Maps of the spatial distributions of radioelement abundances and radiogenic heat indicate the presence of sinuous belts that are nearly coincident with the trajectories of turbidity currents inferred in geologic studies. It is proposed that the method of the present work may be used to map migration trends of radionuclides during subsidence history of continental margins.
Keywords
Natural Gamma Ray Logs, Radioelement Abundances, Namorado Oil Field, Turbidity Channels, Campos Basin, Brazil
Reference
| [01] | Belknap, W.B., Dewan, J.T. Kirkpatricl, C.V., Mott, W.E., Pearson, A.J., and Rabson, W.R.(1959). “API calibration facility for nuclear logs: in Drilling and Production Practice”. American Petroleum Institute, Houston: pp. 289-317. |
| [02] | Dantzig, G.B., Orden, A., Wolfe, P. (1955).“Generalized Method Simplex for Minimizing a Linear from Under Inequality restraints”. Pacific Journal Math., 5: 183-95. |
| [03] | [3} Borgui, L. (2000). “Visão Geral da Análise de Fácies Sedimentares do Ponto de Vista da Arquitetura Deposicional”. Boletim do Museu Nacional, N.S., Geol., Rio de Janeiro, 53: 1-26. |
| [04] | Bacoccoli, G. Moraes, R.G. & Campos, O.A.J. (1980). “The Namorado Oil Field: A Major Oil Discovery in the Campos Basin, Brazil” In: Giant Oil and Gas Fields of the Decade: 1968-1978. Tulsa: American Association of Petroleum Geologist Memoir, 30: 329-38. |
| [05] | Souza, Jr., O.G. (1997). “Stratigraphie Séquentielleet Modelisation Probabiliste des Reservoirs d’un Cône Sous-Marin Profond (Champ de Namorado, Brésil). Integration des Données Géologiqueset Géophisiques”. Ph. D. Thèse, Université Pierre et Marie Curie, 215 p. |
| [06] | Menezes, S.X. (1990). “Modelo Hidrológico do Campo de Namorado”. Internal Report, PETROBRAS/DEPEX/DIRSUL. |
| [07] | Augusto, F. O. A.(2009). “Mapas de Amplitude Sísmica para Incidência Normal no Reservatório Namorado, Bacia de Campos”. UnpublishedM.Sc. Thesis, Observatorio Nacional, Rio de Janeiro, RJ. |
| [08] | Barboza, G.E.(2005). “Análise Estratigráfica do Campo de Namorado (Bacia de Campos) com base na Interpretação Sísmica Tridimensional”. Unpublished Ph.D. Thesis, UFRGS. RS. |
| [09] | Murty, K.G. (1983)“Linear programming”, John Wiley &Sons Inc., New York: 482 pp |
| [10] | MATLAB (200) “Version 8”. The MathWorks Inc., Natick, MA. |
| [11] | Rybach, L. (1986) “Amount and significance of radioactive heat sources in sediments”: in Thermal Modeling in Sedimentary Basins, J.Burus (Ed) Editions Technip, Paris, 311 - 22. |
| [12] | Bucker, C; Rybach, L. (1996). “A simple method to determine heat production from gamma-ray logs”. Marine and Petroleum Geology, 13(4):373-75. |
| [13] | Wahl, L. S. (1983). “Gamma-ray logging”. Geophysics. 48:1536 – 50. |
| [14] | Schlumberger, (2014).http://www.apps.slb.com/cmd/mineral.aspx, September 2015. |
| [15] | Oliveira, E.S.L., Martins, J.L. (2011). “Modeling and Inversion of Gamma-Ray Logs: Estimation of Radionuclide Concentrations”. Proceedings, 12th International Congress of the Brazilian Geophysical Society, Rio de Janeiro, Brazil |
| [16] | Reyes, L. M.G.(2008).“Distribuição vertical da taxa volumétrica de produção de calor radiogênico no Cráton do São Francisco”. Unpublished Ph.D. Thesis, Institute of Geosciences, UFBA, Salvador. |
| [17] | Sapucaia, N.S., Argollo, R.M., Barbosa, J.S.F. (2005). “Teores de Potássio, Urânio, Tório e taxa de produção de calor radiogênico no embasamento adjacente às bacias sedimentares de Camamu e Almada, Bahia, Brasil”. Rev. Bras. Geof. 453-75. |
| [18] | Magalhães, M. F., Martins, J.L. (2012). "Petrophysical Model for Bulk Density of Complex Lithologies" Brazilian Journal of Geophysics, 30(1): 63-79. |
