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Graphic Previous HitCorrelationNext Hit of Biostratigraphic Data as a Powerful Tool for Previous HitOilNext Hit Exploration in Frontier Deepwater Areas: A Previous HitCaseNext Hit Study in the Brazilian Equatorial Margin*

 

Jorge De Jesus Picanço De Figueiredo1, Emilson Fernandes Soares1, Ivo Trosdtorf, Jr.1, João Luiz Caldeira1, Paulus Hendrikus Van Der Ven1, and Elizabete Pedrão Ferreira1

 

Search and Discovery Article #50190 (2009)

Posted June 3, 2009

 

*Adapted from extended abstract prepared for AAPG International Conference and Exhibition, Cape Town, South Africa.

 

1 Petrobras S.A., Rio de Janeiro, RJ, Brazil ([email protected], [email protected])

 

Introduction

Exploration in offshore basins in the Brazilian Equatorial Margin faces a serious problem of lack of well data in deep waters. Despite the good quality of 3-D seismic over deepwater prospects, the response of seismic to the presence, distribution and quality of reservoirs is uncertain, thus precluding confident Previous HitcorrelationNext Hit between wells in the shallow platform with the deep offshore extensions.

The margin consists of six basins (from SE to NW: Potiguar, Ceará, Piauí-Camocim, Barreirinhas, Pará-Maranhão and Foz do Amazonas) straddling over 2000 km of coastline and only six deep water wells (Figure 1).

To mitigate exploration risk it is necessary to establish a reliable chronostratigraphic framework using the geological data to construct the highest possible frequency geological events charts. The recognition of variations in relative sea levels with geological time is a basic necessity, once these events can be correlated to sequence boundaries in the seismic over deepwater prospects.

 

 

 

uIntroduction

uFigures

uMethodology

uBarreirinhas Previous HitbasinNext Hit

uReferences

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

uIntroduction

uFigures

uMethodology

uBarreirinhas Previous HitbasinNext Hit

uReferences

 

Figure Captions

Figure 1. Localization map of basins of the Brazilian Equatorial Margin.

Figure 2. Graphic Previous HitcorrelationNext Hit of biostratigraphic data of onshore and offshore wells from Barreirinhas Previous HitBasinNext Hit. Biostratigraphic hiatuses can be interpreted as sequence boundaries.

Figure 3. Old and new stratigraphic chart (only drift sequence) of the Barreirinhas Previous HitBasinNext Hit. Abbreviations: PER - Periá Formation, BON - Bonfim Formation, PRE – Preguiças Formation, ARE – Areinhas Formation, TRA – Travosas Formation, ISA – Ilha de Santana Formation, PIR – Pirabas Formation, BAR – Barreiras Formation. Modified from Feijó (1994) and Trosdtorf Jr. et al. (in press).

Methodology

The methodology consists of graphic correlations of biostratigraphic zonation of wells in the shallow areas (Wescott et al., 1988; Neal et al., 1998; Aubry et al., 1995; Figure 2). A crossplot of biostratigraphic data on the X-axis, plotted against depth on the Y-axis was built for each well taking into account: a) its position in the Previous HitbasinNext Hit; b) the density of data; and c) the confidence of the data. These were integrated with the global eustatic sea level chart and available seismic data, resulting in the recognition of many unconformities that reflect the main sequence boundaries of each Previous HitbasinNext Hit.

Previous HitCaseNext Hit Study – Barreirinhas Previous HitBasinNext Hit

A Previous HitcaseNext Hit study of the Barreirinhas Previous HitbasinNext Hit is presented. Results revealed the power of this methodology in establishing the sequence stratigraphy for shallow and deep waters, and in detecting sequence boundaries correlative to significant sea level falls (reservoir prediction). Ten major events of fall-rise relative sea level were identified against only three events recognized in earlier works (Figure 3).

References

Aubry, M.P., 1995, From chronology to stratigraphy: interpreting the lower and middle Eocene stratigraphic record in the Atlantic Ocean, in Geochronology Time Scale and Global Stratigraphic Previous HitCorrelationNext Hit: SEPM Special Publication 54, p. 213-274.

Feijó, F.J., 1994, Bacia de Barreirinhas: Boletim de Geociências da Petrobras, v. 8 (1), p. 103-105.

Neal, J.E., Stein, J.A., and Gamber, J.H., 1998, Nested stratigraphic cycles and depositional systems of the Paleogene Central North Sea, in Mesozoic and Cenozoic Sequence Stratigraphy of European Basins: SEPM Special Publication 60, p. 261-288.

Trosdtorf, Jr., I.; Zalán, P.V., Figueiredo, J.J.P. de; Soares, E.F., in press, Bacia de Barreirinhas:. Boletim de Geociências da Petrobras.

Wescott, W.A., Krebs, W.N., Sikora, P.J., Boucher, P. J., and Stein, J. A., 1998, Modern application of biostratigraphy in exploration and production: The Leading Edge, v. 17, p. 1204-1210.

 

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