1887

Abstract

Summary

The Itapema and Barra Velha formations are key carbonate reservoirs in the Pre-Salt section of Brazil’s Santos Basin. However, distinguishing the contact between these units during drilling operations is challenging due to the lack of clear diagnostic features in well logs and the fragmentary nature of cutting samples. This study introduces a geochemical approach using real-time X-ray fluorescence (XRF) analysis of calcium and strontium (Ca-Sr) in cutting samples to identify the Pré-Alagoas Unconformity, which separates the two formations. Results from 20 wells show that in 13 cases, the contact could be recognized by the divergence of Ca and Sr curves, with Sr levels increasing above the unconformity. This geochemical pattern reflects changes in paleoenvironmental conditions, notably increased salinity during the deposition of the Barra Velha Formation. The method’s reliability is enhanced by the integration of XRF with X-ray diffraction (XRD) analyses, although it may be affected by diagenetic processes such as dolomitization or contamination by barite. The Ca-Sr technique proves to be a useful, real-time tool for stratigraphic identification during drilling operations in Pre-Salt carbonates.

© EAGE Publications BV
Loading

Article metrics loading...

/content/papers/10.3997/2214-4609.202535006
2025-11-12
2026-01-19

  • From This Site

    /content/papers/10.3997/2214-4609.202535006
    dcterms_title,dcterms_subject,pub_keyword
    -contentType:Journal -contentType:Contributor -contentType:Concept -contentType:Institution
    10
    5
Loading full text...

Full text loading...

References

  1. Chivas, A. R., De Deckker, P., Shelley, J. M. G. [1985]. Strontium content of ostracods indicates lacustrine palaeosalinity. Nature, 316 (6025), 251–253.
     [Google Scholar]
  2. Leite, C.de O. N., Assis Silva, C. M. de, De Ros, L. F., [2020]. Depositional and diagenetic processes in the Pre-Salt rift section of a Santos Basin area, SE Brazil. Journal of Sedimentary Research, 90, 584–608. DOI: http://dx.doi.org/10.2110.jsr.2020.27.
     [Google Scholar]
  3. Moreira, J. L. P., Madeira, C. V., Gil, J. A., Machado, M.A.P. [2007]. Bacia de Santos. Boletim de Geociências da Petrobras, 15 (2), p. 531–549.
     [Google Scholar]
  4. Netto, P. R., Pozo, M., da Silva, M. D., Gomes, M. E. B., Mexias, A., Ramnani, C. W., & Rios-Netto, A. D. M. [2022a]. Paleoenvironmental implications of authigenic magnesian clay formation sequences in the Barra Velha Formation (Santos Basin, Brazil). Minerals, 12 (2), 200.
     [Google Scholar]
  5. Oliveira, F. V. C. S. R. S., Gomes, R.T.M., Roriz, C. E.D., Silva, K.M.S., & Toledo, R.C. [2022b]. Lithology Identification Through X-Ray Fluorescence (XRF) Analyses on Drill Cuttings While Drilling, in Santos Basin. In SPE Annual Technical Conference and Exhibition (p. D021S027R005). SPE.
     [Google Scholar]
  6. Rollinson, H. R., Rollinson, H., Pease, V. [2021]. Using geochemical data: to understand geological processes. Cambridge University Press.
     [Google Scholar]
/content/papers/10.3997/2214-4609.202535006
Loading
The Calcium-Strontium Signature: An Applied Method for Identifying the Pre-Alagoas Unconformity in Santos Basin, Brazil
Conference Proceedings 2025, 1 (2025); https://doi.org/10.3997/2214-4609.202535006
/content/papers/10.3997/2214-4609.202535006
/content/papers/10.3997/2214-4609.202535006
Loading

Data & Media loading...

Most Cited This Month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error