Wireline logs vs drilling events: Which one to believe in implying subsurface pressure?

Agus Mochamad Ramdhan; Arifin Arifin; Rusmawan Suwarman

doi:10.14203/risetgeotam2021.v31.1176

Wireline logs vs drilling events: Which one to believe in implying subsurface pressure?

Agus Mochamad Ramdhan, Arifin Arifin, Rusmawan Suwarman

Abstract

As generally known, subsurface pressure can be implied using both wireline logs and drilling events. However, there may be a case where wireline logs and drilling events do not indicate the same subsurface pressure. Data from four vertical wells located in the South Sumatra Basin, Indonesia, were analyzed as a case study. Two wells, Wells A and D, encountered high overpressured zones, confirmed by drilling events and wireline logs data. The two others, Wells B and C, only encountered low overpressured zones, inferred by the relatively low mudweight used during the drilling. However, the wireline logs of Wells B and C show a reversal as Wells A and D. There are two hypotheses to explain the condition in Wells B and C. First, the wireline logs reversal is due to shallow carbonate cementation. Second, Wells B and C were drilled in an unintentional underbalanced condition. The method used includes XRD, SEM, and titration analysis. The results show that the first hypothesis is false, while the second is true. It may be due to some missing information related to drilling events in the final well report of Wells B and C.

Keywords

subsurface pressure, wireline logs, drilling events, South Sumatra Basin

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References

Eberli, G. P., Baechle, G. T., Anselmetti, F. S., & Incze, M. L. (2003). Factors controlling elastic properties in carbonate sediments and rocks. Leading Edge (Tulsa, OK), 22(7), 654–660. https://doi.org/10.1190/1.1599691

Heidrick, T. L., & Aulia, K. (1993). A structural and tectonic model of the coastal plains block, Central Sumatra Basin, Indonesia. Proc. Indonesian Petroleum Association, 22nd Annual Convention.

Kamal, A., Argakoesoemah, R. M. I., & Solichin. (2008). A proposed basin scale lithostratigraphy for South Sumatra Basin. IAGI Special Publication, Sumatra Stratigraphy Workshop, Riau.

Pertamina BPPKA. (1997). Petroleum Geology of Indonesia Basins: Principles, Methods, and Applications, Vol. X South Sumatra Basins.

Ramdhan, A. M., Ardjuna, A., Syafriya, A., Hutasoit, L. M., & Goulty, N. R. (2018). Pore pressure regime in the South Sumatra Basin, Indonesia. 80th EAGE Conference and Exhibition 2018: Opportunities Presented by the Energy Transition, 2018(1), 1–5. https://doi.org/10.3997/2214-4609.201801332

Ramdhan, A. M., Hutasoit, L. M., & Slameto, E. (2018). Lateral reservoir drainage in some Indonesia’s sedimentary basins and its implication to hydrodynamic trapping. Indonesian Journal on Geoscience, 5(1), 65–80. https://doi.org/10.17014/ijog.5.1.65-80

Syaiful, M., Hutasoit, L. M., Ramdhan, A. M., & Widayat, A. H. (2020). Wireline log responses, mudweight, clay mineralogy, and implied overpressure condition: Insights from Aru field, North Sumatra Basin. Indonesian Journal on Geoscience, 7(2), 105–119. https://doi.org/10.17014/ijog.7.2.105-119

Syukri, I. Y., Permana, B. R., Heppard, P. D., Ramdhan, A. M., & Hutasoit, L. M. (2019). Pore Pressure Analysis in the Corridor Block, South Sumatra Basin: Distribution, Mechanism, and Prediction. Proc. Indonesian Petroleum Association, 43rd Annual Convention.

DOI: http://dx.doi.org/10.14203/risetgeotam2021.v31.1176