1887

Abstract

Summary

During burial of sedimentary rocks clay mineralogy of shaly units impact how the rock compact, both mechanically and chemically through shale diagenesis, at the same time also affecting its flow properties. Correspondingly, this also affect how the pressure generation and dissipation evolve through the burial history of the sediments. This study use a basin modelling approach for investigating the effect of smectite-to-illite transition in shales on its permeability and the overpressure development, constrained by the availability of potassium. The study focus on well 6507/5-4 in the Norwegian Sea and hence is limited to 1D simulations and vertical effects. To match measured smectite fractions in Well 6507/5-4, the initial depositional smectite fraction and the availability of potassium have been calculated by inverting a forward, kinetic model of smectite-illite transformation through the well’s burial history. The resulting available potassium is not uniform but seen to be varying in the shaly sections, most likely due to different depositional environments. Monte-Carlo simulations for overpressure modelling was carried out by varying the available potassium. The onset of overpressure is modelled to coincide with the onset of smectite-illite transformation. The available potassium is instrumental for the changing smectite fraction, indirectly controlling pressure dissipation vertically.

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/content/papers/10.3997/2214-4609.2025101425
2025-06-02
2026-03-09

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References

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/content/papers/10.3997/2214-4609.2025101425
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The Effect of Smectite-Illite Transformation on Pressure Build-Up in Sedimentary Basins, Constrained by Availability of Potassium
Conference Proceedings 2025, 1 (2025); https://doi.org/10.3997/2214-4609.2025101425
/content/papers/10.3997/2214-4609.2025101425
/content/papers/10.3997/2214-4609.2025101425
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