Integration of physical parameters into decompaction during the restoration.

S. Fuet and Benjamin P. Chauvin and Guillaume Caumon. ( 2015 )
in: 35th Gocad Meeting - 2015 RING Meeting, ASGA

Abstract

The decrease of porosity during sediment burial significantly affects the evolution of basin geometry, petrophysics and fluid migration. In 3D restoration (retro-deformation of geological structures), decompaction can be performed sequentially at various restoration time steps [Durand-Riard et al., 2011]. However, as the compaction process is quite complex, performing decompaction requires to know sufficiently well the processes of compaction to be able to model them. Several compaction models exist among which Athy [1930]’s exponential model which is classically used for decompaction. However, this model only depends on depth, hence ignores the possibly complex interplay between the coupled processes governing compaction. The objective of this work is to take into account more physical parameters. For that we choose to use an exponential model of porosity depending on the effective stress instead of z [e.g. Smith, 1971, Schneider et al., 1996, Allen and Allen, 2005]. This allows taking into account the densities of rocks and the upper layers. However, as the effective stress equation has no analytical solution, the porosity is evaluated thanks to a a numerical method. Then the decompaction is evaluated by computing the thickness variation between two restoration time steps with Newton algorithm. The results are compared to the decompaction with Athy’s model. We observe that the porosity loss differs from Athy’s model.

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BibTeX Reference

@INPROCEEDINGS{FuetGM2015,
    author = { Fuet, S. and Chauvin, Benjamin P. and Caumon, Guillaume },
     title = { Integration of physical parameters into decompaction during the restoration. },
 booktitle = { 35th Gocad Meeting - 2015 RING Meeting },
      year = { 2015 },
 publisher = { ASGA },
  abstract = { The decrease of porosity during sediment burial significantly affects the evolution of basin geometry, petrophysics and fluid migration. In 3D restoration (retro-deformation of geological structures), decompaction can be performed sequentially at various restoration time steps [Durand-Riard et al., 2011]. However, as the compaction process is quite complex, performing decompaction requires to know sufficiently well the processes of compaction to be able to model them. Several compaction models exist among which Athy [1930]’s exponential model which is classically used for decompaction. However, this model only depends on depth, hence ignores the possibly complex interplay between the coupled processes governing compaction. The objective of this work is to take into account more physical parameters. For that we choose to use an exponential model of porosity depending on the effective stress instead of z [e.g. Smith, 1971, Schneider et al., 1996, Allen and Allen, 2005]. This allows taking into account the densities of rocks and the upper layers. However, as the effective stress equation has no analytical solution, the porosity is evaluated thanks to a a numerical method. Then the decompaction is evaluated by computing the thickness variation between two restoration time steps with Newton algorithm. The results are compared to the decompaction with Athy’s model. We observe that the porosity loss differs from Athy’s model. }
}