Approach to model and predict facies-texture-porosity interdependence in a partially dolomitised Lower Cretaceous platform (Basque Cantabrian Basin, Spain).

Abstract : The quality evolution of carbonate reservoirs may strongly depend on depositional environrnents and associated facies with their intrinsic textures and primary mineralogy. These syn-sedimentary parameters may induce different early diagenetic evolutionary paths, which in tum are commonly reflected in the distribution of burial diagenetic overprints. This study contributes to the growing need in developing modelling approaches which take into account the interplay between syn-sedimentary features and subsequent diagenetic events, in order to better predict the overall distribution of reservoir heterogeneities. The present contribution illustrates a complete modelling workflow on a partially dolomitised carbonate platform: from field and sub-surface data acquisition (stratigraphie logs and facies analysis) to the construction of a geometrical model and from statistical characterization of sedimentary and diagenetic constraints (using a log processing tool for well data treatment) to their geostatistical modelling (using advanced geological property grid algorithrns). The case-study consists of a Lower Cretaceous shallow carbonate platform from the Basque Cantabrian Basin (Spain), where a widespread burial dolomitisation occurs. Previous studies suggested that the burial dolomite occurrence is controlled by depositional facies and their modifications after early meteoric diagenesis. Nineteen carbonate facies were distinguished, and grouped according to the dominant texture. They are characterized by various degree of dolomitisation and different pore types and abundance. Depositional facies were grouped in five palaeoenvironrnents: restricted inner platform, open inner platform, shoal, transitional inner-outer platform and outer platforrn. Two depositional sequences corresponding to transgressive-regressive cycles were recognized. The study focussed on the regressive phase of the first sequence and the transgressive phase of the second one. Three stages of the platform evolution were distinguished and are characterized by a different distribution of facies and environments. The statistical data treatment indicates that the dolomitisation is concentrated in the regressive part of first sequence, corresponding to the second stage of the platform evolution. The most dolomitised environments are the inner platforms and the shoal. The pore abundance displays a direct proportionality with the degree of dolomitisation: pores are most abundant in full y dolomitised portions of the succession and particularly in the grain-dominated facies. For modelling purposes, several diagenetic association rules were elaborated; they allow to associate to each depositional environment, in each of the three platform stages, different proportions of dolomitisation and related pore abundance. The grid used for the geostatistical simulation was vertically divided into three units, corresponding to the three stages of the platforrn evolution. The simulation and distribution of the depositional environments were achieved using a plurigaussian algorithrn, constrained with the six studied stratigraphie logs. Diagenetic constraints simulations (degree of dolomitisation and pore abundance) were clone independently, using a nested algorithrn. In this approach, each diagenetic imprint is simulated within each depositional environment, based on the association rules previously defined.
Type de document :
Communication dans un congrès
IAS Meeting of Sedimentology, Sep 2013, Manchester, United Kingdom
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https://hal-ifp.archives-ouvertes.fr/hal-00956900
Contributeur : Françoise Bertrand <>
Soumis le : vendredi 7 mars 2014 - 15:25:38
Dernière modification le : mardi 15 mai 2018 - 14:50:02

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  • HAL Id : hal-00956900, version 1

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S. Blasquez-Fernandez, I. Lopez-Cilla, Martha Gasparrini, I. Rosales, Olivier Lerat, et al.. Approach to model and predict facies-texture-porosity interdependence in a partially dolomitised Lower Cretaceous platform (Basque Cantabrian Basin, Spain).. IAS Meeting of Sedimentology, Sep 2013, Manchester, United Kingdom. 〈hal-00956900〉

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