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Article

Improvement of petrophysical characteristics of chalky limestones by dolomitization-dedolomitization processes. Example of the Upper Senonian carbonates in Central Tunisia

NEGRA Mohamed Hédi, MRABET Ali, 1992

Comptes Rendus de l'Académie des Sciences, 11, 315, 1003-1009, Novembre 1992

Résumé

The Upper Senonian chalky and partly conglomeratic limestones, constituting the Abiod Formation in Maknassy area, exhibit relatively high porosity values (up to 19%) but low permeability (less than 1 md). Dolomitization-dedolomitization processes which create a secondary porosity (mainly intercrystalline and intracrystalline) improve the porosity and, especially, the permeability values. The improvement of petrophysical properties is particularly obvious within the chalky limestones when they are completely dolomitized; their average porosity is increased by about 5% (from 14 to 19%) and their permeability is multiplied by 300 (from 0.2 to 302 md). These porosity and permeability values which, at least locally, are relatively high, indicate that the Abiod Formation carbonates are considered as potential reservoir rocks in Tunisia.