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Sedimentary and
Diagenetic Models of Upper Cretaceous to Paleocene Carbonate Formations,
Toullec, Renaud1, Adrian Cerepi1, Philippe Razin1, Louis Humbert1, Gildas Lageat2, Nicolas Labat2, Christophe Rigollet2, Serge Galaup1, Brigitte Spiteri1 (1) Université Michel de Montaigne Bordeaux III, Pessac, France (2) Gaz de France, Saint Denis La Plaine, France
The
multiscale analysis of Upper Cretaceous to Palaeocene carbonate formations from
basin scale to pore scale of Bas-Adour sub-basin (Aquitaine Basin, France) is
based on different specific tools : seismic, well logging, petrophysics, thin
and polished sections. All these data have been integreted in a carbonate
foreland basin model under halocinetic control. This study intends to unlock
the sedimentary and diagenetic record, especially the dolomitized bodies distribution, so as to predict reservoir properties.
The cores drilling analysis allows us to display the evolution of at least two
carbonate platforms, during Coniacian/Turonian to Campanian and the other one
during Danian to Upper Thanetian/Ypresien. During this period, available space
seems not to be or slightly affected by salt movements relative to the
precinematic form of the seismic reflectors. These carbonate platforms are
characterized by calcarenite deposits with emergences surfaces during
Palaeocene, leading to an important primary porosity and permeability. These
deposits are separated by fine grained fabrics conducting to cover facies
development. The diagenetic imprint differ between high position where
formations are intensily dolomitized with a complex diagenetic history
permitting high secondary porosity development and low positions where
sedimentary record is preserved, especially for Palaeocene sediments. Upper
Cretaceous sediments are not so affected and their diagenetic history is not so
complex. Like this, high positions are better reservoirs than lower ones.
Moreover, an Upper Cretaceous to Ilerdian field analogue has been chosen in the
high subsident Tremp basin (