Geological and
Petrophysical Modeling of a Heterogeneous Mid-Cretaceous Carbonate Reservoir
from
Taghavi, Ali Asghar1, Atle
Mørk2 (1) Reslab Integration AS, Stiklestadveien 1,
The reservoir characterization and
modelling of the mid-Cenomanian to early Turonian upper Sarvak Formation has
been improved through the integration of geological and petrophysical data.
The main heterogeneity of the reservoir
is in the vertical direction due to facies and locally diagenesis, whilst in
the horizontal direction it is due primarily to diagenesis since there are no
significant lateral facies variations. The sequence stratigraphic analysis has
resulted in defining eight medium scale sub-sequences which have been used as
the basis for constructing geological framework. In order to capture the
reservoir heterogeneity, rock types were defined by integrating depositional
facies, diagenesis, and porosity-permeability relationships, as well as capillary
pressure data. Such rock types are an indication of the flow units in this
reservoir. The flow units are thus controlled by sequence stratigraphic
framework. The geological framework and rock type information as well as
porosity-permeability distribution have been used to construct the vertical
layers to achieve the heterogeneity. The horizontal cells have been defined
relatively small to be able to capture small scale heterogeneities.
The rock types were deterministically and
stochastically modeled in the sequence stratigraphic framework by their volume
fraction in each zone. A pixel-based stochastic method has resulted in more
reliable models after understanding the geology of the reservoir. Testing
alternative geological scenarios, as well as different horizontal correlation
ranges have shown petrophysical modelling using stochastic method and
relatively large horizontal correlation range results in more probable adequate
petrophysical models.
Various realizations of reservoir models
have been created. These have been chosen after being ranked and have been used
as input to predict the reservoir performance and to define the development
plan for the field.
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California