Objective
IFP has conceived and achieved a new and original "reaction-transport" numerical code, DIAPHORE. This 3D modelling software simulates mineral dissolutions and precipitations having occurred in the reservoirs during relatively short-term episodes of their geological evolution. Time is considered explicitly, through kinetics of dissolution and precipitation. DIAPHORE predicts the transformations of porosities and permeabilities related to such diagenetic episodes.
TOM and IFP want to demonstrate the performance of DIAPHORE on a real case study, the Brent reservoir of the Dunbar field, North Sea. In this reservoir, now on the way of development, permeabilities have been locally reduced by precipitations of quartz and illite.
The first application of a 3D numerical code to simulate diagenetic phenomena in heterogeneous reservoirs, is a significant innovation. It can provide a key to the prediction of permeability barriers in reservoirs, and consequently to the improvement of oil recovery.
The reaction transport code "DIAPHORE" simulates very correctly the chemicals evolution and the mineral transfers at the reservoir scale in 3D during few million years diagenetic episodes.
a) The DIAPHORE software is a 3D numerical code which couples mineral/water reactions (precipitations, dissolutions) and the transport of water and dissolved chemical species in the porous medium. Inputs of the simulations are provided by:
- analysis of equivalent sediments which have not suffered these episodes;
- regional parameters, such as temperatures and pressures, which prevailed in the reservoirs during these episodes. Outputs of the simulations can be compared and validated on analytical data obtained from core samples in the places where the diagenetic transformations did occur.
DIAPHORE is the first "reaction-transport" numerical code which gathers the following characteristics: - taking explicitely kinetics for mineral reactions;
- applied to porosity/permeability prediction of reservoirs which have suffered diagenetic transformations;
- conceived to take into account rock heterogeneties (sedimentary, mineralogical, textural) at a pertinent scale for reservoir development;
- operating in 3D.
b) DIAPHORE is used as a predictive tool to decipher diagenetic alterations of petrophysical properties. It improves the building of the reservoir engineering model which is made from the geological information for the purpose of field development.
c) At the beginning of the project, the development of DIAPHORE was achieved together with the calibration of the main internal parameters. A series of one-dimensional simulation were made during the project, to test most of the range values admissible for the various parameters of the model, in the particular case of the Dunbar problem.
d) An application of DIAPHORE to a reservoir system in a real case study is a four-phases operation :
- Organisation of a database of "static" data, from which are defined:
* the initial state of the system (before the diagenetic episode, based on the overall knowledge of the regional geology)
* the final state of the system in the places where it is known from cores:
these data must be fitted by the simulation results;
- Organisation of a database of "dynamic" parameters to be tested in the simulations: the conditions having prevailed in the system during the diagenetic episode (temperature, water velocities and composition);
- Finally a comparison with the data given by the future wells will be carried out.
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DEM - Demonstration contractsCoordinator
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