The increase in worldwide activities related to CO2 injection in geological formations, for both EOR/CO2 and CCS projects, has pushed oil companies and universities to enhance the modeling of these processes for their better (1) designing and (2) monitoring. The objective of this paper is to describe new improvements for these two aspects through a multi-scale methodology of simulations from laboratory experiments to full-field modeling passing by studies around the wells including new rock-physics model. When injecting CO2 in carbonate rocks, one of the most critical aspects is to understand the complex chemical reactions occurring between the acidic fluid formed by the CO2, the in-situ water (connate and aquifer) and the carbonate matrix depending on its mineralogy. The mathematical formulation of the simultaneous thermodynamic equilibrium and the chemical reactions will be described completely. An original construction of the rock-physic model developed for this multi-phase flow based an effective medium theory will be described. A specific power law equation will be proposed to fit the relation between porosity and permeability obtained in the laboratory for carbonate rocks replacing the classically used Kozeny-Carman equation not valid in our case. To improve the quality of the forecasts at the entire reservoir level, simulations at different scales are performed and used sequentially. Results of sensitivity studies with various rock and mineralogy characteristics showing the impact on (a) the porosity and permeability field on the CO2 segregation, (b) the pH evolution in space and time, (c) the synthetic seismograms, will be described. This paper demonstrates the practicality of the modeling approach and software tools to address the design and monitoring of CO2 injected in a geological formation for CO2/EOR and or CCS processes. In particular, it helps the geophysicists and reservoir engineers based on the geological description of the reservoir to design injection plans for EOR or CCS processes defining plans for well tests and seismic campaigns around the wells and in between them (2D or 3D) whether such changes may be observable as a function of time. Technical contributions: 1. Multi-phase flows on realistic carbonate reservoirs with multi-phase thermodynamic equilibrium and geochemical reaction, 2. New rock-physic model for the evolution of the density and velocities used to construct surface seismic responses, 3. Methodology to improve the quality of the full-field forecast checking the results of the simulations results at the laboratory scale and generating synthetic seismograms to design seismic campaigns for monitoring.


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