Reservoir simulations and feasibility study for seismic monitoring at CaMI.FRS

Marie Macquet, Donald C. Lawton

The Containment and Monitoring Institute (CaMI) of CMC Research Institutes Inc., in collaboration with the University of Calgary, has developed a comprehensive Field Research Station (FRS) in southern Alberta, Canada. The purpose of CaMI.FRS is to develop new technologies to prevent and monitor early leakages of a deepest, large-scale CO₂ reservoir. To simulate a leakage, a small amount of CO₂ (< 1000 t/year over 5 years) will be inject a shallow surface (300 m depth). In this study, we focus the feasibility study of seismic time-lapse monitoring using surface seismic instruments. A part of the feasibility work is also the determination of threshold of CO₂ gas-phase detection at shallow depth.

The first step of the feasibility study is the reservoir simulation. We test here the influence of the maximum bottom-hole pressure (and reservoir temperature) and of the ratio vertical permeability over horizontal permeability on the amount of CO₂ you can inject and on the gas plume shape. The next step is the fluid substitution, necessitated to estimate the variation in elastic parameters induced by the gas injection. We test different methods to compute the bulk modulus of the fluid (Reuss, Voigt, HRV and Brie) and compare their results. We also test the influence of several parameters (matrix bulk modulus, porosity and initial saturated bulk modulus) on the results of the fluid substitution. We finally use a 3D finite difference modeling to simulate the seismic response in the elastic models generated for the baseline, for 1 year of injection and for 5 years of injection.