State of the art review of CO2 Storage Site Selection and Characterisation Methods

 
1. INTRODUCTION
 
2. GEOLOGICAL CHARACTERISATION OF THE SITE
 
3. FLOW MODELLING
 
4 REACTIVE FLOW MODELLING
 
5. COUPLED GEOMECHANICAL AND FLOW MODELLING
 
6. ENVIRONMENTAL IMPACT AND RISK ASSESSMENT
 
7. ECONOMIC ANALYSIS
 
8. PUBLIC PERCEPTION AND ACCEPTANCE
 
9. CONCLUSIONS AND RECOMMENDATIONS
 
 
5.1 Geomechanical terms and processes in CO2 storage
 
5.2 Geomechanical site characterisation
 
5.3 Case studies and need for geomechanical coupled simulations
 
5.4 Methods of coupling flow and geomechanics
 
5.5 Conclusions
 
 
5.3.1 Large-scale geomechanical modelling
 
5.3.2 Surface uplift
 
5.3.3 Pressure response
 
» 5.3.4 Fault re-activation and/or shear failure
 
5.3.5 Reactive transport
 
5.3.6 Storage Capacity Estimation
 
5.3.7 EOR Operations
 
5.3.8 Leakage risk through a fault
 
 

5.3.4 Fault re-activation and/or shear failure

Shi and Durucan, 2009 assessed the potential for shear failure and/or re-activation of pre-existing faults because of changes in the reservoir pressure due to natural gas production and CO2 injection in a nearly depleted gas reservoir at Atzbach-Schwanenstadt in Austria. A Mohr-Coulomb shear failure analysis was carried out for the gas reservoir undergoing reservoir pressure depletion and then re-pressurisation due to CO2 injection, in particular considering the regional strike-slip fault stress regime relevant to the gas field.

Soltanzadeh et al., 2009 studied the fault reactivation potential during fluid injection or production within and surrounding reservoirs by combining an induced stress change analysis, which was conducted using a semi-analytical model based on the theory of inclusions for a poro-elastic material and the concept of Coulomb failure stress change. The results of a synthetic case study showed that, for a thrust-fault stress regime, fault reactivation is likely to occur within the reservoir and adjacent to its flanks during injection into a reservoir. On the other hand, for a normal fault stress regime, only faults located in rocks overlying and underlying the reservoir tend towards reactivation. In Fig. 5-6, a normal fault stress regime was considered with faults dipping at 60° from horizontal. During production, there is a tendency towards normal fault reactivation within the reservoir and in the rocks near the lateral flanks of the reservoir (i.e., the regions with λ<0). Similarly, there is a tendency towards normal fault reactivation above and below the reservoir during injection (i.e., the regions with λ>0).

E. Fig . 5-6a

Fig. 5-6: Variation in fault reactivation factor (λ) for a rectangular reservoir: a) a fault dip angle of 60° in a normal fault stress regime; and (b) a fault dip angle of 30° in a thrust fault stress regime (Soltanzadeh et al., 2009)