1. Fluid flow dynamics in CO2 sequestration in deep saline aquifers
A. Mukherjee1, P. Dutta2
1. Department of Mining Engineering, IIEST Shibpur, Howrah, WB, India
INTRODUCTION: A 2 dimensional heterogeneous saline porous reservoir (Fig. 1) 700 m x 910 m was fabricated using COMSOL Multiphysics software, using Elder Darcy’s Law module using data from [1]. It emphasises on fluid flow nature following CO2 injection.
Fig. 3(a) – (b) show the nature of mass transfer processes taking place.
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Figure 3. (a)Diffusive flux and (b)convective flux within reservoir.
Fig 4 (a)-(d) shows the flow of CO2 after the plume reaches the maximum possible height.
Figure 1. Reservoir geometry
COMPUTATIONAL METHODS: Using Darcy’s law we got the following expressions for fluid flow [2]:
where,
ρ is the brine density (kg/m3),
t is the time (s),
ε is the porosity,
u is the Darcy velocity.
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Figure 4. Plume behaviour at initial stage of CO2 injection (a) at 0 year (b) 10 years (c) 150 years and (d) 1000 years.
CONCLUSIONS:
On injection CO2 starts to dissolve and migrate both laterally and vertically. The saturation of CO2 first increases and then decreases with time. The extent of plume spread was found to be larger when a fixed plume height was considered. This is because higher the plume height higher the areal exposure of CO2.
RESULTS: Fig. 2(a) – (d) show the fluid flow for 2500 years in the formation. After 230 years, gas started migrating up to the second domain. By 550 years it reached the second domain and started to migrate further upwards reaching the third domain. CO2 was filled in domain 2 and 3 simultaneously owing to injection pressure and permeability effect.
References:
Wurdemann H, Moller F, Kuhn F, Heidug W, Borm G, Schilling FR, CO2SINK—From site characterisation and risk assessment to monitoring and verification: One year of operational experience with the field laboratory for CO2 storage at Ketzin, Germany, 4(6), 2010.
comsol manual
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Figure 2 Spatial and temporal variation of CO2 in the reservoir at (a) 230 years (b) 550 years (c) 900 years and (d) 2500 years.