CO2 Storage Trapping Mechanisms Quantification

Transcription

1 CO2 Storage Trapping Mechanisms Quantification

2 CO2 storage The capture and storage of in deep geological formations is one of the proposed solutions to reduce emissions to the atmosphere.

3 CO2 storage is injected as a supercritical fluid deep below a confining geological formation that prevents its return to the atmosphere.

4 CO2 storage Four trapping mechanisms are expected, which are of increasing importance through time (1) structural, (2) residual saturation, (3) dissolution, and (4) mineral trapping. injection well gas bubble dissolved

5 CO2 storage Four trapping mechanisms are expected, which are of increasing importance through time (1) structural, (2) residual saturation, (3) dissolution, and (4) mineral trapping. injection well gas bubble dissolved Physical instability Capillary trapping

6 CO2 storage Four trapping mechanisms are expected, which are of increasing importance through time (1) structural, (2) residual saturation, (3) dissolution, and (4) mineral trapping. injection well gas bubble dissolved Physical instability Capillary trapping Source: Cooperative Research Centre for Greenhouse Gas Technologies (CO2CRC)

7 CO2 storage The prediction of the mass of stored through time in storage systems is an essential parameter in the preinjection assessment of a geological storage. For safety reasons, it is relevant to know the mass of trapped under these different trapping mechanisms.

8 Objective Identify and quantify the different Co2 trapping mechanisms in a saline aquifer

9 Mathematical description mass species conservation t φs α ρ α m α κ M κ = q α ρ α m α κ M κ φs α ρ α D α m α κ M κ + Q α κ + T α κ α = l, g κ =, w Darcy s law q α = kk r,α μ α p α ρ α g

10 constitutive relations retention curve Mathematical description [1] Brooks, R. H. & Corey, A. T., Hydraulic properties of porous media. Hydrology Papers, Colorado State sum of phase saturations s g + s l = 1 University, Issue March. pressure equilibria p c = p g p l effective saturation s e = s l s l r 1 s l r s g r [1] capillary pressure relative liquid permeability p c = p t s e 1/ω k r 2+3ω l = s e ω [1] [1] relative gas permeability k r g = 1 s 2 2+ω e 1 s e ω [1]

11 constitutive relations gas properties [2] Spycher, N. & Pruess, K., CO2-H2O mixtures in the geological sequestration of CO2. II. Partitioning in chloride brines at C and up to 600 bar. Geochimica et Cosmochimica Acta, 69(13), pp [3] Nickalls, R., A new approach to solving the cubic: Cardan's solution revealed. The Mathematical Gazette, pp [4] Altunin, V. & Sakhabetdinov, M., Application of orthogonal expansions to construct a single equation of state for substances on the basis of various experimental data by means of a digital computer(orthogonal polynomials for computerized construction of equations of state for substances under thermodynamic restrictions). Teplofizika Vysokikh Temperatur, Volume 10, pp [5] Redlich, O. & Kwong, J., On the Thermodynamics of Solutions. V. An Equation of State. Fugacities of Gaseous Solutions.. Chemical Reviews, 44(1), pp Mathematical description volume V g = V g p g, T, m l, m s NaCl [2] phase composition m l = m l (p g, T, V g, m s NaCl ) [2] density ρ g = M V g [3] viscosity μ g = μ g p g, T, m l, m s NaCl [4] enthalpy h g = h g p g, T, m l, m s NaCl [5]

12 constitutive relations liquid properties Mathematical description density ρ l = ρ l ρ b, ρ CO2 [6] ρ b = ρ b CO p l, T, m 2 l, mnacl s ρ CO2 = ρ b CO p l, T, m 2 l, mnacl s viscosity μ g = μ g CO p l, T, m 2 l, mnacl s enthalpy h g = h g CO p l, T, m 2 l, mnacl s [7] [6] [8] [9] [6] Garcia, J. E., Density of aqueous solutions of CO2. [7] Haas, J., Physical Properties of the Coexisting Phases and Thermochemical Properties of the H2O Component in Boiling NaCl Solutions. USGS Bulletin 1421-A, Washington, DC, p. 73. [8] Phillips, S. L. et al., A technical databook for geothermal energy utilization. s.l.:lawrence Berkeley Laboratory, University of California. [9] Pruess, K., ECO2N: A TOUGH2 fluid property module for mixtures of water, NaCl, and CO2. Lawrence Berkeley National Laboratory Report LBNL-57592, Berkeley, CA.

13 Formulation used In this work it will be assumed that water miscibility in gas phase is negligible (m g w = 0). This is quite reasonable since water dissolution is on the order of tan per mil (Spycher & Pruess, 2005). These restricts the system Eq.[1] to three equations. For the derivation of the equations notice the following relationships: M c m α c c=,w = 1 T α c α=l,g = 0 c=,w Q α c = Q α

14 Formulation used The linear combination of the three equations done is the following. A total mass conservation Eq.[a] is obtained by summing over all the phases and components. t φs l ρ l + φs g ρ g = q l ρ l + q g ρ g + Q g + Q l [a] A CO2 equation mass conservation Eq.[6b] is obtained by summing the Co2 chemical component equations over the two phases. t φs l ρ l m l M + φs g ρ g = q l ρ l m l M + q g ρ g ρ l D l m l M CO +Q 2 g + Q l [b] CO Finally, subtracting the equation Eq.[6a] times m 2 l M to the liquid-co2 equation we find Eq.[6c]: CO φs l ρ l t m 2 l M CO m 2 l M t φs g ρ g = q l ρ l m l M + m l, M q g ρ g + ρ l D l m l M q l ρ l M m l m l, + Ql + T l [c] where m l, is the prescribed concentration of the inflow fluid in the boundaries and m l, = ml in the interior domain.

15 Formulation used The unknowns for Eq.a, Eq.b, Eq.c chosen are p l, S g, m l respectively. A conditional kinetic interphase mass transfer is considered. c 1 = if( S g > S r,g ), 1 if( S g S r,g ), 0 c 2 = if m CO l > m 2 l, 0 CO if m 2 CO l m 2 l, 1 T l = φs l ρ l k kin c 1 m l m l + 1 c1 c 2 m l m l

16 2500 m depth 2D synthetic dome problem Well foot Well middle Well top 50 m 200 m 2000 m 4000 m Pumping rate Q g = 0.3 (kg s 1 ) (during 180 days) φ 0.15 (m 3 m 3 ) d l = d m 40 (m) κ 1e-11 (m 2 ) p t ω 1e5 (Pa) 2 ( ) r s l 0.05 (m 3 m 3 ) sr g 0.1 (m 3 m 3 ) mnacl s 1 (mol kg 1 )

17 Results (well foot) Co2 molality on liquid Gas saturation

18 Results (well middle) Co2 molality on liquid Gas saturation

19 Results (well top) Co2 molality on liquid Gas saturation

20 Results foot structural capillary dissolved top structural middle structural capillary dissolved capillary dissolved

21 Results

22 Results

23 Results

24 Conclusions Expected Co2 storage systems can be reproduced in a model Quantification of this systems is numerically feasible The position of the well in a synclinal formation affects the trapping mechanisms.

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