Magnetic Resonance Imaging studies of hydrate growth, dissociation and hydrate reformation and Phase Field Theory modelling of hydrate nucleation, growth and dissociation B. Kvamme University of Bergen, Norway
Contents: - Motivation and Introduction Part I: Theoretical modelling - II. Phase-field theory of homogeneous nucleation & growth of CO2 hydrate from solution - III. Heterogeneous CO2 hydrate formation - VI. Hydrate growth in pores - V. Dissociation of hydrate exposed to pure water Part II: MRI experiments on hydrate in porous structures - Conclusions
Part 1: Modelling nucleation &
growth for phase transitions involving hydrate
Motivation • Exploitation of hydrate reservoirs require fresh thinking and creative approaches for potential exploitationschemes • Theoretical examination of these schemes through reservoir simulations are important tools in the evaluation of the potential success of these schemes • The inner limiting factor to the overall dynamics is the actual phase transition kinetics, and how this phase transition kinetics is influenced by different driving forces (heat addition, pressure reduction, CO2 injection, chemicals etc.) • Available kinetic models for prediction of hydrate phase transitions are empirical and of unverified validity (i.e.: only verified for the specific laboratory equipment used in the original experiment)
Global Gas Hydrate Locations
Polycrystalline solidification: nucleation &
growth
Phase field theory Introduction I.I. Introduction
Nucleation Nucleation Heterophasefluctuations: fluctuations: Heterophase
Wolde & Frenkel, Frenkel, 1996
Gasser et al., 2001
Auer & Frenkel, Frenkel, 2001
Classical(sharp (sharpintf intf.) picture: Classical .) picture: clusterfree freeenergy energy(W (W) volumetric cluster ) ==volumetric interfacialcontributions contributions ++interfacial
Yonezawa, Yonezawa, 1991
Crystal-liquid interface Crystal -liquid interface
Crit. fluct. typically~~10 10––100 100molecules molecules Crit . fluct . typically
Diffuseinterface interfacemodel modelis isneeded needed!!! !!! Diffuse (e.g.phase phasefield fieldtheory) theory) (e.g.
Davidchack & Laird, 1998
Phase field field theory theory for for the the IIII.. Phase homogeneous formation formation of of CO CO22 homogeneous hydrate from from dissolved dissolved CO2 CO2 in in hydrate water water
Phase-field theory: Phase -field theory: Free energy functional:
F
H 2T ½ 2 ³ d r ®¯ 2 I f (I , c ) ¾¿
where
f(I,c) = w T g(I) + [1 p(I)] fS + p(I) fL g(I) = ¼ I2 (1 I)2, p(I) = I3 (10 15I + 6I2), fL,S = polynomials for aqueous solution of CO2 and CO2-hydrate
Modelparameters: parameters:ww &&HH22 intf intf. freeenergy energy&&intf intf. thickness . free . thickness Model calculationof ofnucl nucl. barriercan canbe bemade madewithout withoutadjustable adjustableparameters parameters calculation . barrier
Molecular Dynamics Dynamics (Melting (Meltingof ofCO CO2hydrate) hydrate):: Molecular 2 920 SPC water 104 EPM2 CO2 T =276.15 K p = 200 Bar
22 ps
Kuznetsova & Kvamme, Kvamme, 2003
48 ps Static hydrate – solution 10 % – 90 % interface thickness ??? | 1.5 – 2 nm
Thermodynamics: Thermodynamics: 1.
Bulk hydrate description. Similar approach as already readily available from equilibrium calculations (Kvamme, B., Tanaka, H.: "Thermodynamic stability of hydrates forethylene, ethane and carbon dioxide". J.Phys.Chem., 99, 7114, 1995)
2.
Bulk fluid properties trivially available using standard thermodynamic approaches (equations of state for non-polar fluid phases, activity coefficient models for aqueous solutions)
3.
Interfacial properties: Interface free energy can be estimated from MD simulations though calculation og the reversible work needed to separate the two phases at the interface (se next slide – additional slides describing the theoretical details are available) Interface thickness can also be interpreted from MD simulations (previous slide) Additional purely repulsive interaction between liquid and crystal atoms in order to ”cleave” the interface and calculate the corresponding work And resulting interface free energy Urepulsive = O*4 H (V/r)12
Extended adsorbtion Theory Pw
P w 0 ¦ Q i RT ln(1 ¦ aij ) i
j
• Single cavity integration (small guest molecules)
• Harmonic oscillator approach (large guest molecules)
S
>
a
e x p E P E 1 ln b
b
( m / E 2S ! 2 )3/2
³ e x p > E w ( v ) @d v
@
a
exp> E P ' g u @
g
³ ln( E h Z ) h (Z ) d Z
E
1 / kBT
Vc a g e
a
e g
E
x
³
>
p l
1
n /
E E
( k
B
h
P
Z
' )
h
g (
Z
)
u d
@
Z
T
a exp> EP 'gu @ g ³nl(EZ h )( hZZ )d
E 1/kT B
Destabilisation of lattice due to guest movements • Free path for movement : • • •
Carbon dioxide : 1.020 Å Ethane : 1.088 Å Ethene : 1.274 Å
• Destabilisation increases with decreasing free path in the cavity
Cleaving the water -- CO2 hydrate system by adding repulsive interactions:
Time evolution evolution CA CA & & CH CH eqs eqs.: Time .: wI Phase-field: wt
GF M I + ]I GI
wc wt
Composition: GF º ª « M c » + ]c Gc ¼ ¬
phasefield fieldtheory theory –– mean mean-field typeapproach approach phase -field type
Modeling of of nucleation: nucleation: Modeling - inclusion of noise into governing eqs. - introduction of critical fluctuations + small amp. noise defined by
GF 0 GI
GF º ª 0 « M » Gc ¼ ¬
Critical fluctuations: fluctuations: Critical Extremum of grand potential functional (unstable equilibrium):
: = F Pf ³ dr U Euler-Lagrange eqs. for phase field I (non-conserved):
G: 0 GI and for
wZ wZ wI wI
wZ 2 2 H T m wI
concentration c (conserved):
G: 0 Gc
wZ wZ wc wc
wZ wZ wc wc
f
Critical fluctuations: fluctuations: Critical
Phase-field:
spherical symmetry
I” + 2/r I ’ = 'P(I )/(bT)
Volume fraction: c = c(I )
implicit equation
'P = W T g’(I) + [(1 c) 'fA + c 'fB] P’(I),
Boundary cond.:
©
«
r of : c oc bulk, I o I f; r = 0: c’, I’ = 0
ª W*
Nucleation rate: rate: Nucleation
ª W*
J = J0 exp{ W */ kT } J0 from classical kinetic approach (3D) J is the flux of nucleation for the particle in moles per area and time
Free energy energy surface: surface: Free Aqueous CO2 solution: GL = (1 c) GL,W + c GL,CO2 GL,W = GL,W0 + RT ln[(1 c) JL,W(c)] GL,CO2 = GL,CO2f + RT ln[c JL,CO2(c)]
JL,CO2 – polynomial fit to Stewart – Munjal data JL,W – Gibbs-Duhem GL,CO2f = - 19.67 kJ/mol (MD) GL,W0 – polynomial by Kvamme & Tanaka
CO2 hydrate:
(Kvamme & Tanaka, 1995)
GH = (1 c) GH,W + c GH,CO2 GH,W = GH,W0 + RT (3/23) ln(1 T) GH,CO2 = GH,COinc + RT ln[T/(1 T)] GH,W0, GH,Coinc – polynomials T = c/(3/23)
H2&w Jice = 29.1 mJ/m2 (Hardy, 1977) d1010-90 = 1.5 nm
Initial CO2 content: 3.3% (saturated) T = 274 K, p = 150 Bar
Nucleation: Nucleation: Radialprofiles: profiles: Radial
d (nm) W*PFT(1019 J) W*CDM(1019 J) --------------------------------------------------------------0.5 3.18 1.0 2.66 3.76 1.5 2.23
Note: m in the plots is the phase field
Initial CO2 content: 3.3% (saturated) T = 274 K, p = 150 Bar
Growth: Growth:
Simplifications: - Isothermal - 2 dimensional - Isotropic
The reduction time W is 10^-11 s. The growth rate deceases rapidly and after 1 s estimated growth rate is 11 micrometers per second Experimental value is for a situation of significantly lower driving force (Fluid T=282.2 K, Cold surface T=268, P=45.6 bar, molefraction CO2 in solution is lower) from Ucihda et al. (1995) is between 0.27 micrometers and 0.0027 micrometers per second
Phase-separation inliquid: liquid:(preliminary) (preliminary) Phase -separation in x = 0.50
Interface properties: d1010-90 = 1 nm J = 29.1 mJ/m2 Hc = 20 HI T = 274 K p = 150 bar 500 u 500 grid n = 250 'x = 0.2 nm t = 0.75 Ps
III.. Phase Phase field field theory theory for for the the III heterogeneous formation formation of of heterogeneous hydrate from from CO2 CO2 and and CO22 hydrate CO water water
Heterogeneoushydrate hydrateformation formation(red (redfront) front)on onthe the Heterogeneous interfacebetween betweenCO2 CO2(yellow) (yellow)and andliquid liquidwater water(blue) (blue) interface Thermodynamics: Fugacity coefficients for CO2 from SRK equation of state Aquous description and hydrate description as in the homogeneous case
T = 274 K p = 150 bar 400 u 400 grid n = 100 'x = 0.4 nm t = 0.27 Ps DCO2=1.0•10-9 (liquid like) gives steady growth rate of 0.6 m/s DCO2=1.1•10-12 (clathrate diffusivity of CO2) gives steady growth rate of 0.019 m/s Experiment at T=277.4 K and 39 bar (lower thermodynamic driving force) Reported by Uchida et.al. (2003) indicates growth rate from 0.0001 m/s to 0.01 m/s
What about about growth growth in in porous porous What medium? medium? IV. Solidification Solidification with with walls walls IV. Inaddition additionto toexamples exampleson onnucleation nucleationand andgrowth growthfrom fromsupersatur supersaturated In ated CO2solution solutionunder underthe theassumption assumptionof ofsymmetry symmetryin inthe thethird thirddimen dimension of CO2 sion of 2Dsimulation simulationwe wealso alsoshow showan anexample exampleon ontrue true3D 3Dsimulation. simulation. aa2D The3D 3Dexample exampleis isnot nothydrate hydratebut butaabinary binaryalloy. alloy.But Butwe weexpect expect The somethingqualitatively qualitativelysimilar similarfor forhydrate. hydrate.Noe Noeof ofthese thesesimulations simulations something includeoriental orientalfields fieldsand andas assuch suchcrystal crystalmorphology morphologyis isnot notan anissue issuein in include thesesimulations, simulations,but butoriental orientalfield fieldwill willbe beincluded includedshortly shortly((within these within aa month). month).
Homogeneous hydrate hydrateformation formationin in porous porous medium medium Homogeneous fromsupersaturated supersaturatedCO2 CO2solution solutionin inwater water from (saturationis isfor forx=0.033 x=0.033at atthis thiscondition) condition) (saturation x = 0.05
Interface properties: d1010-90 = 3 nm J = 29.1 mJ/m2 Hc = 0 H I
Composition T = 274 K p = 150 bar 400 u 400 grid n = 100 'x = 0.4 nm t = 0.27 Ps
double fl(double c){ double p0,p1,p2,p3,p4,p5,p6,p7,x; x=c; p7=-1.5955520249860961e+005*x*x*x*x*x*x*x; p6=5.3484589826376655e+005*x*x*x*x*x*x; p5=-6.5248590071680734e+005*x*x*x*x*x; p4=3.4324018390124274e+005*x*x*x*x; p3=-7.3670499518373981e+004*x*x*x; p2=7.9405144606028725e+003*x*x; p1=9.8408296219059048e+002*x; p0=-2.7361926771655735e+003; return (p0+p1+p2+p3+p4+p5+p6+p7); } double fs(double c){ double p0,p1,p2,p3,p4,p5,p6,x;
Interface properties: d1010-90 = 1 nm J = 29.1 mJ/m2 Hc = 0 H I
p6=1.4448589742385730e+008*x*x*x*x*x*x; p5=-5.2553560896910265e+007*x*x*x*x*x; p4=7.4822385024680533e+006*x*x*x*x; p3=-5.2593757673188346e+005*x*x*x; p2=2.1425481255372863e+004*x*x; p1=-1.3044491612244062e+001*x; p0=-2.6892144613235373e+003; return (p0+p1+p2+p3+p4+p5+p6); }
x = 0.075
x = 0.10
T = 274 K p = 150 bar 500 u 500 grid n = 250 'x = 0.2 nm t = 0.75 Ps
Solidificationin inporous porousmatter matterin in3D 3D Solidification Notethat thatthis thisis isnot nothydrate hydratebut butaasimilar similarprogress progressis isexpected expectedfor for Note hydratebut butshifted shiftedwith withrespect respectto tokinetics kineticsaccording accordingto todiffer different hydrate ent thermodynamicdriving drivingforces forcesand anddifferent differenttransport transportcoefficient coefficients thermodynamic s T. Pusztai & L. Grá Gránásy Research Institute for Solid State Physics and Optics, Budapest, Hungary, 2004
Physical properties: T = 1200 K 'Tr | 0.31 300 u 300 u 300 grid 60 u 60 u 60 nm
Foreign particles (cubes) on BCC lattice cube edge = 6 nm 'x = 0.2 nm W = 10 ns
Tf = 1728 K vm = 6.59 cm3/mol 'Hf = 17.47 kJ/mol d1010-90 = 1 nm J = 0.353 J/m2
Heterogeneousnucleation nucleationon onparticles, particles, Heterogeneous walls,&&solidification solidificationin inporous porousmatter matter&&channels channels walls, “no-flux” boundary condition at walls (90º contact angle) (idea of M. Castro, PRB 2003)
1000 u 1000 grid
4000 u 2000 grid
1500 u 1000 grid
1000 u 1000 grid
V V Hydrate exposed exposed to to pure pure water water Hydrate will dissociate dissociate due due to to lower lower will guest chemical chemical potential potential in in guest surrounding liquid liquid water water surrounding
Dissolution of CO2 hydrate in water T=274 K, P=150 bar, Thermodynamic description, including interfacial properties as for the nucleation and growth examples at the same conditions
Initial 8 nm radius spherical hydrate particle Exposed towards pure liquid water phase
VI Crystal morphology • How about hydrate morphology and corresponding impact on formation rates and dissociation rates? This section is essentially for other systems than hydrate but similar behaviour is expected for hydrate. Specific work on hydrate crystal morphology of growing hydrate is in progess at UoB. Work in this section done by Laszlo Granasy Who has a 25% Prof. Position in Kvamme’s Group at UoB
• Crystal morphology is essentially determined by a balance between the thermodynamics of the phase transition and the transport processes that supports ”building material” and gets rid of excess heat. • For same reasons morphology is essential in the kinetics of the formation and dissociation
A few words about methodology • For a spherical growing particle there are no directions that are favorable and x, y and z grow directions for next addition to the growth is equally probably • On the other hand – for irregular skapes of a crystal then gradients in Gibbs free energy depends on the orientation of further growth from a specific point on the surface of the excisting crystal • This can be incorporated into the phase field model in terms of an oriental-dependent field in addition to the phase field
Polycrystalline growth growth Polycrystalline morphologies morphologies
Particulate additives additives Particulate (Staticheterogeneities) heterogeneities) (Static
dendrites ‘‘Dizzy’ Dizzy’ dendrites Work done in collaboration with NIST (L. Grá Gránásy et al. Nature Materials Materials,, 2003)
Pinning centers: areas of fixed orientation Ferreiro et al., PRE (2002) Experiment: PEO/PMMA + clay Simulation: 3000 u 3000 grid
L. Gránásy, T. Pusztai, T. Börzsönyi
color code
Research Institute for Solid State Physics and Optics, Budapest, Hungary, 2002
Tip deflection deflection: Tip : Experiment:
Size dependence:
1 pixel
5 pixels
13 pixels
45 pixels
Orientation misfit:
'T = 0
'T = 0.1
'T = 0.2
'T = 0.3
Lateral disp. (pixels):
'x = 6
'x = 3
'x = 0
'x = 3
Theory vs. vs. experiment: experiment: Theory Simulations shown: selection from 30 computations with different random no. initialization (3000 u 3000 grid)
Experiment: PEO-PMMA blend/clay (Ferreiro & Douglas, NIST)
Message 3: 3: Message Reproduction of of Reproduction particulate-induced particulate -induced disorder disorder
Reduced orientational orientational mobility mobility Reduced ((M MTTvvDDrot rot))
Complex undercooled liquids: Drot/Dtr (v MT/MI ) decreases with increasing 'T
MTT/30 /30 M
Polycrystalline spherulites spherulites Polycrystalline
Se
Ryschenkow & Faivre JCG (1988)
- Se - cast iron (nodular) - polymers - metallic/oxide glasses L. Gránásy, T. Börzsönyi, T. Pusztai Research Institute for Solid State Physics and Optics, Budapest, Hungary, 2002
Category 1 spherulite
Category 2 spherulite
Growth mechanism: polycrystalline branching with fixed misorientation Realization in the phase field theory: f ori
HT ^xF0 (1 x) F1` 2[ 0
F0
° sin 2Sm[ 0 T ® °1 ¯
F1
° sin 2Sn[ 0 T ® °1 ¯
3 4m otherwise
for [ 0 T
1 4n otherwise
for [ 0 T
(Gránásy & Pusztai 2004)
Polycrystallinebranching branchingwith withfixed fixedmisorientation misorientation Polycrystalline
S = 1.10
d0=0.995
1.00
s0 = 0.00
0.95
500u500
0.90
Branching angle: 30º m = 3.0, n = 0.5, x = 0.2
0.85
0.75
6 orientations
Experiment
Simulation
Category 1 Description Description withonly only with fewmodel model aafew parameters parameters
(anisotropies, (anisotropies, branchingangle, angle, branching MSwell welldepth, depth,… …) MS )
Category 2
Message 4: 4: Message Realistic spherulites spherulites Realistic with a few Experiment with a few model parameters parameters model
Simulation
Eutectic spherulites spherulites Eutectic
Al-Si: Allen-Gremaud-Perepezko, Mater.Sci.Eng. A (1997)
Ag-Cu (regular sol.)
CCu,eu = 0.35
- regular solution TD - square-grad term for c - preference for definite orientational relationship at D - E interface
Ag-Cu (regular sol.) : CCu = 0.4
A couple couple of of other other non non-hydrate A -hydrate examples of of PFT PFT predictions predictions of of examples phase transition transition kinetics kinetics without without phase adjustable parameters parameters adjustable 1. Freezing Freezing hard hard spheres spheres as as compared compared to to MD MD 1. Kvamme, B, Graue, A.,Aspenes, E., Kuznetsova, T., Gránásy, L., Tóth, G., Pusztai, T.,Tegze G., Towards
Kvamme, B, Graue, A.,Aspenes, E., Kuznetsova, T., Gránásy, L., Tóth, G., Pusztai, T.,Tegze G., Towards understandingthe thekinetics kineticsof ofhydrate hydrateformation formation: Phasefield fieldtheory theoryof ofhydrate hydratenucleation nucleationand and understanding : Phase magneticresonance resonanceimaging, imaging,Physical PhysicalChemistry ChemistryChemical ChemicalPhysics, Physics,2004, 2004,6,6,2327 2327––2334 2334 magnetic Gránásy, L.,Pusztai Pusztai, T.,Jurek Jurek, Z.,Conti. Conti.M., M.,Kvamme Kvamme, B.,Phase Phasefield fieldtheory theoryof ofnucleation nucleationininthe thehard hard Gr ánásy, L., , T., , Z., , B., sphereliquid. liquid.J.Chem.Phys J.Chem.Phys., 2003,119, 119,10376 10376- -10382 10382 sphere ., 2003,
1. Freezing Freezing Ar Ar as as compared compared to to experiment experiment 1. Granasy, L., Pusztai, T., Tegze, G., Kuznetsova, T., Kvamme, B., Phase field theory of hydrate nucleation: Granasy, L., Pusztai, T., Tegze, G., Kuznetsova, T., Kvamme, B., Phase field theory of hydrate nucleation: Formationof ofCO2 CO2hydrate hydrateininaqueous aqueoussolution, solution,inin““Recent Advancesininthe theStudy Studyof ofGas GasHydrates Hydrates”, Formation Recent Advances ”, 2004, Kluwer Academic/Plenum Publishers, in press 2004, Kluwer Academic/Plenum Publishers, in press Gránásy, L.,Pusztai Pusztai, T.,BBörzsönyi, T.,Warren, Warren,J.J.A., A.,Kvamme Kvamme, B.,James, James,P. P.FF., Nucleationand and ., Nucleation Gr ánásy, L., , T., örzsönyi, T., , B., polycrystallinesolidification solidificationininbinary binaryphase phasefield fieldtheory. theory.Physics Physicsand andChemistry Chemistryof ofGlasses, Glasses,2004, 2004, polycrystalline 45,107 107- -115 115 45,
Nucleation barrier: barrier: Nucleation
No adjustable parameters Classical droplet model overestimates J by 3 to 5 orders of magnitude
50 PFT
upper curve: (110) central curve: average lower curve: (111)
40
W*/kT
30 20 10 0 0.52
CNT
0.525
0.53
0.535
)f calculated assuming spherical shape
triangles: MC (Auer & Frenkel, 2001)
Nucleation rates for real Argon according to experiments (squares), PFT theory (solid) and classical nucleation theory (large dash). Thin dash lines indicate error bars in PFT due to uncertainties in the interfacial free energy
(K)
Summary and and concluding concluding remarks remarks part part II Summary Thephase phasefield fieldtheory theoryhas hasbeen beenapplied appliedto toprediction predictionof of The kineticsof ofhomogeneous homogeneousformation formationof ofCO2 CO2hydrate hydratefrom from kinetics aqueoussolution solutionwithout withoutany anyadjustable adjustableparameters parameters. aqueous . Comparisonwith withexperimental experimentaldata dataat atlower lowerdriving drivingforces forces Comparison showsreasonable reasonableagreement agreementbetween betweenpredictions predictionsand and shows experimentalresults results experimental Correspondingpredictions predictionsof ofheterogeneous heterogeneoushydrate hydrate Corresponding nucleationand andsubsequent subsequentgrowth growthon onthe theinterface interfacebetween between nucleation liquidCO2 CO2and andwater watershows showsvery verygood goodagreement agreementbetween between liquid theoryand andexperiment. experiment. theory Crystalmorphology morphologycan canand andwill willbe beincluded includedshortly. shortly.PFT PFT Crystal withoriental orientalfields fieldshave haveproven provento tobe beable ableto toreproduce reproduce with experimentalmorphology morphologyfor foraanumber numberof ofdifferent differentcomplex complex experimental systems (publications (publicationsavailable) available) systems
Simulations of of dissociation dissociation of of CO2 CO2 hydrate hydrate towards towards Simulations towards pure pure liquid liquid water water phase phase is is also also towards demonstrated but but no no results results from from experiments experiments demonstrated under controlled controlled conditions conditions are are available available for for under comparison with with these these predictions predictions at at this this time time comparison An approach approach ((“cleaving”) for estimating estimating Interface Interface An “cleaving”) for Free Energy Energy for for the the solid/liquid solid/liquid interfacehas interfacehas been been Free extended to to full full Lennard Lennard-Jones interactions. extended -Jones interactions. Work is is also also in in progress progress on on the the application application of of the the Work same approach approach to to the the interface interface between between liquid liquid water water same and solid solid hydrate, hydrate, as as well well as as between between solid solid hydrate hydrate and and CO2 CO2 phase. phase. and
Part II Magnetic Resonance Imaging studies of hydrate growth, dissociation and hydrate reformation OBJECTIVES Visualize formation of CO2 and CH4 hydrate in porous media at different temperatures and various CO2/CH4 concentrations.
MOTIVATION Feasibility study for further investigation of mechanisms controlling deposition and storage of CO2 and production of CH4 from hydrate reservoirs.
EXPERIMENTAL PROCEDURES
1. Pressurize 100% water saturated core at room temperature 2. Inject liquid CO2(l) into core at 1200psi 3. Inject water at 1200psi into core from opposite end creating [CO2] gradient 4. Cool to decided temperature while imaging 5. Perform permeability tests during cooling process
Hydrate Experiments Setup
Liquid CO2/CH4 Const. Pressure
Core plug
Cooled non-imaging confining fluid
Water
CO2 Saturation Setup
CO2
Water Pump
Hydrate Experiments Core Material
Diameter 1.5cm Length
9.4cm
Porosity 22.1% Perm.
1050mD
Along bed. planes
Hydrate Experiments Overview 30 Core Temp [ C] Room Temp [ C] 25 13/9 16:00 Inj 10ml CO2(l)
14/9 09:00 Start cooling
15/9 19:50 Start cooling
17/9 22:00 Inj. 17/9 09:00 17/9 20:00 Core Injecting H2O at "new" 100% 2PV CO2 sat wat. MRI series 100a
19/9 12:30 Inj. CH4(l) MRI 100D
19/9 09:00 Inj. 2PV H2O
m elted
MRI Image series 37192-99
20 MRI Image series 98
15 13/9 13:00 Heating while dP
15 C K>0
18/9 22:00 15C K>0
16/9 15/9 13:45 17.5C K>0
10:00
13C K>0
MRI series 100C
16/9 13:20 8C K~0
5 13/9 12:00 Inj 1PV CO2
K=0
Night 1516/9 8C
15/9 23:00 2C K reduced to 0
13.09.2002 12:00
Heat to 20C MRI 101d
16/9 Heat w/dP 15/9 13:10 Start heating
12.09.2002 12:00
Cool to 6C M RI 101B
Heat w/dP M RI 101A
18/9 21:40 Heating
M orning
10
0 11.09.2002 12:00
20 C
14.09.2002 12:00
15.09.2002 12:00
16.09.2002 12:00
6C K=
18/9 10:20 2C inj CO2(l) 18/9 09:00 2C K=1
11:20 2PV CO2(l) inj
17.09.2002 12:00
MRI
i
100B
15:00 K->0
2C K~1 20:30 K=0
inj CO2(l) 15m l/h
18.09.2002 12:00
20:00 K=0 inj 2.5m l H2O
19.09.2002 12:00
20.09.2002 12:00
CO2 Hydrate Formation at 2oC
MRI Intensity (H2O(l))
1,2
Heating Sample to 20 oC
1,0
0,8
0,6
0,8
Hydrate formation at 2C 0,6
0,4
0,4 0,2
0,2
0
0,0 0
4
8
12
Tim e [hours]
16
20
24
Fraction of Absolute Permeability
1
1,4
CO2 Hydrate Formation at 2oC as Function of [CO2 ] 0.008
[CO2] decrease Liquid Water Concentration
0.007
0.006
0.005
Time development (24hrs at 2C)
0.004
0.003
0.002
0.001
0.000 0
1
2
3
4
5
Length [cm]
6
7
8
9
2-D Dynamics of CO2 Hydrate Formation at 2oC 252 242 232 222 212 202 192 182
CO2 increase
172
0,7-0,8 0,6-0,7
142
0,5-0,6
132
0,4-0,5
122
0,3-0,4
112
0,2-0,3
102
0,1-0,2
92
0-0,1
82 72 62 52 42
12 252
242
232
222
212
202
192
182
172
162
152
142
132
122
112
102
92
82
72
62
52
42
32
2 22
0,8-0,9
152
22
12
0,9-1
162
32
2
Liquid water intensity
2-D Dynamics of CO2 Hydrate Formation at 2oC 252 242 232 222 212 202 192
CO2 increase
182
0,8-0,9
162
0,7-0,8
152
0,6-0,7
142
0,5-0,6
132
0,4-0,5
122
0,3-0,4
112
0,2-0,3
102
0,1-0,2
92
0-0,1
82 72 62 52 42 22 12 252
242
232
222
212
202
192
182
172
162
152
142
132
122
112
102
92
82
72
62
52
42
32
22
2 12
0,9-1
172
32
2
Liquid water intensity
2-D Dynamics of CO2 Hydrate Formation at 2oC 252 242 232 222 212 202 192
Liquid water intensity
182 172 162 152
CO2 increase
142
112
0,2-0,3
102
0,1-0,2
92
0-0,1
82 72 62 52 42
252
242
232
222
212
202
192
182
172
162
152
142
132
122
112
102
92
82
72
62
52
42
0,5-0,6
0,3-0,4
2 32
0,6-0,7
122
12 22
0,7-0,8
0,4-0,5
22
12
0,8-0,9
132
32
2
0,9-1
2-D Dynamics of CO2 Hydrate Formation at 2oC 252 242 232 222 212 202 192 182 172 162
0,7-0,8 0,6-0,7
132
0,5-0,6
122
0,4-0,5
CO2 increase
112 102 92 82 72 62 52 42
12 252
242
232
222
212
202
192
182
172
162
152
142
132
122
112
102
92
82
72
62
52
42
32
2 22
0,8-0,9
142
22
12
0,9-1
152
32
2
Liquid water intensity
0,3-0,4 0,2-0,3 0,1-0,2 0-0,1
CH4 Hydrate Formation at 6oC
0,007
[CH4] decrease
0,006
Liquid W ater Intensity
0 hrs
0,005
0,004
0,003
0,002
0,001
0,000 55
75
95
115
135
Core Length [pixels]
155
175
195
CH4 Hydrate Formation at 6oC 0,007
0.5 hrs
[CH4] decrease
Liquid W ater Intensity
0,006
0,005
0,004
0,003
0,002
0,001
0,000 55
75
95
115
135
Core Length [pixels]
155
175
195
CH4 Hydrate Formation at 6oC 0,007
1.5 hrs
[CH4] decrease
Liquid W ater Intensity
0,006
0,005
0,004
0,003
0,002
0,001
0,000 55
75
95
115
135
Core Length [pixels]
155
175
195
CH4 Hydrate Formation at 6oC 0,007
2.5 hrs
[CH4] decrease
Liquid W ater Intensity
0,006
0,005
0,004
0,003
0,002
0,001
0,000 55
75
95
115
135
Core Length [pixels]
155
175
195
CH4 Hydrate Formation at 6oC 0,007
3.5 hrs
[CH4] decrease
Liquid W ater Intensity
0,006
0,005
0,004
0,003
0,002
0,001
0,000 55
75
95
115
135
Core Length [pixels]
155
175
195
CH4 Hydrate Formation at 6oC 0,007
4.5 hrs
[CH4] decrease
Liquid W ater Intensity
0,006
0,005
0,004
0,003
0,002
0,001
0,000 55
75
95
115
135
Core Length [pixels]
155
175
195
CH4 Hydrate Formation at 6oC 0,007
5.5 hrs
[CH4] decrease
Liquid W ater Intensity
0,006
0,005
0,004
0,003
0,002
0,001
0,000 55
75
95
115
135
Core Length [pixels]
155
175
195
CONCLUSIONS • MRI is capable of imaging CO2 and CH4 hydrate formation and melting in porous media. • Observed formation of CO2 hydrate up to 8°C at 1200psi. • Hydrate formation was identified early, but the rate of hydrate formation decreased with time. Continuous hydrate formation was recorded after 24hrs. • A consumption of CO2/CH4 was measured during hydrate formation. • The core plug gradually became impermeable when hydrates formed. • The CO2 and CH4 hydrate formation tests were successfully reproduced.
Acknowledgements Acknowledgements Financial support support from from Financial The Norwegian Norwegian Research Research Council Council The and and Norsk Hydro Hydro Norsk and and ConocoPhillips ConocoPhillips
is highly highly appreciated appreciated is
