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Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Deep Sea Hydrate Flow Assurance Challenges
Kelly Miller
Center for Research on Hydrates and Other SolidsColorado School of Mines
Norway - North America Petroleum Research WorkshopNovember 2, 2005
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
The CSM Hydrate Flow Assurance Team
John Boxall, Craig Taylor, Patrick Rensing, Joseph Nicholas, David Greaves, Simon Davies, Kelly Miller, Carolyn Koh, Dendy Sloan
Industrial CollaboratorsPatrick Matthews, Alberto Montessi, Ron Morgan,
Larry Talley, Douglas Turner, Zheng Gang Xu
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Acknowledgements
DeepStar
CSM Hydrate Consortium
Additional Funding: NSF, DOE, NURP
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Hydrate Flow Assurance Challenges
� Oil & Gas Production Moving to Harsher Conditions• Longer Flowlines• Transient Behavior: Shut-in and Restart• Traditional Hydrate Inhibition Impractical
� Need to Manage Hydrate Formation• Thermodynamics• Nucleation and Growth Kinetics• Aggregation and Flow Behavior• Hydrate Detection
� CSM Goal: Develop Tool to Predict Blockage Formation• If• Where• Approximately When
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
SimulationCSMHyK / OLGA 2000
Laboratory� Autoclave Cell� Particle Size Analysis� Rheometry� Micromechanical Testing� Calorimetry
Flow Loops• Texaco• ExxonMobil• University of Tulsa
CSM Hydrate Flow Assurance Approach
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
SimulationCSMHyK / OLGA 2000
Laboratory� Autoclave Cell� Particle Size Analysis� Rheometry� Micromechanical Testing� Calorimetry
Flow Loops• Texaco• ExxonMobil• University of Tulsa
CSM Hydrate Flow Assurance Approach
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
CSMHyK Hydrate Kinetics ModuleOLGA 2000: Industry Standard for Transient Multiphase Flow
fluid properties thermodynamic properties
system properties
growth rateamount of hydraterelative viscosity
CSMHyK Module
PipelineSection n-1
PipelineSection n
PipelineSection n+1
Yes
No DissociationModel
Hydrates?
FormationModel
ThermoProperties
RelativeViscosity
DrivingForce
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Subcooling [K] �T=Teq-Top
0 1 2 3 4 5 6
Mol
es c
onsu
med
[mol/m
2 -sec]
0.0000
0.0001
0.0002
0.0003
278 K281 K284 KRegressed
Subcooling (K)
Met
hane
Con
sum
ed(m
ol /
m 2
s)Experimental Goal: Improve Model Assumptions
CSMHyK Assumptions
� Formation model• First order rate equation, proportional to:
� Subcooling� Water surface area
• Rate constant regressed from Bishnoi’smethane-water data
� Rheology model (Camargo & Palermo)• Hydrate aggregation in oil• 40 µm primary particles• Aggregates partially broken by shear• Aggregates flow as effective hard spheres
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
CSMHyK / OLGA 2000:Flow Loop Gas Consumption Predicted
600
700
800
900
1000
1100
1200
0 2 4 6 8 10 12 14 16 18 20Time (hr)
Pres
sure
(psi
a)
DataModel
Two fitting parameters:
� Subcooling atnucleation (matched toexperiment)
� Modified rate constantk = u kB
Petronius Oil in Texaco Flow Loop, 35 GPM Flow Rate
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Industrial Use of OLGA/CSMHyK:Heat Transfer from Flow Line Limits Formation
30
40
50
60
70
80
90
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000Distance (m)
Tem
pera
ture
(F)
ambient T
hydrate formation T
10% water cut Alberto Montessi,Chevron
Understanding Hydrate Slurry Behavior is Key!
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
SimulationCSMHyK / OLGA 2000
Laboratory� Autoclave Cell� Particle Size Analysis� Rheometry� Micromechanical Testing� Calorimetry
Flow Loops• Texaco• ExxonMobil• University of Tulsa
CSM Hydrate Flow Assurance Approach
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Conceptual Model forHydrate Plug Growth
Water
Oil
time, distance Hydrate Shells
WaterEntrainment
Hydrate ShellGrowth Agglomeration Plug
Gas
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
10-6
10-5
10-4
10-3
101 102 103 104
Conroe (Flow Loop)ConroePetroniusWest AfricanAlbacora Leste
Mea
n D
ropl
et D
iam
eter
(m)
��/� (m-1)
•
d �
��10/9
��1/2
�3/5
250
•
d = mean diameter� = shear rate� = oil viscosity� = oil/water interfacial tension
•
Water Entrainment: Droplet Size PredictableFrom Oil Properties, Shear
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Hydrate Growth:Water Droplets Directly Convert to Hydrates
Particle Size Distribution Unchanged Upon Hydrate Formation
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Hydrate Growth From Water Droplets
� Hydrates Grow as Shell onDroplet Surface
� Three Kinetic Limitations• Intrinsic crystal growth kinetics• Mass transfer through oil, hydrate• Heat transfer from hydrate
� Moving Toward Integrated ModelConsidering All Three Effects
Oil
Water
Hydrate Shell
Gas
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
100
101
102
103
100 101 102 103 104
34 vol%27 vol%22 vol%12.5 vol%10 vol%7.5 vol%5 vol%0 vol%
Visc
osity
(mPa
s)
Shear Rate (s-1)
Strongly Suggests Particle Aggregation
T = 4 oC
THF Hydrate/Oil Slurries:Shear Thinning, Yield Stress Fluids
0
1
2
3
4
5
6
7
8
0 0.1 0.2 0.3 0.4 0.5Yi
eld
Stre
ss (P
a)Volume Fraction
T = 4 oC
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
0
5
10
15
20
25
30
35
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
Hydrate volume fraction
�P
(psi
)
Anti-agglomerantsNo anti-agglomerants
Speed: 520 RPM (+)Gas Fraction: 46% (+)Water Cut: 35% (+)
Flow Loop: Aggregation Causes Large ?P
Need to Understand Agglomeration Under Real Conditions
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Hydrate Flow Assurance:Research Challenges
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Hydrate Plug Growth Research Challenges
Water
Oil
time, distance Hydrate Shells
WaterEntrainment
Hydrate ShellGrowth Agglomeration Plug
Gas
Need to Understand and Quantify MechanismsNeed Real World Flow Line Data
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Water Entrainment:Emulsion Formation and Stability
Water
Oil
time, distance Hydrate Shells
WaterEntrainment
Hydrate ShellGrowth Agglomeration Plug
Gas
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Emulsion Formation and Stability
� Hydrates Form at Water-Oil Interface� Emulsion Formation: Predictable Drop Size?
• Crude Oil Properties• Shear in Flow Lines
� Emulsion Property Quantification• Stability and Aging• Surface Properties of Water-in-Oil Emulsions• “Non-plugging” Brazilian Crude Oils
� High Water Cuts• End-of-Life Fields: Up to 90% Water
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Hydrate Nucleation and Growth
Water
Oil
time, distance Hydrate Shells
WaterEntrainment
Hydrate ShellGrowth Agglomeration Plug
Gas
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Hydrate Nucleation and Growth
� Nucleation Mechanisms• Traditional Nucleation
� Induction subcooling: outrunning the hydrates• Particle Collision• Effect of Oil Chemistry
� Formation Rates and Mechanisms• Shell Growth• Interior Growth
� Kinetic Inhibitors• Nucleation Inhibition• Growth Inhibition
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Hydrate Aggregation and Rheology
Water
Oil
time, distance Hydrate Shells
WaterEntrainment
Hydrate ShellGrowth Agglomeration Plug
Gas
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Hydrate Aggregation and Rheology
� Even Small Amounts of Hydrates Could Cause Plugs� Need to Understand and Quantify Complex Slurry
Mechanical Properties• Hydrate volume fraction• Hydrate microstructure
� Shells, particle size, particle roughness, aggregate fractaldimension
• Oil properties• Multiphase morphology
� Hydrates in oil, hydrates in water, hydrate slippage� Hydrate Adhesion Strength
• Hydrate-hydrate and hydrate-wall• Temperature dependence
� Anti-agglomerants
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Hydrate Blockage Formation
Water
Oil
time, distance Hydrate Shells
WaterEntrainment
Hydrate ShellGrowth Agglomeration Plug
Gas
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Blockage Formation: What Is A Plug?
� Qualitative Descriptions• Slush-like, powder-like, dry hydrates, etc.• Pass/fail results for flow loop, wheel tests• Continuous behavior can masquerade as qualitative changes
� Need a Quantitative Answer for “What is a Plug?”• Multiphase problem• Complex fluid: hydrates, oil, gas, water, wax
� Answer Will Involve:• Mechanical properties of multiphase mixture
� Yield stress, viscosity, shear thinning behavior, etc.• Multiphase flow regime and fluid morphology• Flow line dimensions, driving pressure• “In pipeline x, a plug has a yield stress �, a viscosity �, and spans
the pipeline”
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Cold Slurry Flow
Water
Oil
time, distance Hydrate Shells
WaterEntrainment
Hydrate Seedingand Growth Hydrate Flow
Gas
Requires Understanding of Nucleation, Growth, Aggregation
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Gas Dominated Systems
� Very Different Mechanisms from Oil Systems
� Need Basic Understanding of Mechanisms• What is the conceptual picture?• Hydrate formation in mist?• Hydrate formation on contact with wall?
� Field Data is Available
Center for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of MinesCenter for Research on Hydrates & Other Solids, Colorado School of Mines
Conclusions
� CSM is developing CSMHyK, a hydratekinetics simulator integrated into OLGA2000
� Need to understand and quantify hydrateformation mechanisms• Emulsion formation and stability• Hydrate nucleation and growth• Hydrate aggregation and complex slurry rheology• Quantitative definition of pipeline blockage• Cold slurry flow• Gas dominated systems