VAPEX
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Transcript of VAPEX
Beyond CSS, SAGD and VAPEX
Heavy Oil and Oil Sands Reservoir Modeling
Zhangxin ChenUniversity of Calgary, NSERC/AERI/CMG Chair Professor
Participants
SynergiaPolygen Ltd
Outline
• Why? – Importance of the Research• Enhanced Recovery Methods:
- CSS (cyclic steam stimulation)- SAGD (steam assisted gravity drainage) - VAPEX (vapor extraction)
• Problems in Oil Recovery from Heavy Oil/Oil Sands
• Modeling Challenges
Importance of the research
• Reserves of unconventional oil are enormous worldwide and important to economy
• Conventional oil & gas in decline and must be replaced by unconventional resources
• New technology needed to reduce risk and costs and make environmentally sustainable
• Mathematical modeling important for process design & optimization
Importance of the research (cont’d)
• About 10 trillion barrels of heavy oil resources worldwide
•• Roughly triple the combined Roughly triple the combined world reserves of conventional world reserves of conventional oil and gasoil and gas
Global crude reserves by country
0
50
100
150
200
250
300
Saudi Canada Iraq Iran Kuwait AbuDhabi
Venez. Russia Libya Nigeria USA
Canada, with 174 billion barrels in Oil Sands reserves, ranks second only to
Saudi Arabia in global oil reserves
Source: Canadian Heavy oil Association
Proven reserves (billions of barrels)
Oil classification
<10>1,000>10,000Bitumen
10-20934-1,000100-10,000
Heavy oil
>10<934<100Conv. oil
Density (API)
Density (kg/m3)
Viscosity (cp)
Examples of heavy oil/bitumen
2-5 million cp
8-9 APIAthabasca bitumen
200,000 cp9-10 API
Peace river bitumen
1-300,00 cp
11 APICold lake bitumen
What is oil sands ?
• Composition Inorganic material (75-80%, of which 90% quartz sand)Water (3-5%)Bitumen (10-12%)
• Unconsolidated, crumbles easily in hands
Canadian oil sands growth
• Currently about 1.5 million b/d of oil sands (out of total 2.5 million b/d of oil production)
•• 2015=3.5 million b/d 2015=3.5 million b/d (out of total 4.5 million b/d of oil production)
In-situ represents a growing opportunity
Currently 65% of production is mined
More than 80% of reservestoo deep to mine Athabasca
River
Open Pit Mine
Open Pit Mine
Oil Sands
Enhanced recovery methods of Enhanced recovery methods of heavy oil reservoirsheavy oil reservoirs
• The principal obstacle in heavy oil (<20 API, >100 cp) recovery is the high viscosity. Any reduction in viscosity will increase the oil mobility.
Thermal methodsThermal methods NonNon--thermal methodsthermal methods
• CSS
• Steamflooding
• Hot waterflooding
• In-situ combustion (THAI)
• SAGD
• Waterflooding (polymers)
• Chemical flooding
• Immiscible CO2 flooding
• Solvents injection
• VAPEX
Enhanced recovery methods: CSS
• CSS was accidently discovered in 1957 when Shell Oil Company of Venezuela was testing a steam drive in the Mene Grande field.
Problems in oil recovery from oil sands
• In-place hydrocarbons (bitumen): too viscous and thus immobile.
• No communication between injection and production wells.
• Oil sands in shallow formations that do not contain superimposed injection pressures.
Partial solutions
• The viscosity can be lowered by application of heat in the form of:
Steam injection
In situ combustion
Conduction heating
Electrical heating
0.1
1
10
100
1000
10000
0 100 200 300Temperature, C
Pres
sure
, Kpa
1
10
100
1000
10000
100000
1000000
Oil
Vis
cosi
ty,c
P
Steam SaturationAthabasca Bitumen Visco
Thermal Method Favorable zone
( )gzPk
U ooo
oo ρ
μ−∇−= Oil phase effective permeability is a
control on oil flow rate.
Oil phase viscosity is the other.
Partial solutions (cont’d)
• The lack of communication between injection and production wells can be rectified by:
Fracturing
Use of steam stimulation of individual wells
Use of an existing bottom water zone linking the wells
Partial solutions (cont’d)
• Insufficient overburden is related to injection pressure requirements:
Reduction of well spacing to compensate for overburden
Use of horizontal wells
Enhanced recovery methods: SAGD
• Low recovery rate: 30% of initial oil in place
• Relatively new thermal concept: SAGD (steam assisted gravity drainage) by Butler in 1977-78
SAGD concept
SAGD (cont’d)
• Uses heating for viscosity reduction• Drive energy comes from gravity• Process is driven by heat transfer
between steam and cold oil• Heat can pass through rock grains• Thin shale layers are not a big barrier to
heat transfer
SAGD (cont’d)
• Up to 70% recovery• Commercial steam/oil ratio under favorable
conditions• High operating costs and environmental impact
Enhanced recovery methods: VAPEX
• Similar to SAGD, VAPEX (vapor extraction) involves injection of light hydrocarbon vapors such as propane, butane, or mixture of them as solvent into a reservoir to dilate and recover bitumen (late Butler, 1989).
Enhanced recovery methods: VAPEX (cont’d)
Unresolved issues & challenges of VAPEX
• Lower oil rate than SAGD• Loss of solvent to untargeted zones• Accumulation of non-condensable gas
in the vapor chamber• Formation damage by asphaltenes
precipitation• Hydrate formation
Examples of heavy oil/bitumen (cont’d)
2-5 million cp
8-9 APIAthabasca bitumen
200,000 cp9-10 API Peace river bitumen
1-300,00 cp11 APICold lake bitumen
Mining/SAGD
CSS
CSS
Modeling challenges
• Reservoir heterogeneities • Heterogeneities in fluid properties• Moving thermal fronts--thin• For thermal-solvent processes, moving mobile solvent-rich oil
layers are thin• Phase behavior important (e.g., VAPEX)• Presence of mud and shale layers, vertical flow barriers• Geomechanics important (e.g., shearing of sand at chamber edges)• Reactions (in situ combustion and upgrading)• Thin diffusion
Modeling challenges (cont’d)
Reservoir NOT Homogeneous
Modeling challenges (cont’d)
2-5 million cp
8-9 APIAthabasca bitumen
200,000 cp9-10 API
Peace river bitumen
1-30,000 cp
11 APICold lake bitumen
Modeling challenges (cont’d)
• Current simulation models are too simple, homogeneous and does not have sufficient physics for heavy oil/bitumen.
• Need detailed simulation models and robust algorithms that can capture physics.
• Need fast tools because hundreds to thousands of simulations are run for process design and uncertainty analysis.
Oil industry $2 mil8 @ $50K x 5 yr
AERI$1 mil
CMG/SEGP/CFI/SYNERGIAEquipment
$1 mil
NSERC$1 mil
5-year program
Foundation CMG$1 mil
U of CInfrastructure
THE CHAIR RESEARCH PROGRAM
Collaborators
THE CHAIR RESEARCH PROGRAMReservoir
Characterization: Drs. J. Jensen and
S. Larter DR. MANILAB EXPERIMENTS
MODELING
Reservoir Simulation:Drs. M. Dong, I. Gates, L. Nghiem, T. Harding,
and T. Settari
Lab Research:Drs. J. Abedi, R. Heidemann,
B. Maini, R. Mehta, G. Moore, and
T. Okazawa
Reservoir Geomechanics: R. Chalaturnyk, T. Settari, and
R. Wan
Students, PDFs, and RAs
Research resources
• Simulation software• Computing hardware (128 CPU Shared Memory)• Computer server room• CMG Simulation Laboratory• Visualization Centre (i-Centre)• Tomographic Imaging/Porous Media Lab• Advanced oil recovery laboratories• Administrative and technical support staff and
systems• Graduate students and PDFs
Lab Experimental Set Up
Steam
Water
Load Cell
Data Acquisition
Model Temp
Temp
Steam
Weight Cum Steam Inj.
Oil/Water Production
Modification
Modification
Applications
Oil
Oil & Water Mixture
Water
Wells
Modelling of a Reservoir
Applications (cont’d)
THAI ModelModelling Complex Layers & Slanted
Wells
Complex Flow Due to Heterogeneous Geology
Applications (cont’d)
••Given a rock volume, where Given a rock volume, where would the petroleum be found?would the petroleum be found?••Use fluid flow simulations to Use fluid flow simulations to simulate reservoir filling, simulate reservoir filling, charging history.charging history.••For well planning, field For well planning, field economicseconomics••For quantification of mixingFor quantification of mixing
Tracer studyTracer study
Applications (cont’d)
••Unstable displacementUnstable displacement••Fingering, instabilityFingering, instability••Advection, diffusion, gravity Advection, diffusion, gravity segregation, and viscositysegregation, and viscosity••Compositional variationCompositional variation
Fluid mixingFluid mixing
Applications (cont’d)
Demo 1 –Assessing development projects
Demo 2 –Management of reservoirs
Simulation with shales
Applications (cont’d)
• Demo1 – Well architectureWell architecture• Demo2 – Adaptive gridsAdaptive grids• Demo3 – Conner point correction • Demo4 – Streamlines• Demo5 – Fault treatment
Conclusions
• Thermal/solvent processes for heavy oil/bitumen are difficult to simulate. With sufficient physics and good geological characterization, significant improvement in modeling and simulation will be made.
• With all the new tools (gridding, solvers, parallelization, and computer hardware) significant improvements in simulation robustness and speed and optimization algorithms will be made.
• All these mean significant savings in capital costs.
Three recent books
• Finite Element Methods and Their Applications
• Z. Chen• Year 2005• Textbook & reference
Three recent books (cont’d)
• Computational Methods for Multiphase Flows in Porous Media
• Year 2006• Z. Chen, G. Huan and Y.
Ma• Textbook and reference
Three recent books (cont’d)
• Reservoir Simulation: Mathematical Techniques in Oil Recovery
• Year 2007• Z. Chen• CBMS-NSF Regional Conference
Series in Applied Mathematics
Acknowledgements