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


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


2-5 million cp


200,000 cp9-10 API

Peace river bitumen

1-30,000 cp

11 APICold lake bitumen


• 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


••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


••Unstable displacementUnstable displacement••Fingering, instabilityFingering, instability••Advection, diffusion, gravity Advection, diffusion, gravity segregation, and viscositysegregation, and viscosity••Compositional variationCompositional variation

Fluid mixingFluid mixing


Demo 1 –Assessing development projects

Demo 2 –Management of reservoirs

Simulation with shales


• 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

VAPEX

Documents

Transcript of VAPEX