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Best Practices
in Offshore Heavy Oil Development
Cesaltino Matias Pedro
Petroleum Engineer
AcknowledgmentDr. William John LeeDr. Jerome. J. Schubert
Dr. Ben D. Welch
18th February 2009, Angola SPE Section - Luanda
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Background Motivation
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Background Motivation
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Background MotivationAbundant heavy oil resources discovered.
Only +/- 8% of production is from heavyoil.
Over 90% of heavy oil production is fromonshore heavy oil fields.
Increasing demand of fossil fuel leadingto oil price increases.
Continuous technological advancements.
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Background Challenge Offshore Environment.
Remote locations Challenging water depths Reduce space
Fluid properties. High viscosity High sulfur content High TAN number
Reservoir properties. Low reservoir pressure Low reservoir temperature
Unconsolidated formation
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Background Offshore
EnvironmentComplex and expensive producing and
processing facilities.Challenging wells geometry.
Flow assurance problems. Low temperature of flow lines
Oil/water emulsions Solids production
Limited deck space.
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Background Fluid PropertiesLow fluid mobility.
Challenging gas and/or waterfloodPoor well productivity.
Low product price.Reduced market.
Flow assurance problems. Temperature drop in wellbore
Oil/water emulsions
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Background Reservoir
PropertiesChallenging wells to drill.
Well control
Extended reach
Horizontal and/or multilateral
Challenging well completion.
Poor lifting mechanism
Sand production
Low recovery.
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Best Practices Best practices are those practices that members of the industry
agree add significant value to projects and have been in use by the
Project Management teams;(they may have not been validated through IPAs statistical methods).
The recognition and implementation of existing best practices inoffshore heavy oil developments improves the probability of asuccessful development.
Offshore heavy oil developments have been around for over 50years and past experiences showed that some can be economically
developed, when we are able to: Reduce the project implementation cost, Improve well productivity Market opportunities (location and/or high prices).
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Best Practices 3D SeismicIntegrate 3D Seismic interpretation with
local geological understanding
Generate correlations between seismiccharacteristics and reservoir properties.
Critical for reservoir characterization
Main source of data for reservoir simulation
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Best Practices Extended Well
TestPerform extended well test to mitigate
the uncertainty and risk to develop thefield and investigate future producingsystem
Mitigate risk and reduce uncertainty
Determine reservoir and fluid properties Understand producing system
Basis of design for the development plan
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Best Practices Heavy Oil
CharacterizationCapture oil samples in every well during
appraisal phase, measure PVT phasebehavior at reservoir and lowertemperature conditions, and pay special
attention to viscosity determination
Determine fluid properties Understand viscosity temperature
relationship
Production and processing system design
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Best Practices Heavy Oil
Characterization Viscosity: In a light oil reservoir, one sample may adequately
define a reservoir. In a biodegraded reservoir, this is not the case.
20% variation on a single oil sample has been recorded usingcurrent viscosity techniques
Heavy oil reservoirs are generally created by biodegradation/waterwashing of light oil. Since this process is dependent upon fluid
flow within the reservoir, the degree of contact and the amount ofbiodegradation within a reservoir is not uniform, thus, differencesin API gravity, viscosity, and other oil properties can be created.
Sometimes there are general trends in oil property changes withina reservoir. However, the non-uniform water contact generallycauses significant additional heterogeneities which overlay anygeneral trend which may exist, and make localized predictionsdifficult.
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Best Practices Extended Reach
Horizontal and/or Multilateral wellDrill extended reach horizontal and/or
multilateral wells
Increase well productivity
Optimizing the number of barrels producedby drilling-dollars spent
Optimized reduced number of wellbores
Manage pressure drop
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Best Practices Electric
Submersible PumpInstall electric submersible pumps as the
lifting system in the well completion
Enable wells to flow
Manage start up requirements
Lift high quantities of fluids (oil and water)
Allow some production of solids
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Best Practices Upgrade Heavy
OilMix light oil to the heavy oil by injecting
downhole or in the processing facilities
Modify heavy oil viscosity
Improve heavy oil properties
Increase product price
Increase well productivity
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Best Practices Water InjectionWater injection is the most successful
secondary (cold) recovery method
Improve sweep efficiency
Provide pressure support
Improve reserves recovery
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Key Challenges
Water Management
Sand management
Personnel on Board (POB)
Drilling costs
Slot constrained
Rig availability for workovers
Case History Captain
Best Practices
Performed extended well test
Horizontal wells
Water injection
Creative local solution Use of polymer toaugment waterflood results
Located offshore United Kingdom estimated to contain956 million barrels of 19oAPI oil, viscosity 88 cp
C
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Key Challenges
Thin reservoir sands
Distance to producing facilities
Regional weather Drilling costs
Case History Grane
Best Practices
Performed extended well test
Horizontal wells
Detailed study of reservoir fluids
Water and Gas injection
Creative local solution Oil stored in caverns
Located offshore Norway, 405 ft water depth, reservoirpressure of 2,466 psi, estimated to contain 755 millionbarrels of 19oAPI oil
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Key Challenges
Large bottom aquifer
Sand management
Tarmat layer
Drilling costs and smaller pools of reserves
High oil viscosity
Case History Jubarte
Best Practices
Performed extended well test
Horizontal wells
3D seismic interpretation
3D geological and simulation model
Phased development
Creative local solution Value of Information
Located offshore Brazil, over 3,500 ft water depth, reservoirpressure of 2,600 psi, estimated to contain 600 million barrels of 17o
API oil (dead oil viscosity 3,000 cp)
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What works
CO2 gas injection
Gas lift Progressive Cavity Pump
Viscosity modification by addition of heat High well density
Regular pigging of production lines
Polymer flood
Logging while drilling
Open hole wells
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Opportunities
Microbial application to upgrade oil downhole
Downhole catalytic upgrade 4D seismic cost reduction
Increase capacity to handle fluids duringextended well test
Open hole fracpack completion
Increase ESP tolerance to sand production Downhole fluids separation
Thermal bundled flowlines and well completions
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Acronyms
SAGD Steam Assisted Gravity Drainage
CSS Cyclic Steam Stimulation & Steamflood HOSGD Heavy Oil Solution Gas Drive
Vapex Vapor Assisted Petroleum Extraction MEOR Microbial Enhanced Oil Recovery
SARA Saturated Aromatic Resins & Aspalthenes
CHOPS Cold Heavy Oil Production with Sand
THAI Toe to Heel Air Injection
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Conclusions1. Successful development plans of heavy oil fields are
site specific, depending upon oil properties, possibility
to blend with light oil, price scenario, and availabilityof refinery and market for the product.
2. Completing producing wells with electric submersible
pumps is the most efficient lifting method for offshoreheavy oil developments.
3. Interpretation and integration of 3D Seismic with local
geology understanding is the most reliable source ofdata for reservoir and property characterization.
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Conclusions4. During the appraisal phase of a heavy oil offshore
development, extended well test is crucial to mitigate
risk and reduce uncertainties.5. Fluid identification and characterization is essential to
design extended well tests and producing and
processing facilities.
6. Drilling extended reach horizontal wells is thepreferred alternative to improve well deliverability for
offshore heavy oil developments.
7. To date Waterflood is recognized by the industry asthe most successful enhanced heavy oil recoverymethod.
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