Post on 21-Jul-2015
transcript
Change in wettability and enhancing
recovery: application for traditional and
non-traditional fields.
Geoffrey Thyne and Teresa Nealon
1 -
Outline
• What is this technique?
• Why use this technique?
• Science and Engineering.
• Practical Aspects.
• Take Home.
Why do we care about wettability?
• In petroleum reservoirs wettability is the tendency of oil to
adhere to the rock limiting oil movement and recovery.
• Wettability is an important control on the amount of recovery.
• We try to improve wettability by adding surfactants to make
the reservoir more water-wet.
Wettability
• “Hydrocarbon-wet systems retard hydrocarbon mobility”.
• “Water-wet systems promote hydrocarbon mobility”.
• But really we want to be in the middle of the wettability range
Oil-Wet Water-Wet
SPE 157094
Just making the reservoir more water-wet
may not optimize recovery
Sweet Spot
Start here
How do we link wettability to salinity?
• Wettability is the equilibrium between water, rock and oil.
• Wettability is dependent on the balance of forces between
the oil-water and water-rock interfaces.
• Forces (pressure) between surface with a water film and
oil are composed of -
– 1 – electrostatic (attractive or repulsive),
– 2 – van der Waals (attractive),
– 3 – structural or hydration (repulsive below 3-4 nm).
Hirasaki, 1991
Why Alter Wettability by Salinity?
• No Change in Normal Operations.
• Increase in Recovery is High (5-25% OOIP).
• Increase Reserves.
• Cost is Low.
• Works in Clastics and Carbonates.
• Response is Rapid (3-9 months).
• No Surfactants ($$).
• No Environmental Impact.
Key Practical Factors
• Water source can be produced water, imported water, on-site water.
• CAPEX is water treatment equipment.
• OPEX is water treatment maintenance.
• Disposal of treatment reject.
• Recoverable Oil (in-situ saturation).
• Operational Wells (#).
Industry Work Flow
• Evaluate reservoir conditions, water and oil
chemistry and rock properties (mineralogy,
mineral habitat, architecture).
• Preliminary design.
• Laboratory tests.
• Calibrated design.
ESal™ Work Flow
• Evaluation (is my field a good candidate?) – Screening – Generate Field Score
• empirical model generates quantitative score based on field, oil, water and rock properties
• preliminary water source assessment
– Scoping – Economic Assessment of Projects • expense/profit modeling (modified Kinder-Morgan)
• multiple economic evaluations and scenarios
• Experiments and Models – Wettability Measurements
• rapid scan to find optimum chemistry
– Modeling to assess other fluid-fluid-rock interactions
– Design injection fluid chemistry for optimum wettability
• Deployment – Select water source
– Generate water treatment specifications
– Install equipment
Use lab and field data to determine empirical relationships.
Input rock, water, oil and field properties to algorithm and
calculate aggregate weighted score.
Screening for good candidates
Scoping - Economic Benefits Most expensive cost scenario and $50/BBL
Reservoir OOIP wells %OOIP Project Life CumPreTax ($)
Formation BBLS in field recovery Years millions
Nugget 3 127,744,810 19 5 9 64.27
127,744,810 10 11 257.64
127,744,810 15 12.75 476.06
Nugget 2 46,115,627 18 5 7.5 14.39
46,115,627 10 10 81.50
46,115,627 15 10.5 154.61
Almond 40,486,587 125 5 10.25 20.61
40,486,587 10 8.5 79.89
40,486,587 15 9.75 148.94
Mesaverde 2 16,025,030 59 5 8.5 7.36
16,025,030 10 11 32.24
16,025,030 15 10.5 58.28
Nugget 1 9,617,523 10 5 10 4.76
9,617,523 10 10 19.37
9,617,523 15 10 35.05
Inputs
Capex and Opex
Royalty & Taxes
Pricing
Analog Method
(KinderMorgan)
Outputs
Incremental Recovery,
IRR, Revenues, NPV’s
Cum PreTax, etc.
Lab Tests - Modified Floatation
13
Initial separation
After 24 hours
Wettability Models
• Model of aqueous, oil and surface reactions.
• Double layer models assume surfaces are coated with
water and electrostatic forces are dominant.
Take Home Message
• Wettability Alteration can be employed at all stages of
operations.
• Can be deployed during drilling (unconventional).
• Can be deployed at the start of waterflood (secondary
mode).
Take Home Message
• Can be employed at end of waterflood
(tertiary mode).
Take Home Message
Questions?