OPTIMIZING DEFOAMER USAGE IN DRILLING &
CEMENTING APPLICATIONS:
TECHNOLOGY REVIEW & TESTING METHODOLOGIES
Luciana Bava, Amir Mahmoudkhani, Robert Wilson, Leanne Levy, Patricia De
Palma and Henry Masias
Atlanta R&D Center, Atlanta, Georgia, USA
Buenos Aires, 7 al 10 de agosto de 2012
Foam Generation
• Foam is a colloidal dispersion of gas in a
liquid or a solid.
• Pure liquids do not foam
 Tap water, in spite of being aerated,
does not foam
 Bubbles collapse immediately on the
surface
• To generate foam, it is necessary to
have a surface active component that
stabilize the inclusion of dissolved and
entrained gasses.
2
Foaming/Defoaming Systems
Examples of foaming/defoaming systems in upstream Oil & Gas
industry under dynamic fluid conditions
Aqueous
Systems
Non-aqueous
Systems
•Water-based Drilling Muds
•Cement Slurries
•Foam Drillings / Cementing
• Oil & Gas Separators
• Oil-based Drilling Muds
Well Completion
Cement
Drilling and Cementing Additives
• Most common additives used to modify the behavior of drilling and
cement systems are surface active molecules that cause the working fluid
to foam during mixing
• Such additives include:
– Cement: retarders, dispersants, fluid loss control additives, gas migration control agents
and ductility improvement additives.
– Water base drilling muds: salinity chemicals, dispersants, lost circulation materials and
gelling agents and viscosifiers
Cement G + Gas Migration Additive Blend, 1800 ikg/m3 - without defoamer
(left), with defoamer (right)
Foam in Drilling and Cementing Operations
• Excessive slurry foaming can have several undesirable consequences:
– Loss of hydraulic pressure during pumping can occur owing to cavitation in the
mixing system
– Air entrainment may cause higher than desired slurry densities
– Air entrainment also increases the risk of gas permeability and of improper
wetting and mixing
– Liquid or Dry Defoamers are used
Well Cementing – Cement Mixing
Recirculating Centrifugal Pumps
(max 4000 L /min)
Slurry Tubs: 1000 – 8000 L
Well Cementing – Cement Mixing
Solids Mix:
Liquids Mix:
Cement + Solid Additives
Water + Water-Soluble Additives
Dry
Defoamers
Cement Slurry
Liquid
Defoamers
Solids + Liquids
Foam
Generation
Performance Evaluation
Methods
Non-Systematic Testing Methods




Blender Foam Test
Simple & inexpensive
Good for initial screening
Measurements based on foam height
May not accurately represent system
under study (A vs. B)
 Single point data
 Single shear rates and fix mixing time
 Difficulty in replicating field conditions
Foam Height
Sparge Foam Test
A
Time
B
Modified Blender Test
Mahmoudkhani et al., “An Innovative Approach for Laboratory Evaluation of Defoamers for Oilfield
Cementing Applications”, SPE 143825, Brasil Offshore Conference and Exhibition, Brazil, June 2011
Foam and Entrained Air Test (FEAT)
Ancillary
Gas
DFM
Density & Flow Meter
Data Recording
Foam
Cell
Variable Rate
Pump
P
Temp
Controller
Drain
12
Foam and Entrained Air Test (FEAT)
Data collected every 0.5 second
At precision of 0.00005 g/mL
Fluid composition may be altered by
addition of chemical components at any
point during the test
Defoamer performance
Solids Mix:
Liquids Mix:
Cement + Additives
Water + Water-Soluble Additives
Blender Test
Cement Slurry
FEAT Study
Solids+Liquids
This comprehensive study approach (FEAT + Blender) is needed for proper laboratory
validation and qualification under simulated field conditions (accounting for different
dosage practices, additives, mixing regimes, etc.)
Performance Evaluation:
Defoamer Chemistry &
Cement Additives
Dispersant-Salt System
FEAT analysis of silicone and non-silicone chemistries on 4% sodium
polynaphthalenesulfonate + 30% salt solution.
Dispersant-Salt System
Blender foam test data in the dispersant-salt system, 4% sodium
polynaphthalenesulfonate + 30% salt solution. All defoamers are
dosed at 0.20% BWOC (by weight of cement)
Latex System
Silicone A
Non-Silicone D
Blank
FEAT analysis of silicone and non-silicone chemistries on latex solution.
Latex System
Blender foam test data in latex system. All defoamers are dosed at
0.20% BWOC (by weight of cement)
PVA (fluid loss additive) System
Blender foam test data in latex system. All defoamers are dosed at
0.20% BWOC (by weight of cement)
Dry vs. Liquid Defoamers
Mixing Solids:
Mixing Liquids:
Cement + Additives
Water + Water-Soluble Additives
Dry
Defoamers
Liquid
Defoamers
Cement Slurry
Solids + Liquids
 Dry Defoamers are prefer for better stability, ease of handling and storage
 Dry Defoamers are suitable for harsh climate areas
 Cannot be used as trimmer, a second (and liquid) defoamer is required
Improved / Fast Release Dry Defoamers
Conventional Dry Defoamers (silica)
High Surface Area Solids
High adsorption
Adsorption
Slow / incomplete release
Release
Improved / Fast Release Dry Defoamers
Substrate
Defoamer
Fast Release vs. Conventional Dry Defoamers
FR Dry: fast release dry defoamer
Dry: conventional dry defoamers
Liq: liquid defoamer
Fast Release Dry Defoamers:
• Outperform conventional Dry Defoamers with a performance level comparable to Liquid Defoamers
• Reach maximum performance at lower dosages
Summary 1: Foam Generation and Testing
1. What cause foaming?
Additives: Dispersants, Salt, PVA, Latex, etc.
2. Where foaming is created?
3. Test Methods
Blender (static, single point data)
FEAT (dynamic / multipoint data)
Summary 2: Choice of Defoaming Chemistry
Summary 3: Form of Defoamer (Liquid, Conventional Dry or Fast Release)
Thank you
luciana.bava@kemira.com
patricia.depalma@kemira.com