1. Atlanta R&D Center, Atlanta, Georgia, USA
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

2. 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.

3. Foaming/Defoaming Systems
Examples of foaming/defoaming systems in upstream Oil & Gas industry under dynamic fluid conditions
Water-based Drilling Muds
Cement Slurries
Foam Drillings / Cementing
Aqueous Systems
Oil & Gas Separators
Oil-based Drilling Muds
Non-aqueous Systems

4. Well Completion
Cement

5. 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)

6. 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

7. Well Cementing – Cement Mixing
Recirculating Centrifugal Pumps
(max 4000 L /min)
Slurry Tubs: 1000 – 8000 L

8. Well Cementing – Cement Mixing
Cement Slurry
Solids + Liquids
Liquids Mix:
Water + Water-Soluble Additives
Solids Mix:
Cement + Solid Additives
Dry Defoamers
Liquid Defoamers
Foam Generation

9. Performance Evaluation Methods

10. Non-Systematic Testing Methods
Sparge Foam Test
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 A B
Time

11. Modified Blender Test
Mahmoudkhani et al., “An Innovative Approach for Laboratory Evaluation of Defoamers for Oilfield Cementing Applications”, SPE , Brasil Offshore Conference and Exhibition, Brazil, June 2011

12. Foam and Entrained Air Test (FEAT)P
DFM
Variable Rate
Pump
Density & Flow Meter
Temp
Controller
Foam
Cell
Data Recording
Drain
Ancillary
Gas

13. Foam and Entrained Air Test (FEAT)
Data collected every 0.5 second
At precision of g/mL
Fluid composition may be altered by addition of chemical components at any point during the test

14. Water + Water-Soluble Additives
Cement Slurry
Solids+Liquids
Liquids Mix:
Water + Water-Soluble Additives
Solids Mix:
Cement + Additives
Defoamer performance
Blender Test
FEAT Study
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.)

15. Performance Evaluation: Defoamer Chemistry & Cement Additives

16. Dispersant-Salt System
FEAT analysis of silicone and non-silicone chemistries on 4% sodium polynaphthalenesulfonate + 30% salt solution.

17. 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)

18. Latex System
Silicone A
Blank
Non-Silicone D
FEAT analysis of silicone and non-silicone chemistries on latex solution.

19. Latex System
Blender foam test data in latex system. All defoamers are dosed at 0.20% BWOC (by weight of cement)

20. PVA (fluid loss additive) System
Blender foam test data in latex system. All defoamers are dosed at 0.20% BWOC (by weight of cement)

21. Water + Water-Soluble Additives
Dry vs. Liquid Defoamers
Cement Slurry
Solids + Liquids
Mixing Liquids:
Water + Water-Soluble Additives
Mixing Solids:
Cement + Additives
Dry Defoamers
Liquid Defoamers
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

22. Improved / Fast Release Dry Defoamers
Conventional Dry Defoamers (silica)
High Surface Area Solids
Adsorption
Release
High adsorption
Slow / incomplete release
Improved / Fast Release Dry Defoamers
Substrate
Defoamer

23. 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

24. Blender (static, single point data) FEAT (dynamic / multipoint data)
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)

25. Summary 2: Choice of Defoaming Chemistry

26. Summary 3: Form of Defoamer (Liquid, Conventional Dry or Fast Release)

27. Thank you