Emulsions
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Transcript of Emulsions
Emulsions
• Multiple phases that do not separate quickly; usually requires an energy source.
• If oil and water do not separate quickly, then look for the stabilizing mechanism
• Emulsions are frequently blamed for damage, however, most emulsions are formed in the tubing or lift system by gas breakout or added energy.
• Emulsions create back pressure by high viscosities. They also may cause facility upsets that shut-in fields.
8/25/2015 1 George E. King Engineering
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Types of Emulsions
• oil-in-water
• water-in-oil
• gas-in-water (foams and froths)
• solids-in-liquids (muds, etc.)
• Over twenty different combinations that can be called emulsions.
8/25/2015 3 George E. King Engineering
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Foaming of returns can be a major problem.
Have a defoamer on hand?
8/25/2015 4 George E. King Engineering
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Among the worst - Asphaltic Sludges
• Form very viscous masses, often after contact with spent acid; frequently catalyzed by iron
• Sludges are serious problems because they cannot be easily removed.
• Test the oil with spent acid and 1000 ppm iron before acidizing any oil reservoir.
8/25/2015 5 George E. King Engineering
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Oil based mud cleanup is a special case, requiring dispersal of the OBM emulsifying agents and wetting of the particles to prevent damage. Contact with acid, as shown, will produce some severe sludges that are very difficult to break.
8/25/2015 6 George E. King Engineering
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A 50-50 mix of 14 ppg OBM and 15% HCl. The resultant sludge formed immediately and was stable for months.
8/25/2015 7 George E. King Engineering
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Stabilizers
• surfactant (film stiffeners)
• solids (silt, rust, wax, scale, cuttings)
• emulsion or component viscosity (prevents particle or droplet contact)
• Electrical charge (minor influence in most cases).
8/25/2015 8 George E. King Engineering
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Increasing internal fraction of the “emulsion”
52% 74% 96%
Viscosity
Widely Dispersed Contact
Deformation
Inverted
Changes in Fluid Viscosity with Change in Internal Phase of Dispersed or Emulsified Flow
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Energy Sources
• lift system
• gas breakout
• shear at any point in the well
• choke
• gas expansion
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The type of flow pattern changes with the expansion of the gas. One or more of the flow patterns may be present in different parts of the well. The flow patterns may explain differences in lift, corrosion and unloading.
Mist Flow – external phase is gas with a small amount of liquid
Channel or annular flow
Slug or churn flow
Piston flow
Bubble flow
Single phase liquid flow
Depth and Pressure
8/25/2015 11 George E. King Engineering
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