A multitude of options are available for reducing the continuous phase viscosity – and the effectiveness depends on the specific facilities site utilities available.

Option 1 – Temperature:

• Most common “additive” – requires fuel/energy source and heat management
• At least 150°C (300°F) to get to effective FSM treatment region
• Reduces density, interfacial tension, and coefficient of adhesion as well

Option 2 – Dissolved Liquids:

• Liquids dissolved into crude oil phase as thinning agent
• Natural gas condensate (C₅₊), naphtha, kerosene, etc.
• Must be recovered-recycled to be cost effective
• ~10 wt.% gets viscosity in effective FSM treatment region
• Reduces density, interfacial tension, and coefficient of adhesion as well

Option 3 – Miscible Gas:

• Not commonly looked at as thinning agent
• Solution gas, methane, CO₂, and flue gas are viable candidates
• Requires pressure and time to dissolve gas – more effective at normal temperature range

Option 4 – Shear Thinning:

• Decrease in viscosity due to shear strain
• High shear zones (i.e., inside pump impellers or vortex field in cyclones) reduce local viscosity – due to break up of particle (e.g., wax, asphaltene, etc.) aggregates
• Minor, but important, effect

Option 5 – Other:

Chemical Modifiers

• Polymer (biphasic) viscosity reducers – create water external dispersion (reverse oil and water role) and reduce apparent viscosity; useful for transport but not FSM
• Ionic liquids – asphaltene (aggregate) modifiers; 10-35% reduction

Pulsed Electric/Magnetic Field

• Magnetic pulse for paraffin and electric pulse for asphaltene
• Rearranges paraffin and asphaltene particles temporarily (several hours)
• 20% reduction in cP with paraffinic crude and 14% reduction with asphaltenic crude (using 1.33 T pulse)

Ultrasonic energy

• Still being investigated – complex phenomena

References:

1. Rawlins, C.H. 2019. “Enhanced Production Through Surface Facilities Sand Management.” SPE Distinguished Lecturer presentation. Link here

Next week I will discuss effect of viscosity on FSM unit process design.