Crude Oil Interfacial Tension Reference

Water-Oil Interfacial Tension (IFT) for Various Crude Oil Types

Key Information

Interfacial Tension (sigma): Measured in mN/m or dynes/cm (1 mN/m = 1 dyne/cm)
Typical Range: 20-40 mN/m for crude oil-water systems at atmospheric conditions
Measurement Conditions: Deionized water at atmospheric pressure
Temperature Effect: IFT typically decreases ~0.2 mN/m per degree C increase (at atmospheric pressure)
API Gravity Correlation: Heavier crudes (lower API) generally have lower IFT due to higher asphaltene/resin content

Important Note: The IFT values shown are estimates based on API gravity correlations and literature data. Actual IFT values can vary significantly based on crude oil composition (especially asphaltene/resin content), water salinity, pH, and measurement conditions. For critical applications, laboratory measurements are recommended.

LightAPI > 31° | IFT: 33-40 mN/m

MediumAPI 22-31° | IFT: 28-35 mN/m

HeavyAPI 10-22° | IFT: 20-30 mN/m

Extra HeavyAPI < 10° | IFT: 15-25 mN/m

Filter by Type:Showing 16 of 16 crude oils

IFT cell colors:High (>33 mN/m)Medium (25-33 mN/m)Low (≤25 mN/m)

Crude Oil Name	Type	API Gravity (°API)	Asphaltene Content (wt%)	Interfacial Tension (mN/m)			Typical Range @ 20°C
Crude Oil Name	Type	API Gravity (°API)	Asphaltene Content (wt%)	@ 20°C (68°F)	@ 40°C (104°F)	@ 60°C (140°F)	Typical Range @ 20°C
Light Arabian (Saudi Arabia)	Light	33.4	2-4	36.5	34.0	31.5	34-38
Medium Arabian (Saudi Arabia)	Medium	29.0	4-7	32.0	29.5	27.0	30-34
Heavy Arabian (Saudi Arabia)	Heavy	27.4	7-12	28.5	26.0	24.0	26-31
West Texas Intermediate (WTI)	Light	39.6	0.5-2	38.5	36.0	33.5	36-40
Brent Blend (North Sea)	Light	38.3	1-3	37.8	35.5	33.0	35-39
Dubai Crude	Medium	31.0	3-6	33.5	31.0	28.5	31-36
Urals (Russia)	Medium	32.0	3-5	34.5	32.0	29.5	32-37
Maya (Mexico)	Heavy	22.0	12-18	24.0	22.0	20.0	22-26
Cold Lake Blend (Canada)	Heavy	21.0	14-20	22.5	20.5	18.5	20-25
Athabasca Bitumen (Canada)	Extra Heavy	8.0	16-24	18.0	16.5	15.0	15-21
Bachaquero (Venezuela)	Heavy	16.8	15-22	21.0	19.0	17.5	19-23
Tia Juana Light (Venezuela)	Medium	31.8	3-6	34.0	31.5	29.0	32-36
Nigerian Light (Bonny Light)	Light	35.4	1-3	37.0	34.5	32.0	35-39
Iranian Light	Light	33.8	2-4	36.8	34.3	31.8	34-38
Iranian Heavy	Heavy	30.2	5-9	30.5	28.0	26.0	28-33
Kuwait Export	Medium	31.4	4-7	33.8	31.3	28.8	31-36

IFT Estimation Guidelines

Extra Light (35-50° API)

Typical IFT @ 20°C: 36-40 mN/m
Asphaltene Content: 0.5-3 wt%
Very low asphaltene content results in higher interfacial tension values.

Light (31-35° API)

Typical IFT @ 20°C: 33-38 mN/m
Asphaltene Content: 2-5 wt%
Low asphaltene content with moderate-high interfacial tension.

Medium (22-31° API)

Typical IFT @ 20°C: 28-35 mN/m
Asphaltene Content: 4-10 wt%
Moderate asphaltene content with moderate interfacial tension.

Heavy (10-22° API)

Typical IFT @ 20°C: 20-30 mN/m
Asphaltene Content: 10-20 wt%
High asphaltene content results in lower interfacial tension.

Extra Heavy (<10° API)

Typical IFT @ 20°C: 15-25 mN/m
Asphaltene Content: 15-25 wt%
Very high asphaltene content with low interfacial tension values.

Temperature Correction

Formula: IFT(T) ≈ IFT(20°C) - 0.2×(T-20). Example: At 40°C, IFT decreases by approximately 4 mN/m. Valid at atmospheric pressure only.

Practical Application: ISO 3171 Annex A

Parameter: Interfacial Tension, σ (mN/m)
Typical Input Range: 20-40 mN/m
Default Conservative Value: 30 mN/m (when specific data unavailable)
Impact on Separation: Higher IFT (35-40) = easier water separation; Lower IFT (15-25) = more difficult separation

Additional Factors Affecting IFT

Salinity: Seawater typically shows 1-3 mN/m higher IFT than freshwater
pH: Changes in pH can affect IFT, especially with acidic or basic crudes
Pressure: IFT decreases slightly with increasing pressure (at moderate pressures)
Surfactants: Can dramatically lower IFT to ultra-low values (<1 mN/m) for enhanced oil recovery