Reservoir EngineeringPVT and Rock-Fluid Properties
Capillary Pressure Formula
Capillary Pressure calculates capillary pressure for pvt and rock-fluid properties workflows in reservoir engineering.
How engineers use this formula
Use this formula when the listed inputs (sigma, theta, r) are known and the assumptions behind the cited pvt and rock-fluid properties relationship match the engineering case being checked.
Assumptions
- Input values are representative for the well, reservoir, fluid, or equipment case being evaluated.
- The declared units match the field-unit constants used in the formula.
- The cited formula applies to the selected petroleum engineering workflow.
Limitations
- The calculation does not replace a full engineering model or operating procedure.
- Accuracy depends on the source correlation, assumptions, input quality, and unit consistency.
Common mistakes
- Mixing unit systems without converting the inputs.
- Using default example values as field recommendations.
- Applying the formula outside the source assumptions.
Default example
Using the default inputs, P_c equals 4,242.640687 dyn/cm².
sigmadyn/cm
30
thetadegree
45
rcm
0.01
Inputs
sigma
dyn/cmFluid Interfacial Tension
theta
degreeContact Angle (Wettability)
r
cmRadius of Capillary
Outputs
P_c
dyn/cm²
Capillary Pressure
sigma
dyn/cm
Interfacial Tension (rearranged)
theta
degree
Contact Angle (rearranged)
r
cm
Capillary Radius (rearranged)
Source and review
reviewedWikipedia.org. Capillary Pressure. Retrieved 2025.
Source