This document provides an introduction to reservoir engineering concepts including porosity, saturation, surface and interfacial tension. It defines key terms like porosity, saturation, cohesive forces, and adhesive forces. Formulas for surface tension and interfacial tension are presented and derived for gas-water and oil-water systems. A numerical example is worked through to calculate the height of liquid held in a capillary tube given properties of the oil-water system. References and contact information are provided at the end.
2. INTRODUCTION
• Ph.D in Petroleum Engineering from university
of Oklahoma
• Writer of Hydrocarbon Phase Behavior (1989)
3. Fundamentals of Rock Properties
Porosity
• Definition and
its types
• Numerical
problem
Saturation
• Definition and
its types
• Numerical
problem
Surface and
Interfacial Tension
• Introduction
• Important terms
• Formula
• Derivation
• Question?
4. Introduction
• This comes into picture only
when the reservoir is of
multiphase system. Fluids
should be immiscible.
• The reason behind the OWC
and GOC and GWC
• The forces at the interface
of 2 immiscible fluid is
called interfacial or surface
tension. They both are
classified based on state of
matters.
• If force act between gas and
liquid then it is surface
tension. Between 2 fluid is
interfacial tension.
5. Important terms
• Cohesive force
– The property of like molecules to
stick to each other due to
substance mutual attraction.
• Adhesive force
– The property of different
molecules on surface to cling to
each other
• When cohesive force of the fluid is
stronger than the adhesive force,
the liquid concaves down in order
to reduce the contact with other
fluid (shorter transition zone)
• And for vice versa, the liquid is
concaves upwards and the contact
with other will be more than usual
(longer transition zone)
6. Interfacial tension
• When more than one
immiscible fluid present
in the porous medium a
thin film develops at the
boundary between the 2
fluids surface.
• At the interface of the
fluid, the force exerted
by 2 immiscible fluid
phases is dissimilar
which leads to the
phenomenon of
interfacial tension.
7. Surface tension
• The force exerted on
the boundary layer
between a liquid
phase and a vapor
phase per unit length.
• The units are
dynes/cm and they
are denoted by σ
8. Formula
For gas and water For oil and water
• σ = surface or interfacial tension
• r = radius of the object in which the fluids are
present
• g = acceleration due to gravity
• ρ = density
• Ѳ = contact angle
9. derivation
By taking r as a radius of a
capillary tube, the total
upward forces is given as
The upward force is
counteracted by the weight
of the water, which is
equivalent to downward
force of mass times
acceleration
10. Derivation contd.
• Density of air is negligible in comparison of
water
• Equating both the equations
• Finally for gas and water the equation is
• For oil and water the equation is
11. Numerical Approach
• An oil-water system has a radius of 0.001 mm,
whose angle of contact is 45 and density of oil
and water is given as 43.7 and 62.4 lb/cubic ft.
Calculated interfacial tension between fluids is
30 dynes/cm find the height to which the
liquid is held in cm?
12. References and Queries?
• Calhoun, J. R., Fundamentals of Reservoir Engineering. University of
Oklahoma
• Press, 1976.
• Cole, Frank, Reservoir Engineering Manual. Houston: Gulf Publishing
• Company, 1969.
• Dykstra, H., and Parsons, R. L., “The Prediction of Oil Recovery by
Water
• Flood,” In Secondary Recovery of Oil in the United States, 2nd ed., pp.
• 160–174. API, 1950.
• Geertsma, J., “The Effect of Fluid Pressure Decline on Volumetric
Changes
• of Porous Rocks,” Trans. AIME, 1957, pp. 210, 331–340.
• Hall, H. N., “Compressibility of Reservoir Rocks,” Trans. AIME, 1953, p.
309.
• Petrogate academy- Dehradun
Email ID: nawaz.delta.au@gmail.com
