GEOLOGY AND PETROLEUM

1. RESERVOIRROCKANDFLUID
CHARACTERIZATION
RESERVOIR PERMEABILITY

2. PERMEABILITY
Cylinder packed with sand that has 2.50 m in height and 0.35 m
in inside diameter
Metal sieves with (0.002 m).
Pressure measurement made by U pipes pressure gauge
Q - flow rate through sand pack, m3/s
K - hydraulic conductivity, m/s
A - cross section of sand pack, m2
L - length of sand pack, m
H1,2 - hidraulic head at inlet and outlet port, m

3. PERMEABILITY–DARCYLAW
Q - flow rate through sand pack, m3/s
k - permeability of sand pack/rock, m2
 - dynamic viscosity of fluid, Pa s
A - cross section of sand pack, m2
dP/dL - pressure gradient, Pa/m

4. VALIDITY OFDARCYLAW
• The core plug is 100% saturated with the flowing fluid.
• The flowing fluid is incompressible.
• The flow is horizontal, steady state, and under the laminar
regime.
• The flow of fluid through the porous medium takes place under
viscous regime
• The flowing fluid does not react with the porous medium (i.e., no
fluid–rock interactions.

5. PERMEABILITY-DEFINITION
absolute permeability of a given porous medium is the ability to pass
fluid through its interconnected pore and/or fracture network if the
medium is 100% saturated with the flowing fluid

6. PERMEABILITY–INCLINED FLOW

7. PERMEABILITY–RADIALFLOW

8. AVERAGEPERMEABILITY
PARALLELFLOW
Parallel flow

9. AVERAGEPERMEABILITY
PARALLELFLOW

10. AVERAGEPERMEABILITY
PARALLELFLOW
Linear flow
Radial flow

11. AVERAGEPERMEABILITY
PARALLELFLOW

12. AVERAGEPERMEABILITY
SERIESFLOW

13. AVERAGEPERMEABILITY
SERIESFLOW

14. AVERAGEPERMEABILITY
SERIESFLOW

15. DARCYLAWINFIELD UNITS
where:
k = darcies,
A = ft2,
ΔP = psi,
μ = cP,
L = ft,
Q = bbl/day

16. MEASUREMENTSOF
PERMEABILITY BYLIQUID
• Usually the measurements are carried out on formation samples of
well-defined geometry, such as cylindrical core plugs.
• Usual core plug diameters are 1 or 1.5 in.
• Usual lengths are typically varying from 2 to 4 in.
• Prior to measurements, the residual fluids or in situ formation fluids
are removed so that the sample is 100% saturated by air.
• Gases or nonreactive liquids are commonly used as a fluid phase for
the flow test
• The most common liquids used for the measurement of absolute
permeability are formation waters (sometimes called brine) or
degassed crude oil.

17. MEASUREMENTSOF
PERMEABILITY BYLIQUID

18. MEASUREMENTSOF
PERMEABILITYBYLIQUID
• The typical steps for an absolute permeability measurement are:
• The dimensions (length and diameter) of the core plug are
recorded.
• The core plug sample is normally housed in an elastomer sleeve
mounted in a Hassler core holder.
• An appropriate net overburden or confining pressure is applied
radially to the core holder sleeve, via a hydraulic hand pump.
• This confining pressure is determined from the gross
overburden (depth from where the core sample originated) and
the reservoir pressure.
• The confining pressure also helps prevent the flow of liquid
through the annular space between the core plug and the sleeve
during the flow experiment.
• A constant reservoir temperature is maintained using the climatic
air bath.

19. MEASUREMENTSOF
PERMEABILITYBYLIQUID
• A displacement pump and floating piston sample cylinder (for
storage of fluids) combination is used to initiate the flow of
brine or degassed crude oil at either a constant rate or constant
differential pressure. Usually, these floods are carried out at
constant flow rate rather than constant differential pressure
where the inlet pressure is monitored and the outlet is normally
at atmospheric pressure.
• The pressure drop across the core plug is monitored using a
computerized data logging system, and a constant or steady
pressure drop across the sample is recorded for calculations.

20. MEASUREMENTSOF
PERMEABILITYBYLIQUID

21. MEASUREMENTSOF
PERMEABILITYBYLIQUID

22. MEASUREMENTSOF
PERMEABILITYBYGAS
• The experimental setup and procedure for absolute permeability
measurement is similar to the liquid one.
• Using constant differential pressure for performing the flow tests
• Main difference: the determination of absolute permeability using test
results due to the compressible nature of gases. The original Darcy
equation was developed under the assumption of an incompressible
fluid flow.

23. MEASUREMENTSOF
PERMEABILITYBYGAS
Boyle’s law:
Average flow rate:
Flow rate at outlet:

24. MEASUREMENTSOF
PERMEABILITYBYGAS
The main problema is that the permebility measured by gas is always
higher than the one measured by liquid. This is called Klinkenberg effect
- slippage

25. MEASUREMENTSOF
PERMEABILITYBYGAS
Klinkenberg effect - correction
where:
kgas = measured gas permeability
kliquid = equivalent liquid permeability or the Klinkenberg-corrected
liquid permeability
m = slope of the straight-line fit

26. MEASUREMENTSOF
PERMEABILITYBYGAS

27. FACTORSAFFECTING ABSOLUTE
PERMEBILITYMEASUREMENT
• Rock-related factors: such as grain size and shape and clay
cementing. These can in fact also be termed natural factors.
• The type of fluid medium: (i.e., gas/brine/water) used for
permeability measurement as well as the physical and chemical
characteristics of these fluids are also major factors that affect the
absolute permeability.
• The thermodynamic factors: consist of temperature effects that
could cause change in chemical and physical properties of the fluid .
• The mechanical factors: related to the effect of mechanical stresses
or confining pressures.