laboratory measurement of relative permeability - steady state method
TRANSCRIPT
Laboratory Measurementof
Relative Permeability
- Steady State Method
Hysteresis Effect on Rel. Perm.
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DrainageImbibitionkrnw
Wetting Phase Saturation, %PV
Rel
ativ
e P
erm
eab
ilit
y, %
Residual non-wettingphase saturation
Irreducible wetting phase saturation
Non-wetting phase
Wetting phase
krnw krw
What is kbase for this case?
Hysteresis Effect on Rel. Perm.• During drainage, the wetting phase ceases to flow at the
irreducible wetting phase saturation– This determines the maximum possible non-wetting phase
saturation– Common Examples:
• Petroleum accumulation (secondary migration)• Formation of secondary gas cap
• During imbibition, the non-wetting phase becomes discontinuous and ceases to flow when the non-wetting phase saturation reaches the residual non-wetting phase saturation– This determines the minimum possible non-wetting phase
saturation displacement by the wetting phase– Common Example: waterflooding water wet reservoir
• Oil
• Water
• Gas
L
Akq
o
ooo
L
Akq
w
www
L
Akq
g
ggg
Review: Effective PermeabilitySteady state, 1D, linear flow equation (Darcy units):
qn = volumetric flow rate for a specific phase, n
A = flow area
n = flow potential drop for phase, n (including pressure, gravity and capillary pressure terms)
n = fluid viscosity for phase n
L = flow length
Modified from NExT, 1999; Amyx, Bass, and Whiting, 1960; PETE 311 NOTES
Rel. Perm. - Steady State• Purpose: determination of
– two phase relative permeability functions
– irreducible wetting phase saturation (drainage)
– residual non-wetting phase saturation (imbibition)
Rel. Perm. - Steady State• Process (oil/water, water wet case):
– simultaneously inject constant rates of oil and water until steady state behavior is observed
• production will be constant at same oil and water rates as injection
• pressure drop for each phase will be constant
– determine saturation of core sample
• usually by resistivity or weighing
• this is typically not the same as the injection ratio
– change injection ratio and repeat
Rel. Perm. - Steady State• Imbibition Relative Permeability
Functions– Stage 1: Preparation for
drainage• core saturated with
wetting phase• steady state injection of
wetting phase used to determine absolute permeability
– Stage 2: Irreducible wetting phase
• inject non-wetting phase until steady state, measure saturation
– no wetting phase will be produced at steady state
Rel. Perm. - Steady State• Imbibition Relative Permeability
Functions (continued)– Stage 3 (A-C): determination
of points on imbibition relative permeability function
• steady state injection at constant rates of wetting and non-wetting phase
– Initially ratio qw/qnw is small
• measure saturation and phase pressure drops at steady state
– saturation ratio will in general, not be the same as injection ratio
• repeat with increasing ratio, qw/qnw
Rel. Perm. - Steady State• Imbibition Relative Permeability
Functions (continued)– Stage 4: determination of
residual non-wetting phase saturation
• inject wetting phase until steady state behavior observed
• measure saturation and wetting phase pressure drop
STEADY-STATE RELATIVE PERMEABILITY TEST EQUIPMENT
(HASSLER METHOD)
Oil inlet
Oil burette
Toatmosphere
Po
Gasoutlet
Gasinlet
Pg Pc
Core
Porcelainplate
PENN STATE METHOD FOR MEASURING STEADY-STATE RELATIVE
PERMEABILITY
x x x xx x x xx x x xx x x xx x x xx x x x
Differentialpressure taps
PackingnutThermometer
sectionEnd
Bronzescreen
sectionTest
sectionMixing
InletOutlet Highly permeabledisk
InletCopperorificeplate
Electrodes
HAFFORD’S METHOD FOR MEASURING STEADY-STATE RELATIVE
PERMEABILITY
Oil pressure padOil
Gas
Gaspressuregauge
Gas meter
Oil burette
Oilpressure
Porous end plate
DISPERSED FEED METHOD FOR MEASURING STEADY-STATE RELATIVE
PERMEABILITY
Lucite-mountedcore
Gas-pressuregauge Gas
Corematerial
Gas meter
Lucite
OilOil burette
Dispersingsection
Dispersingsection face