Presion Capilary Historia de La Saturacion

8/4/2019 Presion Capilary Historia de La Saturacion

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Capillary Pressure andSaturation History

Capillary Pressure in

Reservoir Rock


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DRAINAGE AND IMBIBITION

CAPILLARY PRESSURE CURVES

Drainage

Imbibition

Swi Sm

Sw

Pd

Pc

0 0.5 1.0

Modified from NExT, 1999, after

DRAINAGE

Fluid flow process in which the saturationof the nonwetting phase increases

IMBIBITION

Fluid flow process in which the saturationof the wetting phase increases

Saturation History - Hysteresis

- Capillary pressure depends on both directionof change, and previous saturation history

- Blue arrow indicates probable path from

drainage curve to imbibition curve at Swt=0.4- At Sm, nonwetting phase cannot flow,resulting in residual nonwetting phasesaturation (imbibition)

- At Swi, wetting phase cannot flow, resulting inirreducible wetting phase saturation (drainage)


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Saturation History

The same Pc value can occur at more than

one wetting phase saturation


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Rock Type

Rock Type (Archies Definition - Jorden and Campbell)

Formations that ... have been deposited under similar

conditions and ... undergone similar processes of laterweathering, cementing, or re-solution....

Pore Systems of a Rock Type (Jorden and Campbell)

A given rock type has particular lithologic (especially pore

space) properties and similar and/or related petrophysical andreservoir characteristics


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Thomeers Parameters for

Capillary Pressure Curves Thomeers Data

Mercury Injection - drainage

Very high capillary pressures

(Vb)P The (assymptotically approached) fraction of bulk

volume occupied by mercury at infinite capillary pressure

(similar to previous parameter, irreducible wetting phase

saturation)

Pd Displacement Pressure, capillary pressure required to

force nonwetting phase into largest pores (same aspreviously discussed)

G Parameter describing pore-size distribution (similar to

previous parameter, 1/. Increasing G (or decreasing ),

suggests poor sorting, and/or tortuous flow paths)


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Modfied from Jordan and Campbell, 1984, vol. 1

Figures 2.4 and 2.5

PT = PORE THROATP - PORE

(Vb)p =is the fractional volume occupied by Hg atinfinite pressure, or total interconnected pore volume.

pdis the extrapolated Hg displacement pressure (psi);pressure required to enter largest pore throat.

Gis pore geometricalfactor; range in size and

tortuosity of pore throats.

Large pd= small pore thorats

Large G= tortuous, poorlysorted pore thorats

.


7/16Modfied from Jordan and Campbell, 1984, vol. 1

Note variation in pore properties and permeability within a formation


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Modfied from Jordanand Campbell,

1984, vol. 1

Figure 2.8

size: lower finesorting: verywell sorted


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Modfied from Jordan

and Campbell, 1984, vol. 1

Figure 2.9

size: lower finesorting:moderately

sorted


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Modfied from Jordan


Figure 2.10

size: uppervery finesorting:

moderatelysorted


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Modfied from Jordan


Figure 2.11

-effect ofsignificantcementing

and clay


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Modfied from Jordanand Campbell, 1984, vol. 1;after Neasham, 1977

Figure 2.12

Effect ofDispersed Clays


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Capillary Pressure in Reservoirs

A B

Reservoir, o

Aquifer, w1

2

3

Pc = po-pw = 0

Pressure

Depth

dpw=wg/D dh

Free

WaterLevel

dpo=og/D dh


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Fluid Distribution in Reservoirs

Gas & Water

Gas density = g

Oil, Gas & Water

Oil & Water

Oil density = o

Water

Water density = w

A

h1

h2B

Free Oil Level

Free Water Level

Capillary pressure differencebetween

oil and water phases in core APc,ow= h1g(w-o)

Capillary pressure differencebetween

gas and oil phases in core BP

c,go= h

2g(

o-

g)

Modified from NExT, 1999, modified after Welge and Bruce, 1947

Fault


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RELATION BETWEEN CAPILLARY

PRESSURE AND FLUID SATURATION

Free Water Level

Pc

PdOil-Water contact

Hd

Heig

htAboveFreeWaterL

evel(Feet)

0 50 100Sw(fraction)

0 50 100

Sw(fraction)

0

Modified from NExT, 1999, after

Pc

0 50 1000

Pd

Sw(fraction)

Lab Data

-Lab Fluids: ,

-Core sample: k,

J-Function

J-Function

- for k,

Reservoir Data


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Saturation in

Reservoir vs. Depth

Results from two

analysis methods (after ABW)

Laboratory capillary

pressure curve

Converted to reservoir

conditions

Analysis of well logs Water saturation has

strong effect on resistivity

curves (future topic)

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Presion Capilary Historia de La Saturacion