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Capillary Pressure and Saturation History

 Capillary Pressure in

 Reservoir Rock 

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DRAINAGE AND IMBIBITIN

 CAPI!!AR" PRESS#RE C#R$ES

Drainage

Imbibition

S wi  S m

S w 

P d 

P c 

0 0.5 1.0

Modified from NExT, 1999, after …

DRAINAGE

• Fluid flow process in wic te saturation

of te nonwetting pase increases

I!"I"I#I$N

• Fluid flow process in wic te saturation

of te wetting pase increases

%aturation &istor' ( &'steresis

- Capillary pressure depends on both direction

of chane, and pre!ious saturation history

- "lue arro# indicates probable path from

drainae cur!e to imbibition cur!e at $#t%&'(- )t $m, non#ettin phase cannot flo#,

resultin in residual non#ettin phase

saturation *imbibition+

- )t $#i, #ettin phase cannot flo#, resultin in

irreducible #ettin phase saturation *drainae+

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Saturation History

% T&e sa'e Pc value can occur at 'ore t&an

one (ettin) p&ase saturation

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Rock Type

% Rock Type *Arc&ie+s De,inition - .orden and Ca'p/ell0

 1  2or'ations t&at 3444 &ave /een deposited under si'ilar

conditions and 444 under)one si'ilar processes o, later(eat&erin)5 ce'entin)5 or re-solution44446

% Pore Syste's o, a Rock Type *.orden and Ca'p/ell0

 1  3A )iven rock type &as particular lit&olo)ic *especially pore

space0 properties and si'ilar and7or related petrop&ysical andreservoir c&aracteristics6

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T&o'eer+s Para'eters ,or

Capillary Pressure Curves% T&o'eer+s Data

 1  Mercury In8ection - draina)e

% $ery &i)& capillary pressures

% *$ /0P∞  T&e *assy'ptotically approac&ed0 ,raction o, /ulk volu'e

occupied /y 'ercury at in,inite capillary pressure *si'ilar to previous para'eter5 irreduci/le (ettin) p&ase saturation0

% Pd  Displace'ent Pressure5 capillary pressure re9uired to ,orce

non(ettin) p&ase into lar)est pores *sa'e as previously discussed0

% G Para'eter descri/in) pore-si:e distri/ution *si'ilar to

 previous para'eter5 ;7λ4 Increasin) G *or decreasin) λ05 su))ests

 poor sortin)5 and7or tortuous ,lo( pat&s0

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  !odfied from )ordan and *ampbell+ 1,-+ /ol. 1

Figures . and .5

# 2 $RE #&R$A#

( $RE

• (V b )  p = is the fractional !olume occupied by at

  infinite pressure, or total interconnected pore !olume'•  pd  is the extrapolated displacement pressure *psi+

  pressure re.uired to enter larest pore throat'

• G  is pore eometrical

  factor rane in si/e and

tortuosity of pore throats'

• 0are pd  % small pore thorats

• 0are G  % tortuous, poorly

sorted pore thorats

'

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 !odfied from )ordan and *ampbell+ 1,-+ /ol. 1

• Note !ariation in pore properties and permeability #ithin a formation

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!odfied from )ordan

and *ampbell+

1,-+ /ol. 1

Figure .-

si/e lo#er fine

sortin !ery

#ell sorted

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!odfied from )ordan

and *ampbell+ 1,-+ /ol. 1

Figure .,

si/e lo#er fine

sortin

moderately

sorted

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!odfied from )ordan

and *ampbell+ 1,-+ /ol. 1

Figure .10

si/e upper

!ery fine

sortin

moderatelysorted

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 !odfied from )ordan

and *ampbell+ 1,-+ /ol. 1

Figure .11

-effect ofsinificant

cementin

and clay

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!odfied from )ordan

 and *ampbell+ 1,-+ /ol. 13

after Neasam+ 1,44

Figure .1

Effect of 

Dispersed *la's

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Capillary Pressure in Reservoirs

A "

Reser/oir+ o

Auifer+ w

1

6

c 2 po(pw 2 0

ressure

   D  e  p   t   

dpw2 wg7D d

Free

8ater

9e/el

dpo2 og7D d

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2luid Distri/ution in Reservoirs

Gas : 8ater 

Gas densit' 2 g

$il+ Gas : 8ater 

$il : 8ater 

$il densit' 2 o

8ater 

8ater densit' 2 w 

;A<

1

;"<

Free $il 9e/el

Free 8ater 9e/el

*apillar' pressure difference

between

oil and water pases in core ;A<

P c,ow  2 h1g = w ( o>

*apillar' pressure difference

between

gas and oil pases in core ;"<

P c,go

 2 hg = 

o( 

g>

!odified from NE?#+ 1,,,+ modified after 8elge and "ruce+ 1,4

  %  e  a   l

F        a      u     

l        t       

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RE!ATIN BET<EEN CAPI!!AR"

PRESS#RE AND 2!#ID SAT#RATIN

Free 8ater 9e/el

P c 

P d 

$il(8ater contactH d 

   &  e   i  g

      t   A   b  o  /  e   F  r  e  e   8  a   t  e  r   9

  e  /  e   l   =   F  e  e   t   >

0 50 100S w  =fraction>

0 50 100

S w  =fraction>

0

!odified from NE?#+ 1,,,+ after @

P c 

0 50 1000

P d 

S w  =fraction>

0ab 2ata

-0ab 3luids σ, θ

-Core sample 4,φ

5-3unction

5-3unction

- for 4,φ

6eser!oir 2ata

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Saturation in

Reservoir vs4 Dept&

% Results ,ro' t(o analysis

'et&ods *a,ter AB<0

 1 !a/oratory capillary pressure

curve% Converted to reservoir

conditions

 1 Analysis o, (ell lo)s

% <ater saturation &as stron)e,,ect on resistivity curves

*,uture topic0