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AAG Presention 58400 r2 .pdf



Original filename: AAG-Presention-58400-r2.pdf
Title: Low Porosity Carbonate Permeability Correlation
Author: Armstrong, OP, PE,

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PERMEABILITY CORRELATIONS FOR
CARBONATE & OTHER ROCKS
Paper #58400 GSA Meeting 2003 Seattle Wa.
Presentation rev. 3

Otis P. Armstrong, PE

The form: k (md) =10φ1.5(1/Sw-c - 1)1.9
(if k calc > 200, use 1, not 10)
It is presented to improve description of
potentially productive zones of carbonates.
Equations that do not use the form:
(1/Sw-c - 1) cannot accurately describe k at
both low & high Swc, .i.e. at Swc=1, k must
equal zero.
Following Graphs are comparisons:

k md

1000.0
100.0
10.0
0.1

1.0

opa BVW=0.02
Archie 1
Archie 2
Ar type 3
low por ss
Data

0.0

por %
2.0

7.0

12.0

17.0

22.0

27.0

32.0

1.E+03

168.0
138.0
109.3
100.0
82.0
63.0
53.0
52.3

1.E+02
24.0

1.E+01

6.1

8.5

14.3
12.8
12.0

3.2
2.53.1
2.3
1.8

1.E+00
0.3
0.2
0.2
0.1

0.8

0.4

1.E-01

0.1

core
0.0

1.E-02

1.E-01

1.E-02
1.E+00

opa

1.E+01

Sch97

1.E+02

Timur

1.E+03

Error w/ opa eqn is 10x’s less than Sch97 and 20x’s less Timur
Only 2 false negatives and 3 false positives at 1md cut point

MOBILE HC VALUE
Provided, a min k can be established, mobile HC factor is simply a
mapping of the Bulk Volume Water Term, BVW. More correct K
forms, with (1/Swc - 1)n are just more complex. Below is a simple
derivation & recall (N^a)(N^-b)=N^(a-b) but ((N^a)^b)=N^(a*b):
Sw-c =BVW/φ in Timor’s equation gives:
Kmin ={92.6(φ)2.2/(Sw-c)}2 => φmin ={√Kmin *BVW/92.6}0.313
and using these terms in the movable HC formula:
φ(Swc0.2 – Swc)7760 = 7760{φ(φ Swc/φ)0.2 – BVW}=
BBL/AcFt = 7760{φ0.8(BVW)0.2 – BVW} =>
Kmin RULE : 7760[{√Kmin /92.6}0.25(BVW)0.513 – BVW]
Other forms give similar results, but with limited range:
Max Swc RULE: (BBL/AcFt)mo =7760(BVW)[(Swc)-0.8 -1]
φmin RULE : (BBL/AcFt)mo = 7760{[φmin0.8 ]BVW0.2 – BVW}

Effect of permeability on min HC mov 0.025 BVW
400
BBL/ac-ft move

375
350
325
300
275
250

opa
sch97
asquith oil

225
200
175
150
125
100

m in k, m d
0

0.1

0.2

0.3

0.4

0.5

0.6

At each BVW, a MINIMUM mobility of BBL/AcFt is defined
using a parametric of Porosity or Connate Water or k.

0.7

850
750
650

bbl/acft, mobil

950 52 53

138
550

0.8
100

0.1
??

0.1
0.05

50
0.005

6

0.2
? 168 12

0.3

82

150

>1

2.5
? 3.2
36

1.8

250

1

100
>1

?

350
14

200
1

2

2109
13

9
450

2 2

core & (md)
0.2

?

0.1md
Sw mx =0.525

0.1

0.48

63

0.3 md

y = 1150x

0.4 ?

Power (0.3 md)
Power (0.1md)

?

0.23

?

0.025

0.045

BVW
0.065

0.085

shale
0.105

0.125

0.145

Plot of Core Data as BVW & Mobility Ratio: BBL/AcFt Minimum
Proposed at 0.2md line or 780BVW0.44

Increased mobility ~ increased chance depo is economical
90% of all USA crb prdn from depo >130bbl/acft. US data
shows: prospecting in low φ Siluran & older rocks; success
rates 2-4x’s higher if dolomites are tested compared to developing
simular age & φ limestone rocks.

Min bvw max bvw min bbl/AcFt mx bbl/AcFt
0.005
0.015
76
123
vug carb
vug & IX carb
0.015
0.025
123
154
.Intr gran crb.
0.025
0.040
154
189
Chalk carb
0.050
0.100
189
283
0.44
780BVW <=crb
Lithology

2nd φ &Vug Carbs: =>bimodal pores
In logging terms: movable HC is:
BBL/AcFt = 7760[√a]*[√(Rmf/Rxo) - √(Rw/Rt) ]
at irreducible H2O= 7760{√ (Rw/aRt)}[ Swc)-0.8 -1]
Where a is term to make F = (a/φ2) , typically a=1 in carb.

Summary
Typical conditions, production < 900 & >130 bbl/ac-ft.
Mobile HC expressed as BBL/Acft is a handy way to evaluate
deposit, provided lithology is understood
The closer values are to litho-minimums, the less the chances
of economic HC extraction
Low mobility values also indicate low permeability, w/o
bimodal pores
Higher values indicate higher effective porosity
Watch for chalk & silt porosity types as they have higher min’s
Rocks with <140 bbl/AcFt = cap rocks unless Vug or coarse ss
porosity types
USA prdn data show Vug type more often dolomite, more brittle &
dolomites more often in Siluran & older formations.

Upper Ordovician Zone, Clean Carbonate, Western Latvia

movable HC
36 wells
W. Latvia
bbl/acft
bbl/acft
200
235 max
94
131 avg
60
90 std
36 n
IX LS
clean
Indication in 36 wells: this zone is a Cap Rock, typically <140
& does not contribute to oil flow, remove this zone in Htests.

Well J-E6

Horner

Analysis Compare
Danish

t, m
por %
k, md
Horner
Geol.
cores

OPA /core
10
11
2.5

0.62
17.4
40.5
md-m

gives
= thickness
Factors
show ~1m sucrosic LS

Indications are: oil flow is from thin lower sucrosic LS/Dolo

Thanks for hearing my considerations. A more detailed
Discussion is available by email request.

‘otis-a@oiljetpump.com’


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