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Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Michael Glinsky

1Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Outline

rock physics model supporting measurements (log and core) numerical rock assembly model model based seismic inversion & practical detectability conclusions

2Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Floating grain model - the link of deposition physics to grain scale properties, permeability

Load-Supporting

Floating

Abundance of potential floating grains in the system is due to two factors overall abundance of silt/mud-sized particles (related to nature of clastic input and system-scale proximal vs distal position) local variation due to depositional processes (e.g. rapid fallout vs traction)

3Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Capture Ratio = 1 (1/1.5) = 33% ie 1/3 of small grains are captured in to the load bearing matrix of the rock. The capture ratio will depend on the

geometries of the original grains.

Capture ratio is another key concept

At a constant Effective Stress - For every 3 small grains, 1 becomes part of matrix and 2 will float

porosity (%) = -1.5*float(%) + B (B is a constant for a particular constant Pe)

Bimodal grain sizes (big and small)

porosity in % = -1.54 * float in % - 88% * ( 1 exp( - Pe / 800 psi ) ) + 110% +- 0.2%

4Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Petrophysical evidence for the floating grain model

Vp (ft/s)

dens

ity (g

m/c

c)

well #2

well #5

well #6

well #3

well #4

well #1

5Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Relationship between size distribution and floating grain fraction

well #1well #2well #3

well #1well #2well #3

6Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Good regression found between the permeability, porosity, and floating grains

10% 30%porosity0

3.5

log(

perm

in m

D)

10% 30%log(perm in mD)0

3.5

log(

pred

icte

d pe

rm)

well #1well #2well #3

log( perm in mD) = 0.198 * porosity in % - 0.325 * floating in % - 1.76 + - 0.37x / 2.3

well #1well #2well #3

7Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Acoustic resonance measurements on well #2 core confirm trend seen in logs

2

2.05

2.1

2.15

2.2

2.25

2.3

2.35

2.4

2000 2500 3000 3500 4000

vp (m/s)

den

sity

(g

m/

cc)

6% float0% floatmeasurment6% float

0% float moderate sorting

moderately poor

poor

8Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

No change in shear velocity as seen on logs and predicted by theory

1800

2000

2200

2400

3000 3200 3400 3600 3800

vp (m/s)

vs

(m/

s)

0% float

6% float

Ps correctedaverage

6% float

0% float

moderate sorting

moderately poor

poor

9Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Floating grains seen in CAT scan and SEM of well #2

sample #3, moderate sorting, 300 mD, 24%

50 micron500 micron

#1, poor, 10 mD, 20%500 micron

#2, moderately poor, 100 mD, 22%500 micron

5 mm

10Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Guide to AVO interpretation

Increasing NG0% to 100%

Brine to Oil

Decreasing Float6% to 0%Increasing perm1 mD to 1000 mD

Decreasing Effective Stress1000 psi

Dimming AVO

Brightening AVO

good

bad

11Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Numerical rocks give important understanding of floating grain model

Create sphere packings (two size) representative of unconsolidated sediment through cooperative rearrangement algorithm

Quantify the number of loose grains in packings Understand capture fraction

12Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Mono-dispersed packing validation

Single grain size Comparison with Finney packing Quality checks:

Porosity 36.3% Finney v. 36.2% simulation

Percent of loose grains 1.8% Finney v. 1.6% simulation

Radial distribution function

13Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Floating grain fraction & capture ratio demonstrated

Little dependence on RR5 vol% 40 vol%

RR = radius ratio

float

ing

grai

n pe

rcen

t

critical point

(small grain load support)

(large grain load support)

capture fraction0

1/3

2/3

1

Thermodynamics of random packing, Physics Today (June 2007)

14Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Phase diagram for random packing of binary mixture of spheres

(large grain load support, small grains float)

(small grain load support)

(large grain load support, small grains part of matrix)

RRc VFc

note: volume fraction dominates over radius ratio critical point

Statistical mechanics of dense granular media, Coniglio et al., J. Cond. Matter 17, S2557 (2005).

Rc 4VFc 0.45

15Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Critical scaling for radius ratio critical point (RRc)

y =

0.0103x2.2609

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

-1 0 1 2 3

RRc-RR

fmax -

f(p

eak)

fit data

data

Power (fit data)

y =

0.0102x2.1708

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

-1 0 1 2 3

RRc-RR

Dp

oro

sity

(max)

- D

po

rosi

ty(p

eak)

fit data

data

Power (fit data)

y =

0.1467x1.8419

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.5 1 1.5 2 2.5 3

RRc - RR

CF0

= C

F(V

F=

0)

fit datadataPower (fit data)

capture fraction @ volume fraction = 0

peak decrease in porosity

peak floating fraction

16Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Critical scaling for volume fraction critical point (VFc)

y = 2.4516x1.31

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

-0.10 0.00 0.10 0.20 0.30 0.40 0.50

VFc-VF

CFmax*(CFmax-CF)/(CFmax-CF0)

fit dataRR=1.5RR=2RR=3RR=4Power (fit data)

capture fraction

17Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Permeability can be simulated given 3D rock matrix from CAT

small capillary pressure large capillary pressure

18Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Implementation of floating grain model in DELIVERY

= A+B vp+Cflt + (from numerical inversion of above, using clusters)

vp= Ap +Bpd + Cp LFIV + Dp flt+p (inverted from this regression, direct from log data and clusters)

=A+Bd+C flt+ , with d(1-exp(-eff/P0))C=-1/(1-fc), fc is capture fraction

Vs= As+Bs vp+ s - direct from log data

19Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Layer based model derived from blocking for well #2

20Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Multiple stack inversion Bayesian inversion is used

before inversion, ignore seismicafter inversion, honour

seismic to within noise level

near far

21Monday, 25 January 2010

CSIRO. Estimation of Permeability with Seismic I really did mean to say permeability not porosity

Floating grain fraction and porosity are determined by seismic

time of layer boundary - seismic determines N/G - seismic does not determine

float fraction & porosity - seismic determines ==> permeability

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