course activities handout

Core Analysis – Reducing Uncertainty

Activities

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Activity 1

Porosity and Grain Density

Problem

Porosity and grain density measurements – SE Asian lab

Porosity measurements did not match logs

Test lab in UK repeated measurementsUsing SE Asian lab procedures

Own procedures

Grain volumeBoth labs use twin cell helium porosimeter (grain volume)

SE Asian lab used caliper bulk volume

UK lab used mercury immersion

Problem Data

Sample Sample Sample Dry Helium Caliper Immersion Caliper ImmersionNo. Length Diameter Weight Grain Bulk Bulk Grain Vb Vb

Volume Volume Volume Density Porosity Porosity(cm) (cm) (g) (cm3) (cm3) (cm3) (g/cm3) (%) (%)

1 4.558 3.791 112.720 40.458 50.8642 4.695 3.778 111.208 40.722 52.3693 4.712 3.773 99.014 38.354 50.9294 4.631 3.777 96.058 36.963 49.7425 4.668 3.782 95.640 37.076 50.4616 4.719 3.770 103.461 37.646 51.2857 4.567 3.786 97.667 36.895 49.924

Requirements

Calculate grain density (to 3D)

Calculate porosity based on caliper bulk volume

Calculate porosity based on Hg immersion bulk volume

Compare and comment on results

Length

Diameter

Activity 2

Klinkenberg Permeability Measurements

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Activity - Klinkenberg

Data from Klinkenberg analysis

4 samples

Calculate Klinkenberg permeabilityKl

Calculate Ka at Pmean = 1 atm

Calculate Ka(1atm)/Kl

Plot Ka(1atm)/Kl versus Kl

Sample Depth Pmean Ka(m) (atm) (mD)

1 2900.5 1.006 1301.353 1261.647 1241.996 123

2 2901.8 1.083 34.61.427 33.31.721 32.52.075 31.9

3 2903.25 1.179 19.61.524 18.81.818 18.32.160 18

4 2927.57 1.001 2771.348 2711.642 2691.984 266

Sample 1 Chart

Sample 1

100

105

110

115

120

125

130

135

140

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Inverse Mean Pressure (atm-1)

Air

Per

mea

bili

ty (

mD

)

Sample 2 Chart

Sample 2

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Inverse Mean Pressure (atm-1)

Air

Per

mea

bili

ty (

mD

)

Sample 3 Chart

Sample 3

15

15.5

16

16.5

17

17.5

18

18.5

19

19.5

20

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Inverse Mean Pressure (atm-1)

Air

Per

mea

bili

ty (

mD

)

Sample 4 Chart

Sample 4

250

255

260

265

270

275

280

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Inverse Mean Pressure (atm-1)

Air

Per

mea

bili

ty (

mD

)

Activity 3

Stress Calculation for SCAL

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Background

It is planned to carry out a SCAL program on plugs from an offshore sandstone reservoir

Tests are to be carried out at representative stress at a depth equivalent to the free water level in the sand – 9000 ft TVDSS (MSL)

Geomechanics data are available including:Average bulk density for principal overburden lithologies to calculate total vertical stress, v

Horizontal stress from mini-frac tests in reservoirh = 0.70*v H = 0.75v

Biot constant from rock mechanics tests = 0.95

Pore pressure from MDT4000 psi at 9000 ft TVDSS

Requirements

Calculate effective stress by two methodsNet effective overburden stress

Effective isostatic stress (Worthington method)

pvNEOB p '

phHv

iso p

3

'

Data

Vertical stress calculation

Calculate total vertical stress increment at base of each zone

H = zone vertical thickness (ft)

0.4335 convert g/cc to psi/ft

Calculate cumulative vv(cum) = v(1) + v(2) +v(3) + etc

Zone Description Top Base Average BaseDepth Depth Zonal Pore

Bulk PressureDensity

(ft TVDSS) (ft TVDSS) (g/cc) (psi)

1 Sea Water 0 300 1.00

2 Overburden 250 1500 1.70

3 Overburden 1500 3000 1.80

4 Overburden 3000 4500 1.90

5 Overburden 4500 6000 2.00

6 Overburden 6000 7500 2.20

7 Overburden 7500 8800 2.30

8 Reservoir 8800 9000 2.35 4000

Hzonev *4335.0)(

Activity 4

Porosity at Stress

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Background/Objectives

Measurements of porosity as a function of confining stress on 1 sampleLab provided experimental data

expelled volume versus stressdata provided enables calculation of sleeve conformance pressure (SCP) and sleeve conformance volume

Calculatesleeve conformance pressure and excess volume

Correctexpelled volume data to determine pore volume reduction

Calculateporosity at each stress “station”

Estimate porosity and porosity compaction factorat effective overburden stress (from last example)at effective isostatic stress ((from last example)

Data

Porosity at stress

Vpstress = Vpamb-Vexp

Vbstress = Vpstress+Vgamb

assume constant grain volume

Check “uncorrected” porosity

Pore volume correction

Vpcorr = Vpexp-VSCP

Recalculate porosity based on corrected pore volume

Porosity compaction factor

Ambient PorositySample ID 7ELength, cm 3.85Area, cm2 11.00Pore Vol, cm3 7.657Bulk Vol, cm3 41.56Grain Vol, cm3 33.903Porosity, frac 0.184

Measured Measured Uncorrected Uncorrected UncorrectedSleeve Volume Pore Bulk Porosity

Pressure Expelled Volume Volume(psi) (cc) (ml) (ml) (v/v)40 1.26 6.40 40.30 0.15970 1.44 6.22 40.12 0.155

100 1.60 6.06 39.96 0.152130 1.70 5.96 39.86 0.149160 1.74 5.92 39.82 0.149190 1.78 5.88 39.78 0.148220 1.80 5.86 39.76 0.147250 1.84 5.82 39.72 0.146280 1.86 5.80 39.70 0.146800 1.92 5.74 39.64 0.1451600 2.04 5.62 39.52 0.1422500 2.10 5.56 39.46 0.1415000 2.18 5.48 39.38 0.139

Stressed Porosity Datastress

stressstress Vb

Vp

amb

stressPCF

SCP Chart

Volume Expulsion Chart

0.00

0.50

1.00

1.50

2.00

2.50

0 100 200 300 400 500 600 700 800 900 1000

Pressure (psi)

Vo

lum

e E

xpel

led

(m

l)

Porosity comparison chart

Porosity versus Stress

0.13

0.14

0.15

0.16

0.17

0.18

0.19

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Effective Isostatic Stress (psi)

Po

rosi

ty (

v/v)

Corrected porosity chart

Porosity versus Stress

0.170

0.171

0.172

0.173

0.174

0.175

0.176

0.177

0.178

0.179

0.180

0.181

0.182

0.183

0.184

0.185

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Effective Isostatic Stress (psi)

Po

rosi

ty (

v/v

)

Activity 5

Stress Corrections

Problem

RCA data from well

SCAL data available to correct data for stress effects

Depth Plug Ambient Grain HorizontalNumber Porosity Density Air

Permeability(ft) (%) (g/cc) (mD)

8472.0 404 19.1 2.64 1598473.0 405 20.5 2.64 2728473.8 406 21.7 2.62 5368475.0 407 22.5 2.638476.0 408 19.4 2.63 2918477.0 409 19.3 2.638478.0 410 17.7 2.648479.0 411 19.4 2.63 1168480.0 412 18.4 2.638481.0 413 19.6 2.63 1728482.0 414 17.2 2.628482.9 415 19 2.63 48

SCAL Data at ambient and NCS

PlugHelium Air Porosity kg@SwiPorosity Permeability 3900 psi 3900 psi

(%) (mD) (%) (mD)1 4.7 1.17 0.232 7.7 1.2 6.1 0.355 9.3 4.85 8.1 3.36 13.6 21.7 12.3 17.39 19.7 18.0

10 20.0 302 17.9 247.312 20.8 4125 17.5 352314 24.2 1985 21.6 152317 12.8 0.88 11.1 0.2118 11.1 2.68 1.0519 16.6 14.020 21.4 19.5

Ambient Data Stress Data

Requirements

Determine relationship between amb and NCS

Force fit (through 0)Free fit

Determine permeability stress & saturation correction transform

between kg @ Swi at overburden and ka at ambient conditions

For cored interval, calculate average:ambient porositystress corrected porosity (free fit and forced fit)air permeabilitystress-corrected effective endpoint gas permeability

Crossplot porosity versus permeabilityambient datastress-corrected data (forced fit porosity)

Porosity Correction Free Fit

Porosity Correction Forced Fit

Permeability Correction

0.1

1

10

100

1000

10000

0.1 1 10 100 1000 10000

Kair at Ambient (mD)

Eff

ec

tiv

e E

nd

po

int

Ga

s P

erm

eab

ilit

y at

Str

ess

(m

D)

Porosity-Permeability Crossplot

POROPERM PLOT

0.001

0.01

0.1

1

10

100

1000

10000

0 5 10 15 20 25 30

Porosity (%)

Pe

rme

ab

ilit

y (

mD

)

Use Force Fit Porosity

Activity 6

Archie and Waxman Smits Parameters

m and m*

Background

Multiple salinity tests (Co-Cw) carried out on 6 samplesDetermine formation factor to SFW at NCP

Rw = 0.901 ohm-m at 20 CCw = 1/Rw = 1.11 S/m

Multiple salinity tests (at 20 C)200,000 ppm brine Cw = 20.20 S/m150,000 ppm brine Cw = 15.87 S/m100,000 ppm brine Cw = 11.90 S/m50,000 ppm brine Cw = 6.80 S/m

Determine Co for each brineCrossplot Co versus Cw (including SFW)

Results: samples # 1 and #2

Sample Brine Cw Co(ppm) (S/m) (S/m)

1 SFW 1.11 0.135200000 20.20 2.246150000 15.87 1.795100000 11.90 1.34450000 6.80 0.763

Sample 1

y = 0.1112x + 0.0134

R2 = 0.9998

0.0

0.5

1.0

1.5

2.0

2.5

0.0 5.0 10.0 15.0 20.0 25.0

Cw (S/m)

Co

(S/m

)

Sample Brine Cw Co(ppm) (S/m) (S/m)

2 SFW 1.11 0.141200000 20.20 2.351150000 15.87 1.875100000 11.90 1.40650000 6.80 0.797

Sample 2

y = 0.1164x + 0.0131

R2 = 0.9998

0.0

0.5

1.0

1.5

2.0

2.5

0.0 5.0 10.0 15.0 20.0 25.0

Cw (S/m)C

o (S

/m)

Results: samples # 3 and #4

Sample Brine Cw Co(ppm) (S/m) (S/m)

3 SFW 1.11 0.135200000 20.20 1.866150000 15.87 1.492100000 11.90 1.12750000 6.80 0.653

Sample 3

y = 0.0911x + 0.0368

R2 = 0.9999

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

0.0 5.0 10.0 15.0 20.0 25.0

Cw (S/m)

Co

(S/m

)

Sample Brine Cw Co(ppm) (S/m) (S/m)

4 SFW 1.11 0.151200000 20.20 2.309150000 15.87 1.843100000 11.90 1.38250000 6.80 0.796

Sample 4

y = 0.1135x + 0.0273

R2 = 0.9999

0.0

0.5

1.0

1.5

2.0

2.5

0.0 5.0 10.0 15.0 20.0 25.0

Cw (S/m)

Co

(S/m

)

Results: samples # 5 and #6

Sample Brine Cw Co(ppm) (S/m) (S/m)

5 SFW 1.11 0.145200000 20.20 1.923150000 15.87 1.535100000 11.90 1.16250000 6.80 0.681

Sample 5

y = 0.0934x + 0.0456

R2 = 0.9999

0.0

0.5

1.0

1.5

2.0

2.5

0.0 5.0 10.0 15.0 20.0 25.0

Cw (S/m)

Co

(S/m

)

Sample Brine Cw Co(ppm) (S/m) (S/m)

6 SFW 1.11 0.120200000 20.20 1.938150000 15.87 1.546100000 11.90 1.17250000 6.80 0.676

Sample 6

y = 0.0955x + 0.0235

R2 = 0.9998

0.0

0.5

1.0

1.5

2.0

2.5

0.0 5.0 10.0 15.0 20.0 25.0

Cw (S/m)

Co

(S/m

)

Requirements

Summary table

Calculate Archie m for each sample

Calculate composite mAverage and regression of log F and log data pairs

Calculate F* and Qv for each sample

Calculate Archie m* for each sample

Calculate composite m*Average and regression of log F* and log data pairs

Sample Stressed SFW SFW B Formation Slope Intercept BQv Qv Intrinsic m m*Porosity Rw Ro Factor F*

(v/v) (ohm-m) (ohm-m) (meqml-1/Sm-1) F (1/F*) (BQv/F*) (meq/ml)1 0.301 0.901 7.41 1.968 8.22 0.1112 0.01342 0.310 0.901 7.09 1.968 7.87 0.1164 0.01313 0.237 0.901 7.41 1.968 8.22 0.0911 0.03684 0.286 0.901 6.62 1.968 7.35 0.1135 0.02735 0.286 0.901 6.90 1.968 7.65 0.0934 0.04566 0.288 0.901 8.33 1.968 9.25 0.0955 0.0235

m m*MeanComposite

Chart

1

10

1 10

Stressed Porosity (v/v)

Intr

insi

c F

orm

ati

on

Fac

tor

or

Fo

rma

tio

n F

acto

r (-

)

Calculation

Y on X regressionSlope = 1/F*

Intercept = BQv/F*

B = 1.968

Sample 5

y = 0.0934x + 0.0456

R2 = 0.9999

0.0

0.5

1.0

1.5

2.0

2.5

0.0 5.0 10.0 15.0 20.0 25.0

Cw (S/m)

Co

(S/m

)

BT T

R Tw

128 0 225 0 0004059

1 0 045 0 27

2

1 23. . .

( . . ).

Activity 7

Archie and Waxman Smits Parameters

n and n*

Background

Resistivity index tests carried out on 1 sample

Qv also determined:by wet chemistry tests (CEC Qv)

by multiple salinity tests (Co-Cw Qv)

Calculate:Archie saturation exponent

For each Sw point

By regression analysis (log I versus Log Sw)

Intrinsic saturation exponentFor each Sw point

By regression analysis (log I versus Log Sw)

For both CEC Qv and Co-Cw Qv

Data

Wet Chemistry Qv

Sample Grain Porosity Wet Co-Cw SFW SFW n* SFW Water Resistivity Intrinsic Archie IntrinsicDensity Chemistry Qv Rw Temp Qv B Saturation Index Resistivity Saturation Saturation

CEC Sw I Index Exponent Exponent

(g/cc) (frac) (meq/100g) (meq/ml) (ohm.m) (Deg C) (meq/ml) (meqml-1/Sm-1) (frac) (frac) I* n n*1 2.65 0.301 2.86 0.061 0.901 20.0 1.967 1.000 1.00

0.820 1.520.370 6.670.322 8.650.256 13.320.235 15.830.211 18.950.193 24.09

n n*Composite

Co-Cw Qv

Sample Grain Porosity Wet Co-Cw SFW SFW n* SFW Water Resistivity Intrinsic Archie IntrinsicDensity Chemistry Qv Rw Temp Qv B Saturation Index Resistivity Saturation Saturation

CEC Sw I Index Exponent Exponent

(g/cc) (frac) (meq/100g) (meq/ml) (ohm.m) (Deg C) (meq/ml) (meqml-1/Sm-1) (frac) (frac) I* n n*1 2.65 0.301 2.86 0.061 0.901 20.0 1.967 1.000 1.00

0.820 1.520.370 6.670.322 8.650.256 13.320.235 15.830.211 18.950.193 24.09

n n*Composite

Charts

1

10

100

0.1 1

Water Saturation (v/v)

Intr

insi

c R

esis

tiv

ity

Ind

ex o

r R

esi

stiv

ity

Ind

ex(-

)

Calculations

Saturation exponent, nRegression analysis of log(I) and log(Sw)

Qv (from CEC)

Intrinsic saturation exponent, n*Calculate I*

Regression analysis of log(I) and log(Sw)

res

resgres

CECQv

100

1

)log(

)log(

Sw

In

)1(

)1(

*w

w

w

BQvR

SBQvR

II

)log(

*)log(*

Sw

In

Activity 8

Saturation Exponent from Dean Stark

Dean-Stark and Rt

Well drilled with OBMNo SCAL dataDean-Stark available

in oil leg above transition zonecorrected for stress

Pickett plot in water legm = 1.81Rw = 0.0413 ohm-m at 79 C

Dean-Stark matched to logsRt versus Dean-Stark Sw

Calculate saturation exponent ‘n’

amb

ambPCFSwSw

1

1

*

Sw and Rt versus depth

9840

9845

9850

9855

9860

9865

9870

9875

0 5 10 15 20 25 30 35

RT (ohm-m)

De

pth

(ft

)

9840

9845

9850

9855

9860

9865

9870

9875

0.0 0.1 0.2 0.3 0.4 0.5

Dean-Stark Sw (v/v)

Dep

th (

ft)

Dean-Stark and Rt crossplot

Dean Stark Sw and RT

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50

Dean-Stark Sw (v/v)

RT

(o

hm

-m)

Dean-Stark Data

Stressed Corrected Log Estimated Estimated Resitivity Log RI Log Sw SaturationShifted Core Dean Stark Rt F Ro Index Exponent

Sample Depth Porosity Sw (1/m) I nNumber Feet (v/v) (v/v) (ohm-m) (ohm-m)1HDS 9843.6 0.155 0.207 22.1672VDS 9844.8 0.145 0.237 21.7193HDS 9845.5 0.168 0.209 21.7194HDS 9846.6 0.151 0.216 24.3185HDS 9847.5 0.179 0.167 24.0886VDS 9848.5 0.165 0.178 25.1447HDS 9849.6 0.163 0.183 26.019

10HDS 9852.3 0.163 0.177 28.45314HDS 9856.5 0.132 0.203 31.63121HDS 9863.5 0.149 0.258 17.30622HDS 9864.5 0.126 0.328 15.35523HDS 9865.5 0.169 0.220 17.33326HDS 9868.5 0.150 0.248 16.47527HDS 9869.5 0.159 0.219 17.19528HDS 9870.5 0.159 0.224 17.63129HDS 9871.5 0.152 0.215 19.573

Tasks

For each datapointcalculate formation factor, F

calculate Ro

calculate resistivity index, I, based on log Rt and calculated Ro

calculate saturation exponent, ‘n’

Calculate composite ‘n’Crossplot I versus Dean-Stark Sw

Saturation exponent plot

1

10

100

0.1 1

Stress-Corrected Dean-Stark Sw (v/v)

Re

sis

tiv

ity

Ind

ex

(R

t/R

o)

Log I versus log Sw

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

-1 -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0

Log Sw

Lo

g I

Activity 9

Mercury Injection Capillary Pressure

Closure Correction

Background

High pressure MICP test on chip sampleInject mercury to fill pore volume (58000 psi)

Lab interpretationClosure correction (entry pressure, Pce)

Pore volume filled with mercury

Mercury saturation (fraction pore volume)

Sw versus Pc curve

Raw data providedCumulative volume of mercury versus injection pressure

Allows alternative interpretationPce

Sw versus Pc

Data

Pore volume

Vp = total injection volume – closure volume

Total injection volume = 0.6768 ml

Closure pressure = 11.1 psi

Closure volume = 0.0155 ml

Pore volume = 0.6613 ml

Sample Depth, feet: 7889.97Plug Kair, mD: 2.3 Entry Pressure 11.1 psia

Plug Porosity, fraction: 0.216 Closure Volume 0.0155 mlInjection Sample Porosity, fraction: 0.212 Pore Volume 0.6613 ml

Injection Sample Pore Volume, cm3: 0.661Injection Sample Bulk Volume, cm3: 3.115

LAB DATA RAW DATAInjection Mercury Equivalent Pore Normalized Comments CumulativePressure Saturation Water Throat Pore Injection

Saturation Radius, Size VolumeDistribution

(psia) (v/v) (v/v) (microns) Function (ml)0.5 0.000 1.000 221.392 0.000 Closure 0.00000.8 0.000 1.000 133.364 0.000 Closure 0.00651.1 0.000 1.000 94.482 0.000 Closure 0.01041.4 0.000 1.000 79.199 0.000 Closure 0.01171.5 0.000 1.000 71.061 0.000 Closure 0.01231.7 0.000 1.000 62.055 0.000 Closure 0.01302.0 0.000 1.000 55.257 0.000 Closure 0.01302.2 0.000 1.000 48.260 0.000 Closure 0.01362.5 0.000 1.000 42.891 0.000 Closure 0.01362.9 0.000 1.000 37.835 0.000 Closure 0.01363.3 0.000 1.000 33.209 0.000 Closure 0.01363.6 0.000 1.000 29.656 0.000 Closure 0.01364.0 0.000 1.000 26.995 0.000 Closure 0.01424.3 0.000 1.000 25.352 0.000 Closure 0.01424.6 0.000 1.000 23.620 0.000 Closure 0.01424.8 0.000 1.000 22.701 0.000 Closure 0.01425.1 0.000 1.000 21.350 0.000 Closure 0.01425.4 0.000 1.000 20.084 0.000 Closure 0.01425.6 0.000 1.000 19.194 0.000 Closure 0.01425.9 0.000 1.000 18.194 0.000 Closure 0.01426.1 0.000 1.000 17.588 0.000 Closure 0.01426.4 0.000 1.000 16.741 0.000 Closure 0.01426.8 0.000 1.000 15.949 0.000 Closure 0.01427.0 0.000 1.000 15.337 0.000 Closure 0.01427.4 0.000 1.000 14.669 0.000 Closure 0.01427.7 0.000 1.000 13.958 0.000 Closure 0.01427.9 0.000 1.000 13.599 0.000 Closure 0.01428.4 0.000 1.000 12.900 0.000 Closure 0.01428.8 0.000 1.000 12.257 0.000 Closure 0.01429.0 0.000 1.000 11.973 0.000 Closure 0.01499.5 0.000 1.000 11.291 0.000 Closure 0.0149

10.2 0.000 1.000 10.618 0.000 Closure 0.015510.3 0.000 1.000 10.467 0.000 Closure 0.015511.1 0.000 1.000 9.749 0.000 Entry Pressure 0.015511.7 0.002 0.998 9.250 0.045 0.016812.5 0.004 0.996 8.649 0.039 0.018113.3 0.004 0.996 8.132 0.033 0.018114.4 0.005 0.995 7.475 0.059 0.018815.1 0.008 0.992 7.124 0.073 0.020716.4 0.010 0.990 6.572 0.059 0.0220

Laboratory Interpretation

Vp

VhgSHg Hgwet SS 1

Lab Pc Curve

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

Wetting Phase Saturation (v/v)

Inje

ctio

n P

ress

ure

(p

sia)

Lab

Closure (Lab)

Pce underestimated?

0

20

40

60

80

100

120

140

160

180

200

0.00 0.05 0.10 0.15 0.20 0.25 0.30

Volume Injected (ml)

Inje

ctio

n P

ress

ure

(p

sia)

Lab entry pressure 11.1psiShglab = 0 : Swetlab = 1

Requirements

Review “raw” dataPlot injected volume versus pressure

Linear scale ( 0 – 200 psi)

Logarithmic scale

Make alternative interpretationPce

closure volume

Correct and calculatemercury filled pore volume (ml)

mercury saturation

wetting phase saturation

Charts – Injected Volume

0

20

40

60

80

100

120

140

160

180

200

0.00 0.05 0.10 0.15 0.20 0.25 0.30

Volume Injected (ml)

Inje

ctio

n P

ress

ure

(p

sia)

Charts – Pc versus Swet

0

200

400

600

800

1000

1200

1400

1600

1800

2000

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00

Wetting Phase Saturation (v/v)

Inje

ctio

n P

ress

ure

(p

sia)

Activity 10

Capillary Pressure Comparison

Problem

Cap pressure data measured on 2 samplesair-brine (porous plate)

air-mercury (mercury injection)

Requirementsconvert both datasets to lab equivalent oil-brine

compare and comment on data

Data

Support Desk Help

To avoid tedious calculations

calculate every second point for air-mercury data (but

calculate last point)

Air-Brine Data Air-Mercury Data

2B Plug 2C Plug12.5 Air Permeability (mD) 5.2 Air Permeability (mD)19.8 Porosity (%) 19.7 Porosity (%)

Water Capillary Air CapillarySaturation Pressure Saturation Pressure

(%) (psig) (%) (psia)100.0 0 100.0 191.1 1 100.0 290.8 2 100.0 389.7 4 100.0 675.0 8 100.0 965.6 16 100.0 1259.5 32 99.2 1553.4 75 96.7 1850.4 200 94.4 21

91.0 2487.5 2784.7 3077.2 4069.5 6065.0 8061.8 10052.5 20049.2 30044.9 50039.8 75036.0 100032.5 125029.3 150026.7 175025.6 2000

Capillary Pressure Chart

Capillary Pressure

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50

100

150

200

250

0 10 20 30 40 50 60 70 80 90 100

Wetting Phase Saturation (%)

Oil-

Bri

ne C

apill

ary

Pre

ssur

e (p

si)

Activity 13

Relative Permeability Endpoints

Waterflood Test

Test ProceduresMeasure plug Ka and Saturate in water (SFW)

Reduce to Swircentrifuge or porous plate at maximum Pc

Saturate in test oil (15 cp)

Measure endpoint oil permeability, Ko’ at Swirat 1000 psi NCS

Waterflood (SFW)flow until 99.9% water cut (fw = 0.995)

measure TOTAL volume oil produced – at Sro

Measure endpoint water permeability, Kw’ at Sro

Endpoints

Measure base parameterska = 150 mD, = 0.23

Saturate core in water (brine)

Desaturate to SwirCentrifuge or porous plate

Swir = 0.xx

Measure oil permeability Ko’ @ Swir – endpointKo’ = xx mD

Waterflood – collect oilSro = 0.xx

Swr = 1-0.xx = 0.xx

Measure water permeability Kw’ @Sro – endpointKw’ = xx mD

So = 1-Swir

Swirr

Oil = Sro

Sw = 1-Sro

Data Input

D

4

2DA

pA

LQk

1 atm = 14.7 psi

Sample DataConfining Pressure 1000 psiAir Permeability (Ka) 150 mD 1 atm 14.7 psiPorosity 0.23 v/vPore Volume 12.63 cm3Length (L) 4.79 cmDiameter 3.82 cmArea (A) 11.46 cm2 Relative PermeabilityOil Viscosity (mu) 15 cp Sw kro' krw'Water Viscosity (mu) 1 cp (v/v) (Ref Ko') (Ref Ko')

0.20 1.00 0Initial water volume 2.53 cm3 0.75 0 0.30Swir 0.20 v/v Sw kro' krw'

(v/v) (Ref Ka) (Ref Ka)Oil produced 6.94 cm3 0.20 0.53 0Final water volume 9.47 cm3 0.75 0 0.16Final water saturation 0.75 v/vResidual Oil, Sro 0.25 v/vRecovery Factor 68.8 %OIP

Endpoint Differential Vol, Time, Viscosity Q dP PermeabilityPressure(psi) (cm3) (sec) (cp) (cm3/sec) (atm) (mD)

Ko' Endpoint 23.05 20 1000 15 0.0200 1.568 80.0Kw' Endpoint 17.07 20 300 1 0.0667 1.161 24.0

Ko' Endpoint

Kw' Endpoint

Endpoints - Tasks

CalculateSwir (fraction)

Ko’ at Swir from Darcy’s Law

Sro (fraction) from oil recovery and material balance

Recovery factor (% OIP)

Kw’ at Sro from Darcy’s Law

Relative permeabilityEndpoint kro’ and krw’ based on Ko’ reference

Endpoint kro’ and krw’ based on Ka reference

PlotEndpoint relative permeabilities versus Sw

Relative permeability chart

Relative Permeability Chart

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Water Saturation (v/v)

Re

lati

ve

Pe

rme

ab

ilit

y,

kr

Syndicate Exercise

SCAL Programme Design

Oil Reservoir - Background

Appraisal well – consolidated sandstone reservoir10000 ft (3300 m) TVDSS

Core drilled with OBM Air Permeability – 10 mD to 500 mDHelium Porosity – 15% to 25%Formation has trace to 10% clays (mainly illite/smectite)RCA completed - ~ 15 preserved samples available

only 3 off 1.5” plugs possible per sample

Water injection planned – facilities design is an issueNo gas cap, produce above Pb

Data Available

RFT data

Welltest kh

Good log suite – density, resistivity etc but local bad hole conditions

PVT properties

Routine core analysis data (total porosity, ka, no Dean-Stark)

Petrographic data

Objectives - Petrophysics

Oil Initially In Placedensity log requires calibration

resistivity logs require calibration (Archie and Waxman-Smits)

FWSalinity ~ 50000 ppm

Saturation-height model.Validate log Sw-height as concerns over bad hole conditions

Validate welltest kh

Objectives – Reservoir Engineering

Establish recovery factor

Waterflood design data

Validate welltest kh

Design SCAL Programme

What tests do you need to do?

How would you do these tests (which method)?

What do you need to consider ?Other data?

Core preparation ?

Core damage?

Test methods ?

Pragmatism

Must have data for FDP in 6 months