HEAVY-OIL SEISMIC MONITORINGat PIKES PEAK, SK

I.A. Watson*, L.R. Lines and K.F. BrittleI.A. Watson*, L.R. Lines and K.F. Brittle

November 20, 2001November 20, 2001

Combined two CREWES papersCombined two CREWES papers– ““Heavy-oil time-lapse seismic monitoring Heavy-oil time-lapse seismic monitoring

at Pikes Peak, Saskatchewan”at Pikes Peak, Saskatchewan”– ““Heavy-oil reservoir characterization Heavy-oil reservoir characterization

using elastic wave properties”using elastic wave properties”

Outline

IntroductionIntroductionGeologyGeologyAnalysis 1: Section DifferencingAnalysis 1: Section DifferencingAnalysis 2: Isochron RatioAnalysis 2: Isochron RatioAnalysis 3: Vp/Vs RatioAnalysis 3: Vp/Vs RatioConclusionsConclusions

Pikes Peak Time-lapse

Injected steamInjected steam– Reduces reservoir impedanceReduces reservoir impedance– Causes increased compressional wave Causes increased compressional wave

traveltimetraveltimeTwo (time-lapse) seismic lines Two (time-lapse) seismic lines

– 2-D lines in co-incident locations2-D lines in co-incident locations 1991 (swath)1991 (swath) 2000 (multi-component)2000 (multi-component)

Pikes Peak

Heavy-oil fieldHeavy-oil fieldOperated by Husky EnergyOperated by Husky Energy40 km east of Lloydminster40 km east of LloydminsterOver 40 million bbls producedOver 40 million bbls producedSteam injection operationSteam injection operation

DATA

• 200+ wells 200+ wells

• 1991 2D swath 1991 2D swath

• 2000 4C-2D 2000 4C-2D

• 2000 VSP2000 VSP

Pikes Peak Field Map

R.23W3 R.24W3

T.49

T.50

1 km H1991 and H2000

3C8-6

D15-6

1A15-6

D2-6

Data Comparison

H1991H1991February 1991

6 sec6 sec8-110 Hz non-linear

3 vibrators over 20 m3 vibrators over 20 m4 sweeps/vp4 sweeps/vp

10 m drag length10 m drag length40 m40 m source interval source interval20 m20 m group interval group interval

9 geophones over 20 m9 geophones over 20 m3030 CDP fold CDP fold

Bandwidth 14 – 110 Hz

H2000March 2000

16 sec8-150 Hz non-linear

22 vibrators over 20 m vibrators over 20 m4 sweeps/vp4 sweeps/vp

NoNo drag drag220 m0 m source interval source interval20 m20 m group interval group interval

66 geophones over geophones over 110 m0 m66 CDP fold66 CDP fold

Bandwidth 14 – 150 Hz

Data Comparison

Pikes Peak Geology

Waseca Trend in Pikes Peak AreaWaseca Trend in Pikes Peak Area

Van Hulten, 1984

Pikes Peak Geology

• Incised valleyIncised valley• Estuarine -point barsEstuarine -point bars• N-S N-S • ~500 m depth~500 m depth

• Salt dissolution structure Salt dissolution structure and stratigraphic trapand stratigraphic trap• 80-90% oil saturation80-90% oil saturation• 5-30 m net pay5-30 m net pay• 32-36% porosity32-36% porosity• 1-10 darcies perm. 1-10 darcies perm. • 1212° API° API

Van Hulten, 1984

Analysis 1: Section Differencing

Time-lapse differences ofTime-lapse differences of– Reflectivity Reflectivity – Acoustic Impedance (AI)Acoustic Impedance (AI)

Calibration

Required prior to differencing Required prior to differencing Hampson-Russell’s Pro4DHampson-Russell’s Pro4DAdjustments for:Adjustments for:

TimeTimeAmplitude Amplitude PhasePhase

Time window above zone of interestTime window above zone of interestTrace-by-trace gave best resultsTrace-by-trace gave best results

Refectivity Differencing

Applied a wavelet-shaping filter to H2000Applied a wavelet-shaping filter to H2000Differences seen below reservoir Differences seen below reservoir Increase in traveltime caused by Increase in traveltime caused by

presence of injected steampresence of injected steamDoes not allow signal to cancelDoes not allow signal to cancel

Other differencesOther differencesNoiseNoiseAcquisition parametersAcquisition parameters

H1991 Reflectivity Section

N S

H2000 Reflectivity Section

Reflectivity Difference Section

Impedance Differencing

Applied a band-pass filter, wavelet Applied a band-pass filter, wavelet shaping and time and phase matching to shaping and time and phase matching to H2000H2000

Significant differences seen within Significant differences seen within reservoir zone – lower impedancereservoir zone – lower impedance

Lower AI extends further than expectedLower AI extends further than expectedHas the steam reached further?Has the steam reached further?Limited by 2-D sectionLimited by 2-D section

H1991 AI Section

H2000 AI Section

AI Difference Section

Analysis 2: Isochron Ratio

Interpretation basedInterpretation based– H1991 and H2000H1991 and H2000– Waseca-Sparky intervalWaseca-Sparky interval

Isochron ratioAddition of steamAddition of steam

– Vp decreaseVp decrease– Increase in 2000/1991 isochron ratioIncrease in 2000/1991 isochron ratio

Position of steam zone predicted on linePosition of steam zone predicted on line

Seismic lineSeismic line

Steam zone Steam zone on lineon line

Steam zoneSteam zoneradiusradiusHusky, 2000

D2-6 Waseca Core Analysis

0

500

1000

1500

2000

2500

0 20 40 60 80 100 120 140 160 180

Temperature (°C)

Vel

oci

ty (

m/s

)

Compressional

Source: Core Laboratories

H1991 Reflectivity Section

H2000 Reflectivity Section

2000/1991 P-P Isochron Ratio (Waseca-Sparky)

0.70

0.80

0.90

1.00

1.10

1.20

1.30

1 51 101 151 201 251

CDP #

inte

rva

l ra

tio

3B1-61D2-6

3C1-63B8-62B9-61D10-6

Waseca thickest sands

N S

Analysis 3: Vp/Vs Ratio

Interpretation based Interpretation based – H2000 multi-component onlyH2000 multi-component only– PP and PS sectionsPP and PS sections– 2 intervals2 intervals

Vp/Vs ratioAddition of steamAddition of steam

– Vs decrease < Vp decreaseVs decrease < Vp decrease Vp/Vs decrease = steamed zoneVp/Vs decrease = steamed zone

Vp/Vs ratio derived from P-P and P-S interpretationsVp/Vs ratio derived from P-P and P-S interpretations

pp

ppps

s

p

t

tt

V

V

2

pp

ppps

s

p

t

tt

V

V

2

Margrave et al., 1998

D2-6 Waseca Core Analysis

0

500

1000

1500

2000

2500

0 20 40 60 80 100 120 140 160 180

Temperature (°C)

Vel

oci

ty (

m/s

)

Shear

Compressional

Source: Core Laboratories

H2000 P-P (Vertical Component)

H2000 P-S (Radial Component)

Vp/Vs Isochron Ratio (Waseca-Sparky)

1.0

1.5

2.0

2.5

3.0

3.5

1 101 201 301 401 501 601 701

CDP #

Vp

/Vs

ra

tio

3B1-61D2-6

3C1-63B8-62B9-61D10-6

Waseca thickest sands

N S

Vp/Vs Isochron Ratio (Mnvl to L.Mnvl)

1.0

1.5

2.0

2.5

3.0

3.5

1 101 201 301 401 501 601 701

CDP #

Vp

/Vs

ra

tio

3B1-61D2-6

3C1-63B8-62B9-61D10-6

Waseca thickest sands

Injection during2000 acquisition

N S

Conclusions

Anomalies are generally located where Anomalies are generally located where expectedexpected

Inferred steam response on both the time-Inferred steam response on both the time-lapse and the Vp/Vs ratio plotslapse and the Vp/Vs ratio plots

Difficult interpretation on converted wave data Difficult interpretation on converted wave data Potential lateral lithology changes identifiedPotential lateral lithology changes identified Minimize all variables external to the reservoir Minimize all variables external to the reservoir 3-D seismic data is recommended3-D seismic data is recommended

Acknowledgements

• Husky EnergyHusky Energy

• AOSTRA (COURSE)AOSTRA (COURSE)

• Jason Geosystems Jason Geosystems

• Hampson-RussellHampson-Russell

• CREWESCREWES

• NSERC and Imperial OilNSERC and Imperial Oil

PS synthetic: GMA

Acoustic Impedance ( AI )

• AI obtained through inversionAI obtained through inversion• Band limited resultBand limited result• Trace-based vs. model-basedTrace-based vs. model-based• Post-stack interpretation techniquePost-stack interpretation technique

i

iii

ii

iii

ii

R

RZZ

ZZ

ZZR

VZ

1

1 Thus,

tyReflectivi

Impedance

1

1

1

i

McQuillin 1984

iZ

1iZ

AI Inversion

Reduces effect of wavelet sidelopes and Reduces effect of wavelet sidelopes and tuningtuning

Interpret boundaries and evaluate internal Interpret boundaries and evaluate internal propertiesproperties

Allows direct comparison of time-lapse Allows direct comparison of time-lapse surveyssurveys

Inversion performed using Jason Inversion performed using Jason GeoscienceGeoscience

WellWell Months Months before H91before H91

Months Months before H00before H00

3B1-63B1-6 00 1414

1D2-61D2-6 3838 2525

3C1-63C1-6 6767 8989

3B8-63B8-6 n/an/a 00

2B9-62B9-6 n/an/a 2626

1D10-61D10-6 n/an/a 1212

Injection Information

PS synthetic: matlab

0 300