vertical single-well sagd with multiple producersgeosierra.com/files/112839123.pdf© geosierra 2013...

SPE165433

Vertical Single-Well SAGDwith Multiple Producers

Grant Hocking1 and Dale Walters2

1GeoSierra, 2Taurus Reservoir Solutions

© GeoSierra 2013

SPE165433 ● Vertical Single-Well SAGD with Multiple Producers ● Grant Hocking

Slide 2

Frac Enhanced SAGDSingle-Well SAGD

12/20 Garnet

Single-Well SAGD with Multiple Producers

Hz open-hole stimulation

Unconsolidated Formations

© GeoSierra 2013


Trenchless PRB Placement

Continuous PRB

Continuous PRB

Azimuth Controlled FracturingAzimuth Controlled FracturingSlide 3


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SEN W

Cross-Section

Plan View

Slide 4Azimuth Controlled FracturingAzimuth Controlled Fracturing

Real Time Active Resistivity Image

Deep PRBShallow PRB

15cm


© GeoSierra 2013


Slide 5

Non-Brittle Weak FormationsWeakly Cemented Formations

– Minimal Cementation, Soft & Weak– Stress State

• Force Chains Fragile– Easily Destroyed– Minor Vibration or Shearing– Grain Contact Dissolution– Over-Pressurization

• Minimal Horizontal Stress Contrast– Horizontal Stress Contrast can not be

maintained over geological time– Constitutive Behavior

• Ductile Frictional Behavior• Anelastic• Skempton’s B parameter

Weakly Cemented Formations– Minimal Cementation, Soft & Weak– Stress State

• Force Chains Fragile– Easily Destroyed– Minor Vibration or Shearing– Grain Contact Dissolution– Over-Pressurization

• Minimal Horizontal Stress Contrast– Horizontal Stress Contrast can not be

maintained over geological time– Constitutive Behavior

• Ductile Frictional Behavior• Anelastic• Skempton’s B parameter

Isotropic Compression Force Chains ShownIsotropic Compression Force Chains Shown

Minor Shear Strain Destroys Force ChainsMinor Shear Strain Destroys Force Chains

Force Chains DestroyedForce Chains Destroyed

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Slide 6

Offset Well Stimulation Comparison

PC-102-MEDHAT2-8-16-3

MLKRC

MLKRB

MLKRA

X-Drain

Current

PC-102-MEDHAT2-8-16-3

MLKRG

MLKRF

MLKRE

MLKRD

X-Drain

Current

MlkR A

MlkR G

450m

350m

Perforations Dilating CasingMilk River

© GeoSierra 2013


100km

Alberta Saskatchewan

Slide 7

Milk River Tight Gas Reservoir

PC-102-MEDHAT2-8-16-3

MLKRC

MLKRB

MLKRA

X-Drain

Current

PC-102-MEDHAT2-8-16-3

MLKRG

MLKRF

MLKRE

MLKRD

X-Drain

Current

Non-Brittle Weak Formation• E~3GPa c’~2.5MPa ϕ~35°UCS*~10MPa• 40,000 wells conventionally stimulated• CO2 fluid 20/40 sand 10tons/horizon• Surface & Downhole Tiltmeter Arrays• Injection Pressures ↑~40% at <400m depth• Vertical ‘Fracs’ >400m Horiz ‘Fracs’ <400m• Stress Crossover at 400m

450m

350m MlkR G

MlkR A

Pfrac

minh

v

horizontal

vertical

Note: UCS*=2c’tan(45+ ϕ/2)

© GeoSierra 2013


Slide 8

Milk River Tight Gas Reservoir

Shoreline Anisotropy

Stimulation Split Dilating Casing• Cemented by Inner String• Mechanically Split & Expanded• 10% Radial Strain• Locked in Open Position• Multiple Wings intersect FormationShoreline Anisotropy

Hocking et al. 2011

© GeoSierra 2013


Slide 9

Conventional Stimulations

Time (min)

Wel

lhea

dP

ress

ure

(MP

a)

Wel

lhea

dS

lurr

yR

ate

(m3 /m

in)

0 20 40 60 800

5

10

15

20

25

30

0

2

4

6

8

10PressureSlurry R ate

A B C D

E F G

PC-102-MEDHAT 2-8-16-3

MLKR C

MLKR B

MLKR A

X-Drain

Current

PC-102-MEDHAT 2-8-16-3

MLKR G

MLKR F

MLKR E

MLKR D

X-Drain

Current

vertical

horizontal

Hocking et al. 2013

© GeoSierra 2013


Slide 10

Split Dilating Casing Stimulations

Time (min)

Wel

lhea

dP

ress

ure

(MP

a)

Wel

lhea

dS

lurr

yR

ate

(m3 /m

in)

0 50 100 150 2000

5

10

15

20

25

30

0

2

4

6

8

10PressureSlurry Rate

A B C D E F G

PC-102-MEDHAT 2-8-16-3

MLKR C

MLKR B

MLKR A

X-Drain

Current

PC-102-MEDHAT 2-8-16-3

MLKR G

MLKR F

MLKR E

MLKR D

X-Drain

Current

vertical fracsHocking et al. 2013

© GeoSierra 2013


Slide 11

Lessons Learnt• Completion Method Controls the Outcome

– How do you interpret stimulation and shut-in pressure records?

– Mapping injected geometries only tells you of the outcome

– Stimulation thru’ perfs or open-hole do not excite least energy dissipating mechanism

– Frac initiation is essential• Why? Non-Brittle Weak Formations

– Anelasticity– Skempton’s B Parameter

• Completion Method Controls the Outcome– How do you interpret stimulation and shut-in

pressure records?– Mapping injected geometries only tells you of the

outcome– Stimulation thru’ perfs or open-hole do not excite

least energy dissipating mechanism– Frac initiation is essential

• Why? Non-Brittle Weak Formations– Anelasticity– Skempton’s B Parameter

© GeoSierra 2013


Slide 12

Brittle Ductile States

Brittle

DuctileDuctileFrictional Plastic

Transitional Zone

Fractures

Cavity ExpansionBolton & Chin (1994)

Hubbert & Willis (1957)

Vertical

Hz

© GeoSierra 2013


Slide 13

Anelasticity

Frequency(Hz)

Atte

nuat

ion

(1/Q

)

10-5 10-4 10-3 10-2

0.2

0.4

0.6

0.8

1

BreaSandstone

WillmingtonSand

Hysteresis strain lagsstress lost energy

tan'

"

EE

1

2tan Q

Loss Factor

Time

Stra

in

0 20 40 60 800

5

10

15

20

25

30

Stress

Strain

Stre

ss0 10 20 30 40

0

5

10

15

20

25

30

Dry Sand/Weak SandstoneQ=5 Quality Factor

Stra

in

StrainTime

Stre

ss

Atte

nuat

ion

Frequency

© GeoSierra 2013


Slide 14

Anelasticity - Cylindrical Cavity

Field Stress p0

σrσθ

120

0

p

pr

Linear Elastic

Non-Linear Elastic

ppppr

0

0

Strain

Stre

ss

0 10 20 30 400

5

10

15

20

25

30

γs

Gs

β=0.5 Q=3 η=0.3

β=0.65 Q=5 η=0.2

β=0.8 Q=10 η=0.1

Shear Strain

Shea

r Str

ess

Bolton & Whittle (1999)

compression +ve

1

ssG

© GeoSierra 2013


Slide 15

Inclusion Tip and MobilitySkempton’s B parameter• >0.75 at low p’• >0.5 at high p’ at significant depth

Inclusion Tip Mobility & Geometry• negative pore pressure in front of tip• inclusion clamped by apparent cohesion• inclusion sucked into the unloaded zone• remains on azimuth due to anelasticity

p

Soft u=p B=1Stiff u=0 B=0

© GeoSierra 2013


Slide 16

Inclusion on Azimuth - AnelasticityProcess zone grows with inclusion length due to anelasticity resulting in a more robust propagating inclusion remaining on azimuth

Propagating inclusion remains on azimuth even with modest stress contrasts

Anelasticity, Skempton’s B parameter – no mention of plasticity

© GeoSierra 2013


Slide 17

Conventional Stimulations

PC-102-MEDHAT 2-8-16-3

MLKR C

MLKR B

MLKR A

X-Drain

Current

PC-102-MEDHAT 2-8-16-3

MLKR G

MLKR F

MLKR E

MLKR D

X-Drain

Current

vertical

horizontal

Hocking et al. 2013Time (min)

Wel

lhea

dP

ress

ure

(MP

a)

9.5 10 10.5 11 11.5 120

2

4

6

8

10

A B C E F G

D

© GeoSierra 2013


Slide 18

Split Dilating Casing Stimulations

PC-102-MEDHAT 2-8-16-3

MLKR C

MLKR B

MLKR A

X-Drain

Current

PC-102-MEDHAT 2-8-16-3

MLKR G

MLKR F

MLKR E

MLKR D

X-Drain

Current

vertical fracsHocking et al. 2013Time (min)

Wel

lhea

dP

ress

ure

(MP

a)

33 34 350

2

4

6

8

10

A B C D E F G

Data lost

© GeoSierra 2013


Slide 19

Well Construction Sequence

Sump

Top Pay

Bottom Pay

Operated in SAGD Mode- no startup - invariant of geology

Injector

Producer

© GeoSierra 2013


Slide 21

Time (days)

Oil

Pro

duct

ion

Rat

e(b

bls/

day)

Cum

mul

ativ

eO

il(M

Mbb

l)C

umul

ativ

eS

OR

0 500 1000 1500 2000 2500 30000

100

200

300

400

500

600

0

0.2

0.4

0.6

0.8

1

1.2

0

1

2

3

4

5

Oil RateCum OilCSOR

Clean SandKv=2DKv=0.8DKv=0.4D

Single-Well SAGD Clean Sand Dirty Sand

Athabasca Bitumen Sp=1,750kPa

Single-Well SAGD vs Vert Perm

SAGD

v

v

v

kCSOR

kt

kq

4

1

1

© GeoSierra 2013


Slide 22

Reservoir Idealization

Modeled Region

Steam InjectionProduced OilLines of Symmetry

1/2 Well SpacingWing Length

High confidence in reservoir simulations due to minimal dependence on vertical perm

© GeoSierra 2013


Slide 23

Single-Well SAGD vs Conv SAGD

Time (days)

Oil

Pro

duct

ion

Rat

e(M

bbls

/day

)

Oil

Rec

over

y(M

Mbb

ls)

Cum

ulat

ive

SO

R

0 500 1000 1500 2000 2500 3000 35000

0.5

1

1.5

2

2.5

3

0

1

2

3

4

0

1

2

3

4

5

50% 50%

X-DrainSAGD

Faster Recovery

4 Single-Well SAGD Conventional SAGD

S-W

© GeoSierra 2013


Slide 24

Vertical Single-Well SAGD with Multiple Producers

Vertical Single-Well SAGD with Multiple Producers

12/20 Garnet

© GeoSierra 2013


Slide 25

Time (days)

Oil

Pro

duct

ion

Rat

e(M

bbls

/day

)

Oil

Rec

over

y(M

Mbb

ls)

Cum

ulat

ive

SO

R

0 500 1000 1500 2000 2500 3000 35000

0.5

1

1.5

2

2.5

3

3.5

4

0

1

2

3

4

5

0

1

2

3

4

5

50%50%

M-W SAGDSAGD

Faster Recovery

© GeoSierra 2013


Slide 26

Hz open-hole stimulation

Frac Enhanced Conventional SAGDFrac Enhanced Conventional SAGD

Benefits:• Simpler & more reliable to operate• SAGD mode at startup• Engineer around geology• Quick re-startup• Operate at low pressure• Flow conformance assured

© GeoSierra 2013


Time (days)

Oil

Pro

duct

ion

Rat

e(M

m3 /d

ay)

Oil

Rec

over

y(M

Mm

3 )C

umul

ativ

eS

OR

0 1000 2000 3000 40000

5

10

15

20

0

5

10

15

20

0

1

2

3

4

5Oil RateCum OilCSOR

Slide 27

Frac Enhanced SAGD @ FirebagFrac Enhanced SAGD @ Firebag

*Bitumen $50/bbl52m pay, 1,850kPa, ϕ=0.3, So=0.79

Frac-SAGD

Actual

Benefits:• Lower CSOR• Faster Recovery• 6x NPV10

Quantified:• Cost

$16 vs $32 /bbl• Capacity

380k vs 180k bpd• Carbon Footprint

<50% carbon/bbl• Net Income

up by 4x ∆$3.4B/yr*

© GeoSierra 2013


Slide 28

ConclusionsConclusions• Stimulation completion dictates the outcome

– Mini-Frac thru’ perfs or open-hole suspect in non-brittle weak formations

– Essential to initiate frac in non-brittle formations– Need to re-assess earlier stimulation data & experience

• Process not depth limited, strength limited• Frac SAGD performance ~invariant of geology• Frac enhance best geology first, not poorest

– Highest ROI, best sustainable and environmental practice• As built issues

– Permeability of planes needs to be high– Demonstrate azimuth control of planes from Hz wells– Steaming trials required to quantify performance

• Stimulation completion dictates the outcome– Mini-Frac thru’ perfs or open-hole suspect in non-brittle

weak formations– Essential to initiate frac in non-brittle formations– Need to re-assess earlier stimulation data & experience

• Process not depth limited, strength limited• Frac SAGD performance ~invariant of geology• Frac enhance best geology first, not poorest

– Highest ROI, best sustainable and environmental practice• As built issues

– Permeability of planes needs to be high– Demonstrate azimuth control of planes from Hz wells– Steaming trials required to quantify performance

vertical single-well sagd with multiple producersgeosierra.com/files/112839123.pdf© geosierra 2013...

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