five things mike vincent

7/28/2019 Five Things Mike Vincent

1/19

Five things you didnt want to knowabout hydraulic fractures

Mike [email protected]

FracwellLLC

Microseismic image: SPE 119636

Why we need to frac The bad news

5 things you didnt want to know

The good news Compensating for some of these problems can

significantly improve production and profitability!

Outline


2/19

Where Do we find Oil and Gas?

(NOT IN UNDERGROUND LAKES!) (NOT IN UNDERGROUND LAKES!)

Why Fracture Stimulate?

Top View

Side View

Unstimulated Wells:

Require high reservoirpermeability for sufficient

hydrocarbon flow

Hydraulic Fractures:

Accumulate hydrocarbonsover enormous area,achieving economicflowrates from low

permeability formations

Figures not to scale!


3/19

Reservoir Contact

Multi-Lateral 15,000 ft of drilled length in 5 laterals

10,000,000 ft 2 >1,000,000m 2 of contact

Transversely Fractured Horizontal Wells let you Repeat this!


4/19

Technology Progression

0.0001

0.001

0.01

0.1

1

10

0

1

10

100

1,000

10,000

100,000

1,000,000

CementedVertical

UncementedVertical

UncementedHorizontal

BiwingFracture

MultipleTransverse

Fractures

R e s e r v o

i r P e r m

m D

R e s e r v o

i r C o n

t a c

t m

2

Reservoir Contact

Economic Gas Reservoir PermEconomic Oil Reservoir Perm

Increasing our reservoir contact by 1,000,000 fold

has allowed pursuit of reservoirs with thousands of times lower perm

In low perm reservoirs, fractures are often the most critical component of our

completion

However, they are the most poorly optimizedelement!


5/19

Fracs Simple (bi-wing), planar, vertical, hydraulically

continuous, highly conductive

Reservoir Homogenous reservoirs (or simplified layering)

Fluid Flow Simple fluid flow regimes

Convenient Assumptions

SPE 128612

Do we envision fracs correctly?

10

We picture fracs as perfect vertical planeswithout restriction to hydrocarbon flow

Fracs are very narrowribbons, massively long!Frac length frequently

thousands of times greater thanthe wellbore diameter


6/19

500

1500

7000

182

1137

5715

72

672

3481

24

225

1243

549

479

1.4

14144

0.6 7130

0.3 496

0

1000

2000

3000

4000

5000

6000

7000

E f f e c

t i v e

C o n

d u c

t i v

i t y

( m d - f

t ) ( D - m

)

API Test Modified 50-Hour Test

"InertialFlow" withNon-Darcy

Effects

LowerAchievedWidth (1lb/sq ft)

MultiphaseFlow

50% GelDamage

FinesMigration /Plugging

CyclicStress

Chinese Sand

Jordan Sand

CarboLITE

Realistic Conductivity Reductions20/40 proppants at 6000 psi

0.3

0.6

0.9

1.2

2.1

1.5

1.8

0.0001 D-m

0.001 D-m

0.029 D-m

Conditions: YM=5e 6 psi, 50% gel damage, 250 F, 1 lb/ft 2, 6000 psi, 250 mcfd, 1000 psi bhfp, 20 ft pay, 10 blpdYM=34e 3 MPa, 50% gel damage, 121C, 5 kg/m 2, 41 MPa, 7000 m 3 /d, 7 MPa bhfp, 6 m pay, 1 .6 m 3l/d

References: ST Sand: SPE 14133, 16415, CL: Carbo typical, LT: Stim-Lab PredK 2002, SPE 24008, 3298, 7573, 11634, CARBO Tech Rpt 99-062, Run #6542, StimLab July 2000, SPE 16912, 19091, 22850, 106301, 84306

Effective conductivities can beless than 1% of API test values

99.9%reduction

99.7%reduction

98.6%reduction

11

Does Conductivity Degrade? McDaniel , SPE 15067

All published lab data show proppantscontinue to crush, compact, rearrange over

time and lose conductivity.

SPE 12616, 14133, 15067, 110451,128612,134330, 136757, Hahn, Drilling Vol 47, No 6,

April 1986

Some proppants are more durable thanothers. But none are constant

Why dont engineers recognize this?


7/19

Pollard (2005) Northeast Ship Rock Dike, New Mexico13

Relatively simple, extremely wide fracture

Extends 9500 feet atsurface, average widthexceeding 7 feet!

We have created hydraulic

fracs 2200 ft half-length butless than 0.1 inches wide

Pollard (2005) Northeast Ship Rock Dike14

Outcrop actually comprised of >30 discrete echelon segments separated by intact host rock

Even this dike appeared discontinuous in outcrop.Are you certain your frac is continuous?


8/19

NEVADA TEST SITE - HYDRAULIC FRACTURE MINEBACK

Observations of Fracture Complexity

Physical evidence of fractures nearly always

complex

Multiple Fractures

Initiation At Perforations Multiple Perforations

Provide Multiple EntryPoints For FractureInitiation

Five SeparateFractures Are VisibleIn These FracturesInitiated FromHorizontal Wellbore

12 Perforations Total 6 Top & Bottom

I would have modeled/predicted a single frac with muchhigher conductivity than 5 narrow fracs added together

[This actually is a bad outcome!]


9/19

NEVADA TEST SITEHYDRAULIC FRACTURE

MINEBACK

Multiple Strands in a Propped Fracture

(Vertical Well)

These fractures are narrow, you are lookingat an angle to the exposed frac face

Mesaverde MWX test, SPE 22876

Physical evidence of fractures nearly always

complex

Multiple Strands in a Propped Fracture (Vertical Well)

7100 ft TVD [2160m]32 Fracture Strands Over 4 Ft Interval

HPG gel residue on all surfacesGel glued some core together (>6yrs elapsed post-frac!)All observed frac sand (20/40RCS) pulverized


10/19

Is complexity

solely attributed to rock fabric?

Many other examples! [TerraTek, Baker, Weijers, CSM FAST consortium]

Unconsolidated 200 mesh sand, 35 lb XLG,Flow SPE 63233

Chudnovsky, Univ of Ill, Chicago

19

Physical evidence of fractures nearly always complex

NEVADA TEST SITEHYDRAULIC FRACTURE

MINEBACK

Fracture Complexity Due To Joints


11/19

Laminated on every scale?

21

Figure 2 On every scale, formations may have laminations that hinder vertical permeability and fracture penetration.Shown are thin laminations in the Middle Bakken [LeFever 2005], layering in the Woodford [outcrop photo courtesy ofHalliburton], and large scale laminations in the Niobrara [outcrop and seismic images courtesy of Noble]

SPE 146376

Woodford Shale Outcrop

Some reservoirs posechallenges to effectively

breach and prop throughall laminations

Rational Expectations?

Our understanding of fracbarriers and k v should

influence everything fromlateral depth to frac fluidtype, to implementation

Narrower aperture plussignificantly higher stress inhorizontal steps?

Failure to breach all laminae?

Will I lose thisconnection due to

crushing of proppant inhorizontal step?


12/19

Fractures Intersecting Stacked Laterals

Modified from Archie Taylor SPE ATW Aug 4 201023

23 ft thick Lower Bakken Shale

Fraced Three Forks well ~1MM lb proppant in 10 stages1 yr later drilled overlying well in Middle Bakken;

Kv


13/19

With what certainty can we explain this production?

SPE 106151 Fig 13 Production can be matched with a variety of fracture and reservoir parameters25

0

200

400

600

800

1000

1200

1400

1600

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0 100 200 300 400 500 600

Production Days

S t a g e

P r o

d u c

t i o n

( m c

f d )

0

20

40

60

80

100

120

140

160

180

200

C u m u

l a t i v e

P r o

d u c t

i o n

( M M s c

f )

Actual Production Data

Nice match to measured microseismic, eh?


0

200

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0 100 200 300 400 500 600

Production Days

S t a g e

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f d )

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C u m u

l a t i v e

P r o

d u c t

i o n

( M M s c

f )

Actual production data

Long Frac, Low Conductivity500' Xf, 20 md-ft, 0.5 uD perm, 23 Acres 4:1 aspect ratio


14/19

Is this more accurate? Tied to core perm


0

200

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0 100 200 300 400 500 600

Production Days

S t a g e

P r o

d u c

t i o n

( m c

f d )

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200

C u m u

l a t i v e

P r o

d u c t

i o n

( M M s c

f )


Long Frac, Low Conductivity

Medium Frac, Low Conductivity

500' Xf, 20 md-ft, 0.5 uD perm, 23 Acres 4:1 aspect ratio

100' Xf, 20 md-ft, 5 uD perm, 11 Acres 4:1 aspect ratio

Can I reinforce my misconceptions?


0

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Production Days

S t a g e

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d u c

t i o n

( m c

f d )

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200

C u m u

l a t i v e

P r o

d u c t

i o n

( M M s c

f )


Long Frac, Low Conductivity

Medium Frac, Low Conductivity

Short Frac, High Conductivity, Reservoir Boundaries

500' Xf, 20 md-ft, 0.5 uD perm, 23 Acres 4:1 aspect ratio



History matching of production issurprisingly non-unique.

Too many knobs available to tweak We can always blame it on the geology

Even if I know it is a simple planar frac, I cannotprove whether it was inadequate reservoir quality, or

inadequate completion with a single well


15/19

1. Complex Flow Regimes 100x higher pressure losses

2. Conductivity Degrades3. Heterogeneous Reservoirs

Dependant on fracs to connect reserves

4. Complex Frac Geometry Require commensurate increase in conductivity

5. Non-unique interpretations

5 Things You Didnt Want to Know

Removing the Uncertainty If we require a production match of two different

frac designs, we remove many degrees offreedom lock in all the reservoir knobs!

Attempt to explain the production results frominitial frac AND refrac

143 published trials in SPE 134330 100 Bakken refracs 136757

Require simultaneous match of two differentfrac designs in same reservoir !

200+ trials in SPE 11914330


16/19

Field Studies Documenting Production Impact with Increased Fracture Conductivity

>200 published studies identified,authored by >150 companies

SPE 119143 tabulates over 200 field studies

Oil wells, gas wells, lean and rich condensateCarbonate, Sandstone, Shale, and Coal

Well Rates Well Depths1 to 25,000 bopd 100 to 20,000 feet

0.25-100 MMSCFD

31

Dataset Limitations Intentional

Eliminated most field examples with dramatic fluidrheology changes

Are production gains attributed to proppant transport(frac length), differing gel cleanup, differing frac heights?

Unintentional Its just my literature review. Certainly I missed some

excellent papers

Publication Bias Industry rarely publishes failures Nonetheless I summarize 10 examples of exceptions to

the rule

A tabulation of 200 papers in SPE 11914332


17/19

Production Benefit

In >200 published studies and hundreds ofunpublished proppant selection studies, Operators frequently report greater benefit than

expected using: Higher proppant concentrations More aggressive ramps, smaller pads Screen outs Larger diameter proppant Stronger proppant Higher quality proppant More uniformly shaped & sized proppant

Frac conductivity appears to be much moreimportant than our models or intuition predict!

A tabulation of 200 papers in SPE 11914333

We are 99.9% certain the Pinedale Anticline was constrained by proppant quality

Effect of Proppant Selection upon Production

0

100

200

300

400

500

600

700

800

900

L L 3

L L 2

L L 1

M V 5

M V 4

M V 3

M V 2

M V 1

M V 0

A v e r a

g e

Reservoir Sub-Interval (Lower Lance and Mesa Verde)

P r o

d u c t

i o n R

a t e 1 0 0 d a y s p o s

t - f r a c

( m c

f d )

Versaprop

CarboProp

ISP-BS

ISP 20/40

Averages based on 95 stages ISP-BS and 54 stages ISP 20/40

SPE 106151 and 108991

70% increasein productivityachieved with

a moreuniformly

sizedproppant!


18/19

Can we learn from refracs?

Pagano, 2006

Gas Condensate wells in DJ Basin up to 5restimulations

Increase Conductivity in Refracs? Dozens of examples in literature

Shaefer, 2006 17 years later,tight gas

0

500

1000

1500

2000

2500

3000

3500

J an -9 0 J an -9 1 J an -9 2 J an -9 3 J an -9 4 J an -9 5 J an -9 6 J an -9 7 J an -9 8 J an -9 9 J an -0 0 J an -0 1

G a s

R a t e ,

M C F D

0

50

100

150

200

250

300

350

400

450

500

W a t e r

R a t e ,

B W P D

GasWater

Initial Fracin1989:

48,000 lb 40/70sand + 466,000lb 12/20sand

May1999Frac:

300,000lb 20/40LWC

May1995Frac:

5,000lb100 mesh+ 24,000lb 20/40

Sand

Vincent, 2002 9 years later,CBM

0

500

1000

1500

2000

2500

3000

3500

4000

M a y-84 May-86 May-88 May-90 May-92 May-94 May-96 May-98 May-00

Date

P r o

d u c t

i o n

f r o m

F r a c t u r e

( b f p d )

Original Fracture (20/40 Sand)Phase I refrac (20/40 Sand)Phase III refrac (16/20 LWC)

IncrementalOilExceeds

1,000,000barrels

IncrementalOilexceeds

650,000barrels

FirstRefrac

SecondRefrac

Pospisil, 1992 6 years later,20 mD oil

0

500

1000

1500

2000

2500

S t a b i l i z e d

R a t e

( M S C F D )

P re Fr ac 1 0, 00 0 g al3% acid +10,000 lb

glass beads

80,000 gal +100,000 lb20/40 sand

75,000 gal +120,000 lb20/40 ISP

Ennis, 1989 sequentialrefracs, tight gas

0

2 0

4 0

6 0

8 0

1 0 0

1 2 0

W e l l A W e l l B W e l l C W e l l D W e l l E

P

r

o

d

u

c

t

i o

n

R

a

t

e

(

t o

n

n

e

s

/ d

a

y

)

.

.

I n i t i a l F r a c

R e f r a c

Dedurin, 2008, Volga-Uralsoil

36


19/19

1) Incredible reservoir contact provided by hydraulic fractures2) Bad News: Fracs are not optimized

Fluid flow is complicated Frac geometry is tortuous Connection between the frac and wellbore is tenuous Laminated reservoirs depend on vertical frac continuity Many fractures collapse or heal

3) Great News: Fracs are not optimized Reservoirs are often capable of tremendous increases in

productivity with improved frac design

Summary

Five things you didnt want to knowabout hydraulic fractures

Mike Vincent

FracwellLLC

.pdf version of [email protected]

five things mike vincent

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