Post on 21-Jul-2020
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Role of multiple fracturing of vertical and Horizontal Wells in Maximizing production and extending life of the field
M. Y. Soliman, Ali Rezaei, Fahd Siddiqui, University of Houston
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Outline• Hydraulic fracturing and field development • Hydraulically‐fractured systems: design and arrangement
– Why multiple fractures – Effect on production– Geomechanical consequences
• Fracturing and reservoir depletion– Low permeability formations– Naturally‐fractured formations– Effect of pore pressure depletion on local stresses
• Re‐fracturing and infill well fracturing– Is it required? – Vertical well: re‐fracturing– Horizontal well: re‐fracturing, infill well fracturing– Geomechanical considerations for infill drilling and refracturing
• Summary
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Hydraulic Fracturing and Field Development
Horizontal well fracturing Pad drilling
Haynesville Shale
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Fracturing Low Permeability Formation
• High density fracturing is important to maximize fluid flow
• Re‐fracturing may be necessary
• Both have Geomechanics consequence
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Oil Phase Pressure, Permeability = 1 md
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Oil Phase Pressure, Permeability = 0.1 md
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Oil Phase Pressure, Permeability = 0.01 md
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Oil Phase Pressure, Permeability = 0.001 md
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Oil Phase Pressure, Permeability = 0.0005 md
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Fracturing Naturally‐Fractured Formations
Kazemi et al, 1992
• Model consists of matrix and fracture (other than hydraulic fractures)
• Flow from both matrix and fractures
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Oil Phase Pressure, Fracture System
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Oil Phase Pressure, Matrix
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
0
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0 500 1000 1500 2000 2500 3000
Cumulative Gas Production, B
scf
Time, days
Fractured
Fractured After 2 Years
Fractured After 4 years
Fractured After 6 Years
Un‐Fractured
Cumulative Gas Production
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
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0 500 1000 1500 2000 2500 3000
Cumulative Condensate
Production, 1000 STB
Time, days
Fractured
Fractured After 2 Years
Fractured After 4 years
Fractured After 6 Years
Un‐Fractured
Cumulative Condensate Production
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Hydrocarbon Recovery at 10 Years; Permeability vs. Well Type
VerticalVerticalFraced Horizontal
HorizontalAxial Frac Horizontal 5
Transv.Fracs
Horizontal11 Transv.Fracs Incr
Lf
5
0.5
0.05
0.005
0%
5%
10%
15%
20%
25%
30%
Recovery at 10 Years (Cum/OOIP)
Well Type
Permeability md
Oil Well
VerticalVerticalFraced Horizontal
HorizontalAxial Frac Horizontal
5 Transv.Fracs
Horizontal11 Transv.Fracs Incr
Lf
0.5
0.05
0.005
0.0005
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Recovery at 10 Years (Cum/OGIP)
Well Type
Permeability md
Gas Well
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Fractured Systems
• Design and arrangement• Effect on production• Geomechanical consequences
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Effect of Fracturing and Refracturing
All fractures Some fractures Re‐fracturing
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Multiple Fracturing of Vertical Wells
• Proposed for – Low perm formation
– Declining fracture productivity
• Observed during drill cutting re‐injection
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
1000
2000
3000
4000
5000
6000
0 10 20 30 40 50 60 70 80 90
Str
ess,
psi
Theta, degree
Tangential Stress No Fracture
Tangential Stress after One Fracture
Tangential Stress at Wellbore Wall
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Tangential Stress at Wellbore Wall
Tangential Stress along the Wellbore Wall
-10000
-5000
0
5000
10000
15000
20000
0 10 20 30 40 50 60 70 80 90
o
Tan
gen
tial
Str
ess,
psi
W Frac, SH=Sh W/O Frac, SH=Sh W Frac, SH=1.5Sh W/O Frac, SH=1.5Sh
W Frac, SH=2Sh W/O Frac, SH=2Sh W Frac, SH=3Sh W/O Frac, SH=3Sh
Sh=3000 psi
Pw=6000 psi
Pf =2000 psi
rw=4.25 inch
Lf=6 inch
E=1,090,000 psi=0.225
Wang, et al, SPE 201719
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Multiple Fractures in Vertical Wells
Cumulative production comparison for one and two fractures
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0 200 400 600 800 1000 1200 1400 1600 1800 2000
Time, days
To
tal
Pro
du
ctio
n,
mm
cfSingle Frac
Two fracs
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Multiple Fractures in Horizontal Wells
Alternating Fracturing
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Propagation of Multiple Fractures (Clusters) from a Horizontal Well
• Intra‐Well fracture Interaction (frac‐hits)– Interaction between active and passive fractures
• Inter‐Well fracture Interactions– Interaction between fracture and offsetting wells
• Stress Shadowing– Stress alteration caused by deformation due to fracturing
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
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Swain 1978, Pollard 1984, Atkinson 1987
Microcrack in Glass
A vein in granite Rock
a dikeOverlapping
spreading centers
Fracture Interactions in Nature
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Propagation of ClustersHorizontal well
Displacement, m Stress anisotropy, MPa
Shear stress, MPa Minimum horizontal stress, MPa Maximum horizontal stress, MPaY, m
Y, m
Y, m Y, m
Y, m
X (horizontal well direction), m X (horizontal well direction), m
X (horizontal well direction), mX (horizontal well direction), m X (horizontal well direction), m
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Overlapping Zones of Two Interacting Fractures
Rezaei, et al 2015ARMA-2015-449
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Modified Zipper Frac (MZF), Non‐Symmetric
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Well A
Well B
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Modified Zipper Frac, Symmetric
Rezaei, et al 2015ARMA-2015-449
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Six SurgiFrac Waterfracs performed consecutively for an Openhole Chert horizontal wellbore
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Re‐Fracturing and Infill Fracturing• Purpose• Vertical wells: re‐fracturing• Horizontal wells: re‐fracturing, infill well fracturing• Geomechanical considerations
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Why is Re‐fracturing Needed?
Original Original + re‐fracturing
SPE 134330
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Effect of Re‐Fracturing on Flow Rate
SPE 136757
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Example of a Successful Re‐Fracturing
SPE 136757
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Re‐fracturing
• In Early 80’s
• Multiple fractures in different orientations from a vertical well– Perpendicular Fractures from late 80’s
– Testing and refrac of a vertical well
– Multiple fractures/application to drill cuttings injections
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Vertical Well Re‐fracturing
• Proposed for – Low perm formation
– Declining fracture productivity
• Improves reservoir access
• Restore production
• Reorientation is desirable– Stress reversal helps
• Usually one fracture exist in the wellbore
Figure Source:American Oil and Gas Reporter
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Issues with Refrac of Horizontal Wells
• Plug existing fracs– Natural loss of conductivity with time
– Use plugging agent –chemical
– Multiple proppant sizes
– Perforate newer areas
• Drill Infill wells (Child Wells)
• Intra‐Well Interaction (frac‐hits)
• Inter‐Well Interactions
• Stress Shadowing and reversal
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Pore Pressure Depletion
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1 day 1 month 1 year 3 years
Rezaei et al (doi: nag.2792)
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Changes of Magnitude and Direction of Stresses with Time
1 day 1 month 1 year 3 years
Black lines are the direction on top of pore pressure depletion Rezaei et al (doi: nag.2792)
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Effect of the Pore Pressure Depletion on Refarc Propagation
Rezaei et al (doi: nag.2792)
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Infill Well Fracturing
SPE-181656-MS SPE-181767-MS
Parent well attracts the fractures that are initiated in the infill well Microseismic activity around parent well
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Infill Well Fracturing Problems
Fracture shadow
Direct hit
Variable pressure hit
SPE 171628
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
SPE 189853
Consequences of Frac‐Hit
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Safari et al, SPE 178513
Propagation Path for Infill Well Fracture
2ye
ars
6 months
1 ye
ar3
year
s
= 57 MPa
Bothparentandchildwellsarepressurized
Onlyinfillwellispressurized
Rezaei et al, 2019
URTeC 2667433
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
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Other Factors Affecting Propagation of Infill Well Fracture
Well spacing Parent well fracture spacing
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HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
= 56 MPa
Stress anisotropy1.38 MPa
= 56 MPa
Stress anisotropy2 MPa
Stress anisotropy3 MPa
= 56 MPa
Other Factors Affecting Propagation of Infill Well Fracture. Cont.'s
Stress anisotropy
= 56 MPa
= 57 MPa
= 59 MPa
Pump pressure
HGS Applied Geoscience Conference (AGC) “Drilling and Completion Through the Life of the Field” November 2019
Summary
• Hydraulic fracturing is an integrated part of field development• Behavior of a hydraulic fractures are affected by:
– Induced mechanical changes in stress regime (stress shadow)– Pore pressure depletion that causes redistribution of stress (stress
reversal)
• Stress shadow affects the fracture behavior in multi‐fracture systems• Stress reversal:
– Helps re‐fracturing vertical wells– Not desirable for horizontal wells
• Both stress shadow and reversal affect the final recovery from reservoir by influencing hydraulic fractures behavior.
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mysoliman@uh.edu
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