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Sustainable Fracturing Rationale to
Reach Well Objectives –
The Impact of Uncertainties and complexities on
Compliance Assurances
OVERVIEW
Ahmed Abou‐Sayed
Advantek International
Variety of Fracturing Configurations EPA
FRACTURIN
G DESIG
N and ASSU
RANCE
Frac Pack High Perm
Selective Stimulation
Longitudinal Fractures
Multiple Transverse Fractures
Selective/ Whole Matrix Treatment
Stimulation for Selective Injectivity
MIGRATION, BREACHING & FAULT/SEAL INTEGRITY
Fault Dipping at ~xo
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
Deepest Protected Aquifer
Distance ft
Distance ft
Top of Injection Layer
Top of Upper Containment Layer
Leak Rate ft3/min
Invasion Rate ft3/min
Lithology Markers
3280 ftCasing e
4752 ftCasing
52 4752
3280 ft
Fracture Shape & Proppant Concentration Diagram For Different Injection
Scenarios and Complex Models
2500 Depth
(ft TVD) 3000
3500
Sho
4000
1. PropConcentration 2. 3. 0.613594 PropConcentration 0.572688 0.624
0.593 0.613594 0.531781 0.572688 0.490875
0.563 0.532 0.531781
0.449969 0.501 0.490875 0.409063 0.471 0.449969 0.368156 4500 0.440
0.409 0.409063 0.32725 0.368156 0.286344
0.379 0.348 0.32725
0.245438 0.317 0.286344 0.204531 0.287 0.245438 0.163625 0.256
0.225 0.204531 0.122719 0.163625 0.0818125
0.195 0.122719
0.0409063 0.0818125 0.0409063 5000
47
Shoe ft ft 5500 1 2. 3.
.4752 ft Injection Point 3280 ft Injection Point 4752 ft Injection Point Mid Sand Layers Modeled Mid Sand Layers Modeled Mid Sand Layers Not Modeled 5390 bbls Injected 14000 bbls Injected 13400 bbls Injected 0.81 psi/ft Shale Stress Gradient 0.85 psi/ft Stress Gradient 0.81 psi/ft Stress Gradient
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
(degrees)
STRESS ANISOTROPY EFFECT
5
6
6
6 6
9 6
Number of wells in
category
600
Increased 500 Intercept Pressure 400
(psi)
300
200
100
0
60-90 40-60 30-60 20-40
0-30 0-20 Well Azimuth Well Deviation σhmax
(degrees) Fracture
Injector
σhmin
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
0 Fractured Horizontal Wells
2,000 Tate Unrein #4 Witt 2-5
4,000
Maersk MF-A156,000 TipTop #77X-17G, 14-8, 33-16
Tip Top 14-16 8,000 Mordred 48/12c-SJ. Snowden #7
10,000 White 3,4 Ameland 204
Parks #19-29, 14-20, 24-1, HC-23, TX-C112,000
Parks 9-4 Rhodes #4 14,000
Soehlingen Z-1016,000 0 1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000 9,000 10,000
Deviation from Vertical (ft)
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
p g
Pump into Pump into annulus
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
Shmax
Shmin
x - linked gel plug
pressure operated vent
1st treatment 2nd treatment
2000 -3000'
tbg
Shmax
Shmin
Fracture
2200' - 5000'
Multiple - Simultaneous transverse fracturing
A - Zone Pre - conditioning Individual breakdownsimultaneous extreme OBperforationstim propellant fracture
( frac 1 bigger than frac 2 )
B - Pumping with double rate in limited entry perforation
Horizontal Well Technology (Completions/Stimulation) : cased hole
Shmax
1
Shmin
1
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
Gas Potential
Effect of Number of Fractures on Cum Production G
as C
um. P
rodu
ctio
n (M
Msc
f × 1
0^3)
30
20
10
0
(1)
(2)
(3)
(1) 7 Fracs
(2) 5 Fracs
(3) 3 Fracs
0 5 10 15 Time (days × 10^3)
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
Gas Potential
Gas
Cum
. Pro
duct
ion
(MM
scf ×
10^
3)
Effect of Fracture Length on Cumulative Production30
20
10
0
(1)(2) (3)(4)
(1) Lf = 500 ft
(2) Lf = 300 ft
(3) Lf = 150 ft
(4) Lf = 100 ft
0 5 10 15 Time (days × 10^3)
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
Multi-Frac Horizontal Well EPA
FRACTURIN
G DESIG
N and ASSU
RANCE
1000m
13- 3/8" @ 1000m MD
9- 5/8" @ 2950m MD
4- 1/2" Frac & Production Tubing
7" Liner @ 4576m MD
Retrievable Bridge Plug
5" Cemented Liner with 5" HW Joints for setting Bridge Plugs (1484m)
5" HW Joints
Cases 2B: 5" Completion
PBR
Atoka Injections
180
PRESSURE DURING SEQUENTIAL PUMPING ASSU
RANCE
EPA FRACTU
RING
DESIG
N and
Plugged Tip Zone
New Fracture
Stress along Well due to Concurrent Parallel Fractures
Concurrent Fractures
Injected Fluid
0 1000 2000 3000 4000 5000 6 0
500
1000
1500
2000
Bot
tom
hole
Pre
ssur
e (P
SI) BHP
Temp
160
Pressure Increase due to Series Fractures
000 7000 8000
Time (min)
80
100
120
140
Tem
p (f)
MULTIPLE FRACTURING OF LONG HORIZONTAL WELLS – ANISOTROPIC STRESS
• Strongly anisotropic, layered stress field
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
FRACTURE NETWORK IN A WEAKLY ANISOTROPIC STRESS FIELD
After Olson, ARMA 2008
Conjugate Fractures
CONCLUDING REMARKS EPA
FRACTURIN
G DESIG
N and ASSU
RANCE
CONCLUDING REMARKS
• Hydraulic fracturing has been a reliable contributor to US O&G supply for half a century. They must be thoroughly designed
• Fracture design requires site/well specific input, routine recipe solutions are not appropriate for assurance.
• Well trajectories vis a vis stress field azimuth play a major role in establishing treatment pressures and well connectivity.
• Breaching, loss of containment and frac fluid migration need always be significant factors in job design and implementation.
• Assurance must be a primary factor in stimulation via complete data collection, sophisticated modeling and live monitoring.
• Pressure transient tests have advanced and are currently sufficient and necessary for better identification of fractures.
• Multiple fractures in single wells must be designed with sufficient certainty and complexities and need close monitoring
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
High StiffnessHigh Leakoff
Stress Barrier Strength
0
Frac
ture
Hei
ght (
ft)
High Stiffness Modulus BarrierHigh Leakoff
1000 Width (in) 0.823 0.768Solids Concentration By Volume 0.714
Frac
ture
Hei
ght (
ft) 0.6592500 500 0.605 Layer with High Elastic Modulus 0.551
0.496 0.442
0.550 0.3882000 0.3330.5040 0.2790.457 0.225
0.411 0.170Solid particles were simulated as 2 ppg proppant. Solid pluggingand dehydration are indicatedwhen the fracture enters into the
1500 0.365 0.116
Frac
ture
Hei
ght (
ft)
permeable sand (at the top). 0.225 0.179
1000 0.133 0.086-1000
0 500 0.040 1000 1500 2000 2500 Half Fracture Length (ft)
500Fracture Shape and Width (inches)(V = 14000 bbls at 4 bpm w/o Solids)
0.0610.318-500 0.272
Solid Concentration by Vomule0500
400 1.106 300-500 1.033 0.6240 1000 2000 30000.959 0.593Schematic of300 0.5630.886 Stress Profile200Half Fracture Length (ft) 0.5320.813
Frac
ture
Hei
ght (
ft) 0.5010.740200 0.667
100 0.594 0.520 0.447 0.374 0.301 0.228 0.155 0.081
0.471 0.440100 0.409 0.379 0.348 0.3170 0.287 0.256 0.225 0.195-100
-200 -200Stress Barrier-300
0 100 200 300 400 500 600 700 -400 Half Fracture Length (ft)
0 500 1000StrengthHalf Fracture Length (ft)
Complex Medelling
EPA FRACTU
RING
DESIG
N and ASSU
RANCE
-100
Sustainable Fracturing Rationale to Reach Well Objectives – The Impact of Uncertainties and Complexities on Compliance
Assurances Ahmed Abou-Sayed
Advantek International
The statements made during the workshop do not represent the views or opinions of EPA. The claims made by participants have not been verified or endorsed by EPA.
The presentation will discuss lessons learned; extract best practices and guidelines applied to injection of fluids and slurries during fracturing and exploration and production (E&P) associated streams disposal (wastes, produced water, drill cuttings, and solids/proppant flow-back). Fracture generation, propagation and multiplication during multiple injections in same well, batch injections and re-fracturing is covered. Design requirements, monitoring and assurance of containment for environmentally safe injections are covered. Results from major worldwide injection projects are viewed from operator's and regulator’s perspectives.