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.