Field Testing of Electrofrac Process Elements at ...€¦ · Field Testing of Electrofrac ™ Process Elements at ExxonMobil’s ... Halliburton’s batch mixer & HT400 pump truck

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Field Testing of Electrofrac ™ Process Elements at ExxonMobil’s Colony Mine

William A. Symington, James S. Burns, Wadood El-Rabaa, Glenn A. Otten,

Norman Pokutylowicz, P. Matthew Spiecker, Richard W. Williamson, Jesse D. Yeakel

29th Oil Shale SymposiumColorado School of Mines

October 20, 2009

Upstream Research

Electrofrac Process Schematic

ElectrofracOil Shale Conversion via Electrically Conductive Fr actures

• Electrofrac laboratory research focused on critical technical issues: Identification of conductant. Maintaining electrical continuity. Expulsion under in situ stress. Completion strategy for effective

heating.

• Planar Electrofracs should heat far more effectively than radial conduction from wellbores.

• Electrofrac field research focused on construction and operation. Pumping an electrically

continuous hydraulic fracture. Building power connections. Operating at low temperature for

several months.

Colorado School of Mines Colorado Energy Research Institute

29th Oil Shale SymposiumOctober 19-23, 2009

Location of ExxonMobil’s Colony Mine Upstream Research

Parachute

Battlement Mesa

I-70

Mine Bench

ColonyRoad



50 feet

Upstream Research



South Drift

North Drift

Cro

sscu

t

DeclineIncline

Mine Drainage

Physical Layout of Colony Mine …

… An Ideal Electrofrac Field Laboratory

50 feet

Upstream Research



• Geologic mapping of natural fractures.

• Fracture pretests to understand hydraulic fracturing in the mine.

• A thermal conductivity pretest to understand in situ thermal rock properties.

• Pumping two Electrofracs with calcined coke. Mapping and verification with observation coring.

• Pumping/squeezing of Electrofrac power connections at EF1 and EF3. Preceded by lab and field pretests.

• Instrumentation and heating of one of the two Electrofracs. And the winner is – EF3 at 51.7 Ohms .

8.5 ft9.5ft ’

1-1.5’

8.5 ft9.5ft ’

1-1.5’

8.5 ft9.5ft ’

1-1.5’

South drift

North

Cross-cut

5’

All holes 2” diameter

Plan View

4’

4’

Built and verified two Electrofracs :EF1 ~140 ftEF3 ~200 ft

Cored 28 observation holes: All intersections probed are electrically connected

EF1

EF3

Instrumentation Holes on EF1

99 ft

132 ft

North Drift

South Drift

Crosscut

Decline



EF1

EF3


99 ft

132 ft

North Drift

South Drift

Crosscut

Decline

Coke-filled Electrofrac

Mine Rib

Insulated Coating on Steel Pipes

Connection Treatments

Electric current


Mine Rib



Electric current

Electrofrac Field Research at Colony has Progressed in Phases

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• Natural fracture trend influences hydraulic fracture direction.

• Minimum principle stress is ~150 psi, parallel to cliff face (normal to natural fracture direction).

• Natural fractures exert stress on fracture fill.

Fracture Pretests Helped Determine the Electrofrac Fracture Design

Location A Location B

Location C

Upstream Research





EF1

EF3


99 ft

132 ft

North Drift

South Drift

Crosscut

Decline



EF1

EF3


99 ft

132 ft

North Drift

South Drift

Crosscut

Decline

Two Electrofracs Pumped, Mapped by Coring

Upstream Research



Halliburton’s batch mixer & HT400 pump truck Freshly prepared gel (400 bbls) for EF1 frac job

Mixing calcined coke and Portland cementPrejob safety meeting

EF1 Hydraulic Fracture Job

Note: worker is not directly beneath sack of calcined coke.

Upstream Research



Two HT400’s and a boost pump provided higher, more stable pressure and flow.

For EF3, coke and cement (39,000 lbs) were premixed and arrived on site in a “W” truck.

EF3 Pumped at Higher Pressure, Rate

Upstream Research



EF1-OB7 Camera/Core EF1-OB2 Core/Electrical EF3 Coke at Crosscut Rib

Continuity Probe (7/18/08)

Electrofracs Observed in Core, on Camera, Electrically, and on the Mine Rib

Resistivity of coke recovered from core is 1-4 Ω-cm (similar to lab values)

Upstream Research



Graphite “Good Juice” Injection Prevents Electrofrac Hot Spots

Function of Graphite “Good Juice”• Provide higher conductivity at power connections.• Provide an electrical connection between steel casing in

the hole and the body of the Electrofrac fracture.

Good juice being mixed in the GJP2000

GJP2000 set up at Location A

Good juice flowing from crosscut mine rib

Modeled Fracture Plane Temperatures (90 days)

Current = 31.6 ampsHeating = 15.7 kWMax temp = 134ºF

With Good Juice

Current = 31.6 ampsHeating = 24.9 kWMax temp = 1678ºF

Without Good Juice

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Squeezing the Graphite “Good Juice”Completes the Electrofrac Circuit

Injecting

Squeezing


Mine Rib



Electric current


Mine Rib



Electric current

Electrofrac Heating Circuit Schematic Flexible Porous Piston Assembly

“Pencil” Electrical Connection

Upstream Research



EF3 Instrumentation Captures Temperature, Voltage, Current, and Rock Movement Data

Roughly perpendicular holes for thermocouples

Roughly parallel holes for Fiber Optic Temperature Measurement

North Drift

Cro

sscu

t

Decline

OB4

OB9

Multi-point extensometers in holes across and adjacent to fracture

Eight open holes (not shown) admit probes for voltage and current measurement.

N

Upstream Research



EF3 Instrumentation Captures Temperature, Voltage, Current, and Rock Movement Data

OK, 21 down -just 315 to go

Did he say miles?

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Electrofrac EF3 Operates Under Thermostatic Control

Thermocouples and electrical data

Fiber optic temperatures

Mine(acquisition & control)

Field Office(recording)

Over temperature

Alarms

If on: any temperature >135ºF - turn offIf off: TC temperatures below 110ºF after TC

thermostatic shutoff – turn back on

Control Logic

Fiber optictemperatures

Fiber optictemperatures

Data Acquisition Software

USBto fiber

USBto fiber

PC network

Voltage, current, power

Voltage, current, power

Thermocouple temperatures

Thermocouple temperatures(12 min freq) (12 min freq)(1 min freq)

TransducerSignals

To OB4and OB9

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Electrofrac EF3 Temperatures Viewed in 3D

North Drift

Cro

sscu

tDecline

OB4

OB9

After 8 Weeks of Operation (9/21/09) at 8.5 kW (ave rage)

Total Energy Input = 11.4 MW-hrs

OB6

I5a

I5b

I5c

I5d

I5e

I5f

OB17OB2

OB15OB1OB4

I6aI7a

OB3

OB16

I6b I6c

I6d

I6e

OB13

I7b

I7c I7d

I7e

I7f

OB12OB7 OB9

OB10

EF3OB6

I5a

I5b

I5c

I5d

I5e

I5f

OB17OB2

OB15OB1OB4

I6aI7a

OB3

OB16

I6b I6c

I6d

I6e

OB13

I7b

I7c I7d

I7e

I7f

OB12OB7 OB9

OB10

EF3

0.90.80.7 0.0

-0.4-0.8

1.000 0.893

0.664-0.019

0.039

-1.000-0.783

0.8950.325

0.667

0.007

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Electrofrac EF3 Voltage and Temperature

OB6

I5a

I5b

I5c

I5d

I5e

I5f

OB17OB2

OB15OB1OB4

I6aI7a

OB3

OB16

I6b I6c

I6d

I6e

OB13

I7b

I7c I7d

I7e

I7f

OB12OB7 OB9

OB10

EF3

1.4

23.2

11.6

24.5 26.6

6.3

3.2 6.8

6.6

2.7

7.9

503070

2010

59.439.4

12.8

35.3

86.2OB6

I5a

I5b

I5c

I5d

I5e

I5f

OB17OB2

OB15OB1OB4

I6aI7a

OB3

OB16

I6b I6c

I6d

I6e

OB13

I7b

I7c I7d

I7e

I7f

OB12OB7 OB9

OB10

EF3OB6

I5a

I5b

I5c

I5d

I5e

I5f

OB17OB2

OB15OB1OB4

I6aI7a

OB3

OB16

I6b I6c

I6d

I6e

OB13

I7b

I7c I7d

I7e

I7f

OB12OB7 OB9

OB10

EF3

1.4

23.2

11.6

24.5 26.6

6.3

3.2 6.8

6.6

2.7

7.9

503070

2010

59.439.4

12.8

35.3

86.2

Operating Resistance = 21-46 Ω

Normalized Voltage – Surveyed on 9/19/09x.xxx Normalized Voltage

Voltage ContourIdealized Graphite

Known “finger” of injected graphite

Suspected “finger”of injected graphite

Fracture Plane Temperature Rise – 9/21/09

xx.x Temperature RiseTemperature ContourIdealized Graphite

After 8 Weeks Operation at 8.5 kW (average)

Total Energy Input = 11.4 MW-hrs

Electrofrac field testing at ExxonMobil’s Colony Mi ne has followed phased approach, with learning opportunities in eac h phase. Thefield program has firmly established that:

• Electrically continuous hydraulic fractures (Electrofracs) can be created by pumping a mixture of calcined coke and cement, at pressure sufficient to break the rock.

• Power connections can be created by pumping mixtures of graphiteand cement into pre-existing calcined-coke-filled Electrofracs. Squeezing and de-watering the graphite can connect the fracture to steel pipe.

• Electrofracs can be heated with electric power for a period of months without developing hot spots that damage the connections.

Upstream Research



Field Testing of Electrofrac™ Process Elements at ExxonMobil’s Colony Mine

Colony Field Research Contributors

Ade Adenekan, Jim Burns, Wadood El-Rabaa, Chen Fang, Mike Gay,Ganesh Ghurye, Larry Harrison, Steve Heiney, Nazish Hoda, Kiera Howell,

Sean Huang,Marvin Johnson, Jerry Kendall, Steve Kerr, Michael Lin,Robert Longoria, Timm Madden, Larry Manak, Nasser Mansoor, Bill Meurer,

Alex Morelos, Tom Murray, Mike Nicholis, Mike Norris, Glenn Otten,Tom Phillips, Norm Pokutylowicz, Jennifer Rainey, J. D. Rice, Kevin Robinson,Matt Spiecker, Bill Symington, Michele Thomas, Jana Van Alstine, Mat Walsh,

Ian Warren, Richard Williamson, Jesse Yeakel, URC Machine Shop,Friendswood Fabrication Facility, SEM/Newpark

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Field Testing of Electrofrac Process Elements at ...€¦ · Field Testing of Electrofrac ™ Process Elements at ExxonMobil’s ... Halliburton’s batch mixer & HT400 pump truck