Rajan N. Chokshi, Ph.D.

Pay-it-Forward Network Training

Houston TX, April 7 2017

Production challenges and some solutions forproducing from Shale and Tight Reservoirs

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• How Lift applications differ for Unconventional & Tight wells Well geometries Flow behavior

• What works Field Practices & Couple of Examples

• Importance of Lift Life Cycle Planning Lift Optimization, Monitoring & Surveillance

• Conclusions

Presentation Outline

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6 out of Top 10 O&G Finds Since 2006 are Shale

Play name, CountryLocation Discovery Type Discovery

Year

Estimated

Discovery

Potential in

billion BOE/dayOnshore Offshore Oil Gas

1. Marcellus, USA X X 2006 47.0

2. Eagle Ford, USA X X X 2009 23.0

3. Libra, Brazil X X 2010 12.4

4. Buzios, Brazil X X X 2010 9.9

5. Montney, Canada X X 2007 9.4

6. Lula, Brazil X X X 2006 9.1

7. Mamba Complex, Mozambique X X 2011 8.9

8. Wolfcamp, USA X X X 2010 8.7

9. Three Forks, USA X X 2007 8.4

10. Utica, USA X X 2010 7.9

From the Houston Chronicle, “Top 10 Finds since 2006 - Most all are Shale,” Sep 08, 2016

Source: IHS Markit, 2016

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Significant Investment & Production Growth

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Images Source:https://www.linkedin.com/company-beta/572589/

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Data-Graphic Source:Rystad Energy Webinar, “The Reality of NorthAmerican Shale: Dark Times Now, Bright FutureAhead?“ Sept 28 2016;https://www.youtube.com/watch?v=Ak6yRpqgeLI

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Typical Shale Well in Different Plays

MD TVD Lateral

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Deep, Long, Slender Well Geometry• TVD 10,000 ft

• Lateral section 5,000 ft

4" � � � � � �

5,000� � � � � � � �≅

¼" � � � � �

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Representative Shale Well Profiles

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Courtesy: Rob Sutton,Marathon Oil, 2012Courtesy: Rob Sutton,Marathon Oil, 2012

Complex Well Geometries

11,100

11,150

11,200

11,250

11,300

11,350

11,400

0 2,000 4,000 6,000 8,000 10,000

Closure Distance, ft

Tru

eV

ert

icalD

ep

th,ft

Austin Chalk

Bakken

Barnett

Eagle Ford

Niobrara

Woodford

Utica

Complex Well Geometries

11,100

11,150

11,200

11,250

11,300

11,350

11,400

0 2,000 4,000 6,000 8,000 10,000

Closure Distance, ft

Tru

eV

ert

icalD

ep

th,ft

Austin Chalk

Bakken

Barnett

Eagle Ford

Niobrara

Woodford

Utica

Toe Up

Hybrid

Toe Down

Source: Sutton, R.: “Wellbore Geometry Effects on Well Production Performance,”SPE Liquids Rich Shale Conference, Rancho Palos Verdes, CA (May 2013).

Source: Sutton, R.: “Wellbore Geometry Effects on Well Production Performance,”SPE Liquids Rich Shale Conference, Rancho Palos Verdes, CA (May 2013).

Lateral Profiles• Toe-up well: The lateral TVD gain is

negative or the TVD at the toe is lessthan the TVD at the heel. Single Liquidaccumulation point close to heel.

• 90 Degrees perfect lateral – A Unicorn!!

• Hybrid / Undulating or “porpoising”well: Common. Many liquidaccumulation points and “A nightmarefor production operations”

• Toe-down Well: The lateral TVD gain ispositive, i.e., the TVD at the toe is morethan the TVD at the heel. Single Liquidaccumulation point farthest from thekickoff.

• Doglegs severity in ‘vertical’ or ‘deviatedsections can be significant.

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Different Flow Behaviors in Wellbore

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Flow behavior in Lateral – Changes with Trajectories

Courtesy: Tulsa Uni Horiz Well Art Lift ProjectSimulations

Courtesy: Tulsa Uni Horiz Well Art Lift ProjectSimulations

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Midland Wolfcamp Oil Well : Flow Simulation Match

Courtesy: Pipe Fraction Flow LLCCourtesy: Pipe Fraction Flow LLC

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• Pumping

• Gas-liquid separation

• Monitoring

• Back pressure

Challenges of Turbulent Flow

Well C – Eagle FordWell A – Eagle Ford

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"... ... the average decline curves for Bakken and Eagle Ford wells havenot shown significant changes since 2010. The major improvement canbe observed in the increased 24-hr initial production, but this raterapidly declines."Source: Rystad Energy: US Shale Newsletter, Vol. 1 No. 3, Jul 2014

"... ... the average decline curves for Bakken and Eagle Ford wells havenot shown significant changes since 2010. The major improvement canbe observed in the increased 24-hr initial production, but this raterapidly declines."Source: Rystad Energy: US Shale Newsletter, Vol. 1 No. 3, Jul 2014

Variable Production Rates

Well Rate Decline Curves for Shale Assets (After Rystad 2014)Well Rate Decline Curves for Shale Assets (After Rystad 2014)

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Variable Production Rates

• Steep production decline in a relatively short period.• Must plan for a wide range of production rates

• Which production systems can handle widely varyingproduction rates?• Production rate constraints – pressure maintenance, lift system

limitations (high initial rates exceed capabilities of most lift systems)

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Marcellus Shale Case Study: Gas Well Zonal Contribution

Blue zones are producing much higher than other zones. This helps operators determinethe potential value of additional well treatments including re-fracturing. Blue zones are producing much higher than other zones. This helps operators determinethe potential value of additional well treatments including re-fracturing.Source: Gonzalez, L. E., Chokshi, R. N., & Lane, W. (2015, August 4). Importance of Downhole Measurements,

Visualization and Analysis in Producing Unconventional Wells. SPE. doi:10.15530/urtec-2015-2164102Source: Gonzalez, L. E., Chokshi, R. N., & Lane, W. (2015, August 4). Importance of Downhole Measurements,

Visualization and Analysis in Producing Unconventional Wells. SPE. doi:10.15530/urtec-2015-2164102

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1. Well Depth & Geometry Deep, long, slender well geometries.

Cost of interventions

Transient mixed phase sluggy and turbulent flow.

2. Ultra-low Permeability Steep & rapid production decline

Production rate constraints

Mixed phase flow

3. Uncertain zonal contribution.

4. Gas, Sand, paraffin, scale, corrosion

5. Operations, power supply, surface facilities, location access

Production Challenges in Shale & Tight Reservoirs

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• Choke the production rate Increases EUR. Reduces possibility of permeability-loss in over-pressured formation.

SPE 147623 on Haynesville Shale modeling: “… a restricted well has higher productivity than anunrestricted well producing in the same field. … this difference can be quantified by the behaviorof the permeability decay function.”

Higher FTHP delays need for artificial lift systems.

Increased FBHP delays gas breakout might reduce pooling in the lateral traps

• Maintain adequate liquid levels 200 ft above liner top

75 to 100 ft above pump.

Early Production

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• Mechanical pumps can pump from low spots but are not effective in“sweeping” liquids through laterals.

• Mechanical pumps can have gas interference issues.▫ Gas anchors are required in gassy wells.

• Where possible, land mechanical pumps:▫ In vertical section 50 to 100 ft above the liner top▫ In straight sections if within the deviated section

• Use continuous lift optimization (surveillance, analysis, prioritizing,adjustment)

Lessons – Deliquifying Laterals

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Well Life Cycle Rate (BPD) Gas Lift ESP Jet PumpPistonPump

RodPump

PlungerLift

CapFoam

Frac-Flowback 500 ()

Initial high rates 500 ()

Medium liquid rates <500

Low liquid rates <200

Summary – Typical Use of Artificial Lift in Shale Plays

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• Need to think about Artificial Lift before Well is onPaper

• Involve production/operations during the well design.

▫ Toe up orientation if possible.

▫ ‘Rat hole’ for better gas separation???

▫ Control tortuosity of horizontal section of well - Minimize undulations/traps

▫ Intentionally plan/control vertical transition to horizontal section

▫ Will casing geometries permit sufficiently sized ALS technology in future?

Importance of Integrated Planning

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Gas Lift

Wel

lPre

par

atio

n-

FFR

Wel

lPre

par

atio

n-

FFR

Jet Pump

ESP

Rod Pump

Hydraulic Piston Pump

Plunger Lift

Foam

Lift Life Cycle Planning

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Hybrid Completion: JP → GL

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SOLUTIONSREQUIREMENTSCHALLENGE

Importance of Monitoring & Surveillance

Rapidly declining orfluctuatingproduction

Real-time continuouslift & adjustments

Well-site flow rateand downhole P/T

Changing inflowphases and zonal

contribution

Visibility of what ishappening

Optimization of fieldresources (injection,service crews, rigs…)

Organized schedulingof limited assets

Surveillance andanalysis software

Field managementdatabase & software

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• Accurate and timely monitoring is critical for production management andoptimization.▫ Tracer chemicals for initial inflow▫ Production logging for snapshot of transients Sporadic measurements are not adequate for managing dynamic production.

• Permanent downhole gage systems provide continuous real-time visibility ofproduction conditions.▫ Artificial lift status▫ P, T, Q▫ Zonal contribution

• Data visualization and analysis software simplify production management andoptimization.

Surveillance & Monitoring

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Continuoushigh granularitymeasurementsrevealed slugs

Case: Permanent Electronic Gauges – Shale Rod Pumping

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Source: Gonzalez, L. E., Chokshi, R. N., & Lane, W. C. (2015, October 20). Real-Time Surface and Downhole Measurements and Analysis for Optimizing Production.Society of Petroleum Engineers. doi:10.2118/176233-MSSource: Gonzalez, L. E., Chokshi, R. N., & Lane, W. C. (2015, October 20). Real-Time Surface and Downhole Measurements and Analysis for Optimizing Production.Society of Petroleum Engineers. doi:10.2118/176233-MS

Case: Accurate Flow Measurements in Shale

Well C – Eagle Ford

Well A – Eagle Ford

Source: WeatherfordSource: Weatherford

• How are artificial lift applications different forunconventional & tight wells?

▫ Well geometries pose production challenges

▫ Understanding of flow behavior is very important and stilldeveloping.

Conclusions

Additional References1. Lane, W., & Chokshi, R. (2014, August 28). Considerations for Optimizing Artificial Lift in Unconventionals. SPE.

doi:10.15530/urtec-2014-1921823.2. Gonzalez, L. E., Chokshi, R. N., & Lane, W. (2015, August 4). Importance of Downhole Measurements, Visualization

and Analysis in Producing Unconventional Wells. SPE. doi:10.15530/urtec-2015-2164102

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•What needs to be done?▫ Involve production & operations during well design

Toe Up.... Avoid Traps in Lateral

▫ Select flexible lift systems Stay current on what works where and why.

▫ Think in terms of the lift life cycle You will need to change to another lift – sooner or later...

▫ Include Lift Monitoring & Surveillance from the beginning Surface Flow and downhole P/T measurements add considerable value to the overall production

optimization and recovery.

Conclusions

Additional References1. Lane, W., & Chokshi, R. (2014, August 28). Considerations for Optimizing Artificial Lift in Unconventionals. SPE.

doi:10.15530/urtec-2014-1921823.2. Gonzalez, L. E., Chokshi, R. N., & Lane, W. (2015, August 4). Importance of Downhole Measurements, Visualization

and Analysis in Producing Unconventional Wells. SPE. doi:10.15530/urtec-2015-2164102

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Questions, Discussion

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