Production challenges and some solutions for producing from shale (unconventionals) and tight reservoirs

1. Rajan N. Chokshi, Ph.D.
Pay-it-Forward Network Training
Houston TX, April 7 2017
Production challenges and some solutions for
producing from Shale and Tight Reservoirs

2. 2

3. • 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
3

4. 6 out of Top 10 O&G Finds Since 2006 are Shale
Play name, Country
Location 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
4

5. Significant Investment & Production Growth
5

6. 6
Images Source:
https://www.linkedin.com/company-beta/572589/

7. ‘Horizontal’WellRevolution
7

8. Impactof‘Horizontal’Production
8

9. Pad-basedDrilling
Data-Graphic Source:
Rystad Energy Webinar, “The Reality of North
American Shale: Dark Times Now, Bright Future
Ahead?“ Sept 28 2016;
https://www.youtube.com/watch?v=Ak6yRpqgeLI
9

10. UnconventionalWells
–LongLaterals
Source: NASWELLCUBE Free, Rystad Energy, Sep 2016Source: NASWELLCUBE Free, Rystad Energy, Sep 2016
6817
11894
3892
6194 5737
6647
8416 9084
12637
9123 9123
7477
9598
0
5000
10000
15000
20000
25000
TypicalMD,TVD,LateralLength,ft
Typical Shale Well in Different Plays
MD TVD Lateral
10

11. Deep, Long, Slender Well Geometry
• TVD  10,000 ft
• Lateral section  5,000 ft
4"
5,000
≅
¼"
104
11

12. Representative Shale Well Profiles
12
Courtesy: Rob Sutton,
Marathon Oil, 2012
Courtesy: Rob Sutton,
Marathon Oil, 2012

13. 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
TrueVerticalDepth,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
TrueVerticalDepth,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 less
than the TVD at the heel. Single Liquid
accumulation point close to heel.
• 90 Degrees perfect lateral – A Unicorn!!
• Hybrid / Undulating or “porpoising”
well: Common. Many liquid
accumulation points and “A nightmare
for production operations”
• Toe-down Well: The lateral TVD gain is
positive, i.e., the TVD at the toe is more
than the TVD at the heel. Single Liquid
accumulation point farthest from the
kickoff.
• Doglegs severity in ‘vertical’ or ‘deviated
sections can be significant.
13

14. Different Flow Behaviors in Wellbore
14

15. Flow behavior in Lateral – Changes with Trajectories
Courtesy: Tulsa Uni Horiz Well Art Lift Project
Simulations
Courtesy: Tulsa Uni Horiz Well Art Lift Project
Simulations
15

16. 16

17. Midland Wolfcamp Oil Well : Flow Simulation Match
Courtesy: Pipe Fraction Flow LLCCourtesy: Pipe Fraction Flow LLC
17

18. •Pumping
•Gas-liquid separation
•Monitoring
•Back pressure
Challenges of Turbulent Flow
Well C – Eagle FordWell A – Eagle Ford
18

19. "... ... the average decline curves for Bakken and Eagle Ford wells have
not shown significant changes since 2010. The major improvement can
be observed in the increased 24-hr initial production, but this rate
rapidly declines."
Source: Rystad Energy: US Shale Newsletter, Vol. 1 No. 3, Jul 2014
"... ... the average decline curves for Bakken and Eagle Ford wells have
not shown significant changes since 2010. The major improvement can
be observed in the increased 24-hr initial production, but this rate
rapidly 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)
19

20. 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 varying
production rates?
• Production rate constraints – pressure maintenance, lift system
limitations (high initial rates exceed capabilities of most lift systems)
20

21. Marcellus Shale Case Study: Gas Well Zonal Contribution
the potential value of additional well treatments including re-fracturing.the 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-2015-2164102
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-2015-2164102
21

22. 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
22

23. 23

24. • 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 an
unrestricted well producing in the same field. … this difference can be quantified by the behavior
of 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
24

25. • 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
25

26. Well Life Cycle Rate (BPD) Gas Lift ESP Jet Pump
Piston
Pump
Rod
Pump
Plunger
Lift
Cap
Foam
Frac-Flowback 500    ()
Initial high rates 500    ()
Medium liquid rates <500   
Low liquid rates <200     
Summary – Typical Use of Artificial Lift in Shale Plays
26

27. •Need to think about Artificial Lift before Well is on
Paper
• 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
27

28. Gas Lift
WellPreparation-FFRWellPreparation-FFR
Jet Pump
ESP
Rod Pump
Hydraulic Piston Pump
Plunger Lift
Foam
Lift Life Cycle Planning
28

29. Hybrid Completion: JP → GL
29

30. SOLUTIONSREQUIREMENTSCHALLENGE
Importance of Monitoring & Surveillance
Rapidly declining or
fluctuating
production
Real-time continuous
lift & adjustments
Well-site flow rate
and downhole P/T
Changing inflow
phases and zonal
contribution
Visibility of what is
happening
Optimization of field
resources (injection,
service crews, rigs…)
Organized scheduling
of limited assets
Surveillance and
analysis software
Field management
database & software
30

31. • Accurate and timely monitoring is critical for production management and
optimization.
▫ 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 of
production conditions.
▫ Artificial lift status
▫ P, T, Q
▫ Zonal contribution
• Data visualization and analysis software simplify production management and
optimization.
Surveillance & Monitoring
31

32. Continuous
high granularity
measurements
revealed slugs
Case: Permanent Electronic Gauges – Shale Rod Pumping
32
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-MS
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-MS

33. Case: Accurate Flow Measurements in Shale
Well C – Eagle Ford
Well A – Eagle Ford
Source: WeatherfordSource: Weatherford

34. •How are artificial lift applications different for
unconventional & tight wells?
▫ Well geometries pose production challenges
▫ Understanding of flow behavior is very important and still
developing.
Conclusions
Additional References
1. 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
34

35. •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 References
1. 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
35

36. Questions, Discussion
36