1. Age of Analytical Multiphase Flow Modeling: Multiphase AP Engine (MAPe) Overview
Dr. Anand S. Nagoo 1

2. Analytical Advances Review Field Use Cases in Practice
Outline
Breakthrough in modeling multiphase flows – new age of analytical prediction
Find optimal lift – reliably predict wellbore downhole pressures (lift performance)
Find optimal rate – diagnose horizontal well liquids loading early (artificial lift)
Analytical Advances Review
Field Use Cases in Practice
Gain Immediate Value
MAPe Overview – 2

3. Key Take Away
Analytical advances in multiphase flow modeling now affords reliable downhole predictions for optimizing production and artificial lift in horizontal wells!
MAPe Overview – 3

4. Analytical Multiphase Flow Modeling
Problem Definition: a set of averaged-equations for reliable predictions of field-scale multiphase flows
“The formulation of a satisfactory set of averaged-equations models emerges as the single highest priority in the modeling of complex multiphase flows.”
Prosperetti and
Trygvasson (2007)
Reality
Mathematical Representation
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5. Analytical Multiphase Flow Modeling
Business case: get reliable downhole pressure from available surface field data at low cost (the prize!)
Lift curves for rate transient analysis (RTA), nodal analysis, reservoir simulation, reserves estimation
- Faster simulations for real-time well surveillance, downhole monitoring and digital oilfield integration
Downhole gas velocities and virtual flow metering
- Eliminate or minimize costs for pressure gauges
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6. Analytical Multiphase Flow Modeling
Pipe Fractional Flow Theory, Nagoo (2013)
Analytical / Digital
Multi-field / CMFD / PDE
Mechanistic
Empirical
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7. Analytical Multiphase Flow Modeling
DEEP (KEY) ANALYTICAL INSIGHT:
In multiphase flow, what matters are the measurable changes in the velocities and volume fractions. They govern the transport processes of the multiphase flow – the transport of conservation quantities like mass, momentum and energy, i.e. why flow patterns matter!
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8. Analytical Multiphase Flow Modeling
Fractional flow paths interconnect flow patterns in continuous (analytical) ways!
CMEM Journal, v.6, n.2, pp , 2018
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9. Wide Range of Industry Applications
Pipe Fractional Flow Theory validated against world’s largest published multiphase flow database (110+ labs)
US, Shell E&P large-diameter riser transient multiphase flow (OTC 23968)
UK, Swansea, Wales horizontal air and viscoelastic polymer Non-Newtonian multiphase flow (Chem. Eng. Res. Ind. Journal, v.62, pp. 22, 1984)
Demonstrates the need for reliable Non-Newtonian flow predictions, e.g. slurries, heavy oils, drag-reducers, drilling fluids (SPE )
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10. Wide Range of Industry Applications
Canada, British Columbia convergent-divergent-convergent nozzle multiphase flow
High water velocity
Low water velocity
Source: Pougatch et al. (2008)
US, Oklahoma subcritical-to-critical air-water choke multiphase flow
Source: Pilehvari (1980)
New obstructed flow capabilities for perforated wellbore, valves, chokes, solid deposits, jet pumps, nozzles (wholly analytical slip ratio for virtual flow metering!)
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11. Wide Range of Industry Applications
ESP, PCP and other pump performance curves can be solved simultaneously with wellbore multiphase flow equations to reliably predict downhole pre- and post-pump variables and local flow characteristics
US, Permian basin horizontal gas-oil-water well with ESP multiphase flow pump intake pressure (PIP) field data available (installed gauge) for entire horizontal ESP well production history
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12. Case Study 1 – Reproducing PLT
Delaware basin gas-condensate-water well
Horizontal wells are uniquely complex systems
Liquids held up in up-flow and gas held up in down-flow - demonstrates strong impact of well trajectory
Extreme slip effects exist as long as up-flow and down-flow exist
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13. Case Study 1 – Reproducing PLT
Extreme slip effects are not captured in pressure profile
Wellbore pressure, by itself, will not reveal the true picture of downhole conditions – need phase velocities, holdups and critical rate profiles
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14. Case Study 2 – Reproducing Gauge
Blind Test: Downhole gauge simulation vs. measured pressure gauge data for Permian basin gas-oil-water horizontal well
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15. Horizontal Well Liquid Loading
Business case: early detection of loading pays!
Source: defopt.com
Critical Rate
Well Flowing
Above
Time
Natural Decline
Well deviates from its natural decline
Well Flowing Below Critical Rate
It is the deferred production that is most costly and most difficult to recover at late-life
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16. Horizontal Well Liquid Loading
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17. Horizontal Well Liquid Loading
Practical significance: an accurate diagnosis of downhole flow behavior directly impacts production
What is the critical (minimum) rate to lift liquids?
Where in the well is liquids loading happening?
Is well pre-loading, slight-loading, severe-loading?
Can we quantify lost liquids production?
How to remediate for immediate impact? (change casing/tubing, end-of-tubing depth, etc.)
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18. Horizontal Well Liquid Loading
Source: Imperial College
Prior art: poor field predictions
Simpler models not applicable
Advanced iterative models not practical, adds more unknowns
Horizontal large diameter flow
Source: slb.com/resources/videolistingpage
Well-defined lab flow characterizations do not exist in the field (flow structures are unknown!)
Vertical small diameter flow
Not so simple as a ‘film’ or a ‘droplet’ even at lab-scale
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19. Horizontal Well Critical Rate Eqn
Strongest effect is diameter!
Simple and direct (explicit) analytical eqn
Extensive validation in horizontal field wells
Critical gas velocity
Gas density, liquid density
Gas-liquid interfacial tension
Inclination angle from vertical
Hydraulic diameter
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20. Horizontal Well Liquid Loading
Use Vg,well vs. Vg,crit curves along entire well to:
Effect of diameter (size and optimize fat casing, tubing)
Effect of EOT landing depth
Effect of wellhead pressures (compression, well control)
Effect of lift location and type (plunger, gas, foam)
Quantify lost production (SPE )
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21. Horizontal Well Liquid Loading
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22. Case Study 3 – Detectable Loading
Casing pressure
Tubing pressure
North America Fayetteville dry gas and water toe-down well with different loading stages detectable from surface field data
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23. Case Study 3 – Detectable Loading
scale magnified
North America Fayetteville dry gas and water toe-down well with different loading stages detectable from surface field data
Vg,well vs. Vg,crit profiles correctly diagnose pre-, slight- and severe-loading data
Severe-loading occurs when both tubing and bend regions load
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24. Case Study 4 – Undetectable Loading
Line pressure
Casing pressure
Days
Casing pressure
Line pressure
North America Marcellus gas-water horizontal toe-down well
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25. Case Study 4 – Undetectable Loading
RUN X1
RUN X2
RUN X ” tubing
RUN B
Casing pressure
Line pressure
North America Marcellus gas-water horizontal toe-down well
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26. Case Study 5 – Test & Validate EOT
North America Eagle Ford gas-condensate-water dew point fluid horizontal toe-down well with EOT lowered to avoid loading
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27. Case Study 5 – Test & Validate EOT
North America Eagle Ford gas-condensate-water dew point fluid horizontal toe-down well with EOT lowered to avoid loading
Vg,well vs. Vg,crit profiles reliably simulate surface field data trends both before and after EOT landing depth lowered
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28. Case Study 6 – Design & Predict EOT
Liquid loading changes drastically with EOT location
Well MD (ft)
Vg,crit, Vg,well 30 60 90
Well incl. (degs)
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29. Case Study 7 – Life-of-Well Lift
FBHP
FBHP
We can now analytically determine unloading point!
Combine FBHP + Vg,well + Vg,crit lift curves to quantify lost production and optimize life-of-well lift against declining rates
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30. Case Study 7 – Life-of-Well Lift
UK North Sea offshore gas-water deviated well with published PLT field measurements (Lea et al., 2008)
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31. Case Study 7 – Life-of-Well Lift
UK North Sea offshore gas-water deviated well with published PLT field measurements (Lea et al., 2008)
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32. Case Study 7 – Life-of-Well Lift
North America Eagle Ford gas-water horizontal well validating the downhole loading proximity metric against field observations
North America Eagle Ford gas-water horizontal well validating the downhole loading proximity metric against field observations
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33. Case Study 7 – Life-of-Well Lift
North America Eagle Ford gas-water horizontal well validating the downhole loading proximity metric against field observations
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34. Case Study 8 – Remediate Loading
A suboptimal liquids-rich horizontal well with liquids loading in ALL regions of the wellbore
North America Permian basin gas-oil-water horizontal well: going from loaded to unloaded using velocity string and gas lift
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35. Case Study 8 – Remediate Loading
North America Permian basin gas-oil-water horizontal well: going from loaded to unloaded using velocity string and gas lift
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36. Case Study 8 – Remediate Loading
North America Permian basin gas-oil-water horizontal well: going from loaded to unloaded using velocity string and gas lift
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37. Conclusions & Take Home Message
New age of analytical multiphase flow prediction
Analytical modeling capability closes lift performance gaps for reliable downhole pressure predictions
Optimal lift + optimal rate (analytical critical rate eqn) = accurate diagnosis of horizontal well loading
Analytical advances in multiphase flow modeling now affords reliable downhole predictions for optimizing production and artificial lift in horizontal wells!
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38. Four Upcoming MAPe Modules
In order of development:
Well and pipeline integrity (multiphase erosion, corrosion, thermal) calculations
Cyclical (plunger lift) and single-instance (pigging) fluid displacement calculations
Combine single-branch calculations for fully-implicit integrated networks (multi-laterals, surface grids)
Solid deposits (flow assurance) and 4-phase flows
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39. Contact us at info@nagoo-associates
Contact us at for arranging an on-site presentation/demo or training session on the MAPe simulator! 39