Gas-Lift Optimization and Diagnosis by using

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Gas-Lift Optimization and
Diagnosis by using
Wellflo and Dynalift Simulators
By Jayant
Sadare Dr. Faleh T.
Al-Saadoon
Texas AM University-Kingsville
ASME/API/ISO GAS-LIFT
WORKSHOP-2004

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Objectives

• Optimization (Wellflo)
• Advanced Gas Valve Modeling
• Diagnosis and Verification (Dynalift)
• Implementation

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Wellflo Simulator (EPS)

• USES Nodal Analysis for
• Designing
• Modeling
• Optimizing
• Troubleshooting

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Input Data Summary

• Fluid Properties
• - Oil Gravity
  35 deg. API
• - Water Gravity
  1.03
• - Gas Gravity 0.70
• - Produced Gas-Oil Ratio 50.00
  scf/STB
• - Percent Water () 45
• Well-bore Data
• - Production Casing 7.000 inch OD
  6.094-inch ID set _at_ 7100 ft (TVD)

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Contd..

• Reservoir Data
• Reservoir shut-in pressure 2400 psig _at_ 7000
  ft
• Reservoir Temperature 206 deg F
• Productivity Index (Straight line) 2.00
  STB/day/psi
• Gas-Lift Data
• Casing Head Pressure 1450 psig
• Operating valve Differential Pressure 150.00
  psi
• Well-head pressure 102.5 psig
• Minimum Valve Spacing 350 ft

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Why Artificial lift??
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Continuous Gas Lift design - Point of Injection

• Specify
• - Casing head pressure
• - GLR or Qgi
• - Pressure drop across valve
• Calculates maximum depth of injection and well
• performance for gas lift
• Sensitivity to CHP, Qgi, GLR

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Inflow / Outflow Performance Curve
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Performance Analysis Curve
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Pressure and Temperature Vs Depth Analysis
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Gas Lift Design - valve spacing for
continuousgas lift installations
Specify - Casing head pressure - GLR or
Qgi - Pressure drop across valve - Kill fluid
gradient - Maximum depth - Target operating
rate - Design Margins Calculates -
depth of unloading and operating valves
(IPO/PPO) - Corresponding
tubing/casing pressures temperatures
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Gas-Lift Valve Spacing
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Advanced Gas Valve Modeling (AGVM)

• True performance of commercial gas lift valves

• True operating point of system

• Sensitivity to valve type, port size, valve
  settings
• and gas injection parameters

• Gas-charged and orifice valve performance

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True Valve Performance Curve
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Valve Performance Curve For Orifice Valve
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Curve Showing Closed Unloading Valve No. 1
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Dynalift Simulator (EPS)

• Dynamic (Unsteady-State) simulation tool for
• Verification
• Troubleshooting
• Learning

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Dynamic Gas-Lift Simulation

• This Dynamic simulator uses all the equations
  used by a steady-state simulator except it adds
  the dynamic variable (Time).
• Uses real correlations to simulate the behavior
  of gas-lift valves under bottom-hole dynamic
  conditions.
• By controlling the injection conditions, the
  production parameters are observed to define if
  the design will work with the selected gas-lift
  valves.
• More realistic performance can be generated
• Simulates the system by considering the casing
  head pressure, gas-injection rate and wellhead
  pressure at the same time.

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Contd

• This Dynamic simulator is an excellent tool for
• identifying operational problems with
  gas-lift
• installations.
• Also best tool to understand the causes for
• unstable production conditions which not
• understood with a steady state simulator
• It is the best tool for gas lift valves to verify
• its performance from the unloading
  operation
• through all the production life.

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Working Screen for Dynamic Simulator
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Valve Data Screen
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Comparison of Dynamic Steady-state Performance
Curve
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Conclusion

• Combination of Wellflo and Dynalift is one of the
  best
• tool for students to understand gas-lift
  simulation.
• Advanced Gas Valve Modeling (AGVM) is the heart
• of steady-state simulation.
• Do we really need Dynamic Simulation?
• - Accurately model the well unloading for
  better
• design and diagnosis
• - Minimize unloading time
• - Accurate valve performance curves
• - Improve operational procedures

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Thank you