Gas Lift Workshop Singapore 7-11 February 2011

Gas Lift Workshop
Singapore
7-11 February 2011
API RP 19G11
Dynamic Simulation
of Gas Lift Wells and Systems
Juan Carlos Mantecon –
1
CONTENT
• This presentation describes dynamic simulation
and its current applications for gas-lift wells and
systems.
• It gives an overview of the new (in draft format)
API Recommended Practice for
Dynamic Simulation of Gas-Lift Wells and Systems:
API RP 19G11.
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API RP 19G11
•
This API Recommended Practice covers the application of
dynamic simulation for gas-lift wells and systems.
•
Dynamic simulation is an important tool to assist in the
design, operation, surveillance, troubleshooting, and
diagnosis of gas-lift processes.
•
Most gas-lift design and diagnosis programs have used
steady-state models. This may lead to inappropriate designs
and inefficient operations because gas-lift wells and systems
are seldom steady. Gas-lift wells usually exhibit dynamic
pressure and flow rate fluctuations.
•
It is important to understand the dynamic behaviour of wells
and systems so they can be more appropriately designed,
operated, and diagnosed.
•
Although the primary focus is currently on gas-lift, this API-RP
addresses a broad range of artificial lift systems and topics
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API RP 19G11 – WORK GROUP MEMBERS
20 members representing 16 companies and one university
Juan Mantecon, SPT Group - Chairperson
Cleon Dunham, Oilfield Automation - Secretary
Adam Ballard, BP
Arne Valle, Knud Lunde, StatoilHydro
Boots Rouen, Schlumberger
Dan Dees, AppSmiths
Eric Laine, Laine Consulting
Fernado Ascencio Candejas, PEMEX
Dr. Fernando Samaniego, UNAM (Mexico Autonomous Nacional University)
Galileu Paulo Henke A. Oliveira, Petrobras
Greg Stephenson, Occidental
Kallal Arunachalam, ConocoPhillips
Ken Decker, Decker Technology
Murat Kerem, Shell
Octavio Reyes, Technip
Shanhong Song, Chevron
Wayne Mabry, Shell
Yaser Salman, YAS Petroleum Eng.
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Yula Tang, Chevron
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DYNAMIC SIMULATION
•
The application of multiphase flow transient
numerical simulation (dynamic simulation)
techniques in wells and production
systems has become an important
methodology to ensure:
─ Wells/field life cycle sound engineering
design,
─ Optimal operation guidelines,
─ Optimization of investment and
operating costs,
─ Production optimization, and
─ Minimization of risk, safety hazards,
and environmental impact.
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DYNAMIC SIMULATION
P12
• Dynamic simulation can be used at any
stage of a field’s life cycle to build a
virtual model of a well and/or production
system.
P11
P10
P9
P8
P7
• It can help to understand transient well
behaviour and determine the optimum
process to eliminate or minimize
instability problems.
P6
P5
P4
P3
• It can be used to analyse "what if"
scenarios and predict results.
P2
P1
• It does not replace NODAL® analysis but
fills gaps where steady-sate analysis
techniques cannot provide adequate
solutions.
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1
2
1
3
2
4
3
5
4
6
5
1,2,3,…,5 (inside) : section volumes
1,2,3,…,6 (outside): section boundaries
NODAL® vs. DYNAMIC SIMULATION
•The weak points of NODAL S.S. analysis comparing with dynamic
(transient) simulation are:
•
•
•
•
•
•
Unable to predict severe slugging introduced by riser / flowline or /
sinusoidal wellbores
Unable to perform instability analysis
Unable to performance gas-lift unloading analysis
Unable to predict dynamic behaviour of plunger lift
Unable to look at gas/condensate gas well liquid load-up issues
Unable to
performance flow
assurance study,
e.g., start-up / shutdown, corrosion /
chemical injection
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7
DYNAMIC SIMULATION for WELL DESIGN
Well design:
Understand effects of well design & associated dynamic
effects on well operations, including:
• Vertical wells
• Horizontal / Sinusoidal wells
• Multi-lateral wells
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DYNAMIC SIMULATION RECOMMENDED AREAS OF USE

Gas-lift unloading /
plunger lift

Instablility / Severe
Slugging

Gas-lift design and
optimisation

Cross-flow analysis

Gas well Liquid load-up

Well Clean-up / start-up

Well Testing: Wellbore
Storage effects /
Segregation effects

Wellbore thermal
calculations

Flow Assurance

Inhibitor requirements
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DYNAMIC SIMULATION APPLICATIONS
• One of the relevant areas of
application is for gas-lift wells
and systems.
• In particular, it is useful for
subsea and deepwater gas-lift
wells, where transient issues
related to flow assurance,
complex wellbore profiles, long
flowlines, and risers play a
significant roll in gas-lift system
design and production
optimization.
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Sea
level
Mud
line
DYNAMIC GAS LIFT APPLICATIONS
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Continuous gas-lift / Gas-lift valve performance
Intermittent gas-lift
Gas-assisted plunger lift
Dual gas-lift
Single-point gas-lift
“Auto” gas-lift (gas from one zone is used lift other zones)
Riser gas-lift
Gas-lift for gas well deliquification
Gas-lift unloading
Kick-off of gas-lift wells
Use of gas-lift for wellbore clean-up
Gas-lift system distribution with various types of system
configurations
Use of un-dehydrated gas
Use of non-hydrocarbon gases such as CO2 and N2.
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TYPICAL GAS LIFT WELL CONFIGURATION
Sea
level
Modelling concerns:
a) Annular Flow
Mud
line
b) Heat Transfer
c) Non-constant Composition in
Tubing above Injection Point
d) Unloading Valves Operation
Gas Lift is clearly a transient problem
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Well Clean-up – Case Study
Problem Description
• Estimate the minimum rate and time required to
clean-up the well
– Horizontal Oil Well
• Verify the planned well clean-up and testing program
using dynamic simulation
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Well Clean-up – Case Study: NO GAS LIFT
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Well Clean-up – Case Study: GAS LIFT
When using gas lift
(300 scf/min of N2
during the first 4 hrs),
it took 4.3hrs
to clean the well.
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Well Clean-up – Case Study
Problem Solutions
•
It was found that a mud plug was form at the base of the
vertical section of the well which could not be lifted using the
planned choke opening program.
•
The injection of N2 at the base of the riser was simulated to
evaluate if the amount of N2 in cylinders required to produce
the well was realistic or other methodology should be
considered
•
When using gas lift (300 scf/min of N2 during the first 4 hrs),
it took approximately 4.3 hours to clean-up the well.
•
Risk and uncertainty were reduced and value added to the
ROI required for a successful clean-up and well test
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Integrated Modelling Application
All-in-One Gas Lift Example
Reservoir-Well-GL-Flowline-Riser-Separator-Facilities
ID=8-in,
Depth=120 m
Gas Lift
ID=8-in, Length=4.6 km
Annulus
ID=0.2159 m
PC
Depth=2840 m
PCV
W1 W2
ID=2 m, Length=6 m
NLL=0.842 m
HHLL=1.687
LLLL=0.315
W3 W4
Tubing ID=0.1143 m
Gas
Outlet
LC
Production
Separator
•
•
Riser
Quasi-dynamic Reservoir:
incorporated explicitly
Facilities: Simple model
LCV
Emergency
Drain
Valve
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Emergency
Liquid
Outlet
Liquid
Outlet
Integrated Modelling Application
Gas Lift Example
Gas rate
Reservoir-Well-GL-Flowline-Riser-Separator-Facilities
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Example: Using a DS for Unloading GL Wells
Data provided by a well with 6 gas lift valves and a gas
injection valve.
Well Profile
GLV details
Elevation profile
PRODUCTION_TUBING
500
Valve
Depth
(m)
Size
R
Dome
Pressure
(bara)
1
761
20/64”
0.104
105.4
2
1327
20/64”
0.104
110.3
3
1651
20/64”
0.104
112.8
4
1795
20/64”
0.104
113.4
5
1921
20/64”
0.104
113.9
6
2049
20/64”
0.104
114.4
7
2192
24/64”
-
-
0
-500
1
Elevation [m]
•
-1000
-1500
2
3
-2000
4
5
6
-2500
7
-3000
0
500
1000
1500
Helix RDS Well Instability - Kick-of f Gas Simulations - T14
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2000
2500
Length[m]
3000
3500
4000
4500
5000
Example: Using a DS for Unloading GL Wells
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Example: Using a DS for Unloading GL Wells
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INFORMATION PROVIDED BY DYNAMIC SIMULATION
Slugging flow:
• Understand slugging flow effects and the impact on well performance
• Understand when, where, and under which conditions slug flow is
originated
• Understand how slug flow conditions can be minimized or eliminated
Water and/or hydrates:
• Understand the effects of accumulated water and hydrates in lines,
gas-lift valves, etc.
• Understand the effects of water-induced corrosion and how this can
affect stability.
• Understand when, where, and under which conditions hydrates may
be formed.
Production chemistry:
• Understand the effects scale, wax, and/or paraffin formation and the
impact of this on well performance and stability. SSSV location.
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INFORMATION PROVIDED BY DYNAMIC SIMULATION
Gas-lift valve performance:
• Understand information for dynamic gas-lift valve optimum location
and orifice performance – design/troubleshooting
Well equipment:
• Understand the effects of downhole pressure restrictions such as
safety valves, corrosion deposits, scale deposits, wax deposits
• Understand the effects of tight spots or holes in the tubing
• Understand the effects of risers
• Understand the effects of surface equipment such as flowlines,
manifolds, separators, separator back-pressure, etc.
Well design:
• Understand the effects of well design and the associated dynamic
effects on well operations. This includes:
• Vertical wells
• Horizontal wells
• Multi-lateral wells
• Understand when and where to inject gas into a well: in the vertical,
in the knee, in a rat hole, in the
horizontal section
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THE API RP 19G11 DRAFT DOCUMENT
Table of Contents
This document contains nine chapters to assist the gas-lift
industry in understanding and applying dynamic simulation
for gas-lift wells and systems:
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THE API RP 19G11 DRAFT DOCUMENT
Table of Contents
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THE API RP 19G11 DRAFT DOCUMENT
Summary of RP (17 pages)
• After reading this summary chapter,
the reader should understand the
RPs that need to be followed to
successfully use and deploy dynamic
simulation of gas-lift wells and
systems.
•
A reference on where to turn in the
document for more detailed
information is provided.
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THE API RP 19G11 DRAFT DOCUMENT
Status od API 19G11
• The document can now be used in its current draft form, by
anyone who wishes to use it. This means that anyone will be able
to download it from ALRDC website. The API won’t sell it in its
draft form and will provide it to people free of charge.
• The draft document is copyrighted.
• API will begin immediately to move the document through the
balloting, final editing, and publication process.
• Once it has been finalized by API, we will begin the process to
edit the document.
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