2005 Gas-Lift Workshop
2012 Gas-Lift Workshop
Page 18
2012 Gas-Lift Workshop
Technical Presentations
Session: I
Offshore, Sub-Sea, Deep Water, TLP
Session Chair:
Mike Johnson
Presentation Title: I – 1
Is the State of Gas-lift currently ready to support the Deep
Gulf of Mexico Production Planned for 2015 and Beyond?
Company(ies):
Shell International
Author(s):
Wayne Mabry
Contact Information:
[email protected]
Abstract:
It is clear that the gas-lift community has been providing fit
for purpose solutions for land and shelf applications for many
years. The next step out has already tested the robustness of
existing designs and has fueled a resurgence of gas-lift product
development to meet these challenges.
The cost of intervention (estimated to be between $25,000,000 to
$60,000,000 USD) in the deep water Gulf of Mexico wells demands a
new level of assurance relating to design, design validation, third
party witness, functional testing, and systems integration testing
than has ever been experienced by the gas-lift community
before.
All design and manufacture elements for gas-lift equipment will
require a never-before-seen focus if the requirements for deep Gulf
of Mexico applications are to be properly satisfied. This
presentation will discuss a few of these issues.
Notes:
2012 Gas-Lift Workshop
Technical Presentations
Session: I
Offshore, Sub-Sea, Deep Water, TLP
Session Chair:
Mike Johnson
Presentation Title: I – 2
High Angle Removal and Replacement of GLV in Single Run
Company(ies):
Welltec
Author(s):
Almir Dulic
Contact Information:
[email protected]
Abstract:
An operator in Prudhoe Bay, Alaska required the ability to
replace gas lift valves in their completion for improved oil
production. Conventional methods had reached their limits.
Slickline was unable to overcome the higher deviations while coiled
tubing, with imprecise depth control, took multiple run-in-hole
attempts to pull and replace the valve. Based on previous, positive
experiences with electric line - mechanical solutions, the customer
chose a newly modified Kick-Over Tool (KOT) to be run in tandem
(two KOTs) combined with a tractor and a hydraulic stroking to pull
the existing gas lift valve (GLV) and replace it in a single run.
The tractor conveyed the tool string to the correct depth where the
stroking tool and the first KOT provided the pulling force for
removal. Then, the stroking tool and second KOT successfully
installed the new GLV into the mandrel.
The operator is now enabled to optimize their gas lift design
without limitations imposed by the previous, conventional means
such as slickline and coiled tubing. This allows them to place gas
lift valves in the high angle sections if that is the best possible
location for increased oil recovery from their reservoirs. Few
changes have been made to the Kick-Over Tool technology in the past
40 years but has been recently improved to operate more reliably in
deviated and horizontal wells and has been modified to accommodate
the forces generated by the hydraulic stroking tool.
This paper will describe the challenges with the planning and
execution of this operation and the implications for future gas
lift design.
Notes:
2012 Gas-Lift Workshop
Technical Presentations
Session: I
Offshore, Sub-Sea, Deep Water, TLP
Session Chair:
Mike Johnson
Presentation Title: I – 3
Installation of a Gas-Lift Valve using Riserless Light Well
Intervention Technology
Company(ies):
Island Offshore
Author(s):
Siri Nordbø Jøssang
Contact Information:
[email protected]
Abstract:
Island Offshore together with alliance partners FMC and Aker
Solution has become the world‘s largest and most experienced
provider of downhole services through Riserless Light Well
Intervention (RLWI). Since the start in 2005 the alliance has
completed approximately 170 well interventions with great
success.
At present time three vessels are in continuous operation in the
North Sea. The large number of well interventions performed
verifies that the alliance is adding great value to our customers.
The service has proven itself to be cost-efficient, time saving and
reducing risk, when compared to traditional subsea intervention
methods.
Various interventions have been performed, i.e. logging
operations, perforations, setting/retrieval of plugs, pumping
operations, milling and leak detections etc. In a few occasions gas
lift valves have been installed or changed.
In 2010 a Gas Lift Valve was successfully changed on the Draugen
Field from Island Constructor. This operation included:
· Retrieval of Orifice GLV from SLB dual SPM at 1571m MD
· Displaced 1,5 x well volume through GLV
· Installed new PTC GLV
The objective for this operation was successfully performed
according to operational plan and time planner.
Notes:
2012 Gas-Lift Workshop
Technical Presentations
Session: I
Offshore, Sub-Sea, Deep Water, TLP
Session Chair:
Mike Johnson
Presentation Title: I – 4
Fishing in Deepwater, Subsea Completions
Company(ies):
Weatherford
Author(s):
John Segura
Contact Information:
[email protected]
Abstract:
Fishing in deep water completions requires proper contingency
planning. The casing size dictates dimensions of completions
tools as well as the size of fishing components. There are
several situations that can result in a deepwater fishing operation
including parted pipe, parted screens, tubing or components leaks,
well repairs, and maintenance. When gas lift
mandrels are part of the completion, one needs to consider how to
retrieve the tubing if a fishing situation occurs. Gas lift
mandrels cannot be retrieved with typical washover operations to
remove external debris without risking damage to the completion
component.
In most cases, the pipe will need to be separated below the gas
lift mandrels via a pipe recovery operation. This operation
includes lowering a cutting or back-off tool with e-line and
separating the tubing above the free point of the tubing string of
the completion. The tubing and gas lift mandrels above
this point can then be retrieved, allowing the fishing operation to
progress without the complications of the gas lift mandrel shape.
The type of separation tool used will be dependent on the
completion components, well geometry, hole conditions, subsea
conditions and the forward plan for workover, repair, recompletion
or abandonment.
Notes:
2012 Gas-Lift Workshop
Technical Presentations
Session: I
Offshore, Sub-Sea, Deep Water, TLP
Session Chair:
Mike Johnson
Presentation Title: I – 5
Application of Self Lift Concept, Offshore Nigeria
Company(ies):
ExxonMobil
Author(s):
Olawale Ayeni
Contact Information:
[email protected]
Abstract:
A combination of factors is always at play in a bid to sustain
oil production especially when operating on a remote platform in an
offshore environment. In this paper, the reference case is offshore
Nigeria that relies heavily on gas-lift as the primary artificial
lift method to sustain and improve oil production.
Basic requirements for gas-lift on a platform include having a
gas source, surface facilities, and a well installed with gas-lift
mandrels or some other set-up to allow injection of gas into the
tubing. The self-lift concept provides the ability to place a
potential gas source well on gas-lift without having surface
gas-lift facilities and sustain production to the well until top
side facilities are completed; in essence, minimizing deferred
production as a result of delays associated with the surface
gas-lift facilities.
This paper will review the design considerations, well set-up
for self-lift, the learning curve, and also the unique
circumstances that made this innovation an economic success
story.
Notes:
2012 Gas-Lift Workshop
Technical Presentations
Session: I
Offshore, Sub-Sea, Deep Water, TLP
Session Chair:
Mike Johnson
Presentation Title: I – 6
A Revolutionary IPO Unloading Valve That Improves Gas Lift
Design Flexibility and Reliability, While Significantly Reducing
Life Cycle Costs
Company(ies):
Petroleum Technology Company (PTC)
Author(s):
Alan Brodie
Contact Information:
[email protected]
Abstract:
The presentation will describe the benefits that OPCO's
worldwide are enjoying following the development of a revolutionary
new IPO unloading valve design. These benefits include:
· A significant reduction in installation costs, because of the
unique unloading valve shear facility, which means any number of
live unloading valves can be installed in a new completion,
eliminating the requirement for wireline operations to pull dummy
valves and install live valves following completion testing.
· The elimination of the potential for multi pointing ( and
significantly reduced well performance) because of the unique
spring assisted, edge welded, double acting bellows design, which
means that bellows reliability is much enhanced and even in the
event of bellows failure, the valve is held in the closed
position.
· The unique flexibility to reliably use unloading valves as
operating valves, whenever well conditions preclude getting gas to
the deepest valve setting depth, because of the uniquely long
unloading valve stem travel, which means that when it is open it
does not constrict the flow of lift gas and is therefore not prone
to erosion.
Notes:
2012 Gas-Lift Workshop
Technical Presentations
Session: II
Gas-Lift Automation & Optimization
Session Chair:
Greg Stephenson
Presentation Title: II – 1
Batch Gas-Lift Trouble Shooting in the Kuparuk River Field,
Alaska
Company(ies):
ConocoPhillips
Author(s):
Grant Dornan
Contact Information:
[email protected]
Abstract:
ConocoPhillips developed a Batch Gas-Lift Trouble Shooting
(GLTS) program to monitor gas-lift performance in the Kuparuk River
Field, Alaska. This presentation will provide an overview of Batch
GLTS, discuss results, and outline planned enhancements.
ConocoPhillips operates 630 producing wells in the Kuparuk River
Field. The Batch GLTS program is used to identify opportunities to
increase rate on wells that are not lifting efficiently or where
the gas-lift performance can be improved.
The program allows the user to select a grouping of wells to
compare actual well test data with predicted performance based on
installed gas-lift design, wellbore description, hydraulic
correlation model and Inflow Performance Relationship. Results are
output to a spreadsheet for review.
Notes:
Session: II
Gas-Lift Automation & Optimization
Session Chair:
Greg Stephenson
Presentation Title: II – 2
Automated Gas-Lift Optimization
Company(ies):
Schlumberger
Author(s):
Daniela Hackl
Contact Information:
[email protected]
Abstract:
This presentation shows SIS Technology – Avocet Gas Lift Manager
– which utilizes the PIPESIM network engine to automatically
optimize the production network by varying gas-lift injection
rates. The automated approach significantly reduces the
optimization runtime, enhances communication via customized alarms,
hence induces faster decision making, which ultimately leads to
enhanced production efficiency and recovery.
Avocet Gas-Lift Manager is fully integrated with PIPESIM and
bridges the gap between SCADA systems, automated workflows and
network update and optimization.
Notes:
Session: II
Gas-Lift Automation & Optimization
Session Chair:
Greg Stephenson
Presentation Title: II – 3
Honeywell’s On-line Gas Lift Optimization Solution
Company(ies):
Honeywell
Author(s):
Todd DeCuir
Ravi Nath
Sanjay Sharma
Contact Information:
[email protected]
Abstract:
Continuous flow gas lift is a common artificial lift method that
is widely used in the oil industry. Determining the optimum
allocation of the lift gas to maximize production from a site with
multiple wells that are connected to a common compressor however is
challenging as it requires careful consideration of all top side
constraints. Implementation of the optimum allocation is also
challenging as the top side constraints are not static but change
dynamically.
Honeywell’s on-line Gas Lift Optimization solution (HGLO)
effectively addresses both of these concerns by utilizing
Honeywell’s state of the art non-linear optimizer (NOVA) that is
directly coupled to Honeywell’s robust multi-variable predictive
controller (Profit Controller).
This paper will present the Honeywell Gas Lift Optimization
solution and a case study illustrating the solution.
Notes:
Session: II
Gas-Lift Automation & Optimization
Session Chair:
Greg Stephenson
Presentation Title: II – 4
Software Technology Maximizes Production for On-shore Gas-Lifted
Field
Company(ies):
OVS Group
Author(s):
Sebastiano Barbarino
Norman Kroon
Contact Information:
[email protected]
Abstract:
Despite the abundance of data in its various formats such as
service reports, processed data found in models and spreadsheets,
operational data (sensors, well test, etc.), and allocated
production, many decisions are delayed or hampered as the
transformation of information into a format to base decisions on
are typically not readily available. Valuable engineering resources
are consumed with tasks and processes to convert raw data for
analysis in spreadsheets or modeling applications as part of the
overall decision making process.
New software technology exists that creates an opportunity for
any asset, a step change in the approach to maximizing the
potential of their field without disrupting or changing current
investments in databases and applications. Essentially the new
technology provides guided workflows as designed by the client for
their specific needs, complete with automating as much as possible
many repetitive routines.
Optimizing a gas-lift process through model validation is a key
task to ensure maximum well deliverability and the most efficient
use of available resources such as gas-lift gas and lift equipment.
Fine tuning models requires an orchestration of timely data
delivery, execution of models and engineering input to make the
final decision for operational changes. Automation of this process
through technology can be scheduled on a daily basis or on demand
enabling the operation to cope with the constant change in
operational conditions.
To best describe the technology, let’s look at a case study from
an on-shore gas lifted PEMEX field in Mexico.
Notes:
Session: III
New and Emerging Gas-Lift Techologies
Session Chair:
John Martinez
Presentation Title: III – 1
Extending the Range of Gas-Lift toLong Perforations
Company(ies):
Production Control Services
Author(s):
Lindsay Martin
Contact Information:
[email protected]
Abstract:
Problem being addressed: Operators face many challenges when
producing deep vertical wells and long horizontal or deviated well
bores. Traditional artificial lift methods can prove inefficient or
ineffective when applied to this breed of wells.
Challenges: In wells with long perforated intervals,
insufficient velocities below the packer can cause liquid loading.
Many traditional artificial lift methods are limited in their
ability to address liquid loading issues in these types of
wells.
Solution: If gas can be injected below the packer and deep into
the perforated zones, gas lift can be an effective means of
deliquification. Advances in gas lift system design now provide
several options for effectively recovering liquids from completion
intervals below the packer. We will discuss a few of these systems,
including Annular Bypass Assembly (ABA), Dip Tube, Enhanced Annular
Velocity (EAV), Marathon AVE, and Packerless Dead String. Each
employs unique techniques that allow for gas injection deep into
the perforated zone by passing the lift gas through or around the
packer. Using the basic principles of gas lift, the injected gas
aerates the liquid in the perforated zone, decreasing the flowing
gradient and improving inflow from the formation. By also
increasing velocity in the production string, these gas lift
systems allow operators to more efficiently recover fluids and
minimize or prevent liquid loading.
Results: Below-packer gas lift systems are being used
successfully to economically produce wells in unconventional plays.
We will review the design and mechanics of each of the
above-mentioned systems, share our experiences working with
operators and discuss the selection criteria in choosing a
system.
Notes:
Session: III
New and Emerging Gas-Lift Techologies
Session Chair:
John Martinez
Presentation Title: III – 2
Bringing Digital Intelligence to Artificial Gas Lift
Solutions
Company(ies):
Camcon
Author(s):
Ian Anderson
Contact Information:
[email protected]
Abstract:
Conventional side pocket gas lift applications have been used
for decades to assist the hydrocarbon lifting processes for oil
extractions. Recent technology innovations have generally not been
applied to this technique, other than “incremental” developments.
With the focus on smart wells and intelligent fields, there is a
demand to improve oil extraction techniques and reduce operational
costs in areas like gas lift.
Camcon Oil has developed an Intelligent Artificial Lift Unit –
APOLLO – a new solution for assisting the lifting of oil from
production assets. APOLLO and its portfolio of injection control
solutions enables operators to vary gas injection rates in
real-time without production interruption or well intervention.
Pressure and temperature readings throughout the gas injection
process are relayed back to the control room to provide the
necessary information to initiate any required gas injection rate
changes. This intelligent device introduces management and
operational advantages far beyond current the capabilities with an
emphasis on field optimisation as well as individual well
optimisation.
The introduction of APOLLO to oil operators is ongoing, with
first production installations now scheduled to go “live” in Q1
2012, deployed in an on-shore installation. Camcon Oil seeks to
extend this technology and bring to a wider market, including high
performance wells, initially on-shore and then off-shore.
At the ALRDC event in Singapore 2011, Camcon Oil Limited
suggested that the first trial results would be presented at the
ALRDC event in 2012, but project and program delays have delayed
the trial installations. Camcon Oil Limited will provide a product
and technology introduction for the APOLLO units including specific
reference to the their experiences in bringing new technologies and
product to the market.
Notes:
Session: III
New and Emerging Gas-Lift Techologies
Session Chair:
John Martinez
Presentation Title: III – 3
Clamp-on Gas Flowmeter Flow Loop and Field Trials
Company(ies):
ExxonMobil Production Company
GE Sensing and Instrumentation Southwest Research Institute
Author(s):
Michael C. Romer
Tony W. Hord
Frederic Baudart
Terry Grimley
Contact Information:
[email protected]
Abstract:
Description
An ultrasonic, portable, clamp-on gas flowmeter was tested in a
gas flow loop with various pipe sizes to determine if it would be
suitable for gas lift gas injection metering. Following the flow
loop trials, the portable meter was applied in the field at various
gas-lifted assets. This presentation will describe the fundamentals
of the meter’s operation, the results of the flow loop and field
trials, and the challenges that were encountered during
testing.
Significance of Subject Matter
An important input for gas lift optimization is the volumetric
flow rate of injection gas. This data can help an experienced gas
lift technician determine if a well is being over- or
under-injected, thus providing directional guidance on what
change(s) should be made to improve a well’s performance. The
volumetric flow rate can be used to estimate the transit time of
injected gas, which can then be combined with other tools to
determine downhole injection points.
Application
Field injection gas metering is typically unreliable. Lack of
personnel, time, OPEX, and/or training can result in poor (or
nonexistent) maintenance and calibration of field meters. In some
legacy fields, there is no functional gas injection metering. To
compound the problem, it can be difficult to justify facilities
expenditures for late-life, artificially lifted wells. A portable,
non-invasive, moderately accurate gas flowmeter would be ideal for
obtaining the injected gas flow rate in these situations.
Results, Observations, Conclusions
The meter was successfully tested in a flow loop on ¾”, 1½”, and
2” pipes, and was consistently within 5% of the actual gas flow
rates. The field trials produced generally positive results on 1¼”,
1 ¾”, 2”, and 3½” pipes. Gas lift injection lines proved to be a
challenging application for the ultrasonic flow metering
technology. Several hours of setup were typically required to
ensure a high quality signal for measurements, as a combination of
physical dampening techniques and meter parameter tweaking was
necessary. A systematic installation approach that guarantees a
high quality signal is still a work in progress for our
application. However, the to-date results have shown promise, and
the clamp-on flowmeter has the potential to become a valuable tool
in our gas lift optimization efforts.
Notes:
Session: II
New and Emerging Gas-Lift Techologies
Session Chair:
John Martinez
Presentation Title: III – 4
A New Life of Field Approach to Gas Lift Installation Design and
Unloading Valve Set Up That Optimizes Production and Reduces
Installation Uncertainty
Company(ies):
Petroleum Technology Company (PTC)
Author(s):
Alan Brodie
Contact Information:
[email protected]
Abstract:
The presentation will describe a new approach to gas lift system
design which:
· Adopts a probabilistic approach to take any uncertainty (or
expected life of field variation) in the design parameters such as
productivity index, reservoir pressure, or produced fluid
composition into account when selecting mandrel setting depths. As
a result the conservatism or limited range of applicability that
can be inherent in the traditional approach to gas lift system
design can be avoided.
· Systematically assesses the requirement for a venturi type
orifice to reduce the differential pressure across the orifice for
critical flow in order that the likelihood of slugging in the well
is minimized.
The presentation will also describe a unique approach to setting
up IPO unloading valves. By charging the IPO valve dome pressures
while the valve is maintained at the anticipated well temperature,
the uncertainty of the correction factor between ambient conditions
and well conditions is removed. More importantly the IPO valve
opening and closing pressures can be confirmed at valve
operating temperature before leaving the workshop.
Notes:
Session: III
New and Emerging Gas-Lift Techologies
Session Chair:
John Martinez
Presentation Title: III – 5
Implementation of the VPC Database in the OLGA Multiphase Flow
Simulator
Company(ies):
SPT Group
Author(s):
Bin Hu
Dewayne Anderson
Ayn Becze
Cheryl Cash
Eric Kowalewski
Contact Information:
[email protected]
Abstract:
OLGA is the proven industry standard for modeling transient
multiphase flow from the near-wellbore reservoir to the receiving
facilities on the platform. The OLGA simulator initially was mainly
used to investigate the dynamic multiphase flow behavior in
offshore pipelines. In recent years, the simulator has seen rapid
uptake by the production engineers to model the flow transients in
wells such as gas-lift, cleanup, liquid loading, shut-in and
start-up etc.
One of the big simulation applications is to model the dynamic
process of the gas-lift unloading process. Before 2010, the
gas-lift unloading valves in the OLGA simulator has to be modeled
in such a way that the users need to tabulate the characteristic
curves of the valves, which is a tedious process that makes the
modeling a “mission impossible”. To solve this challenge, SPT Group
had a collaboration with the VPC JIP to implement the capability of
reading the VPC database from the OLGA simulator. This presentation
will cover how this capability was implemented, tested, and then
certified by the VPC JIP representative. The presentation will also
exemplify the new concept on how to design and test the gas-lift
unloading process interactively in a dynamic simulator.
Notes:
Session: III
New and Emerging Gas-Lift Techologies
Session Chair:
John Martinez
Presentation Title: III – 6
Field Trial of a Non Intrusive Gaslift Surveillance Tool – Well
Tracer Technology
Company(ies):
SPDC NigeriaAppSmithsWeatherford
Author(s):
Nkili Nwadike
Larry Peacock,
Azubike Ofodile
Felix Obike
Stella Oyemade
Abbas Ayoku
Uwem Essien
Contact Information:
[email protected]
Abstract:
Historically, evaluation of the performance of installed
gas-lift valves in gas-lifted well(s) has been through the
acquisition of flowing gradient and temperature surveys. In rare
cases where there are constraints in acquisition of this critical
data, gas-lift valve change out interventions (a process of
gas-lift optimization) have been dependent on the engineer’s
judgment and other available surface and subsurface data.
Some of the cons of the traditional survey method include but
are not limited to; inability to accurately detect leak paths other
than the defined mandrel depths, multipointing scenarios, and risk
of losing tools in the hole, deferment, etc.
The Well Tracer Technology which is a non intrusive, man
portable device addresses most of the identified shortfall above
within a 2-4 hr duration of the trace. The tool also provides the
additional capability of estimating the percentage of gas injection
for each string of duals which has been an industry challenge,
preliminary data for full field exception based surveillance,
interventions and optimization. It achieves these feats by
injecting a slug of CO2 gas through a temporary connection point on
the gas injection line and one connection point on the production
line through which it takes returns of the produced fluid and any
injected volume of CO2. The produced well fluid alongside the
injected CO2 slug is passed through an analyzer which generates a
plot of CO2 concentration versus time. CO2 concentration peaks help
in the back calculation of injected gas volumes per string of
duals.
The binary data received from the analyzer is uploaded into a
gas-lift surveillance and analysis software (WinGLUE) to determine
lift depth(s), multi-pointing scenarios, or holes in the tubing.
The results of the field trial have validated its capability as a
fit for purpose, non intrusive gas-lift surveillance tool. It
enables exception based surveillance, intervention, optimization,
and proactive well integrity management.
Notes:
Session: IV
Field Reviews, Recommended Practices
Session Chair:
Wayne Mabry
Presentation Title: IV – 1
Acoustic Testing in Gas Lifted Wells
Company(ies):
Echometer
Author(s):
Carrie Anne Taylor
Contact Information:
[email protected]
Abstract:
Stringent safety requirements imposed by major operators when
fluid level measurements are performed best offshore or in enclosed
wellhead spaces such as in Alaska’s North Slope create procedural
complications, such as the requirement for hot permits, when
performing fluid level measurements in producing wells. This need
has been eliminated by the development of a small, self contained,
fully digital, battery powered instrument that is approved for use
in hazardous areas. Examples from North Sea platforms and Alaska
North Slope of acoustic liquid test of gas lifted wells will be
presented.
The signal from the liquid level echo and the signals that
correspond to the echoes from the gas lift mandrels are frequently
identifiable on the acoustic trace. An “Anomaly” analysis method
using the known depth of each mandrel is used to accurately
determine the liquid level depth. For this method the software
initially places tick marks on the depth axis that correspond to
the depth of the known down hole markers in the well. The user then
manually relocates the markers, starting with the topmost signal,
at the exact point in time of the signal arrival. The acoustic
velocity for that time interval is computed knowing the depth to
the marker. This procedure yields a more accurate calculation of
the liquid level depth especially in those wellbores where there
are significant temperature variations, such as in offshore
platforms, or when the gas column is stratified.
The acquisition and interpretation of the data through an
advanced software package automates the analysis even in
acoustically noisy environments. Results are observed immediately
on the instrument screen then saved in the data base for eventual
transfer to external data base. This presentation shows detailed
information about the new system and reviews data acquired in gas
lift wells
Notes:
Session: IV
Field Reviews, Recommended Practices
Session Chair:
Wayne Mabry
Presentation Title: IV – 2
Intrinsically Safe Instruments
Company(ies):
Echometer
Author(s):
Carrie Anne Taylor
Contact Information:
[email protected]
Abstract:
Stringent safety requirements imposed by major operators when
fluid level measurements are performed offshore or in enclosed
wellhead spaces such as in Alaska’s North Slope create procedural
complications, such as the requirement for hot permits, when
performing fluid level measurements in producing wells. This need
has been eliminated by the development of a small, self contained,
fully digital, battery powered instrument that is approved for use
in hazardous areas.
Different types of intrinsically safe instruments and their
unique features developed for specific needs are covered.
Notes:
Session: IV
Field Reviews, Recommended Practices
Session Chair:
Wayne Mabry
Presentation Title: IV – 3
Gas-Liquid Flow Optimization with a
Bubble Breaker Device
Company(ies):
Petrobras
Author(s):
Hendy Tisserant Rodrigues
Alcino Resende de Almeida
Contact Information:
[email protected]
Abstract:
Pressure losses in two-phase flow inside vertical wellbores are
largely affected by the mixture density, which depends on the
flowing oil and gas fractions. Increasing the gas fraction should
reduce the bottom-hole pressure and increment well production. It
can be shown that, without modifying the liquid and gas flow rates,
gas fraction can be increased by decreasing the average gas
velocity. One way to reduce gas velocity is to reduce bubble sizes,
relying on the fact that bubbles with smaller diameters have lower
lift velocity. This kind of flow optimization can be performed
using a device called Bubble Breaker. This device consists of a
flow restriction which creates localized turbulence and breaks the
bubbles.
This work presents results from lab-scale air-water experiments
performed with different geometries of Bubble Breaker and
gas/liquid flow rates. Emphasis is given to Venturi-type geometries
with different throat diameters in order to reduce the localized
pressure loss. The used flow rates represent mainly the slug flow
pattern. Pressure measurements were taken in four positions along a
vertical 11-meter pipe, which allowed calculations for the pressure
drop through the Bubble Breaker and the ratio between the pressure
gradients before and after the Bubble Breaker.
High speed camera films were also obtained. An important result
was that Bubble Breaker is not effective in breaking bubbles at
Slug Flow pattern, since the liquid slug already contains small
diameter bubbles and the elongated bubbles coalesce soon after the
Bubble Breaker. The best application of the Bubble Breaker is at
the Bubbles flow pattern, because it breaks the bubbles so as they
become finely dispersed. In this pattern the small size postpone
the bubbles coalescence, prolonging the hydrostatic reduction, and
delaying the transition to slug flow.
Notes:
Session: IV
Field Reviews, Recommended Practices
Session Chair:
Wayne Mabry
Presentation Title: IV – 4
Accuracy of Nitrogen Temperature Correction Factors
Company(ies):
Marathon Oil Corporation
Author(s):
Rob Sutton
Contact Information:
[email protected]
Abstract:
Nitrogen gas is used to charge domes in gas-lift valves and some
downhole safety valves, to provide the closing force for the valve.
The design pressure and temperature conditions in the well must be
equated to the shop conditions where the valve is set up and
tested. Shop conditions are typically established at 60°F so the
nitrogen pressure at operating conditions in the well must be
adjusted to the shop conditions; hence, the name “temperature
correction factor.”
Early downhole design conditions were typically in the 500 -
1,000 psig range which formed the basis for the development of
early tables used within the industry. As more challenging
conditions were encountered, the accuracy of these tables
diminished and new methods were developed that form the basis of
the procedures used today. These methods were developed using
published nitrogen Z factor data that ranged to 3,000 psig and 300
°F. The new methods used 2nd and 3rd order polynomial equations as
the model. These types of polynomial equations typically do not
offer an accurate extrapolation as boundary conditions are reached
or exceeded.
This talk examines the calculation methodology and accuracy of
nitrogen temperature factor methods at operating conditions ranging
to 5,000 psig and 400 °F.
Notes:
Session: IV
Field Reviews, Recommended Practices
Session Chair:
Wayne Mabry
Presentation Title: IV – 5
A Dehydration Discussion
Company(ies):
Production Associates
Author(s):
John Martinez
Contact Information:
[email protected]
Abstract:
Gas-lift systems should include dehydration to prevent hydrates
and corrosion. A review of dehydration methods and reasons to
include the process are discussed.
Notes:
