American Oil and Gas Reporter - June 2017 - 96

FIGURE 4
Gas Lift Valve Test Fixture

and methane and water were the test
fluids. The results showed that the test
well could be unloaded and kicked off on
gas lift with an injection pressure of 300
psi using LAGL while single-point injec-

96 THE AMERICAN OIL & GAS REPORTER

tion of single-phase gas required a 1,200
psi injection pressure to kickoff gas lift.

Gas Lift Center Of Excellence
In addition to testing the LAGL method,
LSU has added new test facilities and is
seeing greater involvement with gas lift in
general. With a new and highly versatile
multiphase flow loop and the movement of
the Valve Performance Clearinghouse (VPC)
to LSU, the university is emerging as a
center of excellence for gas lift technology.
The multiphase test facility was donated
to the LSU Petroleum Engineering Research & Technology Transfer Lab in
2013. This loop allows circulating flow
at 4 million cubic feet a day and liquid
rates of 400 gallons/minute. The loop
can test equipment at pressures up to
1,400 psig. Figure 3 shows the new test
facility, including a large high-pressure
vessel, state-of-the-art instrumentation,
control building and gas compressor.
Figure 4 shows the test fixture for
testing gas lift valves under multiphase
flow conditions or with single-phase
liquid or gas. This loop is utilized to understand gas lift valve performance under
multiphase unloading conditions and to
investigate erosion of the orifice valve
under multiphase conditions. This facility
provides LSU with valuable new capa-

bilities and can be utilized to perform
full-scale testing of compact separators,
multiphase pumps and multiphase meters
in addition to gas lift valves.
Recognizing that understanding valve
performance is essential to gas lift design
and operations, the VPC was formed in
1996 as a nonprofit joint industry project
to test and model gas lift valves. In 2015,
the VPC was donated to LSU, which is
now a university lead JIP. The consortium
is supported by BP, Chevron, ConocoPhillips, ExxonMobil, PTC, Schlumberger and Shell. Over the years, VPC
has tested and modeled 60 valves with
various port sizes, with a total of 226
configurations in its database.
The future of the VPC consortium is
to continue to test valves and continually
expand its database, which is integrated
with various third-party software such as
Schlumberger's OLGA™, Weatherford's
DynaLift™, Petroleum Experts' Prosper™,
Rider Scott's SNAP™, and AppSmiths'
WinGLUE™. Plans are in place to expand
user access to the database by developing
Web-based software, and to expand the
research component of the consortium to
focus on developing new valve testing
methods, valve configurations and alternative gas lift techniques such as LAGL.

Field Deployment Steps
While laboratory testing has successfully qualified the LAGL method, several
steps are needed to optimize the technology
for field deployment. That includes evaluating and modeling gas lift valve performance under multiphase conditions.
Historically, valve erosion tests have been
performed using water and performance
testing has often been done using nitrogen.
Valve erosion and performance under
multiphase conditions remains largely
unknown. LSU has conducted multiphase
flow erosion and valve performance testing, but more testing is needed to fully
qualify the life cycle impact of multiphase
unloading through a gas lift valve.
The LAGL concept is dependent on
understanding downward multiphase flow
in a tubing-casing annulus. Historically,
this has been an area where little modeling
research and testing has been conducted.
Additional work is needed to develop,
improve and verify mechanics models
for downward two-phase flow. Of particular interest are the minimum velocities
and GVFs required for the quickest unloading of the well and the optimum
method to reduce liquid injection once
gas entry into the tubing has been achieved.
Also, the use of trace amounts of surfactants is expected to enhance the LAGL
process, and this benefit needs to be more
fully investigated as well as any impact

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American Oil and Gas Reporter - June 2017

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