PRODUCTION OPERATIONS
Smart valve system provides
interventionless completions
Technology applied for gas lift offshore Thailand
Zhiyue Xu
B. M. Richard
James H. Kritzler
Baker Hughes
The artificial lift method of gas lift is an increasingly popular means of boosting production from wells with lagging res- ervoir pressure. The method injects a compressed gas into well annulus between the production tubing and casing. Tub- ing and casing pressures cause the valve to open and close,
which introduces the gas into the produced fluid in the tubing. The
injected gas aerates the fluid to reduce its density, thus allowing the
reservoir pressure to push the mixture of produced fluids and gas
up to the surface.
Multiple gas lift valves are typically installed in a well to ensure
optimal production as the well’s pressures, fluid compositions, and
productivity change. In a representative four-valve gas lift system,
each gas lift valve is installed in a side packet mandrel (SPM), which
in turn is placed on the production tubing of a gas lift well. Gas lift
valves are designed for installation and removal by wireline while
the mandrel remains in the well, which eliminates the need to pull
the tubing to repair or replace the valve (as is required in a conventional gas lift mandrel).
After initial installation of a live gas lift valve system, pressurization is required to confirm the pressure integrity of the tubing or
annulus, set a hydraulic packer, activate an isolation device or run
cement through completion. Any unplanned pressure reversal or cement debris may damage the live gas lift valve, resulting in costly
well completion failures.
Dummy valves are commonly deployed as a means of avoiding
damage to a live valve. These higher pressure-rated dummy valves
are loaded in the SPM to isolate the annulus from the tubing during
initial pressurization or the cementing-through operation. Should
the well then require gas lift to unload the completion fluid or to
get the well flowing, the dummy valves must be replaced with the
live gas lift string via a wireline intervention. Not only can an inter-
vention be a time-consuming process that poses risks to the exist-
ing well infrastructure, but it also delays the onset of production.
Slickline crews are a finite and in-demand resource, and sometimes
cannot be scheduled for a valve change-out project for many weeks.
Some industry estimates suggest that waiting up to one month for
a valve change out on a 20-well platform translates to as much as
100,000 bbl in lost production.
A nanostructured solution
The industry need for lower risk, interventionless
alternatives to gas lift valve changeouts prompted
Baker Hughes to develop a smart gas lift valve that
could function as a dummy valve during completion
operations and then convert to a live valve, without the
need for a well intervention. This is achieved through the
use of a disintegrable barrier or plug made of nanostruc-
tured composite material. This plug provides the necessary
annulus isolation while performing comple-
tions work, and then disintegrates in the
presence of brine during the cleanup
process, thus increasing comple-
tion operation efficiency of offshore
wells. The nanostructured composite
A representative scanning electron microscope micrograph of a nano-
structured composite shows the cellular nanomatrix (white grain bound-
ary) and metallic grains dispersed in the nanomatrix. (All images courtesy
Baker Hughes)
Design of smart gas lift valve
showing the time-controlled
disintegrable plug assembled
in the nose section of a standard gas lift valve.
