Figure 5. Conventional automated system
Figure 6. Automatic gas lift system
transducer and a temperature sensor,
which are all equipped with transmitters
and typically connected to a distributed
control system (DCS) or a programmable logic controller (PLC). This process
allows operators to control and monitor
these critical indicators remotely and
change the flow control of the injection
gas accordingly.
Automating the injection of natural
gas into the down-hole annulus has
numerous advantages over manual control. For example, automation stabilizes
the natural gas flow, leading to less slugging of the process and a more consistent flow of oil to the surface. This is
accomplished by controlling the flow of
natural gas down the well rather than
having the choke valve in a fixed position, pressure on a natural gas regulator
or a control valve.
Eliminating surging and intermit-
tent flow means less maintenance
because it becomes possible to main-
tain the optimal flow rate for each well
in the system. The increase in overall
production of oil and decrease in over-
all injection of gas not only helps the
bottom line, but also reduces the envi-
ronmental impact.
INTEGRATED CONTROL
MAXIMIZES REVENUE
Conventional automatic control systems
are superior to manual control in gas-lift
applications. However, they require complex, multiple installations of equipment
that is expensive to put in place, program, maintain, tune and communicate
with. Conventional automation systems
also add significant weight and require
more space.
Conventional automation also
requires multiple instruments so each
one of those instruments must be
installed and connected to the other
instruments. To provide maximum performance, communication between these
instruments must be established, and the
entire system tuned. All of this takes
time and requires training, experience
and significant resources. These costs
and the resulting production delays are
the most common reasons wells are not
updated to automatic controls.
Facilities should consider installing
an integrated gas-lift automatic gas
injection system to optimize the gas-lift
and realize the largest return on invest-
ment (Figure 6). An integrated solution
contains all elements needed for flow
control in one package.
Figure 7. Injection rate—manual vs. automatic
Figure 8. Production—manual vs. automatic
