American Oil and Gas Reporter - June 2024 - 48

SpecialReport: Artificial Lift Technology
for quiet and unobtrusive artificial lift
equipment has grown, says Ron Peterson,
principal engineer at Unico LLC. In response,
the Franksville, Wi.-based artificial
lift company is making its linear rod
pump units even quieter by upgrading
the tooth profile on their rack-and-pinion
lift system's rack. These upgrades build
on noise reductions achieved by powering
the units electromechanically instead of
hydraulically, he mentions.
The units are popular in Australia and
are replacing many traditional pumpjacks
in urban areas of California and Colorado,
he reports.
Like a pumpjack, a linear lift unit activates
a traditional rod string and downhole
plunger pump. Unlike a beam pump,
it includes a slim, vertical housing that
varies in height depending on the rod
weight, which corresponds to well depth.
Standard-duty units for shallower wells
have stroke lengths ranging from 20 to
86 inches, while tandem heavy-duty units
for deeper wells extend to 120 inches,
Peterson describes.
The housing bolts to a standard API
casing flange using a traditional rod stuffing
box. An AC-powered, reversible electric
servo motor, or potentially a pair of
motors in deeper wells that require high
torque, is mounted about halfway up the
unit, Peterson continues. He says motors
vary in size from five horsepower to 60
horsepower, with a combination of two
on a tandem unit providing 120 horsepower.
Powered
by a drive in a standard electrical
box next to the pumping unit, the
motors activate a rack-and-pinion system
housed in an oil bath inside the unit. Motors
turn the pinion, or circular gear,
which moves a serrated rack up and
down. A polish rod, clamped at the top
of the unit, passes through the rack with
each cycle. On the down cycle, the servo
motors help control rod descent.
The controller can optimize speed at
the surface by assessing the load on the
motors and estimating liquid and gas
pump fill, Peterson reports. " By adjusting
the speed and acceleration independently
to create a controlled motion profile, we
can protect the rods, tubing and pump
down hole better than a conventional
pumpjack, " he says.
If a pump valve gets stuck, the linear
system automatically detects the condition,
then initiates a patented cleaning function
that shakes the pump to remove debris,
he says.
Linear rod pump costs range from
$10,000 to $90,000 depending on capacity
and size. The units' simple installation,
ability to reduce downhole failures and
built-in automation easily justify the cost
in many applications, Peterson says.
Linear ESPs
Linear ESPs (LESPs) can be an excellent
choice for unconventional wells
that are ready to move away from traditional
ESPs, especially if their well bores
have enough deviation to be hard on rod
lift systems or are located in environmentally
sensitive areas, suggests Kelsey
Gonzalez, director of engineering for
Valiant Artificial Lift Solutions. While
rod lift likely will be more economical in
conventional vertical or less deviated
wells that produce little gas, he says
LESPs can reduce the cost associated
with transitioning from ESPs in unconventional
shale wells.
" The price point is in the $100,000$150,000
range versus $300,000 or more
for a complete transition to rod lift, "
Gonzalez details.
These savings are significant enough
that Gonzalez says Valiant, through a
joint venture with Ukrainian company
Triol, is rolling out LESPs with some of
the Permian's biggest operators. LESP's
lower cost comes partly from less expensive
equipment change outs. An ESP
driver can be removed easily and an
LESP driver of similar dimension installed
in its place, he explains, adding that
LESPs have a similar wellhead set up
and use the same power cable as an ESP.
LESPs are plunger-style devices powered
by a variable speed drive similar in
appearance to one for an ESP but with
different electrical capacity and software,
Gonzalez says, noting that one of the
LESP units delivers 50-400 barrels a day.
This unit's drive activates the linear pump
by turning a series of magnets on and off
intermittently to move the plunger up
and down at 17 cycles a minute. The 40foot-long
tool has a stroke length of 50
inches, Gonzalez adds. Unlike an ESP
with fluid intake at the bottom of the
pump, the intake on an LESP is at the
top.
A typical ESP in the Permian has a
lifespan of about a year and three months
compared with the longest LESP field
trial runtime of 440 days, although Valiant
hopes to extend it up to two years, Gonzalez
says.
About a decade ago, others attempted
Moving from high-volume traditional ESPs to lower-volume linear ESPs can be easy and
affordable because the two technologies' ancillary equipment shares many similarities,
Valiant Artificial Lift Solutions says. To take advantage of the low transition costs, many of
the Permian Basin's largest operators are testing LESPs.
48 THE AMERICAN OIL & GAS REPORTER
to develop and deploy LESPs in the
United States with little success, Gonzalez
acknowledges. Oklahoma City-based
Valiant, formed in 2016, discovered promising
technology in 2019 from Triol. At
first, the pump was unsuccessful in Permian
wells because most had harsher
conditions than the more chemically simple
wells in Russia where the tool was

American Oil and Gas Reporter - June 2024

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