Dynomax Drilling Tools Inc., a Canadian-based company, in
conjunction with Hydra
Partners L.L.C., a United States based company, has developed the new generation
of
“Purpose Built Motors” or PBM Series.
The PBM Series is a sealed bearing system and incorporates the
latest technology from
bearing section through to a newly-designed power section. The new features make
it
both reliable as well as economical.
The latest 2 7/8” / 3 1/16” motors are designed for the work
over and remedial needs,
and more specifically for the purpose of drilling out composite plugs.
The PBM Series of motors takes in to account today’s costs
associated with drilling and
trip times. The efficiency and cost of the PBM Series makes it economical for
the
producer to operate the tool “one” time and leave it in the well.
The design allows for the motors to operate on fluid or a
combination of fluid (soap) and
air or nitrogen. It is however, not recommended to re-run the power section if
it has
been operated with air or nitrogen environment.
The motor, while drilling or milling should be monitored
mainly by changes in standpipe
pressure. The amount of torque created at the bit or mill face will be reflected
by an
increase in standpipe pressure over the “Off Bottom” circulating pressure. The
difference in the two readings is called “Differential Pressure”. When applying
weight,
note that the higher differential pressure is achieved with less bit weight if
PDC (drag)
bits or mills are used versus the traditional roller cone type bits.
To maximize motor life (power section) we recommend keeping
differential pressures at
65-75% of maximum motor differential referred to on the specification sheet.
Special precautions should be considered in high temperature wells as the stator
elastomer may swell creating premature failure. Pumps should be brought up to
speed
slowly to allow the rotor to begin turning and then gradually increase until
reaching
desired volume. This will help reduce the shock loading of a swelled stator
elastomer.
If a motor stalls, a sudden increase in standpipe pressure will occur. It is
important to
reduce pump strokes before lifting off bottom. This will reduce pressure in the
power
section which could otherwise create over speed and eventual chunking causing
premature failures.
The design, engineering, manufacturing and assembling of the
PBM Series are provided
through facilities in North America.
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