Challenge: Mill 19 frac plugs in a high-temperature, high-flow environment where most elastomer-based thru-tubing motors would not survive.
Solution: Use a DynaForce TT high-performance thru-tubing motor and the NBR-HR elastomer to enable high-torque milling in high temperatures.
An operator in West Texas needed to bring a recently completed well into production. To do this, the
operator needed to mill 19 frac plugs that were in the 4,200-ft horizontal zone of the 5-in completion.
This zone measured at 310 degF, a temperature that most elastomer-based thru-tubing motors cannot
survive because of premature chunking.
Further, the horizontal section was long enough to create debris beds if the flow rate was not high
enough. The optimal flow rate was calculated to be 4.45 bbl/min.
After communicating with the operator, Schlumberger proposed running a 3 1/8-in, 7 /8, 3.3-stage
DynaForce TT motor. Schlumberger also determined that the motor should have a 3-loose fit, achieved
by installing a double-undersized rotor (2US) and an oversized stator (1OS). Such a fit would enable
the elastomer to swell to an optimal level in bottomhole conditions and provide the necessary torque
to mill the plugs. The fit would also enable the operator to keep a continuous 4.5 bbl/min, with peaks
of 5 bbl/min if a higher flow speed were needed.
Additionally, Schlumberger determined that the motor needed to be injected with an NBR-HR elastomer,
which holds good hardness at high temperatures and delivers up to 30% more power while minimizing
the risk of premature chunking. The specially formulated elastomer enables the motor to withstand high
temperatures in water-base fluid environments, virtually eliminating the possibility of debonding.
Using the DynaForce TT motor, the operator completed the job in one run and in just 40 hours, saving
20 hours when compared with the time estimated in competitors’ proposals. The high torque created
by the motor eliminated stalls during the job, so the motor was able to mill all the plugs in an average of
20 minutes per plug, or 6 minutes shorter than what was calculated during the prejob plan.
After postjob evaluation and surface testing of the motor determined that it was in good condition,
the motor was sent to a subsequent well in the same pad to complete another job.
Download: Operator Saves 20 Hours of Milling Time and Completes West Texas Job in One Run (0.36 MB PDF)