Conventional techniques for valve operation during zipper fracs were high risk
Enerplus Corporation uses the zipper frac technique for efficiency on
its well pads in North Dakota’s Bakken Shale. Standard workflows for
these operations require wireline and fracturing crews to constantly
alternate between wells, isolating a well and rigging up wireline or
opening a well to begin pumping fluids downhole.
The frac fluid delivery system—including all the isolation, zipper, and
frac tree valves—facilitates frac fluid flow and movement of wireline
toolstrings into and out of the wells, but the valves must be opened
and closed accurately and in proper sequence. All the wells are in fluid
communication with each other via the zipper manifold, making valve
operations risky and increasing the potential for costly NPT incidents,
such as unintentionally cutting wireline, shutting in on a frac stage,
or exposing the environment and crew to frac fluids at high rates
and pressures.
Cross-checks by multiple stakeholders proved inefficient
To mitigate risk, Cameron was required to send two technicians per
12-h shift, and the Enerplus completions manager, frac ground
supervisor, and wireline engineer all had to engage and agree on the
procedures before any valve was operated. This practice diverted time
and resources away from pumping and still did not provide true visibility
on valve positions. With about 1,700 valve operations on a typical job,
the mandated process could generate over 5 miles of foot traffic per day
and consume 20–30 hours by the end of the zipper frac job on a single
pad. Enerplus wanted to further reduce risk, expedite operations, and
minimize presence of personnel in the red zone.
