MARCH 3, 2015
The incident, which happened last March, involved workers
for Trinidad Drilling Ltd., who were contracted by Progress Energy to perform
drilling activities at a location about 200 kilometres north of Fort St. John.
Neither the OGC nor WorkSafeBC would say what the extent of
the man's injuries were, other than to say that he was taken to Fort St. John
Hospital, and it was non-fatal.
About 9,400 cubic metres of sweet natural gas leaked over
five days, but most was diverted to a flare stack, where it was burned off, and
the OGC said there were "no significant offsite or environmental
impacts" because of the leak.
The incident occurred northwest of Fort St. John, near the
Alaska Highway.
The crew had finished cementing the well, which is part of a
procedure to prevent leaks.
Workers had been told it would take six hours for the cement
to set. But apparently a change in the type of cement used at the site meant
that it would take 24 hours to set.
Around six hours later, the well was depressurized at the
surface. (The difference between the pressures on the surface and underground
allows gasses underground to rise to the surface.) The decision to depressurize
the well before the cement had set allowed a natural gas leak to develop, the
BC OGC said.
Around 12 hours after the cementing job was finished, the
crew discovered that the pipe was leaking gas.
It took this long, said Alan Clay, a spokesman for the BC
OGC, because "it took time for the natural gas to migrate to the surface
where it could be detected."
Then, the crew attached a hose, called a blowout prevention
stack, to depressurize the well and fix the problem.
The hose was not properly restrained, however, and it struck
and injured one of the workers.
A BC OGC investigation found that the on-site supervisors
did not do an adequate job of telling their workers about the change in the
cement setting time.
"It is the responsibility of the on-site supervisors to
ensure that changes to the nature of the job are reviewed with those employees
involved with the work and that a hazard assessment is carried out beforehand
and built into the work plan."
The last time the OGC issued a safety advisory was in 2013.
Stacie Dley, a Progress spokesperson, said they are still
concluding the matter with the OGC.
The injured worker has "recovered and is back at
work."
"Worker safety is paramount" she said. "We
learn from all incidents that may occur in our operations and thoughtfully
implement necessary mitigation measures to ensure the safety of workers, the
environment and the communities."
Questions directed to Trinidad asking for comment were not
returned as of press time.
The well was "sweet," meaning that it did not
contain poisonous hydrogen sulphide, which can be found in some natural gas
fracking operations.
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BC OIL & GAS COMMISSION ISSUES ADVISORY FOLLOWING
INCIDENT INVESTIGATION
FEBRUARY 17, 2015
The BC Oil and Gas Commission (Commission) is reminding
operators Division 2 of the Drilling
and Production
Regulation contains regulatory requirements related to well control
equipment, procedures, training and competency. Permit holders must ensure that
reliably operating well control equipment is installed at all times and that site
personnel have adequate training and competency to safely carry out well operations.
This follows an investigation into a March 2014 incident where
approximately 9,400 cubic metres of sweet natural gas leaked from a well over
five days, most of which was diverted to a flare stack before the leak was
successfully repaired. The incident occurred following cementing operations on
a natural gas well targeting the Montney formation. Drilling operations were
complete, and production casing was installed in the well and cemented with nitrogen
foam cement. The well is located in a remote area approximately 200 kilometres
north of Fort St. John and there were no significant offsite or environmental impacts.
Approximately two-and-a-half hours after cementing was complete,
the rig crew proceeded to partially unbolt the flange that secures the BOP (blowout
prevention) stack to the well. Approximately three-and- a-half hours later, the
well was de-pressurized at surface. Approximately 12 hours after cementing was complete,
the well was found to be leaking gas. A hose was attached to the BOP stack in an
attempt to de-pressurize the well and allow the leak to be repaired. The hose was
not properly restrained when flow was diverted, and one worker was injured.
Medical aid was provided at the scene and at the Fort St. John hospital.
The planned cement job included the pumping of nitrogen foam
cement with a “cap” cement. The cap cement is a rapid-setting cement capable of
providing pressure containment at surface while the foam cement cures. On
arrival at the site, it was determined the cementing company did not have
sufficient additives for the cap cement, so the decision was made to only pump
the foam cement. Due to the job scope change, the cement setting time increased
from six hours to 24 hours.
Key findings of the investigation are as follows:
·
Removal of some of the BOP flange bolts while
the well was pressurized allowed a leak path to develop. The bolts were removed prior to cement setting
time elapsing.
·
Depressurizing the well prior to the cement setting
time elapsing compromised the cement integrity, allowing a natural gas leak to
develop.
·
The cementing job scope change was not
adequately communicated to on-site personnel.
·
Adequate assessment and control of hazards were
not completed during initial attempts to control the natural gas leak.
