Investigation into the January 30, 2014 Loss of Well Control,
Lease OCS-G 17921,
Vermilion Block
356, Well A-007
Gulf of Mexico Region,
Off the Louisiana Coast
On January 30, 2014, at approximately 8:30 a.m., the
Rowan Louisiana crew,
drilling for Energy Ventures,
LLC, had
13-3/8 inch conductor casing set
at 1,217’ measured depth (MD) and 1,200’ true vertical depth
(TVD) and had drilled the well to 2,217’MD/1,935’TVD.
The
crew started a method known as a “short trip” where the drill pipe is moved in and out of the wellbore in order to gauge
whether a hole is clean
and/or the mud weight is
sufficient.
When pulling the bottom hole assembly (BHA) into the casing shoe, the driller noticed a 30,000 (30K) pound over-pull followed
by
a 10 barrel (bbl) increase in
the rig’s trip tank.
The crew
stopped the short trip, checked
for flow (static), made up
the top drive to the drill
string, and began circulating fluid when
the well started to flow resulting
in a loss of well
control.
The driller
responded by closing the rig’s
diverter annular which
automatically opened the diverter valve allowing water
and gas out of both diverter lines and
away from the rig.
The Offshore
Installation Manager (OIM),
in consultation
with the company representative,
ordered the adjacent platform shut in and all personnel
evacuated from the rig.
The well flowed from the port side diverter
line for approximately 36 hours until the
flow was killed using a “dynamic kill procedure”.
The Bureau
of Safety and Environmental
Enforcement Gulf of Mexico
Regional Director appointed an Investigation Panel for the purpose of
determining the possible cause(s) of the Loss of Well Control, determining regulatory findings (if
any), and to make recommendations (if appropriate) on how to strengthen implementation of
existing Safety and Environmental Management Systems
(SEMS).
The
Panel reviewed requested
documents, conducted
interviews, and met several times
to discuss all facts relevant to the
incident.
The BSEE Investigation
Panel determined that, during the short trip, the BHA was being pulled up through
the 13-3/8 inch casing.
As the first stabilizer was pulled into the shoe,
it got caught up in a clay build-up
within the formation, or “Gumbo”, which
caused a 30K pound over-pull and reduction in wellbore pressure due to a “swabbing effect”.
The driller
tried to circulate the fluids but the reduced wellbore
pressure allowed gas and water to flow up through the casing
string to the surface.
The Driller, following the pre-approved procedures, closed
the diverter annular and opened
the overboard diverter lines.
Conclusions
Cause
of Loss of Well Control
The Investigation
Panel has concluded that the immediate direct cause of the loss of well control
was due to the
following events:
I.
Drilling into a shallow
gas, “high risk”, environment. Pursuant to geologic review as a part
of the Application for Permit to Drill a New Well, there
were indications of the existence of shallow gas at
1,309 feet and 2,069 feet TVD.
II.
While conducting a short trip operation within the “high risk” zone, the BHA was
pulled into the shoe casing where it is believed a combination of clay and
drilling mud had built up to form
a “Gumbo Ball,”
which is supported
by the 30K pounds of overpull
during the two attempts to pull
out of hole with positive mud returns. This resulted
in the lowering of bottom hole
pressure below that of the formation pore pressure to a point where the well was capable
of flowing, created
by
the “swabbing effect”.
Possible
Contributing Cause of Loss of Well
Control
In addition
to the immediate cause, this Investigation Panel
has identified the following possible contributing causes to the loss of well
control incident:
1)
A Morning
Report for the Rowan Louisiana recorded that on January 30, 2014 between 0630-hours to 0830-hours, the rig
crew connected to the TDS and began Pumping
at 500 gallons per minute
after twice attempting to pull the BHA through the casing shoe with 30K pounds of overpull, and receiving returns
totalling 11 bbls.
It is the conclusion
of the Investigation Panel that a possible
contributing cause may have been
the failure to have the TDS
made up and circulation started prior to, and
during the “short trip” operation.
Recommendations
The Investigation
Panel submits the following recommendations
for EnVen and Rowan Companies:
·
When conducting “short trip” operations with
the knowledge
of shallow gas zones, if and when the
BHA is required to be pulled through
the casing shoe, make up
the TDS and start pumping prior to pulling into the shoe to eliminate the risk of swabbing.
Also, consideration should
be given
to “pumping out” when
pulling the BHA out of the hole.
·
Improve
communications to ensure
all relevant crewmembers are made
aware of shallow
gas hazards and any guidance
to mitigate the hazards.
·
Limit drilling penetration rates,
ROP, while drilling into zones with potential shallow gas to reduce
build-up of cuttings and drilling mud,
“Gumbo.”
Recommendations for BSEE
·
When reviewing
Applications for Permit to Drill, the BSEE may consider requesting more detailed
shallow hazard mitigation procedures for those applications that involve drilling
into an area with
previously known shallow hazard incidents.
·
The Investigation
Panel recommends the BSEE Lake Charles District Office review the Panel Report in detail and considers any appropriate regulatory violation(s). If regulatory violation(s) are found,
the District Office should issue an Incident
of Non-Compliance(s) to EnVen
or Rowan Company Inc. with any authorities
supported by specific findings and
bullet the individual items accordingly.
Safety and Environmental Management Systems
The Investigation Panel recommends EnVen and Rowan Companies
consider the following relevant to their SEMS Program:
·
Hazard Analysis
Review
and strengthen the levels of hazards analysis, hazard mitigation
and
JSAs that are developed and implemented for the
specific drilling environment,
shallow gas, operations with the
existing or potential safety, health and environmental hazards associated
with each step; and the recommended action(s) and/or procedure(s) that will
eliminate or reduce these hazards, the risk of a workplace injury or illness, or environmental impacts.
·
Operating Procedure
Review and improve written drilling operation procedures that provide instructions for conducting safe and
environmentally sound activities and work practices
for identified hazards
during operations and the degree of hazard present.
·
Safe
Work Practices
Improve
communications to ensure all relevant personnel
involved in the specific drilling operations
are made aware of any known potential hazards, such as the potential for drilling
into shallow gas zones, and any guidance to mitigate
the hazards.
