What happened: Crew was conducting routine slick line operations' The objective was to determine tub

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Shell EPW Wells HSE Early Learning Bulletin
Fountain No 131031 Location West Cameron
565 Date 05/02/2007 Risk Ranking
Actual Level 1 Environmental, Potential
D2 People D-1 Environmental
What happened Crew was conducting routine slick
line operations. The objective was to determine
tubing integrity. This well has been out of
commission gt 5 years. Well is not hooked up to
any flow line, and SCSSV was not hooked up to
safety shut down system. SCSSV in the closed
position is a TA barrier and as part of the TA
process is not hooked up to any automated
controls to prevent an accidental opening of the
SCSSV. The only means of operation of the SCSSV
is by stand-alone hydraulic pump. The initial
tubing pressure was 200 psi, shut in casing
pressure was 0 psi. Crew surveyed wellhead to
determine if tree valves were functional and to
verify valve position. Main Valves (Master
Swab) OK. Some of the wing valves were frozen and
had limited movement. The conclusion was the
valves must be in the closed position because the
flow lines were disconnected and blind flanges
had been installed. The crew rigged up the slick
line equipment. Tested lubricator against the
swab valve (top valve on the tree) to 1250 psi.
(Note this pressure was not applied to the wing
valve). Bleed down to 500 psi. opened swab
valve (at this time the whole tree was being
tested to 500 psi) no flow from any wing valve
on tree. All indications pointed to wing valves
in closed position. Opened well, pressure dropped
to 300 psi. (still no flow out of the wing
valve). Production operator pressured up SCSSV
control line to 5000 psi with a manually operated
hydraulic pump to open up SCSSV. The lease
operator was manning the hydraulic pump during
entire slick line operations. Wireline Operator
ran in hole and tagged the SCSSV indicating that
the SCSSV had not opened. Picked up on tools.
SCSSV control line pressure was at 4000 psi so
the Lease Operator pressured up SCSSV control
line to 5200 psi in order open the SCSSV. Set
down tools and tagged SCSSV again. It appears
that the SCSSV valve opened when the tools tagged
the SCSSV. The crew heard gas escaping from a 1/2
inch connection at the wing valve. The lease
operator immediately released the pressure from
the SCSSV control line, closing the SCSSV.
Response at the wing valve indicated the SCSSV
had closed, gas immediately started to slow down.
Two ESD stations were immediately activated,
shutting down the platform. Muster initiated for
POB count, 6 POB on platform. The wireline
operator began picking up on the tool string as
soon as he noticed the loss of weight on the
indicator. The wire line operator was able to
bring the tools to the surface. After closing
the SCSSV and activating the ESDs the Lease
Operator went to the wellhead and closed the
master valve and swab valve. All personnel
mustered at the designated muster station. There
were no injuries and no environmental impact
except for a gas release for approx. 1.5 minutes
though the 1/2" NPT connection at the wing
valve.      

• Preliminary Learning Points
• Well Services procedures will provide more
  details on equalizing across SCSSV and testing
  the wellhead for integrity.
• Site assessment to ensure proper tree valve
  operation and assure valves have proper double
  block and bleed before well services will
  commence operations.
• Amended wireline work plan to include learnings
  from this incident and stored in the Well
  Services group folder for future projects.

The blind flange with the needle shown in this
picture was installed after the incident.
Initially there was a blind flange in place with
a hole in the center and no needle valve.
This Learning Bulletin provides preliminary
learnings. A detailed investigation is pending.
Shell EPW.