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EXXONMOBIL PROPRIETARY
Jotun Gas Pipeline Leak - August 20, 2004
OLF Presentation to PSA December 9
1
7/7/2015
Esso Norge AS
An ExxonMobil Subsidiary
EXXONMOBIL PROPRIETARY
Incident Description
The Jotun gas export pipeline ties into the Statpipe system via a manifold and hot tap, which is
located on the Gassco-operated Statpipe gas export pipeline system between Heimdal and Draupner
(155 km section). The pipeline was installed in January 1999 as part of the Jotun Project. The
majority of the pipeline was trenched and back-filled, with an approximately 100m section near the
tie-in manifold being covered in rock. Within the rock covered area, a 2m section of pipe and 6”
flange were not covered.
On Friday 20th August, just before noon, the Jotun 6" gas export pipeline experienced a sudden drop
in pressure. Upon verifying that the pressure drop was likely due to a leak, the Jotun gas export
pipeline was shut in. After notifying Gassco, the Statpipe system was shut in shortly thereafter.
Statpipe depressurization continued throughout the subsequent 1.5 days to approximately 91barg
(normal operating pressure approx. 140barg) via Draupner, along with continuous leakage through
the failed Jotun pipeline.
Isolation of 6" valves on the subsea Jotun Tie-In manifold were closed by ROV in the morning of
August 22nd, isolating the Statpipe from the leak point. Leak stopped and Statpipe went back to
normal operation.
2
7/7/2015
Esso Norge AS
An ExxonMobil Subsidiary
EXXONMOBIL PROPRIETARY
Overview
PIPELINE TIE-INS
Rockwater/EMC
HOT TAP
SRJV
Installed 04/99
diver-assisted installation of 16” and 6” closing
spoolpieces from DSV Bar Protector
Completed 10/98
16” tie-in inlet with protection
structure
GAS EXPORT PIPELINE
ETPM
Installed 01/99
6” carbon steel pipeline with actuated ball
valves for SSIV
GAS EXPORT MANIFOLD
Rockwater
Pipe fractured
at bend
Installed 03/99
16” header for future tie-ins, 6” piping
with temporary subsea pig trap for
Jotun gas export
6” flange where pipe
fractured at flange neck
ROCK DUMPING
Rockwater subcontractor Van Oord ACZ
Installed 06/99
Rock dump cover (approx 1.5m) covering the spool piece and
approx. 100m of the pipeline.
Rock dump area marked red. Rest of
6” pipeline trenched and back-filled
3
7/7/2015
Esso Norge AS
An ExxonMobil Subsidiary