Is it necessary to install a downhole safety valve in a subsea ... - NTNU

Is it necessary to install a downhole safety valve in a subsea oil/gas well?
10 4 NO Riser pipes are not
present in the time of
11 5 OTHER
THAN
12 5 REVER
SE
operation
The riser pipes are not
connected; the roughneck
is screwing the pipe the
opposite direction.
The riser pipes are not
connected, they are
upside down
13 5 LESS Riser is not properly
connected to BOP
14 5 MORE Riser is screwed to tight
to the BOP
15 5 MORE Roughneck damages the
rise by holding to tight
16 5 PART
OF
The Riser pipe is
lowered, but in the wrong
position to be screwed on
17 6 LESS The riser flange
dimension is too narrow
to hang on drilling deck.
18 6 MORE The drilling deck does
not hold the weight of the
BOP.
Diploma thesis, NTNU 2002
Delayed operation Make sure riser pipes are
present
This may lead to a delay in
the operation and in worst
case dropping the BOP
Delayed operation and
possibility dropping the
BOP.
The riser is not screwed
properly to the BOP. The
BOP may fall down
Threads are damaged and
may not hold the BOP as
intended. BOP may fall
down
The riser may leak or be
damaged.
The riser is not connected to
the BOP
The riser and BOP will fall
down
The riser and BOP will fall
down
Check the programming of the
iron roughneck prior to
operation
Make sure the riser pipes are
stacked in the right direction
Use instruments to measure the
torque and position
Use instruments to measure the
torque and position
Make sure the riser pipe is
controlled before the pipe is
lowered
Use instruments to measure the
position
Control dimensions prior to
workover and use eye control
when operating
Check the drilling deck for
corrosion and wear
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