Page 100 - impiantistica_3_2015

Fig. 8 - FLNG FSC system about 18% of the overall losses. Based on this
criticalities – Top 5 information, operator will be able to reassess IMR
strategy in order to investigate if some components
Fig. 9 - FLNG equipment can be inspected or maintained in a shorter period
items criticalities of time or simultaneously with particularly long
repairs predicted by the RAM model.
Subsea equipment of field A represents also
about 18% of overall losses of the FLNG project.
As interventions on well equipment items can
be extremely long to be carried out because of
Mobile Offshore Drilling Units (Modu) mobilization,
operator will have to concentrate on the availability This transverse view allows the operator to give
of Modu near the field to optimize mobilization time. a priority for its IMR strategy. Detailed analysis
Operator will also assess as precisely as possible
the wells capacity to ensure main producing wells
will less be impacted or at least that production can associated with the type of mobilization (crew, ISV,
be maintained in a partial manner.
“Restarts”, that corresponds to the ramp-up
state when to installation has been completely
shut downed, contributes to 6% of overall losses.
A dedicated analysis has then been performed
to understand which equipment items were
responsible for the greatest number of restart
in order to investigate either a change in the
configuration, additional bypasses when possible
98 Impiantistica Italiana - Maggio-Giugno 2015
or a different repair or maintenance strategy to
reduce the repair time or restart time.
Most of the other systems were accounting for less
than 2% of the overall losses. It has been concluded
that any action performed on this remaining
systems will then only increase the availability of the
unit in a very limited way and often, for a very high
cost. By proceeding in a transverse analysis i.e.,
not by system but by type of equipment, the main
equipment items contributing the most to the loss
of availability were also analyzed (figure 9).
performed presented also many other outputs
such as the number of maintenance mobilization
Modu etc.) in order to provide a good basis for the
Operational Expenditure (Opex) allocations.
Similarly, annual production availability as well
as production capacity duration per range of
production capacity were presented in order to
provide Operator with an efficient decision tool
based on level of production capacities (time where
the unit produces between 0 to 0.25 mtpa, 0.25 to
0.5 mtpa, 0.5 to 0.75 etc.) and annual production
graphs impacted by extensive inspection scheme
or other periodic effects like cyclones. Annual
production allows also the operator to understand
the gravity of potential penalties that may be faced
in case they do not meet contractual requirements.
Conclusions
This paper presented the benefit of RAM analyses
for FLNG process optimisation, the detailed
methodology as well as an application of the
process. Even if very powerful and cost efficient,
the value of RAM is constrained by the lack of
available reliability data for such new installation and
by the ability to think ‘outside of the box’ to develop
worthwhile and value adding ‘what-if scenarios’. It
has been found that it is of the utmost important
to define clearly all the assumptions to be taken
into account and invest as much time as possible in
sensitivity cases to assess the different options but
also to valid successfully the design phases, not
only with the good design, but with the best one.
This paper was presented at the 12th Offshore
Mediterranean Conference and Exhibition in
Ravenna, Italy, March 25-27, 2015. It was
selected for presentation by OMC 2015
Programme Committee following review of
information contained in the abstract submitted
by the author(s). The Paper as presented
at OMC 2015 has not been reviewed by the
Programme Committee.