Many opportunities are lost through not assessing all the work that
has to be done in the mob/demob to/from a well.
Often marine dept is in control of ops until rig moored up, then
drilling takes over and visa versa. However this is far from optimal.
Best examples of optimal execution of this is the Sedco 601, SBOP
operations mob/demob in SE Asia.
Here in water depths up to 2000m, pre-lay systems are installed off-
line, rig moves on location 'deep drafted', installs pre-lay and
spuds within 18-24hrs. At end of well as soon as riser is cut from
seabed, while laying out SBOP and riser, pre-lay anchors are bouyed
off simultaneously and rig is on its way in less than 18-24hrs.
(Saving up to $1Mm dollars per well.)
In Norway I have supervised wells where MODU will start deballasting
immediately once on location, i.e. while anchors are being run. This
gets rig to work quicker, get ROV in for a 'wet check' where this
whole accelerated 'through critical draft' process delivers several
benefits. (That will save $350-$600K mob/demob costs per well.)
For short moves e.g. up to 50NM, a deep draft tow (@2-3knots)will
deliver cost savings and operational benefits. We have executed two
such moves in N.SEa, 2005 alone.