Advances
in technology have been made in many areas from improved seismic
techniques to horizontal drilling in thin or poor reservoir rocks
enabling exploration and production costs to be kept down to maintain
viability in a stringent financial climate. This has resulted in
more reserves being found and more of these reserves being accessible
to economic recovery.
The
revenue generated from existing production can be invested, ever
more effectively, in future production. That there is no shortage
of opportunities the accompanying Table 1 clearly shows.
A grand
total of 366 fields in all sectors of NWECS await potential development
in the next ten years. They hold an estimated 4,788 million tonnes
of oil equivalent of recoverable reserves, and will require 232
platforms and 1,107 subsea completions to fully develop them. In
addition 15,849 kilometres of pipelines, of all diameters, and 3,289
km of control lines will be needed to service these developments.
The Table separates the various national sectors, by water depth,
showing clearly the levels of interest per 50 metres of water depth.
Norwegian waters have the greatest potential for deep-water production
with about half of all reserves lying in waters of greater than
300 metres. On the UK. sector deep-water developments are going
to be of increasing importance west of Shetland, but the strength
of the offshore market will still lie in shallower water depths
than those pertaining in Norwegian waters. One other interesting
difference between the two sectors is that on the UKCS satellite
subsea trees tied back by short jumper pipes to manifolds are the
most popular development option. Whereas in Norwegian waters small
standardised, HOST, 4 well templates, with the wellhead trees actually
on the template/manifold are the most popular subsea development
choice.
Details
of all these up and coming projects can be found on the INFIELD
Database, which also contains information on all existing fields
and facilities, both in the North Sea and in the rest of the world.
And
the next ten years in the Gulf of Mexico
Turning to the rest of the world the U.S. sector of the Gulf of
Mexico has long been viewed as the most mature of all the world's
offshore oil and gas producing provinces, but the recent advances
in exploration techniques and production technologies have led to
a major rejuvenation. This is based almost entirely on deep water
finds off the continental shelf.
The
accompanying Table 2 shows the distribution of fields and reserves
by depth range. The continental shelf generally extends to about
200 metres of water depth. This is equivalent to a depth of about
656 feet of sea water. Fixed piled platforms are the dominant development
option for the slightly less than 50% of the fields awaiting production
on the shelf. Beyond this point, on the continental slope, platform
based developments swiftly lose their economic viability compared
with subsea based systems, doubling in price very quickly with increasing
water depth.
A staggering
87% of the reserves awaiting future development are lying in water
depths in excess of 200 metres. In the past accessibility has been
the main draw back to initiating production here, but two recent
projects have made major advances in the lengths that subsea wells
can be controlled from host platforms. These are both SOI operated
fields. At present Popeye is controlled by a 38.1km umbilical from
its shallower water host platform and shortly Stolt Comex Seaway
is to lay umbilicals in excess of 100km to connect a manifold on
Mensa field in 1,650 msw to a host platform in the West Delta area.
The
challenges faced by platform designers for deep water production
facilities have been answered in several ways mostly in terms of
a permanently anchored, but floating unit of some kind; either a
semi-submersible, TLP or SPAR. Two of the latter are now at the
construction stage. |
