The Next Ten Years

By Dr Roger Knight, August 1996

With the Offshore Northern Seas exhibition taking place this August Infield Systems has used the Infield Database to see what is in store for Norway and the other countries on the North West European Continental Shelf over the next 10 years.

The first thing that can be said is that there can hardly have been a time when the region has generated such great and varied interest as the present.

So many trends and predictions, that seemed certainties a few years ago, are being confounded. Production rates in all national sectors are reaching new heights. Not only to satisfy the growing European demand for gas, but also in terms of oil and liquids production. All the trends are onwards and upwards. Ten years ago the belief that 'the best production figures were yet to come' would have been seriously questioned, but not today.

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.

The tables below show the numbers and lengths of different project types within each water depth range:-

Denmark:-

The Netherlands:-

Norway:-

UK:-

Rest of North West Europe:-

Gulf of Mexico:-