New platform will assist oil drilling

Press, 27 March 1980, Page 28

New platform will assist oil drilling

NZPA , - London The* Continental Oil Company is developing a ’ giant production platform for the North Sea that oilmen say will revolutionise offshore technology and pave the way to tapping oil from previously unreachable deep-sea fields. L , Unlike conventional production platforms, which stand on concrete and steel legs on the seabed, the United States firm’s 51,700-tonne tension leg platform (T.L.P.) floats and is anchored to the seabed by 23cm thick steel cables.

The most important factor is that it will be able to work in depths up to 600 m or 425 m deeper than conventional platforms. Experts say T.L.P, opens up vast new areas of the North Sea around the Shetlands and west of the Hebrides in the Atlantic Ocean where oilmen believe several hundred million tonnes of oil are located.

North Sea fields already discovered contain an estimated 1.5 thousand million tonnes to 2.6 thousand million tonnes, but another 1.8 . thousand million tonnes may be recoverable with the new technology, say industry exprtyd.

Potentially, the . increased producion could make Britain self-suf-ficient in oil until the end of the century. At present, North Sea output is expected to start declining about 1990.

Exxon, Shell, and Mobil also plan new recovery systems expected to start working in the next few years in the North Sea. British petroleum is working on two new systems, one similar to the Continental Oil Company’s called the tethered buoyant platform, and the single well offshore production system, or 5.W.0.P., which experts say is even more flexible, doing away with platforms altogether. S.W.O.P. is an all-in-one system — a converted tanker that plugs into an underwater well-head, pumps the oil, separates oil and gas in its own onboard processing plant, stores them on board, and then sails to the nearest

land terminal when its tanks are full. ' With North Sea oil selling at $3O a barrel, double the price of a year ago, the industry now hopes to exploit “marginal fields” those with reserves estimated at 50 million barrels- or less which had been passed over as uneconomic. The Mobil system is much the same, except it transfers recovered oil to

other tankers for trans* portation and continues pumping without interruption. It is designed to work in depths to 760 m. A factor hastening the development of these new systems is that oilmen underestimated the impact harsh North Sea conditions would have on rigs and platforms. Corrosion and stress have taken a greater toll than experts expected.