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Canadians Consider Compressed Gas Carried by Ships at Sea

June 28, 1999
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Canadians Consider Compressed Gas Carried by Ships at Sea

With a strong push from the leading producer offshore of Canada's East Coast, an intense development effort is under way on a new marine technology intended to tap natural gas on the Grand Banks of Newfoundland sooner than anyone now thinks possible. Andrew Adams, vice-president in charge of Mobil Oil Canada's Newfoundland exploration and production business unit, told an industry conference in St. John's the technique "looks like it has great potential."

The method, invented by the Calgary engineering firm of Cran & Stenning Technology Inc., adapts the methods of high-volume container shipping to transporting CNG or compressed natural gas by sea. The new element is a container called the Coselle, which is short for coiled and carousel. Each container is a coil of small-diameter pipe. The engineers calculate 3.09 MMcf of gas can be carried at a pressure of 3,000 pounds per square inch in nine miles of 6.6-inch-diameter pipe wound into a single Coselle container 50 feet across and 11 feet tall.

The concept has advanced as far as designs for an 800-foot, 60,000-ton vessel that would transport 330 MMcf of gas in 108 Coselles arranged in 18 stacks of 10. The idea is especially aimed at fetching "associated gas" from oil production platforms. The design includes handling raw gas to be loaded after a minimum of processing to remove water and corrosive hydrogen-sulphide.

In St. John's, the engineers tantalized Atlantic Canada's budding oil and gas industry with a portrait of the new system as an easy alternative to long pipelines. The inventors project a US$1.40 per MMBtu toll for a fleet of seven Coselle carriers to transport gas continuously to Boston 1,100 miles from the Jeanne d'Arc Basin on the Grand Banks, where the Hibernia project has been producing since November of 1977 and at least three more offshore platforms are advancing towards construction.

That rate is competitive with the cost of reaching Boston via the Maritimes & Northeast Pipeline, now under construction simultaneously with the Sable Offshore Energy Project. Mobil Canada, which has been drilling offshore of Atlantic Canada since 1943, is the senior partner in both Hibernia and SOEP.

The C$5.8-billion (US$4-billion), 150,000 b/d Hibernia platform taps 3.5 Tcf of gas but has to re-inject it. While SOEP taps a region offshore of Nova Scotia estimated to harbor 18 Tcf of gas, Canadian authorities project the more remote regions farther north around Newfoundland have 33 Tcf or more.

The eastern Canadian gas endowment prompted Tatham Offshore Inc. of Houston to step forward in late 1997 with a US$3-billion proposal for a 1,330-mile subsea pipeline grid linking New England and Canadian markets with Newfoundland and Nova Scotia gas.

The Tatham proposal was shelved following Canadian approval of MNE, but hopes of tapping East Coast gas did not fall dormant with it. Mobil Canada is one of six companies that have signed up for a joint industry project to do further work on the Coselle system. BG International (formerly British Gas) has also revealed it is participating in the group. Other partners remain undisclosed, although industry sources in Calgary say keen interest is being shown by an inner circle of planners from the producer-marketer community that founded Alliance Pipeline Project.

The technology's developers say Coselle CNG technology has at least the potential to be the lowest-cost delivery system in cases where production and markets are less than 2,500 miles apart. The system is billed as overcoming processing costs and safety issues associated with liquefied natural gas and subsea pipelines - especially offshore of Atlantic Canada, where the industry has to contend with annual iceberg migrations. In Mobil's view, the Coselle plan "is an excellent example of the kind of innovative thinking that's helping to move development of Newfoundland natural gas resources closer to reality," Adams said.

Gordon Jaremko, Calgary

©Copyright 1999 Intelligence Press, Inc. All rights reserved. The preceding news report may not be republished or redistributed in whole or in part without prior written consent of Intelligence Press, Inc.

ISSN © 2577-9877 | ISSN © 1532-1266
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