By A.E. Barroll*

Mobil Oil Canada, Ltd., has been active in the eastern Canadian offshore exploration drilling since 1967, principally in the vicinity of Sable Island and on the Eastern Grand Banks.

In the early 1970s, these exploration drilling activities led to involvement with the Canadian shipbuilding industry. We participated in the contractural arrangements for construction of the Sedco J semisubmersible in the Halifax Shipyards and for construction of three workboats in Vancouver. This equipment, and other rigs, were used in a jointly funded exploration program operated by Mobil over a span of 12 years. Now, this long program of exploratory and appraisal effort has come to fruition in both areas. We are currently operating three semisubmersible rigs, one jackup rig, and a fleet of nine workboats on the East Coast.

The objective of this paper is to tell you something of the operating problems caused by the physical environment in each area and to tell you how you may become involved in the solution of these problems.

Our gas discoveries have taken place in relatively shallow water in the vicinity of Sable Island.

If this production remains commercial under the onerous vicissitudes imposed by the National Energy Policy, preliminary studies indicate that it can be devel- *Mr. Barroll, vice president of Mobil Oil Canada, Ltd., is Exploration and Producing Manager with overall responsibility for Canadian exploration, land, and producing operations. He presented the paper condensed here before the recent technical session of the Annual Meeting of the Canadian Shipbuilding and Ship Repairing Association.

oped in a conventional manner: by that is meant that conventional steel platforms can be used as a base for drilling development wells, and in the conventional manner, the drilling equipment can be replaced by gas separation and dehydration facilities on completion of the drilling. The gas can be dehydrated on the platforms and the recombined gas and liquids pipelined to a processing plant on the mainland.

The shipbuilding industry will, in all probability, be interested in the construction of the templates, piling and deck sections that would go into the construction of a conventional steel offshore platform. However, this is a very specialized and competitive industry not normally undertaken in conventional shipyards.

The specialized McDermott yard on Bayou Boeuf at Morgan City, La., is a good example of the shipyard required. The templates require the extensive use of large cranes and specialized steel-forming facilities to fabricate tubular members from very heavy plate.

The deck sections are built under cover in a very large building.

For a platform designed for about 200 feet of water, the piling and t e m p l a t e s comprise some 3,000 tons of tubular members and the deck section would comprise approximately 1,000 tons of tubular and structural steel.

Drilling is continuing on the Scotian Shelf, and it is possible that industry might ultimately find reserves of such a configuration and magnitude as to justify the capital investment necessary to produce this specialized equipment in Canada.

Current evaluation of the potential demand for this type of platform does not suggest that a viable long-term industry specifically adapted to build this type of structure in Canada is indicated.

Perhaps it would make more sense for Canadian yards to consider construction of the deck section and assemblage of the processing facilities as a more e c o n o m i c a l l y r e w a r d i n g and adaptable endeavor.

The Grand Banks oil field has major significant differences in physical environment from the Sable Island area. There are no bergs or floe ice in the vicinity of Sable Island.

Recently, the iceberg Frances, which floated by the Nain Bank of Labrador, was somewhat over 1,000 feet long, about 200 feet above water, and about 350 feet in draft. This berg had a mass of about five million tons when it passed over the Grand Banks.

The periodic occurrence of such bergs on the Grand Banks makes consideration of conventional bottom- supported platforms such as are used in the North Sea dubious, at best. Obviously, a berg of this size has great kinetic energy.

We have been studying bottom- supported structures having the design potential of absorbing impact energy of this magnitude and we have not, as yet, been able to find a satisfactory engineering solution within anything approaching economic viability.

We are continuing to study the p o t e n t i a l for bottom-supported gravity platforms but as it currently stands, we anticipate difficulty in arriving at a design that is satisfactory in either an engineering or an economic sense.

We have been carrying on simultaneous studies investigating the use of floating production facilities.

Our reasoning is that, if we cannot design a structure which can withstand the tremendous destructive forces imposed by a large iceberg, we have no alternative except to consider using facilities which can be removed from the area when threatened by bergs or massive floe ice. We have considered two basic types of floating facilities — shipshape and semisubmersible. We have largely abandoned the shipshape concept because of problems relating to excessive motion in a seaway, high mooring loads, and the internal .stresses imposed on a very large moored vessel in the sea-state conditions which can obtain on the Grand Banks. We have, therefore, focused on the semisubmersible system as being the most practical.

We have not as yet selected a hull design. However, we do know that the vessels we will require will be over 400 feet in length and 270 feet in the beam, that they will have a draft of at least 80 feet and an air gap in excess of 50 feet. They will have an estimated weight of structural steel of about 18,000 tons and will have a displacement of about 53,000 tons with a deckload capacity of about 15,000 tons. They will have accommodations for over 100 people.

They will be self-propelled and be capable of surviving 115- foot waves and 100-knot winds.

The storage vessel, which has been considered, will be capable of staying on station and functioning in sea-states approaching those for which the semisubmersible production facilities are designed.

It also is designed in the semisubmersible mode. It is some 774 feet by 217 feet and has a designed load draft of 164 feet.

It has a displacement of about 400,000 tons. The vessel will be capable of disconnect and move out under its own propulsion if threatened by bergs. It will be e q u i p p e d with thrusters and equipment to moor and load shuttle tankers over the stern.

To meet the transportation requirements, d e d i c a t e d tankers s h u t t l i n g between the Grand Banks and East Coast ports would be approximately 80-feet long by 120 feet in the beam and draw about 40 feet loaded. They would have about 18,000 horsepower, single-screw propulsion, with bow and stern thrusters, double-hull construction and segregated ballast and cargo.

The floating production system would require workboats which would be ice-strengthened North Sea type boats: about 240 feet in length, 55 feet in the beam and drawing about 17 feet — deadweight of 1,650 tons, about 11,000 horsepower, twin-screw propulsion with bow and stern thrusters and anchor-handling capacity.

The foregoing summarizes estimated requirements for facilities which you may be called upon to consider — semisubmersible producing vessels, a storage and loading vessel, shuttle tankers and workboats. In addition to this, there will be other related facilities, such as subsea templates, which could be fabricated in shipyards.

We have had preliminary enquiries from several shipyards and some newly formed companies who would like to get into the rig-building business. We have received direction from several provincial government agencies and the federal government concerning the use of goods and services from local sources. We are entirely sympathetic with these objectives—but we also are aware that Canadian shipyards are fairly busy now, and that there are drilling c o n t r a c t o rs looking for additional yard space to build ships and semisubmersibles.

We think that potential requirements may overburden existing capacity. We would anticipate that some measure of cooperation within the industry is indicated, and that some of the new shipyards and smaller shipyards would be able to participate through subcontracting components.

The foregoing, in very broad terms, describes the directly related type of shipyard workload r e q u i r e d to d e v e l o p a Grand Banks oilfield and a Scotian Shelf gas field. There are many related types of fabrication activities in which shipyards can become involved.

The next question is when will the work be available. That is a good question. First of all, we have a jurisdictional problem that we are attempting to have settled — we want to know which government controls the offshore oil industry—to whom are we responsible for all aspects of our operations? Once this jurisdictional problem has been resolved, we can proceed with the appropriate approval process. Regardless of which government is confirmed in authority, the public hearings and extremely detailed analyses and reports to various government d e p a r t m e n t s and commissions are time consuming.

Particularly on the Grand Banks, we are extending known technology to accommodate the extremely difficult operating conditions, and this requires much careful and detailed engineering.

In common with the Canadian oil industry at large, we have other problems of a financial nature which also bear consideration and inevitably are part of the timing formula. The eightbillion- dollar Alsands project at A t h a b a s c a and the Esso Cold Lake project involving about the same capital i n v e s t m e n t have been deferred due to the inability to finance projects because of product pricing and fiscal uncertainties ; these uncertainties caused in turn by disagreements between federal and provincial governments.

This demand for billions of dollars of investment capital occurs at a time when governments are adopting policies which seriously limit the ability of the industry to generate capital. The federal government continues to price crude oil at less than 50 percent of world price. Under the cloak of the National Energy Policy, the federal government also has imposed the 8 percent Petroleum and Gas Revenue Tax. The tax calculation i n c l u d e s production royalties paid to provincial governments.

Let us hope that we will soon see the development of realistic fiscal and pricing policies which will enable us to proceed expeditiously with our task of developing Canada's offshore resources of oil and gas. Then, we will see an expanding strong Canadian shipbuilding industry.

Other stories from June 1981 issue


Maritime Reporter

First published in 1881 Maritime Reporter is the world's largest audited circulation publication serving the global maritime industry.