During 1979, the offshore drilling industry had a remarkable increase in activity off Canada's east coast. As drilling operations proceeded further offshore and into greater water depths, the need to provide site specific weather forecasting support became an integral part of the operation. This paper describes the system that Esso Resources Canada Limited utilized during their 1979 drilling operation off the east coast of Canada to provide site specific weather forecasts to their drilling locations. The operation of land based and buoy mounted weather sensors used to augment the weather forecasting system is also described. The intricate communications network required to make the weather forecasting systei.1 a functional entity will be described. The overall effectiveness and reliability of the weather forecasting operations during the 1979 season are discussed.
In 1979, Esso Resources conducted an exploratory drilling program in two distinct regions off Canada's east coast (Figure 1). The first well was located 440 km due east of St. John's, Newfoundland in an area known as the Flemish Pass. The well was situated in 1100 m of water. Helicopter support to the offshore site was provided from St. John's. Drilling began in late April and was suspended in late June. The exploratory drilling program then moved into the Davis Strait region between Baffin Island and Greenland. Esso's second exploratory well was situated approximately 275 km east of the southern tip of Baffin Island in 1000 m of water. Esso maintained a helicopter base at. Brevoort Island for this drilling program. The drilling of this well began in early July and was completed by the end of September which is within the ice free period for this region – July to November. At that point, the Esso operation again roved Loco the Flemish Pass to complete the previously suspended well.
The drilling of these two wells was conducted using a dynamically positioned semi-submersible drilling vessel Sedco 709 (Figure 2). The semi-submersible drilling vessel has been designed to continue drilling operations in extremely severe weather and sea state conditions as outlined in Table 1.
By using a semi-submersible, the operations are much less weather and sea-state sensitive compared to ship-shape drilling: vessels. However, (Figure 3) some extreme weather events nay occur during the drilling season of which the rig personnel should be aware of be forehand.
During the planning and scheduling stages of the support operations for the east coast drilling program, it became evident that of the two operating areas (Flemish Pass and Davis Strait), only the Flemish Pass possessed a very detailed data base of environmental conditions. For the Davis Strait, shipping reports of weather and sea state data were very limited due to light traffic in this region. Although other offshore drillinghad taken place off Greenland and Labrador, these wells were drilled in shallower waters and closer to shore.
Wind and sea state forecasts are required for all phases of the offshore operation.