Offshore Drilling in Western Canada

Page 1 | 2

Foreword

Those who face danger daily in the frontiers may have every right to pooh-pooh the Great Slave Lake 1967-68 drilling program. Nevertheless, there were perils unique to this exercise that were to send shudders down the spines of those on the job. I am grateful to R.J. (Jim) Kirker of Canada Northwest Energy for his story and notes. Al Barlow, Roy Murray and John Gillard also supplied information.

The Rainbow 1965 oil discovery in a Devonian reef set off a second boom in the general area (Red Earth in 1956 had been the occasion of the first activity although it had been a Granite Wash find). Unlike Red Earth, the play moved to the northeast simply because the rocks which reservoir oil and gas outcrop along the shore of Great Slave Lake, These had been mapped many years before and their names were taken from topographical features along the shores of that lake (Pine Point, Slave Point, etc.). Early workers in the area also reported oil seeps on the north side of the lake.

This prompted J. Ray McDermott Canada to file on federal lands covering the western portion of the lake, knowing that there was little sedimentary section (the outcrop of the Canadian Shield was only a short distance away to the east). During the summer months of 1966, there had been some seismic shooting from a scow (owned by the Arctic Missionary Society). An early version of the air gun was the energy source and Raydist was used for location fixing. Records revealed a number of anomalies and it was decided to go ahead and evaluate these.

Permission was obtained from the Department of Indian and Northern Affairs and the Department of Fisheries in 1967 to drill out in the lake.

In late February a modified Failing 1500 owned by Roy Murray was moved in over an ice road. This track had been bulldozed the eleven miles from Hay River and had encountered only one pressure ridge. However, this was a fresh one and should have been a warning of dangers yet to come. The ice over this ridge broke again and required new planking to bridge it. On March 2, the pressure ridge started moving once more and the bridging had to be relocated.

The ice at the wellsite was 40 inches thick and all agreed that it was sufficient to support the weight of the rig. This was yet another miscalculation which later caused problems. The water depth was 80 feet. The lake bottom consisted of soft clay so it was possible to drive the seven-inch conductor pipe some 34 feet into the lake bottom. Surface casing (31/2 inch) was cemented with 19 sacks at 180 feet. A six-inch Cameron blowout presenter was installed. Two-inch drill pipe (no collars) was used with a BQ wire line core barrel to which was attached a 2 15/16-inch diamond bit.

Despite the fractured nature of the Slave Point limestones, core recovery was remarkably good. Murray remembers restoring lost circulation in the upper porous sections with Jel Plug, a mixture of aquajel and diesel fuel which set up like jelly. However, the deeper limestone turned out to be arterial, flowing warm sulphurous water. It overflowed the mud tanks and started to melt the ice. It was essential that fractures from which this water was flowing be squeeze-cemented, and quickly. There was some concerns that the sulphur water might cause an H2S hazard and for a while, masks were in popular use.

As drilling proceeded, the driller reported the chuck was resting on the surface casing, This meant that the weight of the rig and the plasticity of the ice caused it to sag despite its 40-inch thickness. The rig had to be jacked up and timbers were laid in to raise the drill.

At one stage, a fierce blizzard blew up and drilling had to be stopped. Murray recalls having the three-ton van with the lighting plant spotted half-way between the cook house and the rig and these three landmarks were linked with a nylon rope. This was the only way of being sure of not being blown away in the white-out. Murray's wife cooked for the nine to twelve people on the location.

[Next>>]