How it works
Horizontal drilling
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It might sound strange that oil and gas resources found thousands of metres below our feet could be reached by “horizontal” drilling. But the technique has become one of the most valuable technologies ever introduced in the Canadian oilpatch.
HOW DOES IT WORK? Horizontal drilling starts with a vertical well. The drill bit bores through layers of rock until it reaches the “kick-off point” — the start of an arc that levels off the well’s trajectory — whereupon it continues horizontally.
The horizontal “leg” of a well can be thousands of metres long, and sophisticated navigation instruments allow drillers on the surface to expertly guide the drill bit as it creates the well.
The first advantage that a horizontal well has over a vertical one is that the well can penetrate a long way through a layer of rock that contains oil or gas. This allows the well to drain more of the resource.
For instance, a vertical well might produce 100 barrels per day from a well that goes straight through a 50-metre thick layer of oil-bearing rock. If the well is drilled horizontally through that oil-bearing layer, and extends out 1,500 metres, then the production per day may go up to 1,000 barrels. So this allows more oil and natural gas to be produced with fewer wells and less surface disturbance.
The second advantage relates to the way in which fractures form in the rock. Because they are vertical, a vertical well won’t hit very many of them, and since these fractures provide an easy flow of oil and gas to a well, then the well will not show very much production.
If the well is horizontal, however, then it will intersect many of these natural fractures and allow the rock to be more easily drained of its valuable resources.
The Canadian oilpatch is drilling more and more of its wells horizontally.
Horizontal wells, used in combination with multistage fraccing, which artificially creates fractures in the rock, have opened up new plays across Western Canada and allowed producers to revisit older fields that were uneconomic to produce using vertical wells.
The Canadian oilpatch saw a spectacular rise in horizontal drilling in 2010, with a record of about 6,700 horizontal wells licensed for the year, compared to the previous record of 4,019 permits in 2008.
