by Matt Duguid
With more than 50 years of exploration, oil companies have a much better understanding of what is underneath Saskatchewan today. It was not always this way.
Major commercial development of oil did not start in Saskatchewan until the early 1950s. In the beginning, finding oil in the province required a good deal of luck. With little information on the province’s oil and gas reserves, oil companies would simply pick a location they thought might have oil and drill a “wildcat” or exploratory well.
If they struck oil, the well would begin production and if they did not they moved on to try again. Many did strike oil though and the industry has now become a major sector in the Saskatchewan economy, paying $1.7 billion in oil and gas royalties to the province in 2012. Saskatchewan is the nation’s second largest producer of oil, behind Alberta, and sixth largest producer among American states and Canadian provinces.
Oil is found in two broad locations in Saskatchewan- in the southeast near Weyburn and Estevan, and also along the western edge of the province from Lloydminster, through Kindersley and Kerrobert, and down to Swift Current.
A few things are key to the areas where oil is found. First there needs to be a source rock- a rock which is rich in organic material that eventually breaks down and forms petroleum. Secondly there needs to be a trap, a zone underground that stops the low density petroleum from migrating to the surface, for instance some folding in the layers of the earth that creates a high spot. Thirdly a cap rock is needed. The cap rock is a layer that has low permeability, stopping the oil from migrating upwards to the surface.
Today companies find oil by examining years’ worth of core samples taken from previously drilled wells, as well as information gained from seismic sensing. In seismic sensing waves are sent into the the earth and reflect back towards measurement equipment, revealing the makeup of the rock below the surface. Seismic sensing cannot predict the location of oil for sure but it can reveal whether a trap exists, necessary for the formation of oil deposits.
If a trap is found, a drilling rig is brought in. Rigs drill anywhere from several hundred to a few thousand metres underground to reach oil. New technology has changed the way many wells in Saskatchewan are drilled, moving from vertical to horizontal drilling and incorporating hydraulic fracturing or “fracking”. Horizontal drilling is used to access more pockets of oil, allowing the well to be able to draw from multiple pockets of oil.
One of the most difficult parts in horizontal drilling is the “build”, where the vertical well is curved to the horizontal, said Kyle Weir, a wellsite geologist with Coyote Consulting.
“Sometimes you have to hit a half metre zone that is a kilometre and half underground. If you go too low in some cases you end up drilling a water well instead because there is an oil and water contact, with the oil floating on the water,” Weir said.
Following the drilling of a horizontal well, it is often fracked. Water, combined with sand and chemicals to create fracking fluid, is pumped under high pressure into the well. The pressure turns cracks in the surrounding rock into fissures, allowing more oil to reach the well bore, increasing productivity.
“This is the only way it is economically feasible in some areas; if (the rock layer) is not porous they have to bust it open,” Weir said.
Once the well is fracked a service rig is brought in to install a pump jack, used for sucking oil out of the well. Above ground the pump jack performs a rhythmic dance, levering up and down in perfect time. The actions serve one purpose - below ground a rod is lifted up and down, driving a set of ball valves at the bottom of the hole. These valves then pump oil to the surface.
Once the oil is out of the ground, it is either stored locally near the well site or plumbed directly into a pipeline. The large black steel tanks that dot the prairie in oil bearing regions, used to store crude, are known as batteries.
The oil is then shipped to refineries where the raw crude is turned into several different products.
