Fracturing earth below | Hydraulic fracturing is used to retrieve oil and gas reserves trapped in sandstone and shale
Roberto Aguilera wants his students to get out of the lab and see first hand how the industry works.
Education about the industry is needed, said Aguilera, a fracturing engineer who spent decades in the oil fields before becoming Conoco Phillips chair in tight gas engineering in the University of Calgary’s Schulich School of Engineering.
“Part of the problem is we have not done a good job educating the people about these issues,” he said.
“The way I see it as a citizen is that we have to reach an equilibrium between the needs we have for energy and the risk we are taking with some of these things.… I am not saying it does not exist, but based on the science we are examining in my research lab, it is limited.”
Much of his work develops models to study fracturing as well as the growth of vertical and lateral fractures under the Earth’s surface.
Public concerns over the effects on ground water have become an international issue.
There is a two-year moratorium on fracking in Quebec to address public concerns and develop regulations.
However, Aguilera said Alberta has decades of experience in exploration and drilling with sound rules and clear regulations.
“In some of the areas where I see some problems, it is lack of clear regulations. That is a blessing we have here.”
A major concern is the impact on ground water, but wells may be fractured at depths of 7,000, 12,000 or 14,000 feet.
“Based on what we see, strictly from a scientific point of view, we see the possibilities of these fractures reaching ground water are very limited,” he said.
Groundwater is also protected with a casing that is cemented in place.
“If the construction of the well is done properly, and there is a lot of experience in the industry doing this, then the only possibility for the contamination will be actually if the fracture grows vertically and reaches the ground water,” he said.
After examining thousands of fracks and looking at formations that were hydraulically fractured, Aguilera found that the fractures did not grow high enough to reach the ground water.
“We don’t see that happening,” he said.
The fractures are narrow and are often less than a millimetre wide. The gas molecules are also small, so they do not need a large crack through which to flow. The fracture will close when the work is done.
Hydraulic fracturing is the only way to retrieve the resource because many oil and gas reserves are trapped in rock such as sandstone and shale.
“These formations are very tight and permeability is very low,” he said.
“The only way you will be able to get any kind of commercial production from there is if you fracture.”
In the case of shale gas, the natural gas was generated in the shale and remained there. The shale is the source rock and the reservoir rock.
In the case of unconventional gas, it migrated into the tight formation from where it was generated.
“Hydrocarbons are moving until they get trapped,” he said. “Sometimes it doesn’t get trapped and sometimes naturally the oil reaches the surface, and you have a seepage.”
This has nothing to do with fracking.
Aguilera said the subject of earthquakes following fracturing is also under investigation, but the Earth is always moving.
“It is Mother Nature in action. The Earth is never quiet. It is always pulsating, and this is being measured continuously with different devices. It is unlikely this fracturing it is going to produce any major problems.”
The Alberta Geological Survey launched a large study in 2009 to understand the province’s seismicity. The first step was to set up seismic stations with the universities to monitor ground disturbance throughout the province.
“It is important to know what is normal before you can say what is abnormal or what might be of interest to people who say, ‘what is that causing that,’ ” said seismologist Virginia Stern from the survey.
The federal government has monitored earthquakes since the 1920s and set up seismic stations at Leduc, Alta., Suffield, Alta., and southeastern British Columbia in the 1960s.
More stations were added 20 years ago, and in 2010 the geological survey group and the University of Calgary added new stations at Grande Prairie, Manning, High Level, Fort Smith, Raymond, Priddis and Medicine Hat. These provide close to real time information.
The University of Alberta installed a network in the central part of the province in 2005, but the data is collected only twice a year.
The information will be merged so that researchers can study the seismicity patterns throughout Alberta.
B.C. and California have high seismicity, but activity in Alberta is barely discernible. However, that doesn’t mean the Earth is not moving.
“In Alberta, since they have been recording earthquakes, there have only been somewhere between 700 and 800 earthquakes. Most of these have not even been felt,” Stern said.
The information gathered in this study will be useful to the Energy Resources Conservation Board, which regulates the oil industry in Alberta, to determine what is normal or elevated activity in an area.
Stern said she is not in a position to judge whether fracking is responsible for earth tremors, but added the stimulations are far below anything that could be felt.
“I think what people are concerned with is if it induces natural events on faults that are nearby,” she said.
“Those would be positive. It isn’t the fracking that they are worried about. It is what may occur during the fracking process.”
Stern wants more stations to continue monitoring what is going on.