Truck Mounted Screening Technology Speeds Up Methane Monitoring
With the introduction of new federal and provincial methane regulations, rapid and cost efficient monitoring of fugitive emissions will be more critical than ever before for the upstream oil and gas industry.
A new technology developed by researchers in the FluxLab at St. Francis Xavier University in Nova Scotia and licensed and commercialized by GeoVerra, which is offering it to operators in Western Canada, promises to provide just that. (Note: GeoVerra was formed in late June, after the close of a transaction between Altus Group and WSP. As part of the transaction, two of the country’s leading geomatics providers were carved out from the two organizations to form GeoVerra.)
The technology consists of commercially available hardware — gas concentration and meteorological measurement instruments, including outside wind and temperature sensors — mounted on a truck. The information it collects is then analyzed through computational algorithms.
“The truck is like a rolling lab, measuring gases and various different meteorological phenomena,” says Dave Risk, science lead for the lab. The instruments include outside wind and temperature sensors digested through special computing. As the data comes in, it is sent to the truck’s driver and co-driver as they drive around a wellsite.
“It’s all about trying to figure out what constitutes a plume from one of these sites,” he says, comparing it to the ability to identify whether a vehicle is gasoline or diesel and its volume of emissions. “That’s the sort of service that they do for well pads.”
According to GeoVerra, ExACT is not only a detection service but can simultaneously quantify site-level methane emission rates. It can provide statistics on potential factors including infrastructure age, class and production type. In addition to methane, ExACT can detect and quantify air toxins such as hydrogen sulphide, for health and safety, and liability monitoring.
Operators can use ExACT as a screening mechanism to cost-effectively determine which of their sites need repair, by identifying larger emissions which require quick repairs and eliminating the need for costly optical gas imaging (OGI) surveying of the site with hand-held cameras if there are no emissions.
“We can't entirely replace them [cameras] because it's useful to send hand helds to sites because they can see exactly which valve is leaking, whereas we can't necessarily pinpoint that,” says Risk. “But what we can do with the truck is we can say: ‘Nobody with a handheld should go to this site because it's not emitting anything,’ and so it saves on those cost-intensive visits.”
The ExACT technology, which can obtain its information from a site in two or three minutes, also is “quite a bit faster” than another truck method, he says. The OTM 33-A developed by the Environmental Protection Agency (EPA) in the United States takes about 20 minutes to monitor a site while someone with a hand-held camera takes about an hour, according to Risk.
GeoVerra says it expects that ExACT would have a similar or higher per-day cost to OGI surveys.
However, ExACT has the advantage of the speed with which measurements are taken as well as the area that can be covered, says Chelsie Hall, FluxLab manager.
“We're doing dozens to maybe over 100 sites [a day] in some cases, whereas they're getting up to 10,” adds Risk.
Canadian and Alberta provincial regulators have said that alternative leak detection and repair (LDAR) methods will be permitted if their mitigation impacts are greater than or equal to the mitigation results of a LDAR method using OGI and Method 21 (an EPA protocol for detecting volatile organic compounds). Before a new technology or method is used in an alternative LDAR program, its ability to detect fugitive emissions must be evaluated.
The ExACT technology underwent single-blind controlled field testing during the Petroleum Technology Alliance Canada’s (PTAC) Alberta methane field challenge, which was administered by independent experts.
The current measurement uncertainty is 63 per cent, with a slight bias to underestimate. However, this level of uncertainty is comparable to the OTM-33A that calculates emission rate estimates within 60 per cent accuracy, using lengthy (15-20 minute) stationary measurements, according to GeoVerra, which plans to use the results to improve and develop performance metrics and quantification certainty.
Put in context, as the emissions from a high emitting well pad and a low emitting well pad might vary between 1,000 to 10,000 per cent, “63 per cent is not too bad,” says Risk. “In terms of the whole range, it's not a very large error,” he says. “It’s still sort of measuring a football field in inches, as opposed to ten of metres.”
And even though there's some uncertainty, “there's still quite good resolution … they can tell whether it's [emission] small or big really, really easily.”
Under Alberta methane regulations, truck based mobile surveying, such as ExACT, is included as one of the approved alternative methods that could be used, says Hall. “So it's already been given the stamp of approval that it is an acceptable method that people can use.”
“It's advantageous that is within the Alberta regulations where the majority of the monitoring is occurring,” notes Risk.
The ExACT technology originated at Weyburn, Saskatchewan, where Risk was involved with the carbon capture and storage project then operated by Cenovus Energy Inc., which had an alleged leak that was proven false.
“That didn't change the way they did anything on the production and injection site,” he says. “But it did change their approach to monitoring and the intensity with which they wanted to monitor their own assets to protect against false allegations.”
Risk and his team were commissioned to develop a more efficient monitoring technique for oil and gas and CO2, and came up with the idea of a truck-based monitoring system. “[Whitecap Resources Inc. now] owns that property and we still are running the truck around for Whitecap every couple of years checking on all of their assets, and making sure that they don't have substantial leaks,” he says.
Everything FluxLab does is gas measurement related. Lately, it has been doing a lot of work on advancing gas migration measurement techniques, says Risk. “When a well fails, stuff that is supposed to hold will squeeze out into the soil and rock around the well and then move up to the surface and, because it comes out of the dirt . . . it’s hard to measure and capture.”
The lab has been working on stationary monitors — lower cost methane sensors that could be installed at sites for the long term where the monitoring needs to be more continuous.
It also is continually trying to improve the ExACT technology itself, including using it on boats and on an all-terrain vehicle in an effort to access different types of data and infrastructure that might need measuring, says Hall.
“We've also been trying to improve the speed at which the information gets back to the people who need it and want to see what was actually measured to make it more like a real-time drive around,” she says. “They would get the data instantaneously.”
Although the driver and co-driver of the vehicle see some information right away, there's usually a data processing step afterward, says Risk. “I think basically [GeoVerra] eventually hopes to be able to post those numbers when the truck drives off the well pad,” he says. “So we're not quite there yet but we're getting closer and we're working hard on that.”
At present, the quickest turnaround is about 24 hours, but “we're still striving to improve it,” says Hall.