During turnaround at Spectra Energy's McMahon natural gas processing plant in Taylor, British Columbia this June, the company introduced a new process designed to eliminate flaring of sour gas at the facility.
The process was actually used at their Grizzly Valley natural gas gathering system near Chetwynd, B.C. last summer, but this is the first time it has been used at McMahon. It involves purging the raw gas from the pipelines and re-injecting it into gas reservoirs instead of incinerating the gas - sour gas can't be vented for health and safety reasons - prior to the maintenance work that must be performed at the facility on a regular basis.
The initiative began with the Area Operating Committee (AOC), a group consisting of Spectra and area gas producers who meet a few times every year to discuss a range of topics related to gas production in that region. It was during one of those meetings prior to the Grizzly Valley turnaround last year that one of those producers, ConocoPhillips, suggested re-injecting the sour gas into a reservoir. The preparation for the new process was done in partnership with the AOC companies and the BC Oil and Gas Commission.
"Basically," said Doug Gulevich, Spectra's Area Business Leader in Fort St. John, who previously held that position for the Grizzly Valley operating area, "what they do is they turn their compressors around. And instead of compressing [gas] from their well sites, they compress [gas] back into their well sites. So, we went through the whole process with [the Commission, ConocoPhillips] and the rest of the producers. And it was the first trial at doing this. It worked very successfully."
The process purged approximately 100 million cubic feet (mmcf) of gas from Spectra's pipelines, re-injecting it into two of ConocoPhillips' reservoirs.
Gulevich noted that all the companies operating in the area were onboard with the project.
"I think it's a great thing that the producers are doing this," he remarked.
The main motivation for developing the process was to reduce flaring of sour gas.
"We have to draw the pipelines right down to zero to work on them," said Gulevich,
"We're always trying to, not necessarily save gas, but do the right thing and come up with new ways instead of flaring off, which is not a good thing," he added. "We have to actually incinerate the gas, it's so sour."
So, the process does help Spectra and the producers reduce their environmental footprint, but saving 100 mmcf from the flare stack is also a significant benefit. That amount constitutes approximately one third of the daily natural gas production in the area.
"There would be no carbon tax paid on it by all of the producers," said Gulevich, addressing the economic side of the new process. "When we flare it, they have to pay carbon tax."
Gulevich admitted that ConocoPhillips did incur a substantial cost during the Grizzly Valley turnaround last year, considering they had to turn their compressor around to redirect the flow of gas.
"But there was a small benefit to them," he added. "But the idea right from the start was getting rid of our flaring."
Spectra did face a few challenges bringing this process from Grizzly Valley to McMahon, particularly considering that Grizzly Valley's total daily production is about 440 mmcf - and it is currently processing about 300 mmcf per day - and the total daily production at the McMahon plant is in the neighbourhood of 750 mmcf.
"McMahon is a lot larger gathering area," said Gulevich. "We have a spiderwork of pipes in the ground and then a command area [that is] fifty years old. We've got old pipes, new pipes. So, not everything's connected as nicely as Grizzly Valley. And instead of having ten producers, we've got forty producers. And getting them all onside. So, it was fairly well received at the AOC. We had a bunch of companies put their name forward to help us out. And what we had to do was coordinate our work."
The trick was finding the companies that were able to help with gas re-injection where maintenance was being conducted.
"It turned out there was basically one company [who] was able to help us out in two or three of the areas," said Gulevich.
Gulevich began discussing the idea as a possibility for McMahon as soon as he arrived from Grizzly Valley and encouraging the local producers to commit to the plan.
"The problem going forward is then you have to plan all of your maintenance," he said. "And your maintenance [planning] is probably done three to four months ahead of the turnaround."
So, there was a tight timeline for bringing the producers onboard. Also, complicating the matter for Spectra this year was the fact that they had plans for a major project on their sour gas mainline.
"Which isn't normal for us," said Gulevich. "We don't normally cut out big sections of mainline."
"The outage didn't only include the regular integrity and maintenance projects that we typically address with an outage," added Rosemary Silva, Team Leader for External Communications at Spectra. "It also included the facility upgrade to accommodate the new projects coming online."
"When we have an outage the size of McMahon, when the plant is totally shut down, there's opportunities to do some tie in work," Gulevich continued.
"When we're flowing, you don't have the ability to do that," he concluded.
The new re-injection process added four days to Grizzly Valley turnaround last year. It only added two days to McMahon turnaround this summer, however. Partial outage was from June 10 to 15. Full outage was from June 15 to 29.
"We actually had crews in the area for about six weeks because we were doing single train turnarounds and prep work and everything else," Gulevich explained. "We had a large contingency of pipeline crews and our maintenance crews here at the plant probably six weeks in advance."
At the peak of turnaround, there were approximately 600 workers per day at McMahon and 200 additional workers at other locations. The new re-injection process didn't require any additional manpower, just additional time.
"Last year was 100 million standard cubic feet," said Gulevich, describing the difference in natural gas volumes re-injected between Grizzly Valley in 2010 and McMahon in 2011. "This year was a little less. We did about 30 million of sweet gas on the mainline. And we did about 35 million of raw gas this year."
"Those are just estimates," he added.