Petersen represents the second generation of Petersen Drilling Inc. of Virginia, Minn. "Fifty-four years in the current location," he proudly proclaims. "My father started the firm during the 1930s and moved the company from its original location following World War II."
Petersen explains that his company primarily drills residential water wells, but also does some mineral exploration, blast hole work and some monitoring wells. Currently, hydrofracturing represents about 10 percent of his work volume but that percentage has been increasing as time goes on.
"The hydrofracturing replaced blasting," Petersen explains. "We used to blast these rock holes and had about 25 percent real success; the rest of the time, we were blowing the casing out of the ground. And blasting is dangerous - especially in residential areas. Another thing about blasting is it wasn't profitable. In so many cases, we ended up creating more problems for ourselves. We've had extremely good luck with the hydrofracturing process. We've not yet had a well in which we weren't successful. We've had a couple of wells that we had to go back and frack a second time, but we've been very fortunate.
"We normally use a single packer, but we've got straddle packing also. Only in a couple of cases did we have to go back and straddle-pack the well. We use the expandable packers, which are donut-like packers - they hold very well and their replacement cost is relatively low."
Lighthouse ProjectSplit Rock Lighthouse is owned by the Minnesota Historical Society. The lighthouse is no longer being used for its original function. It now serves Northeast Minnesota as a popular tourist site/visitors center - "The view is phenomenal," Petersen relates. Well over 100,000 people a year visit the attraction and there are plans in the works for future expansion.
"The well originally was drilled to 370 feet and produced about a gallon a minute. Holding tanks were being used as part of its water system," Petersen explains. "A problem in this area is if you go too deep, you'll hit saltwater, so the historical society contracted with us to frack the well.
"The existing well pump was pulled out and we went in there with a casing indicator to verify the casing's depth. If the hole is low on water, we fill it up; you have to be into the water to hydrofrack, otherwise it will start ballooning on you. While air is compressible, water is not. So we've got to be down to static level, which in this particular case was 98 feet. So we started fracking just into the water. We knew water was going to be down about lake level. The well previously had been blasted and we didn't want to get into that blasted zone way down in the bottom, so we went down to about 180 feet with our packers to frack it. We did four settings: 110-, 120-, 140- and 180-feet. Once that was done, we pumped in about 2,000 gallons of water. Then we re-installed the pump and test pumped the well. If we wait a day or two before we test pump it, we don't have to pump out as much water to determine the recovery. If you're going to test it right away, you've got to pump out as much water as you put in, just in case it's cavernous in there.
"We drove 80 miles down to the job site, set up by 9 a.m. and done fracking around 11 o'clock. One of the great things about these donut-system packers is they're quick to inflate and quick to release.
"We feel it was pretty successful. The rock is almost vertical there, making it difficult to hydrofrack. But we were able to increase it four-fold to about 4 gallons a minute and that appears to be meeting the center's needs."
Climate Concerns"We have to be well organized up here because we have a small window of time," notes Petersen. "We've got weight limits on the roads in the spring so we can't move until the middle of May. By November/December, it can be down to 20 below zero already. So we've only got about six months of decent working conditions. But we work year 'round when we can - when the temperature is acceptable. With the new rigs now, if it's not going to get to 15 above during the day, we normally don't drill. It's the same for the fracking because we're working with water. That stuff still freezes at 32 degrees. It just doesn't pay when it's too severe to go out there and work.
"We're in basic bedrock. Once you get beyond 300 feet or 400 feet, it usually isn't successful - you're just drilling a drier, deeper hole. There are exceptions, but 95 percent of the time, it doesn't pay to go much beyond 300 feet or 400 feet because you're not going to find any more water anyway. There's no other successful method we can use up here besides the hydrofracturing."