The technologies that set off the shale gas and tight oil revolution, reviving the onshore industry across North America, still have some kinks that can be costly to straighten out.
For example, the massive hydraulic fracturing completions required to liberate the oil and gas from the shale and extremely tight rock can pose unintended—and potentially dangerous—consequences to adjacent wells.
In 2012, the blowout of a well near Innisfail, Alta., was caused by fracking in a nearby well, when frac fluid pumped under high pressure came into communication with the producing well—both targeting the same formation some 1,800 metres underground—and blew its top. Almost 500 barrels of oil and water blasted from the wellhead, impacting 4.5 hectares of surrounding area.
Where sour gas might be present, a blowout presents the additional danger of exposure to toxic hydrogen sulphide (H2S). Thus, in many jurisdictions, offset wells are required to be shut in, typically with their hardware removed, while fracking takes place nearby—a potentially costly procedure.
It’s a problem for which a Calgary-based start-up has a solution. Well Suspension Tools (WST) produces two deceptively simple tools that enable the temporary shutting-in of wells without the need to remove downhole pumps, sucker rod assemblies and associated hardware by allowing them to remain suspended within the well.
“In the past there hasn’t been an easy way to shut in the well properly. To do a frac safely, companies would have to pull all the rods and lay them down at surface. For each of the affected offset wells, it takes about a day to pull out the rod assembly and a day to re-install them—per well. The associated costs and the lost production due to downtime can really affect the economics of an area,” says Leslie Kohnen, WST’s president.
“If you use our tools, you can leave the rods in the hole, and if you want to leave them for more than a few days, you can inhibit the well so that there is no corrosion, and you could leave them for 20 years if you wanted to.
“As a case in point in North Dakota, a major operator using the WST tools successfully shut in 14 wells in a day and a half. Then after the frac, got them back on production even faster,” Kohnen says. “Because they had 14 adjacent wells [to shut in], they saved over $500,000 on that one frac. It’s the kind of thing that saves a huge amount of money for very little cost.
“Tool installation and retrieval is being done in less than one hour. The operator has re-used the tools several times, so the economic benefits of using them increases each time. The tool design also allowed the pressure to be monitored during the frac, which has been a great asset in determining their frac design and effect.”
Protection of offset wells during frac operations represents about 60 per cent of WST’s business. The tools also offer effective solutions for other challenges involving rod pumped wells, such as for short- and long-term well shut-ins, well maintenance and well servicing.
They have most recently been used as a solution for emergency shut-ins, such as where a weather event like a tornado requires hasty evacuation. “We had a call from a service rig operator in Oklahoma out of the blue. They wanted a tool which allowed them to quickly and safely shut in a well during the pulling or running of the rod assembly. They can now secure the rods and well safely and be off the wellsite in minutes,” says Kohnen.
Ken Gordey, senior vice-president and technical manager at WST, was a consultant specializing in finding efficiencies for oil companies. He came up with the concept for the tools after he became one of the many casualties of the 2014 oil price collapse.
With his past experience on well operations, he says he challenged himself, thinking, “There has to be a better way to suspend, re-activate and workover oil wells.” Suspending an oil well leaving the polished rod and the stuffing box as a seal is not safe as it requires scheduled maintenance to work effectively. The seals dry out and start to leak, which can cause a huge liability and environmental catastrophe, he says. “Stuffing boxes were never designed as a valve.”
So Gordey created the C tool and the T tool, both internal rod hangers named for the shape of the devices. They allow the rods to be hung and a wellhead valve placed on top, thus implementing a simple economic operation to suspend and re-activate the well. WST has patents pending on the tools and applications procedures.
“The cylindrical C tool slides over the sucker rod and is seated at the top of the tubing, raising the rod string and pump off the bottom. The polished rod/stuffing box is removed, and a wellhead assembly is installed. With the pump unseated, fluid and inhibitors can be pumped past the C tool and down the tubing assembly easily,” Gordey explains.
“The T tool threads onto the rod string, holding it in place. Bypass slots on the side allow for fluid to be pumped into the well and for pressure to be bled off. It is the first tool to allow operators to squeeze solvents and chemicals safely using a 3,000 or 5,000 psi wellhead valve and pumping at high pressure through the tool,” he says.
Two different tool designs allow for many different applications, from conventional rod wells to steam injection. The tools can be landed in the wellhead or installed in the tubing hanger.
“If the rods are being put into or being pulled out of a well, and the operation needs to stop due to safety, mechanical or weather issues, simply install the tool and put on a wellhead valve and shut down the well,” Gordey says. “It can be done in less than three minutes.”
With sucker rods and the bottomhole assembly left in the well—protected within an inhibited environment against degradation—well suspensions, re-activations and production optimization operations are faster and cheaper, he adds. Working on horizontal wells has also become more efficient. By unseating the bottomhole pump and hanging the rod string, fluids can be pumped and circulated to the tubing tailpipe, which is situated in the horizontal section, of the well more effectively.
Alberta Oil Tool, a major rod manufacturer in Edmonton, produces the tools for WST following API standards, ISO 9001 and certified engineered drawings. In addition, C-FER Technologies has tested the tools to the highest industry standards. The tools can be used in any well environment including high H2S and CO2. WST has also recently introduced a version of the T tool adapted for cyclic steam stimulation for heavy oil, developed for a senior operator.
The company expects to see more opportunities going forward as the downturn has left maintenance neglected and companies continue to focus on costs amid a modest oil price recovery.
“Due to current procedures, a lot of wells haven’t been worked over or been maintained in a fairly long time, and with these tools, you can go into an existing rod well and do your stimulation or your chemical work, get rid of your issues and do a lot of the maintenance jobs that need to be done—for a lot less money than it would be if you didn’t use it,” Gordey says.