THE DRILL: Plugged and abandoned wells in the state – the goal is to restore surrounding landscapeIf all goes as expected, it’s hard to imagine that the thousands of Bakken oil wells being drilled now and in the future will one day become plugged and abandoned wells (P&A wells).
By: Sid Pranke, The Drill
If all goes as expected, it’s hard to imagine that the thousands of Bakken oil wells being drilled now and in the future will one day become plugged and abandoned wells (P&A wells).
The state already has a list of 24,978 permitted wells. Since the 1980s, part of the state’s goal in plugging wells is to restore the surrounding landscape so that one wouldn’t necessarily even notice that an oil well was once there, a process called reclamation. Of the 24,978 permitted wells, 10,234 have been “reclaimed” or are going through the reclamation process, according to Alison Ritter, public information officer for the Department of Mineral Resources.
According to the National Petroleum Council (NPC), P&A oil and gas wells are wells that are no longer economically viable or have wellbore issues that require closure. Production wells that can no longer be used must be plugged to prevent the oil and gas reservoir fluids from migrating uphole over time and to prevent possible contamination of aquifers and other formations.
Lynn Helms, director of the Department of Mineral Resources, is proud that his office knows the location of nearly all wells in the state, including P&A wells. The only exception to that is “maybe 10 or 15 very shallow wells that were drilled right after the turn of the century that we don’t have an actual physical location on,” Helms said. “But everything from well No. 16 through well No. 25,000, we have an exact location for.”
Well No. 16 goes back to the 1930s, Helms said, but North Dakota oil production is said to have begun in earnest after April 4, 1951, when a well struck oil in Tioga. Someone from the Geological Survey or the Oil and Gas Division of the state witnessed the plugging of all those wells, Helms said.
“We have witnessed every well plugging since 1951. Because we as a state understand how really important our underground drinking water is,” Helms said.
A well is plugged by setting mechanical or cement plugs in the wellbore at specific intervals to prevent fluid flow. The plugging process usually requires a workover rig and cement is pumped into the wellbore. The plugging process can take two days to a week, depending on the number of plugs to be set in the well, according to the NPC.
“On some of the older plugged wells, you’ll notice a piece of casing sticking out of the ground with a welded number on it – that was one of the requirements of the federal government ... before GPS and metal detectors. They wanted some visible sign that there had been an oil well there,” Helms said. “Since about 1985 or so, we’ve been requiring that the land be returned to its pre-drilling contours, the topsoil be put back and vegetation be re-established. We won’t release the well from the company’s bond until all that’s been done.”
Oil operators must get their plugging procedures approved by the state. “We don’t let them go out there and plug it the way they want. They have to get approval of their procedure from the Industrial Commission, and then it has to be witnessed to make sure they followed it,” Helms said.
And besides the state requirements, Helms said there are more economic incentives for oil companies to properly plug wells since the advent of advanced oil recovery. “What’s been discovered in states like Ohio and Illinois and other places that have a legacy of wells over 100 years old, is that those improperly plugged wells make it impossible to do a proper water flood or a carbon dioxide flood,” Helms said.
The technology for plugging wells has changed since the days of inserting wooden or clay plugs into the wells, Helms said. Helms used to work in the oilfields and he has seen how wells used to be plugged long ago. “My first job with Texaco with working on an oilfield that was drilled in the 1920s and that field was drilled with cable tool drilling processes down to about 3,000 feet,” Helms said.
“The wells were drilled out and shot with nitroglycerin to stimulate the wells for completion. So wells that were plugged back in those days, there was very little cement and casing used.”
The state maintains a special reclamation fund for defraying costs related to plugging wells.
Sid Pranke is editor of The Drill. She can be reached at email@example.com.