A Permanence Agenda for Abandoned Oil and Gas Wells in PA and Beyond
The Federal Bipartisan Infrastructure Law provided $4.7 billion to begin the enormous and urgent work of plugging the nation’s estimated 2 million+ abandoned oil and gas wells. Those wells leak methane—nearly 3 percent of the U.S. total—and pose other serious environmental risks.
Pennsylvania will receive at least $400 million of that funding to jumpstart severely underfunded state plugging efforts. But it’s only a start.
The Commonwealth has identified about 27,000 abandoned wells. It likely has somewhere between 300,000 and 750,000 of them. And the total continues to grow as drillers abandon wells due to inadequate bonding requirements, a “culture of non-compliance” among conventional oil and gas drillers and some shale gas drillers, chronic understaffing of inspection and oversight, and insufficient enforcement of state laws and regulations.
In Pennsylvania, well plugging costs range from tens of thousands of dollars to over $100,000 per well, or more. The federal funding coming to the Commonwealth, then, isn’t nearly enough to plug all the wells we know about, let alone all the wells that are out there, somewhere. The immediate task is to prioritize, find efficiencies, and plug as many wells as possible with available funds.
But there’s another related problem that hasn’t received enough attention. Sooner or later, plugged wells can, and do, leak.
Current plugging methods have been used for decades. An abandoned well is first cleaned out as deeply as possible, then plugged using Portland cement and bentonite gel through the gas and oil-producing zones. Additives are frequently used to achieve specific plug properties such as viscosity, setting time, and strength; to minimize shrinkage, or ensure compatibility with the chemistry of groundwater in the well. The surface area around the well is also usually restored.
But Portland cement can degrade, other materials can shrink, break down mechanically or chemically, and cause leaks underground or into the atmosphere. To complicate matters further, plugged wells are not monitored for leakage.
Achieving a permanent seal capable of withstanding subsurface geomechanical and geochemical changes will require the development of engineered materials and processes to provide sealing in the early decades after plugging, and leveraging geological processes to take over and provide permanent seals.
More research is needed into plugging materials and placement methods to meet this permanence challenge and reduce costs. The oil and gas industry has recognized this need, and current research on improved plugging includes:
- using self-healing materials for plugs
- thermal plugging/rock fusion that melts well components to form a plug
- developing magnetic cements and applying magnetic fields to change the properties of plugging material
- alternatives or additives to Portland cement such as geopolymers,pozzolans, and nanoparticles to improve mechanical and physical properties and durability of barrier materials
- ultrasonic cleaning of the wellbore to remove contamination and improve the placement of barrier materials
- expandable tubular technology to close downhole gaps
- activating shale to form a long-term natural barrier
- flexible expanding cement systems—currently used for well integrity in shale wells—for use as a permanent plugging material
Still, plugging materials and methods research has been found to be significantly lagging behind advancements in drilling and completion technology.
Current well plugging efforts are a vital step in combatting climate change and environmental degradation. But the job will be far from over when all the current funding’s spent. A permanence agenda for well plugging is needed, and should:
- stop the abandonment of new wells by:
- reforming well bonding requirements
- funding more inspections and better oversight
- enforcing tougher penalties for new well abandonment; i.e., increased fines and blocking new well permits
- intensify the search for abandoned wells
- develop long-term funding sources for abandoned well plugging
- propel research on well plugging permanence, and incorporate results into well plugging requirements
- leverage technological advances in remote sensing to monitor producing, abandoned, and plugged-and-abandoned wells.
