When the production from oil and gas wells drops below levels that make them economically viable to operate or if they develop wellbore issues, the responsible action to take is plug and abandonment (P&A). This operation prevents oil and gas reservoir fluids from migrating up the wellbore and possibly contaminating other formations, fresh water aquifers or both.
The EPA estimates the nation’s 2 million abandoned wells are the 10th highest source of methane, after sources like agriculture, oil and gas drilling, and landfills. Pennsylvania leads the nation with over 20,000 abandoned wells. Estimates vary regarding the actual number of abandoned wells in the state, home of the world’s first commercial oil well drilled in 1859. The Department of Environmental Protection (DEP) says there are likely 200,000 unaccounted-for wells in Pennsylvania. The Bipartisan Infrastructure Bill, passed in 2021, allocated a record $4.7 billion for plugging oil and gas wells, with Pennsylvania expected to receive $330 million over the next decade. “Our agency is using the state’s first allotment of $23 million from the bill to plug 235 wells this year,” said Rich Negrin, acting secretary of the Pennsylvania Department of Environmental Protection. “Over the last eight years, it has averaged about 18 wells per year.”
A well is plugged by setting mechanical or cement plugs in the wellbore at specific intervals to shut off fluid flow. The plugging process usually requires a workover rig and pumping cement into the wellbore. The entire operation can take a week to a month depending on the complexities of the well. Modern regulatory standards in all U.S. jurisdictions require specific provisions for plugging and documenting oil and natural gas wells before they are abandoned. And, while these regulations vary to some degree among states, all state regulations prescribe the depth intervals that must be cemented and the materials that are allowed to be used in plugging operations.
P&A requires enlisting technical services to complete a number of operational tasks:
And, to conduct these types of operations effectively and efficiently, the P&A service company must field multi-skilled crews capable of performing all required services.