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P&A
P&A (Plug & Abandon) is the process by which an oil or natural gas well is sealed and decommissioned.

Process
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 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.

Costs
The cost of plugging onshore wells in the United States ranges from a few thousand dollars to over $100,000 depending factors such as well depth, pressures, and mechanical characteristics of the well such as pipe size and type.

Environmental Benefits
Unplugged or poorly plugged wells are an environmental hazard as they provide potential conduits for fluids to migrate between formations, and potentially into the fresh water zones. Poorly plugged wells also can provide pathways for natural gas to seep to the surface and potentially cause fire or be a health hazard. An abandoned well’s potential for causing a hazard is largely dependent on the type of well. Oil wells that have been pumped for years will typically have very low formation pressure, and the risk of contamination is low, while a gas well that is capable of flowing at a rate that is non-economical can still posses enough pressure to be a risk to the environment.

Category:Oilfield terminology