P&A
P&A is a commonly used abbreviation of Plug & Abandon. It is the process of permanently abandoning a well by setting a set of abandonment plugs. Usually, when a well is drilled to the intended target depth and after evaluation if it is determined that the well will not be completed for production in near future, the well is abandoned. A set of cement and/or mechanical plugs are placed in the well to ensure complete isolation as per regulatory requirements. Every company has its own guidelines and policies for well abandonment. The type and number of plugs depend on the type of well and expected reservoir pressure, fluid, etc.
A well can be temporarily abandoned as well if it is planned to complete, produce or reenter in the future. Offshore, a Mud Line Suspension (MLS) system is installed to be able to tie back the well in the future once the platform is installed. A corrosion cap is also installed on the top of the well to protect tieback threads and to avoid any debris getting into the well. The Corrosion Cap can be removed and retrieved before tying back the well to the platform.