An oil well is referred to as abandoned if the economic limit of the well is reached.
Thereafter, the tubing of the well should be removed and sections of the wellbore filled with concrete.
This process is known as Abandonment and it is required to isolate the path of the flow between water and gas zones from one another and from the surface as well.
Depending on well conditions, abandonment operations can however be quite time-consuming and thus very costly.
Moreover, offshore wells are considerably costlier to abandon than onshore wells.
After a well becomes abandoned, its tubing is removed and the wellbore sections are completely brimmed with concrete.
The filling of the wellbore sections is required so as to make the flow path amid gas and water zone isolated from the surface and from each other.
The Abandoned Well waits to see if the market can do something before its permanent abandonment.
After the well becomes abandoned, the platforms are sometimes plunged in place or moved somewhere else to be dropped into the ocean floor to produce artificial reefs.
Recent technology developments such as the perforate-wash-cement technique and utilizing shale as annulus barrier have significantly reduced the time spent on plug & abandonment operations.
Furthermore, risk-based approaches to determining plug length and the number of plugs may further reduce time-consumption while maintaining well integrity.There is still need for further technology developments however.
Operators, service companies, vendors, research institutes and universities are all working on reducing risk of leakages, developing new technologies and improving plug & abandonment operations further.