Agr Subsea, Inc.

Ikm Cleandrill As

Harald Hufthammer

Roger Sverre Stave

Nils Lennart Rolland

David E Smith

The invention provides a method and apparatus for performing a plug and abandonment operation on a subsea well. A wellhead interface module is located on a wellhead, which accommodates a volume of wellbore fluid in fluid communication with the wellbore. A system control module receives a signal from a sensor in the chamber and is configured to derive volume data relating to a change in volume of wellbore fluid in the chamber and compares the derived volume data with a volume change expected due to the removal of tubing from the wellbore. In embodiments of the invention, this enables a change in wellbore conditions to be characterized, for example a fluid influx or a fluid loss, from the volume data. The method may comprise providing wellbore fluid to the apparatus to replace fluid which enters the wellbore to occupy the volume vacated by the tubing, and/or removing or adding fluid in fluid influx/loss situations respectively.

Method and apparatus for subsea well plug and abandonment operations

Systems and methods for drilling a well bore in a subsea formation from an offshore structure positioned on a water surface with a drill string that is suspended from the structure and includes a bottom hole assembly adapted to form a top hole portion of the well bore. A drilling fluid source on the offshore structure supplies drilling fluid through the drill string to the bottom hole assembly where the drilling fluid exits from the bottom hole assembly during drilling and returns up the well bore. A suction module is disposed at the sea floor and collects the drilling fluid emerging from the well bore. A pump module is disposed on a return line, which is in fluid communication with the suction module, at a position below the water surface and above the sea floor. The pump module is operable to receive drilling fluid from the suction module and pump the drilling fluid through the return pipe to the same offshore structure or a different offshore structure.

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Straume, Norway

Harald Hufthammer