JANUARY 2008
The Corrib Wells
Five wells have been drilled in the Corrib reservoir to date.
The five appraisal wells will be ‘completed’ when the semi-submersible drilling rig returns to the Corrib field. This will enable the wells to produce gas when the Corrib development is ready to come on-stream.
To drill a well more than 3000 metres below the sea bed,
the semi-submersible rig drills the well
section-by-section until it reaches the reservoir. When
each section is complete, steel casing is installed and
held in place with cement. This makes the well strong
enough to withstand the pressure from the reservoir.
In case gas enters a well unexpectedly from the reservoir
during drilling, a safety mechanism called a
“blow-out preventer” is fitted which will
safely close off the well in an emergency situation.
Wells are wider at the top (at the seabed) than at the
bottom (at the reservoir). Corrib wells are 36 inches in
diameter at the top and decrease in size
to 8½ inches in diameter at the bottom.
The rock that is cut away by the drill is known as
“cuttings”. It is removed and brought to the
surface by a mixture of drilling chemicals known as
“mud”. The cuttings and mud are carefully
recycled and brought ashore. (WHERE IS THIS POSSIBLY
RADIO-ACTIVE ROCK AND MUD GOING TO - "on
shore"JB. EDITOR)
WELL CASINGS AND LITHOGRAPH:
