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Oil and gas will remain crucial to meeting our energy demand
for decades to come.
Shell is committed to helping meet the world’s needs
in a safe and responsible way.
As the company explores and develops reserves around the globe,
it also invests heavily in developing and deploying
a range of new technologies.
Technologies that it hopes will never be used.
Capping stacks are a key component of Shell’s safety equipment.
They are used to control, or shut-in, wells in the event of a blow out.
These modular systems are ready and available for deployment
to Shell operations worldwide.
In addition to Shell’s own capping stacks,
Shell is a founding member of two major industry initiatives,
giving them access to five more capping stacks
located at key sites around the globe.
Both organisations develop state-of- the-art capping technologies
that improve the industry’s capability
to quickly regain control of a well blow out.
A capping stack stands approximately 30 feet high
and weighs in at almost 100 tons.
It contains series of rams and valves
that can handle pressures of up to 15,000 pounds per square inch
and can operate at depths of up to 10,000 feet.
Shell’s capping stacks are regularly tested and maintained
in a state of continuous readiness
and, whilst in 40 years of deepwater well operations
we have not had an event that would require us to use a capping stack,
the procedures are in place to deploy one instantly
should an emergency arise...
..in which case, the first step is a site assessment
by a remotely operated underwater vehicle or ROV.
Once a capping stack is requested, it is transported to the dock
and loaded onto a deep water supply vessel.
Back at the well,
the blow out preventer is prepared for capping
as the ship heads to the incident location.
Prior to its arrival,
the top section of the blow out preventer
is lifted away leaving the base ready for capping.
The accumulator pack,
which provides the capping stack with hydraulic power,
is lowered to the sea bed.
The capping stack is then deployed and guided by the ROV
onto the leaking blow out preventer.
With the capping stack installed,
oil now flows through the main bore and from four diverter lines.
Meanwhile, the ROV connects the accumulator pack to the capping stack
and powers up the hydraulics.
The ROV is then able to start to control the flow of oil
by closing the rams that shut down the main bore.
With the oil now flowing from the diverter lines,
the ROV progressively closes valves or chokes...
..gradually reducing the flow of oil...
..until it is eventually stopped completely.
With the well back under control,
pressures within the capping stack are monitored
before a secondary seal is installed and recovery operations can begin.
While Shell is doing everything it can
to prevent this equipment from being needed,
the company also recognises the need to be prepared
and is able to respond instantly
to keep its wells safe, wherever they are.