Subject: Drilling Engineering It's about the Offshore Drilling Rig Equipment.

1. Offshore Drilling
Rig Equipment
Presented To:
Sir Adnan Aftab
Presented By:
Aijaz Ahmed (K-17PG10)
Umar Farooque (K-17PG13)
Abdul Aleem (K-17PG15)
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2. • The rig is a complex system of inter-related subsystems. Here are a few
of those subsystems simply explained.
• The Legs, Chords, Jacking System
• The three legs are what give the jack-up its name. They can be raised
and lowered on ratchets in a process known as jacking up or jacking
down. During jacking up, the legs go down and the rig goes up. During
jacking down, the legs go up and the rig goes down until it floats on the
surface of the water, then the legs continue to travel up until they tower
above it. The verticals that form the outside of the lattice are
called chords. Legs can have a square cross-section with four chords, or
a triangular cross-section with three chords.
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3. • The legs are operated by jacking motors, which drive cogs that
move notches on the jacking chords up and down. This is known as
a rack and pinion system. The rack is the series of notches on the
chord and the pinion is the gear whose teeth interlock with the
rack.
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6. • Hull
• Much like the hull of a boat, a Jack Up unit’s hull is watertight,
and houses or supports the equipment, systems, and personnel
needed to carry out normal operations. While the Jack Up is
afloat, the hull also provides the buoyancy needed to stop the
Jack Up from sinking. The parameters of the hull can vary
depending on the different modes of operation of the unit.
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8. • The Cantilever Deck and Skidding System
• The derrick is where all the drilling equipment is located. If the
rig is not precisely where the well needs to be drilled, it’s
important that the derrick can easily move forward, backwards
and side-to-side to get the drilling equipment exactly where you
need it. This also allows several wells to be drilled by the same
rig, just a few feet apart.
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9. • The cantilever deck is a whole deck that slides backwards and
forwards, left and right, to get the derrick in place. The sliding
process is known as skidding and it’s controlled by gears and
motors a bit like a horizontal version of jacking. The left-right
movement is controlled by the transverse skidding system and the
forward-backward movement by the longitudinal skidding system.
The part of the cantilever deck under and around the derrick,
where the drilling activities take place, is called the rig floor.
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12. Thruster:
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16. • The Blow-Out Preventer (BOP)
• Oil and gas underground are frequently under very high pressures. This, combined with
their flammability and explosiveness makes drilling for them potentially dangerous. To
avoid the pressure building up and blasting up the well uncontrollably in what is known as
a blow-out, the rig uses a blow-out preventer (or BOP).
• Subsea BOPs
• A typical subsea BOP weighs in a range from 450‐850,000 lbs.
• They have more complex control systems and usually additional ram and
annular preventers.
• Typical deepwater BOPs today have an internal diameter of 18‐3/4” and are
rated to 15,000 psi maximum wellbore pressure.
• The BOP is run subsea after the surface well has been drilled and a wellhead has
been landed and cemented in the seabed
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18. • Choke and Kill Valves
Valves called choke and kill valves on the BOP allow for high
pressure gas and oil to be transmitted to the drilling rig to bring a
well under control.
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20. • Lower Marine Riser Package
• The BOP has two sections, the Lower Marine Riser Package
(LMRP)and lower stack.
• The LMRP usually has one annular, one connector to attach to
lower BOP, the control system, gas bleed valves and a flex joint.
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22. • Choke Manifold
Choke manifolds are a series of gate valves and valves with variable
orifices which are used to bring a well, which has had an influx of
high pressure fluids into the wellbore, under control.
High pressure wellbore fluid is directed to a degasser where the
drilling mud is separated from the gas and the gas is vented to
atmosphere.
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24. • Pipe-Handling System
• On the derrick there is a system of overhead cranes and platforms for
maneuvering pieces of drill pipe out of the pipe rack (where they are
stored) to the top of the drill string, where they are screwed in to make
the drill string longer. The same system is used in reverse for dismantling
the drill string and putting the drill pipe back into storage.
• Cranes
• An offshore rig would typically have two to four cranes each sitting on
a pedestal that allows rotational movement. The architect of the rig will
have chosen the location of the cranes so that together they can move
heavy objects anywhere on any of the decks. Where one crane can’t
reach, another crane can.
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27. • The Top Drive and Drawworks
• Suspended on the derrick is the Top Drive. This is a device for
spinning the drill string. It moves up and down the derrick using
the drawworks to control its vertical movement. When it reaches
the bottom of the derrick, a fresh piece of drill pipe is picked up
and screwed on to the top of the drill string; the Top Drive returns
to the top of the derrick and starts spinning it round again.
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28. • Main Engines, Generators and SCRs
• All this drilling equipment needs a lot of power, which is
generated by several main engines that normally run on fuel oil
(same as on most ships). One or more silicon controlled rectifiers
(SCRs) are used to stabilize the level of current that the
generators put out so that it can flow into the rig’s many
electrical systems.
• In the event of a failure, each rig has emergency engines and
generators that can create a bare minimum amount of power for
cooking, heating or air conditioning and making water, but not
enough to continue drilling operations.
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30. • The Flare-boom
• In wells that are producing or are close to producing, you would
expect some gas to come up through the well. To mitigate the
threat of poisoning (via inhalation) and explosions, and to regulate
pressure, excess gas is vented under controlled conditions and
burnt off. It is burnt off in a process known as flaring, and this
happens at the end of a directional boom known as a flare
boom. The flare boom ensures that the flare is several meters
from the rig and pointing in a safe direction.
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32. • Safety Equipment
• The rig is vulnerable to pretty much every natural and man-made
hazard you can think of; fires, explosions, flooding, gas leaks,
helicopter crashes, punch-through, BOP blow-outs and collisions
with other ocean-going vessels.
• Needless to say that considerable amounts of space, time and
thought is dedicated to safety systems such as watertight doors,
spill clean-up kits, lifeboats, life-jackets, fire and gas
alarms/detectors, portable fire extinguishers.
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34. • Supply vessel
• Offshore installations need supplies such as food, fuel, and spare parts.
They also need old machinery, oil parts, sewage and rubbish to be taken
away. Supply ships visit the rig for this. Sometimes supply ships also
bring/take personnel to and from the rig as an alternative to a
helicopter.
• Accommodation Vessel
• Space on any offshore installation is limited according to its size. A
medium sized rig might have beds for about 110-120 people. When more
people are needed, an accommodation vessel is moored nearby to house
the extra people. There are also jack-up accommodation modules that
act like a drilling rig.
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35. • Helicopter
• People come and go via boats or helicopter. Helicopters are
normally organized by the oil and gas company that controls the
oil field, and shared between several drilling contractors and all
their subcontractors. Flights could be several times daily but in
some areas they might be as rare as once a week. All the vessels
mentioned above would normally have a helipad on-board.
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36. Control Systems
• Subsea BOP have control systems that are supplied with fluid from a
pump and accumulator system on the rig.
• Anchored rigs typically have a fully hydraulic system, with hydraulic pilot
signals sent from the surface to operate the functions on the BOP subsea.
• Early dynamically positioned drill ships had electro‐hydraulic systems.
With these systems an electric signal is send to a solenoid on the BOP
which then sends a hydraulic pilot signal to a control valve.
• Multiplex (MUX) systems were developed to enable an ever increasing
number of functions to be operated with just a few conductors in the MUX
cable.
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