Faculty of Engineering

Petroleum Engineering Department

Drilling Engineering I
Third Stage

Lecture # 4
Drilling Rigs

Pshtiwan Jaf 1
pshtiwan.jaf@koyauniversity.org
 Types of Rigs
Offshore Rigs, cont.
1. Posted Barge
• The barge is a shallow draft, flat-bottom vessel equipped as an offshore drilling unit,
used primarily in shallow water depth (typically 8 – 20 ft) such as lakes, swamps, rivers,
and canals.

• It can be towed to the location and then ballasted to rest on the bottom.

• Operating water depth and weather limit the areas for the drilling barge.

• A minimum water depth of 6 – 8 ft is required for vessel draft during transportation to

the location.

• The upper range on the water depth can be extended to 30 – 40 ft if a shell mat or pad
is built as a support for the barge.
2
 Types of Rigs
Offshore Rigs, cont.
1. Posted Barge, cont.

3
 Types of Rigs
Offshore Rigs, cont.
2. Jackup Rigs
• Rigs are similar to drilling barges, with one
difference.

• Once a jack-up rig is towed to the drilling site, three

or four leg' are lowered until they rest on the sea
bottom.

• This allows the working platform to rest above the

surface of the water, as opposed to a floating barge.

• These rigs are typically safer to operate than drilling

barges, as their working platform is elevated above
the water level. 4
 Types of Rigs
Offshore Rigs, cont.
2. Jackup Rigs, cont.
• The jackup is towed to the location and spotted over
the well site.

• During the towing process, the legs are up in the air

and the barge floats on the water.

• Upon reaching its location, the legs are jacked down

to contact the seafloor and the rig is raised into the
air.

• When drilling is completed, the rig is lowered to the

water level, the legs are raised, and the rig is towed
to the next location. 5
 Types of Rigs
Offshore Rigs, cont.
2. Jackup Rigs, cont.
• These rigs are typically designed for use in
13 – 25 ft minimum water depths and as
much as 250 – 350 ft maximum water
depths in some cases.

• The maximum operating depth is restricted

in hurricane or severe weather conditions.

• For instance, a jackup designed for a 300 ft

maximum operating depth may have upper
limit of 200 ft operating depth in hurricane
conditions.
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 Types of Rigs
Offshore Rigs, cont.
3. Submersible Rigs
• Submersible rigs, also suitable for shallow water, are like jack-up rigs in that they come
in contact with the ocean or lake floor.
• These rigs consist of platforms with two hulls positioned on top of one another.
• The upper hull contains the living quarters for the crew, as well as the actual drilling
platform.
• The lower hull works much like the outer hull in a submarine - when the platform is
being moved from one place to another, the lower hull is filled with air - making the
entire rig buoyant. When the rig is positioned over the drill site, the air is let out of the
lower hull, and the rig submerses to the sea or lake floor.
• This type of rig has the advantage of mobility in the water, however once again its use is
limited to shallow water areas.
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 Types of Rigs
Offshore Rigs, cont.
3. Submersible Rigs, cont.

8
 Types of Rigs
Offshore Rigs, cont.
4. Semisubmersible Rigs
• Semisubmersible rigs are the most common type of offshore drilling rigs,
combining the advantages of submersible rigs with the ability to drill in deep
water.

• A semisubmersible rig works on the same principle as a submersible rig through

the inflating and deflating of its lower hull.

• The main difference with a semisubmersible rig, however, is that when the air is
let out of the lower hull, the rig does not submerge to the sea floor. Instead, the
rig is partially submerged, but still floats above the drill site.

• When drilling, the lower hull, filled with water, provides stability to the rig.
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 Types of Rigs
Offshore Rigs, cont.
4. Semisubmersible Rigs, cont.
• Semisubmersible rigs are held in place by
huge anchors, each weighting upwards
of 10 tons.

• These anchors, combined with the

submerged portion of the rig, ensure
that the platform is stable and safe
enough to be used in turbulent offshore
waters.

• Semisubmersible rigs can be used to drill

in much deeper water than the rigs
mentioned before. 10
 Types of Rigs
Offshore Rigs, cont.
5. Drillships
• Drillships are exactly as they sound, ships designed to carry out drilling operations.

• These boats are specially designed to carry drilling platforms out to deep-sea locations.

• A typical drillship will have, in addition to all of the equipment normally found on a
large ocean ship, a drilling platform and derrick located on the middle of its deck.

• In addition, drillships contain a hole (or moonpool), extending right through the ship
down through the hull, which allows for the drill string to extend through the boat
down into the water.

• Drillships are often used to drill in very deep water, which can often be turbulent.
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 Types of Rigs
Offshore Rigs, cont.
5. Drillships, cont.
• Drillships use what is known as 'dynamic
positioning' systems.

• Drillships are equipped with electric motors

on the underside of the ship’s hull, capable
of propelling the ship in any direction.

• These motors are integrated into the ship’s

computer system, which uses satellite
positioning technology, in conjunction with
sensors located on the drilling template, to
ensure that the ship is directly above the
drill site at all times.
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 Types of Rigs
Offshore Rigs, cont.
5. Drillships, cont.

13
 Types of Rigs
Offshore Rigs, cont.
6. Platforms
• In some instances, when exploratory wells
find commercially viable natural gas or
petroleum deposits, it is economical to build
a permanent platform from which well
completion, extraction, and production can
occur.

• These large, permanent platforms are

extremely expensive, however, and generally
require large expected hydrocarbon deposits
to be economical to construct and usually up
to 40 wells are drilled from one platform.
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 Types of Rigs
Offshore Rigs, cont.
6. Platforms, cont.
• There are a number of different types
of permanent offshore platforms, each
useful for a particular depth range:
➢Fixed platforms
➢Tension leg platforms
➢Compliant towers
➢Subsea system
➢Seastar platforms
➢Spar platforms
➢Floating production system 15
 Rig Components
Rig Components
• There are many individual pieces of equipment on a rotary drilling rig.

• The most important items of equipment are shown in figure in the next slides.

• Although the pieces of equipment associated with these systems will vary
in design, these systems will be found on all drilling rigs.

• The equipment discussed in this chapter will be found on both land-based and
offshore drilling rigs

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 Rig Components
Rig Components, cont.
1. Crown Block
2. Mast
3. Monkey Board
4. Traveling Block
5. Hook
6. Swivel
7. Elevator
8. Kelly
9. Kelly Bushing
10. Master Bushing
11. Mouse Hole
12. Rat Hole
13. Drawworks
14. Weight Indicator 17
 Rig Components
Rig Components, cont.
15. Driller’s Console
16. Dog House
17. Rotary Hose
18. Accumulator Unit
19. Catwalk
20. Pipe Ramp
21. Pipe Rack
22. Substructure
23. Mud Return Line
24. Shale Shaker
25. Choke manifold
26. Mud Gas Separator
27. Degasser
28. Reserve Pit 18
 Rig Components
Rig Components, cont.
29. Mud Pit
30. Desander
31. Desilter
32. Mud Pump
33. Mud Discharge line
34. Bulk Mud Component Storage
35. Mud House
36. Water Tanks
37. Fuel Storage
38. Engines & Generators
39. Drilling Lines
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 Rig Components
Rig Components, cont.
• These individual pieces of
equipment can however be
grouped together into five
subsystems.

• These systems are: the hoisting

system, the circulation system,
the rotary system, the power
system and the blowout
prevention system.

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 Hoisting System
Hoisting System
• The hoisting system is a large pulley system which is used to lower and raise equipment
into and out of the well.
• The main components of hoisting system are:

➢ Derrick or mast
➢ Drawworks
➢ Crown block
➢ Traveling block
➢ Hook
➢ Drilling lines
➢ Fast line
➢ Deadline
➢ Deadline anchor
➢ Storage reel
➢ Drum
➢ Drum brake 21
 Hoisting System
Derrick or Mast
• Derrick is a large load-bearing structure, usually of bolted
construction.
• In drilling, the standard derrick has four legs standing at the
corners of the substructure and reaching to the crown block.
• The substructure is an assembly of heavy beams used to elevate
the derrick and provide space to install blowout preventers, casing
heads, and so forth.
• Mast is a portable derrick that is capable of being raised as a unit,
as distinguished from a standard derrick, which cannot be raised to
a working position as a unit.
• For transporting by land, the mast can be divided into two or more
sections to avoid excessive length extending from truck beds on
the highway. 22
 Hoisting System
Derrick or Mast, cont.
• The derrick and its substructure support the weight of the
drillstem at all times, whenever it is suspended from the
crown block or resting in the rotary table.

• The height of the derrick does not affect its load-bearing

capacity, but it is a factor in the length of the sections of
drillpipe that can be handled.

• The taller the derrick, the longer the section of pipe that
can be handled when going in or pulling out of the hole.

• This can allow for the adding of two or three joints of pipe at
the same time (called doubles and triples), which reduces
down-time during the drilling process. 23
 Hoisting System
Drawworks
• This is an assembly of a rotating drum, a series of shafts, clutches, chains and
gears for changing speed and for reversing.
• The main purpose of the drawworks is to reel out and reel in the drilling line.

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 Hoisting System
Drawworks, cont.
• One outstanding feature of the drawworks is the brake system, which enables the
driller to easily control a load of thousands of pounds of drillpipe or casing.

• On most rigs, there are at least two brake systems.

• One brake is a mechanical friction device and can bring the load to a complete
stop.

• The other brake is hydraulic or electric; it can control the speed of the descent of
a loaded traveling block, but is not capable of bringing it to a complete stop.

• An integral part of the drawworks is the gear system. This gives the driller a wide
choice of speeds for hoisting the drillstring.
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 Hoisting System
Drawworks, cont.
• Another feature of the drawworks are the two
catheads.

• The make-up cathead, on the drillers side, is used to

spin up and tighten the drillpipe joints.

• The other, located opposite the driller's position on

the drawworks is the breakout cathead. It is used to
loosen the drillpipe when the drillpipe is withdrawn
from the borehole.

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