DRILLING TECHNIQUE
Prof. dr. Davorin Matanović
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
Drilling rig
• The
purpose of drilling rig is-to
enable drilling the hole.
•The difference to stationary
facilities is that such rigs are
mobile, because they have to
be moved frequently.
•That requirement can not limit
the ability of the rig to drill
desired hole.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
2
Drilling rig
CROWN BLOCK
WIRE ROPE
TRAVELING BLOCK
HOOK
SWIVEL
ROTARY TABLE
DRAWWORK AND
BRAKES
MUD PUMP
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
3
Drilling rig
• The hole is a “mining object” that has minor diameter compared to the
length.
•It serves as the conduit for hydrocarbons from the layer to the surface.
•Drilling of the hole is accomplished by:
- connecting the bit and drill string,
- adding the pipes as the bit progresses,
- work of bit or crown at the bottom of the hole (drilling), along
with circulating mud to take out drilled particles
- withdrawing the drill string (e.g. to change worn bit).
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
4
1. Bit
2. Sub: bit – drill collar
3. Drill collars
4. Drill pipes
5. Sub: drill pipe - kelly
6. Kelly
7. Preventer stuck
8. Rotary hose
9. Swivel
10. Rotary table
11. Draw work
12. Power engines and transmission
13. Mud pumps
14. Mud tanks
15. Hook and traveling block
16. Mast/derrick
17. Wire rope/drilling line
18. Crown block
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
5
• Drilling rig schematics through three aspects of
energy transmission
a – sub; drill collar - bit
b – sub; kelly – drill pipe
c – sub; swivel - kelly
d – hook
e – wire rope
f – mechanical transmission
g – mud discharge lines
h – mechanical transmission
i – mechanical transmission
j – drive bushing
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
6
Drilling rig
• To
drill the hole it is necessary to:
- rotate the bit or crown,
- put weight on bit,
- remove drilled formation from the bottom of the
hole, to enable bit contact with clean surface of intact
formation.
• Drilling is unique mechanical and hydraulically process
that defines drilling rig construction and energy
transmission.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
7
Bit rotation
• There
are three ways to rotate
the bit:
- with rotary table,
- top drive and
- down hole motor.
•When rotation is generated
from the surface, all drill pipes
and drill collars with the bit are
rotated:
• by the use of rotary table
(needs kelly),
• or by top drive (no kelly).
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
8
Weight on the bit
• To penetrate with destructing
elements of the bit, certain
amount of the weight must be
obtained on the bit.
•The weight is achieved by the
use of the weight of the part of
drill collar, and the rest of the
weight of the bit, drill pipes,
kelly, swivel, traveling block
and hook are suspended on
the drill line and the draw work
through friction effect of the
brake.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
9
Removing parts of drilled formation
from the bottom of the hole
• When
bit rotates and is
weighted with certain axial force
his teeth or inserts crush or cut
the rock.
•Formation cuttings have to be
removed from the bottom hole
immediately.
•That enables bit contact with
intact rock and prevents pipe
stacking.
•That is the third component that
completes the term drilling in
basic sense.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
10
Drilling rig
• According to mobility drilling rigs can be:
- light, mobile, often set on adequate vehicle
and
- heavy plants, that are driven on the location in parts and there
assembled.
• Main defining parameters of the drilling rig are:
- rated derrick load (hook load),
- rig power, ability to rise and lower certain amount of drilling
equipment and the hook average speed,
- pumping volume and the working mud pump pressure,
- rotary table rotation speed or indirectly bit rotation speed,
- derrick dimensions and substructure dimensions and ratings.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
11
Derrick (mast)
•Derrick is trussed steel construction, that
serves as a carrying structure while drilling.
• Sheave blocks suspended on the drilling line
in such structure, carry drill stem during
drilling process or maneuver.
•A standard derrick is a structure with four
supporting legs situated on the picks of the
square supporting base.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
12
Derrick (mast)
•There are two different ways of
installing the derrick on the working
place (location):
- first is to assembly the derrick of
the segments in stand up position,
- second is to assembly the
segments when laying on the ground
and that erect the mast by the use of
own draw work and transmission.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
13
• Often
the mast or derrick is
erected on a substructure,
which serves two main
purposes:
(1) supports the rig
floro, and provides the
working space for equipment
and workers,
(2) provides the space
under the floor for well head
and blowout preventers.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
14
• Substructure
supports full
derrick load, rotary table load,
and the load of the drill stem that
can be suspended in the hole by
the slips, on the hook, or rests i
finger.
•When lowering casing in the hole
special spider serves to
accommodate pipes of large
diameter.
• Working floor also
accommodates draw work, rotary
table, control panels and auxiliary
equipment.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
15
Derrick (mast)
• Derrick
height does not
influence of his loading rating,
but influences on the length of
drill string that can be
manipulated as a section.
•Such length is defined by the
“working height” of the derrick,
that defines the distance of
hook traveling from the lowest
to the highest point inside the
derrick.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
16
Derrick (mast)
• As
the standard enabled
is the use three pipes
connected in the stand
with threaded connections.
•For average stand length
of 27 meters, standard
derrick height is about 41
meter.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
17
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
OPPENING HEIGHT
(FRONT SIDE)
CROWN WIDTH
STAND PIPE HEIGHT
BASE WIDTH
AT
BT
m
m
24,38 6,10
26,52 6,10
28,65 7,32
37,19 7,32
41,45 7,92
41,45 9,14
42,67 9,14
44,81 9,14
56,61 11,28
OPPENING HEIGHT
(DRAWWORK SIDE)
10
11
12
16
18
18A
19
20
25
Derrick (mast)
HEIGHT
MARK
Derrick characteristics are
defined in API spec.4F
CT
m
2,29
2,29
2,29
2,29
2,29
2,29
2,29
2,29
2,29
CT
m
7,21
7,21
7,21
7,21
7,21
7,21
8,08
8,08
8,08
DT
m
1,68
1,68
1,68
1,68
1,68
1,68
2,29
1,97
2,29
ET
m
2,44
2,44
2,44
2,44
3,66
3,66
5,18
5,18
5,18
Basic
derrick
dimensions
Tolerances:
AT ±0,1524 m;
BT ±0,127 m;
CT +1,0668 m;
DT ±0,0508 m;
ET ±0,1524 m
18
Derrick load-bearing
capacity
• The
derrick must carry full load of drill stem while drilling or
when suspended in rotary, or set up in finger. That results with
stresses and strains. Additional load is generated when
derrick with pipes in finger is exposed to strong wind or
vibrations of any kind or reason. Because of that the derrick
must be designed to withstand loads of doubled amount
compared with those calculated for the job:
Derrick load-bearing capacity is that amount of weight that can be
suspended in the derrick with adequate safety factor if additional
preconditions are fulfilled:
- all four legs are equally weighted
- there are no pipes in the derrick and no additional load due high
wind
- the weight of the derrick is neglected.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
19
Derrick load-bearing
capacity
•Maximal static hook load of conventional derrick is such load
that can be carried by the derrick and the hook with safety
factor (about 2). In that case the derrick weight, crown and
traveling block weight, wire rope weight and similar must be
included. Maximal hook load is:
2⋅k
Qk =
+ Qt
2⋅k + 4
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
Qk – maximal static hook load, N
k – number of sheaves in traveling
block,
Qt – allowed derrick load
(manufacturer data), N
20
Derrick erection
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
21
• Two
common means of
power transmission are:
mechanical and electrical.
• In the past most rigs were
mechanical.
• Analyzing efficacy of energy
transmission on drill rigs
greater effect is in use of
diesel-electric rigs.
• Mechanical transmission
uses clutches, couplings, belts,
gears, sprockets, chains,
shafts, bearings and pulleys to
transfer the power.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
Power
transmission
22
• On a diesel-electric rig, diesel
engines, which on land rigs are located
at ground level, away from the rig floor,
drive electric generators.
Power
transmission
• Produced electricity is sent through
cables to electric switch and control
station.
• Thereof, through additional cables
electricity goes to electric motors that
are attached directly to the drive shaft
of the user; mud pumps, draw work,
rotary table .
• Main advantage of such energy
transmission is in avoiding complicated
mechanical compound, that needs
precise aligning.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
23
Systems of energy transmission on rotary
drilling rig
(a) mechanical
(b) diesel-electric
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
24
Pipe manipulation system – Hoisting
system
•Draw work is a huge piece of
machinery that consists of a
drum with spooled wire rope,
additional drum called cathead
spool with catheads on either
end.
• To facilitate speed and
direction change, several other
shafts, clutches, chain-and-gear
drives are used.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
25
Pipe manipulation system – Hoisting
system
•Two main purposes of the
drawworks are:
• to lift pipes out of the hole,
and
• to lower the pipes back in the
hole.
•Work of hoisting system is done
by spooling (wrapping) wire rope
on the drum.
•When lowering, the gravitation is
used to initiate pipe movement.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
26
Pipe manipulation system – Hoisting
system
•Connected to the hoist are additional system that
allow driller to control the weight on the bit while
drilling, and with good accuracy the amount of drill
pipes or casing that is suspended on the hook – the
brakes.
•System comprises at last two kinds of brakes:
•friction brake (main brake)
•and hydraulic or electric brake (auxiliary
brakes).
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
27
Drawworks
• The
way of transforming or
energy transport is achieved by
- transmission system.
• System allows driller to change
drum rotation speed in two, four,
six or more (complicated)
values.
• Optimal system has minimal
two speeds, optimal four, and
maximal eight speeds.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
28
Drawworks - Catheads
• Another
feature of the drawworks
is achieved through cat shafts and
catheads.
•The makeup or spinning, cathead
on driller’s side is used to spin
and tighten drill pipe joints.
•The other on opposite side –
breakout cathead is used to
loosen the drill pipe when pulled
from the hole
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
29
Drawworks - Catheads
•Hemp rope or chain are used
to connect catheads with
pipes.
•Cathead can also be used to
manipulate with light weights
(e.g. one drill pipe from the
storage to the rig floor).
•For such purposes air hoists
are used mostly.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
30
Blocks
• The traveling block, crown block, and
drilling line are the three components are
essential in pipe manipulation.
• Their function is to support the load of
pipe in the derrick or mast as it is lowered
into or withdrawn from the hole.
CROWN
BLOCK
DEADLINE
FASTLINE
• During drilling operations, this load
consists of the hook, swivel, kelly, drill pipe,
drill collars, and a bit attached to the bottom
of the drill collars.
• During cementing operations, a string of
special pipe called casing, often a heavier
load than the drill pipe and collars, has to
be lowered into the hole and cemented.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
TRAVELING
BLOCK
WIRE
ROPE
α
DRUM
BRAKE
31
Blocks and drilling
line
• Three
main parts of the
system are:
•traveling block
•crown block, and
•drilling line
• The purpose of the system is
to accept all pipe loads
suspended on hook and
transfer them to the drawworks.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
32
Drilling line – wire
rope
• Wire rope is produced of same or different
diameter of steel wires.
•The inner core i produced of hemp fiber core
• Rope diameter is from 28,58 mm (1 1/8”) to
38,1 mm (1 1/2”).
• Proper use of the wire rope implies lubrication.
• Bending and dynamic loading of the rope
when combined with blocks cause the wear of
the rope so it has to be moved periodically
(slipped or cutoff).
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
33
Drilling line – wire rope
• One end of the rope is
suspended in the brake crest.
•The other end is fixed in the
dead line anchor
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
34
Blocks
• Large
pulleys or sheaves mounted
on a framework through which the
drilling line is fitted are up to 1,32 m
(52”) in diameter, and their axes up
to 0,3048 m (1ft).
•Number of sheaves in traveling
block is always for one sheave les
than in crown block (dead line
sheave).
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
35
Blocks
•The hook is suspended on the
traveling block.
-Hook can be an integral part of the
traveling block or can be hung on
the bail.
-Bail is also used to hung up the
swivel on the hook.
-On both sides of the hook are two
additional bails that bear elevator,
that serves in pipe manipulation.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
36
The rotating
equipment
•
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
The rotating equipment from top
to bottom consists of the:
1. swivel,
2. the kelly,
3. the rotary table,
4. the drill stem and
5. the bit.
37
The rotating
equipment
• The drill stem is the assembly of
equipment between the swivel
and the bit; including the:
- kelly,
- drill pipe, and
- drill collars.
• The term drill string simply refers
to the drill pipe and drill collars;
however, in the oil patch drill
string is often used to mean the
whole works.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
38
Swivel
•
•
•
A swivel is a remarkable
mechanical device.
It is attached to the
traveling block by a large
bail.
The swivel has three main
functions:
1.
2.
3.
it supports the weight of the drill
stem;
it allows the drill stem to rotate;
and
it provides a pressure-tight seal
and passageway for the drilling
mud to be pumped down the
inside of the drill stem.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
39
Swivel
•
•
•
The drilling fluid is under
extreme pressure sometimes exceeding 21 MPa
(3,000 pounds per square
inch (psi)).
The fluid comes in through
the gooseneck, a curved pipe
that connects the swivel to a
hose carrying the drilling fluid
from the mud pump.
The fluid then passes through
the washpipe, a vertical tube
in the center of the swivel
body, and into the kelly and
drill string.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
40
Kelly and Rotary Table
• The kelly is a three-, four-, or
six-sided length of pipe, about
12,19 m (40 feet) long, that is
the upper part of the drill stem.
– It serves as a passageway for the
drilling fluid on its way into the hole
and transmits the rotary movement
to the drill pipe and bit.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
41
Kelly and Rotary Table
• The kelly's upper end is
connected to the swivel,
and its lower end is
connected to the drill
pipe.
• The drill pipe screws onto
a device called a kelly
saver sub, or a saver sub.
• The sub is a short,
connecting fitting that
screws onto the bottom
of the kelly.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
42
Kelly and Rotary Table
• The kelly fits into
corresponding square
hexagonal opening in
device called a kelly,
drive, bushing.
a
or
a
or
– The kelly bushing fits into a
part of the rotary table
called the master, or
rotary, bushng.
– As the master
rotates, the kelly
and as the kelly
the drill string
rotate.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
bushing
rotates;
rotates,
and bit
43
Kelly and Rotary Table
• The bottom threads on
the sub are temporarily
joined with threads on
the top of each length of
drill pipe that is added to
the stem.
• The sub saves wear on
the threads of the kelly;
when the threads of the
sub become worn, the
sub
is
replaced
or
rethreaded.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
44
Upper kelly cock
• An upper kelly cock is a special
valve that can often be
recognized as a bulge on the
upper part of the kelly.
– The kelly cock can be closed to
shut off well pressure coming up
from inside the drill stem.
– Most kelly cocks require a special
wrench to operate the closing
valve, and the driller should make
sure that the kelly cock wrench is
kept in one place and that every
crew member knows where to
find it.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
45
Lower kelly cock
• A lower kelly cock (also called a drill
pipe safety valve or a drill stem
valve) is usually made up between
the lower end of the kelly and the top
joint of drill pipe.
– When the kelly is pulled up high above
the rotary table, as it usually is when a
joint of pipe is being added to the drill
stem (i.e., when a connection is being
made), the upper kelly cock cannot be
reached easily should it be necessary to
close in the drill stem.
– However, the lower kelly cock is readily
accessible when the kelly is raised.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
46
Rotary table
• Rotary drilling derives its name
from the rotary table.
– The rotary table is powered by the
compound or by its own electric
motor.
– The rotary table also accommodates
the slips - a tapered device lined with
strong, teeth like gripping elements
that hold the pipe suspended in the
hole when the kelly is disconnected.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
47
Rotary table
– The rotary table also
accommodates the slips - a
tapered device lined with
strong, teeth like gripping
elements that hold the pipe
suspended in the hole
when
the
kelly
is
disconnected.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
48
• The drill string is made
up of the drill pipe and
special,
heavy-walled
pipe called drill collars.
Drill String
– Each length of drill pipe is
about 9,14 m (30 feet)
long and is called a joint
of pipe.
– Each end of each joint is
threaded.
– The end of the joint with
the interior threads is
known as the box, and
the end of the joint with
the exterior threads is
called a pin.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
49
Drill String
– When pipe is made up
(joined together), the pin is
stabbed into the box and the
connection is tightened.
– The threaded ends of the
pipe are called tool joints
and are actually separate
parts that are welded onto
the outside of the drill pipe
body by the manufacturer
who cuts the threads to
industry specifications.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
50
Drill String
• Drill collars, like drill pipe, are steel
tubes through which mud can be
pumped.
a)
b)
a) standard
b) square
c) spiraled
C)
– Drill collars are heavier than drill pipe and
are used on the bottom part of the string
to put weight on the bit.
– This weight presses down on the bit to
get it to drill.
– Drill collars are about 9,14 m (30 feet)
long and, unlike the drill pipe that has
tool joints welded on, they have the
boxes and pins cut into them.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
51
Bits
• Two main types of bits have been
developed through the years for more
efficient drilling.
– Roller cone, or rock bits have cone-shaped
steel devices called cones that are free to
turn as the bit rotates.
– Most bits have three cones, although
some have two and some have four.
– Bit manufacturers either cut teeth out of
the cones or insert very hard tungsten
carbide buttons into the cones.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
52
Bits
• The teeth are responsible
for actually cutting or
gouging out the formation
as the bit is rotated.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
– All bits have passages drilled
through them to permit
drilling fluid to exit.
– Most bits have nozzles that
direct a high-velocity stream
or jet of drilling fluid to the
sides and bottom of each
cone so that rock cuttings are
swept out of the way as the
bit drills.
53
Diamond bits
• Diamond bits do not have
cones, nor do they have
teeth.
– Instead, several diamonds
are embedded into the
bottom and sides of the bit.
– Since diamonds are so hard,
diamond bits are especially
suited for drilling hard rock
formations but can also be
used effectively on soft
formations.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
54
Polycrystalline
diamond bits
• PDC bit cutting elements
have polycrystalline diamond
cutter with transitional layer
for strike absorption.
• They are embedded in bit
body and some
manufacturers make them
interchangeable.
• Are produced with steel
bodies or with impregnated
matrix.
• PDC bits have
interchangeable jet nozzles
made of tungsten carbide.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
55
Circulating System
• One of the essentials of rotary
drilling is a circulating system.
– For the rotary drilling system to
function, fluid must be circulated
downward through the drill stem,
around the bit, and upward in the
annular space between the drill stem
and the wall of the hole or the
casing. borehole.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
56
Circulating System
•
The principal purposes of circulation
fluid are to:
1.
2.
3.
4.
clean the bottom of the hole;
cool the bit;
flush cuttings from the hole;
support the walls of the well so that they do
not cave in; and
5. prevent the entry of formation fluid into the
borehole.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
57
Drilling Fluid
•
The circulation fluid is usually a liquid
but can also be air or gas. (Remember,
a fluid can be either a liquid or gas.)
– If the circulating, or drilling, fluid is a liquid,
it is made up mostly of water, although
occasionally oil is the major component.
– Both types of drilling fluids are called muds,
or drilling muds, because that is what they
appear to be.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
58
Drilling Fluid
•
Nevertheless, some drilling muds are quite a
bit more than just muds; literally scores of
special chemical additives and weighting
materials are put into them in order to achieve
their purpose with the greatest efficiency.
–
–
Special clays are used to give body to the mud, and
barite -a heavy mineral- is added to increase the
density of the mud.
Chemicals are used to control the thickness, or
viscosity, of the mud and to improve the ability of
the solid particles in the mud to deposit a layer, or
cake, on the wall of the hole.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
59
Drilling Fluid
•
In perhaps 1 percent of all oilwells drilled,
compressed air or natural gas is used as the
circulating fluid instead of mud.
–
–
Conditions are usually such that air drilling,
although a very efficient drilling method, cannot be
used.
Circulating with a liquid is less efficient but offers
the advantages of hydraulic lift (such as its ability
to lift cuttings made by the bit), pressure buildup
as depth increases, and so on.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
60
Mud Tanks and Pumps
•
The mud is mixed in the
mud tanks (often called
mud pits) with the help
of a mud hopper into
which most of the dry
ingredients for the mud
are poured. (It is very
important to note that
some dry ingredients,
especially one called
caustic, should never be
added to the mud
through the hopper.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
61
Mud Tanks and Pumps
•
The hopper works in such a
way that it often throws
out
a
little
of
the
ingredients being added to
it. Since caustic is just that
-caustic- one can easily
receive a severe burn from
such ejected particles.)
–
–
The tanks contain agitators
(paddle like projections) and
jets that mix the mud.
The mud is mixed with either
oil or water, depending on
the mud properties needed.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
62
•
The mud pump is the
primary component of any
fluid-circulating system.
–
–
–
Mud
Pumps
Pumps are either powered by
electric
motors
attached
directly to them, or driven by
the compound.
The pumps for rotary drilling
rigs have high ratings and
are capable of moving large
volumes of fluid at very high
pressures.
When circulating with air or
gas, the pump is replaced by
compressors, and mud tanks
are not required.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
63
The Mud Cycle
• The mud is pumped from
the mud suction tank
through a discharge line to
a standpipe.
– The standpipe is a steel pipe
mounted vertically on one leg
of the mast or derrick.
– The mud is pumped up the
standpipe and into a flexible,
very strong, reinforced rubber
hose called the rotary hose,
or kelly hose.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
64
The Mud Cycle
• The rotary hose is
connected to the swivel.
– The mud enters the swivel,
flows down through the kelly,
drill pipe and drill collars, and
exits at the bit.
– It then does a sharp U-turn
and heads back up the hole
through the annulus, a space
between the outside of the
drill string and wall of the
hole.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
65
The Mud Cycle
• Finally, the mud leaves the
hole through a steel pipe or
trough, called the mud
return line, and falls over a
vibrating, screen like device
called the shale shaker.
– The shaker screens out the
cuttings and dumps them into
a reserve pit.
– The mud then drains back
into the mud tanks and is
recycled back down the hole
by the mud pump.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
66
• If fine silt or sand is being
drilled, devices called
desilters and desanders are
mounted on the mud pits to
remove these very small
particles.
– Recirculating silt and sand
back down the hole makes the
mud heavier than desired and
might erode the drill string and
other components.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
67
Mud-Gas Separator
• A mud-gas separator is
an essential item of rig
equipment for handling a
gas kick.
– The mud-gas separator
saves the usable mud
coming out of the well
while a kick is being
circulated
out
and
separates the flammable
gas so it can be burned at
a safe distance from the
rig.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
68
Mud-Gas Separator
• Most mud-gas separators are made of a length of
large-diameter pipe.
– Interior baffles are used to slow down the mud-gas
stream, and a gooseneck arrangement at the bottom
permits the mud to flow to the shaker tank while
maintaining a fluid head to hold the gas at the top.
– The gas vent pipe at the top permits the gas to be flared
without too much back-pressure on the mud.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
69
• And, if a formation containing small amounts
of gas is encountered, a degasser is often
employed to remove the gas from the mud
before it is recirculated into the hole.
– Mud containing gas (gas-cut mud) should not be
recirculated because it decreases the density of the
mud, which could lead to a blowout.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
70
Well Control Equipment
• When the subject of well
control is mentioned, the
first thing to come to mind is
a blowout.
– A blowout is a very
undesirable occurrence on any
rig, because it endangers the
lives of the crew, can destroy
a rig worth millions of dollars,
wastes much-needed
petroleum, and may damage
the environment.
– Although relatively rare, a
blowout is an awesome sight.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
71
Well Control Equipment
• Fluid (either liquid or gas)
erupts from the well, usually
with great force, and often
ignites into a roaring inferno,
especially if the fluid is gas.
– The trouble arises when the
pressure in the formation is
higher than that in the well.
– The pressure in the well is
maintained by the type and
amount of drilling fluid being
circulated through it.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
72
Well Control Equipment
• Ordinarily, the drilling mud prevents the formation
fluid from getting into the borehole and blowing
out, but under certain conditions fluid sometimes
enters the hole and causes difficulties.
– The well kicks-that is, formation fluid enters the hole,
and some of the drilling mud is forced from the hole.
– If the crew does not take prompt and proper action at
the first indications of a kick, then eventually all of the
mud could be spewed out of the hole, allowing the
formation fluid to flow uncontrolled to the surface.
– The result is a blowout.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
73
Blowout Preventers
• Blowout preventers (BOPs),
in conjunction with other
equipment and techniques,
are used to close the well in
and allow the crew to control
a kick before it becomes a
blowout.
– The two basic types of
blowout preventers on a
drilling
rig
are
annular
preventers
and
ram
preventers.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
74
Blowout Preventers
• An annular preventer has
a rubber sealing element
that, when activated,
closes tightly around the
kelly, drill pipe, or drill
collars; or, if no part of
the drill stem is in the
hole, it closes on the
open hole.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
75
Blowout Preventers
• Ram preventers consist of
large, steel valves (the rams)
that have sealing elements.
– One type of ram preventer is
called a pipe ram because it
closes on the drill pipe and is
not able to affect a seal on an
open hole.
– Blind-ram preventers are used
to close an open hole.
– Shear rams, used mostly in
offshore drilling, cut the drill
pipe completely, thus sealing
the hole.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
76
Blowout Preventers
• Usually
several
blowout
preventers are installed on
top of the well in a stack
with the annular preventer
at the top and the pipe rams
and blind rams below.
– Several
preventers
are
installed together in this way
so that an impending blowout,
or kick, can be controlled even
if one or more of the
preventers fail.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
77
Accumulator
“Koomey”
• Blowout preventers are
opened and closed by
hydraulic fluid, which is
stored under pressure in a
device called an accumulator
– Several bottle-shaped or ballshaped containers are located
on the operating unit, and
hydraulic fluid is stored in
these containers.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
78
Accumulator
“Koomey”
• The accumulator is usually located at least 30,48 m
(100 feet) away from the rig floor so that, if a
blowout and fire occur, the accumulator is not
damaged and valves on the accumulator can be
used to close the preventers.
– A master control
panel
located on
the rig floor is
normally used to
operate
the
preventers.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
79
Choke Manifold
• When a kick is incurred, closing in the well
with one or more of the blowout
preventers is only the first step that must
be taken.
– In order to resume drilling, the kick must be
circulated out, and mud of the proper weight
must be circulated in (i.e., the well must be
killed, or brought under control).
– Therefore, a series of valves called the choke
manifold is installed as part of the system.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
80
• The
choke
manifold
is
connected to the
blowout
preventer stack
with a choke line.
Choke
Manifold
– When the well is
closed in with the
blowout
preventers,
the
mud and intruded
formation
fluid
are circulated out
the choke line
and through the
choke manifold.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
81
• A choke is simply a
valve.
Choke
– There are adjustable
chokes
and
fixed
chokes.
– An adjustable choke is
operated pneumatically
or hydraulically and
has an opening that is
capable
of
being
restricted or pinched
in; it may be infinitely
variable
in
size
between full open and
closed.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
82
– A fixed choke has a
flow
restriction
of
permanent size.
– In either case, the idea
is that the well can be
circulated "through the
choke" and adequate
back-pressure held on
the well to prevent the
further
entry
of
formation fluids while
well-killing procedures
are being carried out.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
Choke
83
Auxiliaries
• In addition to the major assemblies of
equipment that make up a drilling rig, a
great number of minor pieces of
equipment are necessary to carry on the
work.
– Some of these auxiliaries are:
• generators,
• air compressors,
• mud storage facilities, and
• various instruments.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
84
Electricity Generators
• Modern rotary rigs are provided with alternatingcurrent generators, nearly always diesel powered.
– Most of these generators have capacities of 50 to 100
kilowatts, although larger units are sometimes installed.
– They have enough capacity to carry the main power load
of the rig-excluding hoisting, pumping, and rotating-using
only one unit.
– Alternating-current electricity is used for rig lighting, shale
shaker motors, mud pit agitators, centrifugal pumps, rig
instruments, engine-cooling fans, and air conditioning for
the bunkhouses furnished on many large rigs.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
85
Air Compressors
• On mechanical rigs, a small compressor is usually
mounted on the engine compound to supply air for
the pneumatic controls and clutches.
– The compressor has a volume tank to allow reserve
storage of compressed air.
– Diesel-electric rigs usually have an electrically powered
compressor to furnish high-pressure air to pneumatic
controls and for other purposes, including starting the
main engines and operating the air-powered hoists, air
slips, air pumps on the BOP-operating equipment, water
wells, air-operated tools, and the like.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
86
Mud Storage Facility
• A complete mud system for a heavy-duty
drilling rig usually includes not only settling
tanks, or pits, but suction tanks, or pits, to
which the pump is connected.
– It also frequently includes a reserve or waste pit
where surplus mud and cuttings are accumulated
as drilling progresses.
– Some form of storage for the dry and liquid mud
materials that are to be added as the drilling
progresses is found on most rigs.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
87
Mud Storage Facility
• Dry mud storage bins, an oil tank, and
centrifugal pumps for mud mixing are
necessary for the circulating system.
– If a rig is in a remote location, adequate storage
for the dry components of the drilling mud is
especially desirable so that the mud may be
treated readily without waiting for a mud company
to deliver a supply from its warehouse.
– Sacked mud materials and chemicals are usually
stored under cover for protection from severe
weather.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
88
Drilling Instruments
• An instrumentation system is a
key part of almost all rigs today.
– It may be no more than one simple
weight indicator, or it may include a
great variety of things such as a
mud level recorder, a mud density
recorder, torque indicators and
recorders, and logging devices to
keep a continuous graphic record of
work being done on the rig,
particularly the depth being drilled.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
89
Drilling Instruments
• Figure shows the instruments
placed at the driller's position
for observing drill stem
weight, mud pit level, pump
pressure, rotary speed, tongline pull, and other variables.
– A mud logging unit, generally
supplied by a contracting
service company, may be used
to keep track of any indications
of oil and gas brought up in the
circulating fluid.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
90
Other Facilities
• Drilling rigs also generally include such facilities as fuel
storage installations; a change house (a place for rig
workers to change from their work clothes to street
clothes); a doghouse (a small structure on the rig
floor that serves as an office for the driller and as a
storage place for small tools); a tool house (a place to
store spare parts for the pumps and other
equipment); and other facilities. Rigs located in
remote areas frequently have a bunkhouse where the
rig crews live while on duty.
– Sometimes, the tool pusher is provided with a trailer that serves as an
office with a telephone and radio for communication with the head office
and as his living quarters while on duty.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
91
Other Facilities
• Offshore rigs are provided with sleeping quarters,
mess facilities, electric power, water supply, and
sewage facilities, as well as storage for enough dry
mud, chemicals, cement, oil, and other supplies to
operate the rig for many days.
– Most large rigs are equipped to continuously transmit
operation data by radio to the company headquarters.
– Good rig housekeeping requires that there be a place for
everything while drilling is underway.
– Pipe racks and casing racks are standard items used for
temporary storage.
– Provisions are made for moving and storing hand tools used
in rig maintenance.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
92
The Crew
• Although not a component of the rig as
such, the crew is a very important part of
the rig. Without the individuals in the
crew, the equipment for rotary drilling
would be worthless.
• Crews may consist of four, five, six, or
more individuals, depending on the size
and service rating of the rig itself.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
93
The Crew
• The tool pusher also called rig manager – is
the man in charge.
– His experience includes years of work on a drilling
rig as a crewman and driller;
– He has expert knowledge of well drilling, rig
machinery, tools and equipment.
– He directs the actual operation of the drilling rig
and the work performed by the drilling crew,
authorizes the employment of the crew and
coordinates the affairs of the operating company
and drilling contractor.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
94
The Crew
• The driller is in charge of
drilling; he operates the
drilling machinery.
– He is under the direct
supervision of the tool pusher
and is the overall supervisor
of the floor men.
– The driller gives the actual
instructions concerning work
on the rig to the other five or
six crew members.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
95
The Crew
• The derrick man works on the
monkey board, a small platform
located up in the derrick at a
level even with the upper end of
a stand of drill pipe.
– When the pipe is being tripped in
or out, he handles the upper end
of the pipe, guiding it to and from
the finger.
– When drilling is going on he is
responsible for maintaining the
drilling fluid or repairing the
pumps and other circulating
equipment.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
96
• The motorman is responsible
for the engines, fuel, and
auxiliaries.
• Electrician
maintains
and
repairs the electrical generating
and distribution system on the
rig.
• The floor man; rotary helper or
roughneck, is responsible for
handling the lower end of the
drill pipe when it is being
tripped in or out of the hole,
handle the tongs, maintain
equipment, keep it clean and
painted, and keep the rig in
general repair.
RudarskoRudarsko-geološ
geološkoko-naftni fakultet
The Crew
97