This document provides an overview of rig operations and equipment used in drilling wells. It describes the personnel involved in drilling, including the tool pusher, driller, derrick worker, and floor workers. It then explains the major surface and subsurface equipment used, including the hoisting system, drawworks, block and tackle, drilling line, mud circulation system, rotary system, and mud pumps. Finally, it discusses different types of rigs and factors considered when selecting a rig, such as water depth, load capacity, and stability.
4. Personnel Involved during Drilling
• The tool pusher. The drilling company
provides a supervisor for the rig while the well
is being drilled. At one time, this individual
was called a tool pusher.
• The driller. The driller is directly in charge of
the drilling four- or five-person rig crew and
generally operates the draw works, the
system of cables and pulleys used to run pipe
into the hole and to pull pipe from the well.
4
5. Personnel Involved during Drilling
• The derrick worker. The derrick worker
works high above the floor when the pipe is
being pulled or run during regular operations.
This position is commonly referred to as a
derrick man.
• The floor workers. These personnel are also
referred to as floor hands or roughnecks.
• Company representative.
• Third party personnel. 5
8. Rig Power System
• Most rig power is consumed by hoisting & fluid
circulating systems.
• The early drilling rigs were powered primarily by
steam. It become impractical, because of high fuel
consumption & large boiler plant required.
• Modern rigs are powered by internal combustion
diesel engine & classified as :
- diesel electric type
- direct drive type
8
9. Rig Power System
Figure 2: Engine Power Output
P = Power output, hp
= angular velocity, rad/min
T = output torque, ft-lbf
33,000 ft-lbf/min/hp
9
T
33,000
P
Q W H i f d 0.000393
P
t Q
i
E
2 N
10. Rig Power System
10
Where :
P [hp] shaft power developed by engine
[rad/min] angular velocity of the shaft
N [rev/min] shaft speed
T [ft-lbf] out-put torque
Qi [hp] heat energy consumption by engine
Wf [gal/hr] fuel consumption
H [BTU/lbm] heating value (diesel: 19,000 [BTU/lbm])
Et [1] overall power system efficiency
d [lbm/gal] density of fuel (diesel: 7.2 [lbm/gal])
33,000 conversion factor (ft-lbf/min/hp)
11. Rig Power System
• When the rig is operated at environments with non-standard
temperatures (85 [F]) or at high altitudes,
the mechanical horsepower equirements have to be
modified. This modification is according to API
standard 7B-11C:
a) Deduction of 3 % of the standard brake
horsepower for each 1,000 [ft] rise in altitude above
mean sea level,
b) Deduction of 1 % of the standard brake
horsepower for each 10 ◦ rise or fall in temperature
above or below 85 [F], respectively. 11
12. Hoisting System
• The main task of the hoisting system is to
lower and raise the drillstring, casings, and
other subsurface equipment into or out of the
well.
• The hoisting equipment itself consists of:
(1)draw works, (2) fast line, (3) crown block,
(4) travelling block, (5) dead line, (6) dead line
anchor, (7) storage reel, (8) hook and (9)
derrick.
12
15. Hoisting System
• “Making a connection”, the periodic process
of adding a new joint of drillpipe to the
drillstring as the hole deepens is referred.
• “Making a trip”, the process of moving the
drillstring out of the hole, change the bit or
alter the bottom-hole assembly, and lower the
drillstring again into the hole is referred.
15
16. Hoisting System
Figure 5: Sketch of slips for drill pipe(a), drill collar(b)
and casing(c)
16
19. Hoisting System
• Sometimes the drillstring is not completely
run out of the hole. It is just lifted up to the top
of the open-hole section and then lowered
back again while continuously circulating with
drilling mud. Such a trip, called “wiper trip”, is
carried out to clean the hole from remaining
cuttings that may have settled along the
open-hole section.
19
21. Derrick
• Derricks are classified (or rated) by the
American Petroleum Institute (API) according
to their height as well as their ability to
withstand wind and compressive loads.
• The higher the derrick is, the longer stands it
can handle which in turn reduces the tripping
time. Derricks that are capable to handle
stands of two, three or four joints are called to
be able to pull “doubles”, “thribbles”, or
“fourbles” respectively. 21
23. Block and Tackle
• The crown block, the travelling block and the
drilling line comprise the block and tackle
which permits the handling of large loads. To
lift and lower the heavy loads into and out of
the borehole, the drilling line is strung multiple
times between the crown and the travelling
block
23
25. Block and Tackle
• When no friction is assumed in the travelling
and the crown block (constant tension in the
drilling line), the hook load W creates a load
to the drawworks with is equal the load in the
fast line Ff which in turn depends on the
number the line is strung n between the
travelling and the crown block. This is
expressed with:
W = n . Ff
25
26. Block and Tackle
• The input power Pi of the block and tackle is
equal to the drawworks load Ff times the
velocity of the fast line νf .
Pi = Ff . vf
• The output power or “hook power” Ph is given
by the hook load times the velocity of the
travelling block.
Ph = W . vb
26
27. Block and Tackle
n
EB (0.98)
Where:
EB = efficiency factor
n = no. of lines
Figure 11: Efficiency factors for
different tacklings
27
Number of Lines
(n)
Efficiency
(E)
6 0.874
8 0.841
10 0.810
12 0.770
14 0.740
28. Drilling Line
• The drilling line is a wire rope that is made of
strands wounded around a steel core. It
ranges in diameter from ½ to 2 inch. Its
classification is based on the type of core, the
number of strands wrapped around the core,
and the number of individual wires per strand.
Examples of it can be see in figure 12.
28
30. Drilling Line
• Since the drilling line is constantly under
biaxial load of tension and bending, its
service life is to be evaluated using a rating
called “ton-mile”. By definition, a ton-mile is
the amount of work needed to move a 1-ton
load over a distance of 1 mile.
• When the drilling line has reached a specific
ton-mile limit, which is mainly due to round
trips, setting casings, coring and drilling, it is
removed from service.
30
31. Drilling Line
• The ton-mile wear can be estimated by:
a) Round trip
b) Drilling operation
c) Coring operation
d) Running casing
31
32. Round Trip
c
2
b
2,640,000
s e
10,560,000
Where:
Wb [lb] effective weight of travelling assembly
Ls[ft] length of a drillpipe stand
We [lb/ft] effective weight per foot of drillpipe
D [ft] hole depth
WC [lb] effective weight of drill collar assembly
less the effective weight of the same length of drillpipe
• It should be noted that the ton-miles are
independent of the number of lines strung. 32
R
W
D W
D L D W
T
33. Drilling Operation
• drilling a section from depth d1 to d2.
Coring Operation
TR2 (ton mile), work done for one round trip at depth d2 where coring stopped
TR1 (ton mile), work done for one round trip at depth d1 where coring started
33
2 1 T 3 T at d T at d d R R
2 1 2 c R R T T T
34. Running Casing
D L D W DW
0.5 cs cs b
(
)
10,560,000 2,640,000
T
sc
where:
• Lcs [ft] ... length of casing joint
• Wcs [lbm/ft] ... effective weight of casing in mud
• D [ft] ... hole depth
• Wb [lb] ... effective weight of travelling assembly
34
35. Drilling Line
• The drilling line is subjected to most severe wear at
the following two points:
1. The so called “pickup points”, which are at the
top of the crown block sheaves and at the
bottom of the travelling block sheaves during
tripping operations.
2. The so called “lap point”, which is located
where a new layer or lap of wire begins on the
drum of the drawworks.
35
36. Drawworks
• The purpose of the drawworks is to provide the
hoisting and breaking power to lift and lower the
heavy weights of drillstring and casings. The
drawworks itself consists of: (1) Drum, (2) Brakes,
(3) Transmission and (4) Catheads, see figure 13.
• The drum provides the movement of the drilling line
which in turn lifts and lowers the travelling block and
consequently lifts or lowers the loads on the hook.
36
38. Drawworks
v f n vb
E
W v
P b
h
33,000
Where:
• Ph [hp] ... drum power output
• νf [ft/min] ... velocity of the fast line
• νb [ft/min] ... velocity of the travelling block
• W [lb] ... hook load
• n [1] ... number of lines strung
• E [1] ... power efficiency of the block and tackle system
38
39. Drawworks
• The input power to the drawworks is influenced by
the efficiency of the chain drive and the shafts inside
the drawworks. This is expressed with:
K K
(1
)
n (1 K
)
E
n
Where:
• K [1] ... sheave and line efficiency, K = 0.9615 is an often used value.
39
40. Drawworks
• When lowering the hook load, the efficiency factor
and fast line load are determined by:
n K K
n
n
Lowering
K
E
1
(1 )
W K K
n
n
f Lowering
K
F
1
(1 )
Where:
• Ff [lbf] ... tension in the fast line 40
41. Circulation System
• The principle components of the mud circulation
system are:
(1) mud pumps
(2) flowlines
(3) drillpipe
(4) nozzles
(5) mud pits and tanks (settling tank, mixing tank,
suction tank)
(6) mud mixing equipment (mud mixing hopper)
(7) solid control equipment (shale shaker, degasser,
etc.) see Figure 14. 41
45. Circulation System - Mud
Pumps
There are two types of mud pumps in use today:
(1) duplex pump
(2) triplex pump
• Duplex Pump:
The duplex mud pump consists of two cylinders and
is double-acting.
• Triplex Pump:
The triplex mud pump consists of three cylinders
and is single-acting. 45
47. Mud Pumps
Pumps are generally rated according to their:
1. Hydraulic power,
2. Maximum pressure,
3. Maximum flow rate.
• Since the inlet pressure is essentially atmospheric
pressure, the increase of mud pressure due to the
mud pump is approximately equal the discharge
pressure.
47
48. Circulation System - Shale
Shaker
Figure 19: Shale Shaker
When the mud returns to the surface, it is lead over
shale shakers that are composed of one or more
vibrating screens over which the mud passes before
it is feed to the mud pits.
49. The Rotary System
• The function of the rotary system is to transmit
rotation to the drillstring and consequently rotate the
bit. During drilling operation, this rotation is to the
right.
• The main parts of the rotary system are:
(1) swivel
(2) rotary hose
(3) kelly
(4) rotary drive (master bushing, kelly bushing)
(5) rotary table
(6) drillstring 49
51. The Rotary System
• Swivel
The swivel which established a connection between
hook and kelly, has to be constructed extremely
robust.
• Kelly
The kelly has a square or hexagonal cross-section
and provides the rotation of the drillstring.
51
53. Rotary System
• Rotary Drive
The rotary drive consists of master bushing
and kelly pushing. The master bushing
receives its rotational momentum from the
compound and drives the kelly pushing which
in turn transfers the rotation to the kelly.
53
57. Rig Selection
• Following parameters are used to determine the
minimum criteria to select a suitable drilling rig:
(1) Static tension in the fast line when upward
motion is impending
(2) Maximum hook horsepower
(3) Maximum hoisting speed
(4) Actual derrick load
(5) Maximum equivalent derrick load
(6) Derrick efficiency factor
57
58. Rig Types
• Rig can be categorized as land and marine rig.
• Land rig :
(1) Cable tool
(2) Rotary rig (portable, standard derrick &
conventional rig)
• Marine Rig :
(1) Bottom supported : - Jackup
- Barge
(2) Floating rigs : - drillships
- semi-sumbersibles 58
59. Rig Selection
• Many design criteria are used in selecting the proper marine
rig. Major criteria are as follows:
- water depth rating
- derrick & substructure capacity
- physical rig size and weight
- deck load capacity
- stability in rough weather
- duration of drilling program
- rig rating features, such as horsepower, mud mixing
capacity
- exploratory vs development drilling
- availability & cost 59
60. Rig Selection
Pi Ff v f
P
v h
b
W
W
E E n
E n
Fd
1
W
n
n
Fde
4
4
1 1
F
d
E n
E n
F
E
de
d
60
61. Rig Selection
Where:
• Fd [lbf] ... load applied to derrick, sum of the hook load,
tension in the dead line and tension in the fast line
• Fde [lbf] ... maximum equivalent derrick load, equal to four
times the maximum leg load
• Ed [1] ... derrick efficiency factor
61
62. Drilling Cost Analysis
• To estimate the cost of realizing a well as well as to
perform economical evaluation of the drilling project,
before commencing the project, a so called AFE
(Authority For Expenditure) has to be prepared and
signed of by the operator.
• Within the AFE all cost items are listed as they
areknown or can be estimated at the planning
stage. During drilling, a close follow up of the actual
cost and a comparison with the estimated (and
authorized) ones are done on a daily bases.
63. Drilling Cost Analysis
• Generally, an AFE consists of the following
major groups:
(1) Wellsite preparation,
(2) Rig mobilization and rigging up,
(3) Rig Rental,
(4) Drilling Mud,
(5) Bits and Tools,
(6) Casings,
(7) Formation evaluation
64. Drilling Costs
• On of the most basic estimations of drilling
costs is given by:
C C t t
t
( )
C
b r b c t
f
D
Where
• Cf [$/ft] ... cost per unit depth
• Cb [$] ... cost of bit
• Cr [$/hr] ... fixed operating cost of rig per unit time
• D [ft] ... depth drilled
• tb [hr] ... total rotation time during the bit run
• tc [hr] ... total non-rotating time during the bit run
• tt [hr] ... trip time
65. Drilling Costs
• It has been found that drilling cost generally
tend to increase exponentially with depth.
Thus, the relationship as follow:
C a ebD
Where
C [$/ft] ... cost per unit depth
D [ft] ... depth drilled
66. Drilling Time
• The drilling time can be estimated based on
experience and historical penetration rates. Note
that the penetration rate depends on:
(1) type of bit used
(2) wear of bit used
(3) drilling parameters applied (WOB, RPM)
(4) hydraulics applied (hydraulic impact force due to
mud flow through nozzles)
(5) effectiveness of cuttings removal
(6) formation strength
(7) formation type.
67. Drilling Time
• To estimate the drilling time, the so called “penetration
rate equation”,
a D K e
dD
dt
2
• When the historical values of depth [ft] versus ROP
[ft/hr] are plotted on a semilogarithmic graph paper
(depth on linear scale), a straight line best-fit of the
equation estimates the drilling time.
a D
1
t 2.203 2
d e
a K
2 2.303
68. Drilling Time
• Here a2 is the reciprocal of the change in depth per
log cycle of the fitted straight line, K is the value of
ROP at the surface (intercept of fitted straight line at
depth = 0 ft).
• The depth that can be drilled with each individual bit
depends on
(1) bit condition when inserted,
(2) drilling parameters,
(3) rock strength
(4) rock abrasiveness.
69. Drilling Time
• Estimations of possible footages between trips can
be obtained from historical data or applying
equation:
1
D
2.303 2
where:
• Di [ft] ... depth of the last trip
• D [ft] ... depth of the next trip
a Di
b a L t
a
2
2
ln(2.303 2
2.303
70. Tripping Time
• Tripping time is also a major contributor to the total
time spent for drilling a well. Tripping can be either
scheduled (change of bit, reach of casing point,
scheduled well-cleaning circulation) or on-scheduled,
due to troubles.
• Following relationship can be applied to estimate
the tripping time to change the bit. Thus the
operations of trip out, change bit, trip in are
included:
71. Tripping Time
t
s
D
t 2
l
t
s
where:
• tt [hr] ... required time for round trip
• ts [hr] ... average time required to handle one stand
• D [ft or m] ... length of drillstring to trip
• ls [ft or m] ... average length of one stand
73. Subsurface Drilling Equipment
• Drill Bit
• MWD tools
• Mud Motor
• Drill Collar
• Heavy Weight Drill Pipe
• Drill Pipe
• This chapter will be discussed further in upcoming
class session.