Drilling rigs description

1. CHAPTER # 1
ROTARY DRILLING
RIGS
DRILLING ENGINEERING

3. Objective
To familiarize the student with
(1) the basic rotary drilling equipment and operational
procedures.
(2) introduce the student to drilling cost evaluation.
Drilling Team
 Large companies vs. small
 Specialized skills
 Service companies

4. Types of Wells
(1) Wildcat Well: to discover new petroleum reservoir.
(2) Development Well: exploit a known reservoir.
 Geological Group: recommends wildcat location.
 Reservoir Engg. Group: recommends development
 Drilling Group: designs and cost estimate.
 Tool pusher
 Driller
 Ass. Driller
 Derrickman (monkey board)
 2-3 rotary helpers (floormen – or – rough necks)
 Motor man
 Rig mechanics

5. Types of Wells...
 Rig electrician
 Company man
 Roust abouts
 Head roust about is the crane operator
 Mud engineer
 Casing crew
 Cementing service
 Legal Group: secures drilling rights
 Surveyors: establish and stake well location
 Drilling Contractor (Bid basis)
 Cost per Foot – drilling in area is routine.
 Cost per Day – unknown area
 Location Preparation
 Water Wells

6.  South Louisiana marshlands: inland barge
 Canadian Arctic Islands: man-made ice platform
 Extensive storage & Supply
 Manpower: Contractor
Operator
Service Company
Consultants
Types of Wells...

7. 1.1 Types of Drilling Rigs
Drilling and workover rigs come in a variety of shapes and sizes with
each having its own characteristics suited for a particular job.
Although there are many factors to be considered in selecting the
best rig for the job, a few are especially critical. They are:
 Surface location (land, inland water, offshore)
 Estimated maximum hole depth
 Horsepower requirements
 Cost
 Availability
 As can be imagined, the selecting of drilling and workover rigs is
best accomplished by use of good, sound judgement and
engineering experience.

8. Rigs
Marine Land
Bottom
Support
Semi/
Submersible
FLoating Mobile
Conventional
Platform
Drill ship
Jackup
Barge
Self -
Contained
Tendered
Jacknife
(Deeper)
Portable Mast
(Small)

9. Common Types of Drilling Rigs

10. 1. Land Rigs
As the name implies, these rigs are primarily used on
land; however, some have been transported offshore for
structure rig assignments. Most land rigs have to be
transported to location in sections, but some are self-
contained, permanently mounted on trucks. On location
they are usually set up on a board mat with a
substructure of 8 to 40 feet high, and a few are capable of
drilling holes to 30,000+ feet.

15. 2. Inland Barges
Inland Barges are composed of two types:
a. Barge mounted rigs
This type rig is capable of drilling in water depths from
0 to 12 feet. After being towed on location, the rig’s
hull is filled with water until it rests on bottom.
b. Posted barge mounted rigs
These type rigs have an upper deck supported by posts
from the lower hull. The deck contains all drilling
equipment and accommodations. Posted barges are
capable of drilling in water depths from 0 to 20 feet.
The rig is towed on location and the lower hull filled
with water to secure it on bottom.

16. 3. Submersible Rigs
These rigs are towed on location and are capable of working
in water depths from 18 to 70 feet. They are composed of an
upper deck and lower hull connected by beams. On some
types a large bottle, or something similar, is located on each
corner of the rig for stability. These bottles, as well as the
lower hull itself, are filled with water to set the rig on bottom
and stabilize against movement.
4. Jack-up Rigs
These rigs are normally towed on location, but a few are self-
propelled. They are composed of an upper deck supported
by either three or more legs attached to mats or spud cans
and are capable of working in water depths from 30 to 350
feet. These mats or cans rest on the ocean floor with the
deck jacked up into drilling position. There are two common
types of jack-up rigs; Bethlehem and Letourneau. The former
uses stabilized column legs attached to mats while the latter
uses three, truss-type legs mounted on spudcans.

17. 5. Semi-Submersible
These rigs can be towed on location, or some types are
self-propelled. They are capable of drilling in water depths
of 20 to 2,000+ feet. The rig itself remains stationary in the
the drilling position by a series of anchors (usually two
connected at each corner of the rig) positioned on the
ocean floor at a distance away from the rig. It should also
be noted that some Semis can be used as a submersible
rig.
6. Drill Ships
Drill ships are self-propelled drilling vessels capable of
drilling in water depths of 18 to 2,000+ feet. There are two
basic types of drill ships - one that positions itself with
anchors and one that uses dynamic positioning.

18. 7. Structure Rigs
Structure rigs are mounted on a fixed platform
with all drilling equipment secured on deck. The
rig itself is capable of changing positions on the
structure; however, the structure is permanently
based and designed to last many years. Structures
are capable of being set in water depths of 10 to
850+ feet. Structure set-ups usually follow a
successful exploratory program in order that many
development wells can be drilled from one
location. These wells are almost always
directional.

19. Rotary Drilling Process
Rotary table rotates the drill string
 Downward force applied to the bit
 Cuttings are lifted to the surface by circulating a fluid
down the drill string.
Main Component Parts of a Rotary Rig are:-
1. Power System
2. Hoisting System
3. Fluid Circulating System
4. Rotary System
5. Well Control System
6. Well Monitoring System

20. A Rotary Drilling Rig

21.  Most power consumed by :
hoisting system and fluid circulation
 Not used at same time
 Total power requirements 1000 – 3000 hp
 Old days steam
 Now internal combustion diesel engines types (1) diesel-
electric type (electric motors), (2) direct-drive type (gears-
chains) depending on power method.
1.2 Rig Power System

22. Are stated in terms of:
1. Output horse power
2. Torque
3. Fuel consumption for various engine speeds
P =  T = 2N.F.r (1.1)
Where,
P = shaft power (hp)
 = 2N, Angular velocity of the shaft (engine speed), rad/min
T = output torque (lb-ft)
N = Rev./min
Power-System Performance Characteristics

23.  Overall power efficiency determines the rate of fuel
consumption (Wf) at a given engine speed.
 Heating values (H Btu/lbm) of various fuels for internal
combustion engines are shown in Table 1.1.
Fuel Density (lbm/gal) Heating Value H(Btu/lbm)
Diesel 7.2 19,000
Gasoline 6.6 20,000
Butane 4.7 21,000
Methane -- 24,000
 Heat energy to the engine Qi
Qi = Wf.H (hp) (1.2)
Et = P /Qi = Energy Output / Energy Input (1.3)
Et = overall power system efficiency
Power-System Performance Characteristics …...

24. Example 1.1: A diesel engine gives an output torque of
1,740 ft-lbf at an engine speed of 1,200 rpm. If the
fuel consumption rate was 31.5 gal/hr, what is the
output power and overall efficiency of the engine?
Solution: The annular velocity, , is given by
=2(1,200) = 7,539.8 rad/min.
The power output can be computed using Eq. 1.1:
P=  T
hp
lbf
ft
lbf
ft
/
000
,
33
min
/
)
1740
(
8
.
539
,
7


 = 397.5 hp
Since the fuel type is diesel, the density  is 7.2 lbm/gal
and the heating value H is 19,000 Btu/lbm (Table 1.1).
Thus, the fuel consumption rate is wf is

25. wf = 31.5 gal/hr (7.2 lbm/gal) 





utes
hour
min
60
1
= 3.78 lbm/min
The total heat energy consumed by the engine is given by Eq.
1.2:
Qi= wf H
hp
lbf
ft
Btu
lbf
ft
lbm
Btu
lbm
min/
/
000
,
33
)
/
779
)(
/
000
,
19
min(
/
78
.
3



= 1,695.4 hp.
Thus, the overall efficiency of the engine at 1,200 rpm given
by Eq. 1.3 is
4
.
1695
5
.
397


i
t
Q
P
E = 0.234 or 23.4% Answer

26. Function:
Used to lower or raise drill strings, casing string and other subsurface equipment
into or out of hole.
Principal Components:
1. Derrick and substructure
2. Block and tackle
3. Draw works
Functions of Derrick:
1. Provides vertical height required to raise sections of pipe.
2. Rated according to their ability to withstand compressive loads and (wind
loads)
Components of Block and Tackle:
1. Crown block
2. Travelling block
3. Drilling line
1.3 Hoisting System

27. Components of
the hoisting
system

29. draw works
the
on
imposed
Load
block
ing
by travell
supported
Load

Principal Function:
To provide a mechanical advantage which permits easier
handling of large loads.
M= Mechanical advantage
F = tension in the fast line
The ideal mechanical advantage that assumes no friction in
the block and tackle can be determined from a force analysis
of the travelling block.
n Ff= W
f
F
W
M 
Mi = n
n
W
W

/

30. Input power of block and tackle = pi
Pi = Ff Vf (1.5)
Ff = draw works load
Vf = velocity of fast line
Ph = output power of the hook load
Pn = W.Vb (1.6)
W = travelling block load
Vb = velocity of travelling block
n
V
V f
b 
h
V
V f
b 
friction
no
V
F
n
V
nF
P
P
E
f
f
f
f
i
h
1
)
/
(
)
(





31. Power efficiency is
n
F
W
E
f
 actual system
Tension in the fast line
h
f
E
W
F  (1.7)
Eq. 1.7 is used to select drilling line size.
Fd = W + Ff + Fs (1.8a)
Fd = load applied to the derrick
Fs = tension in the lead line





 





En
En
E
W
n
W
En
W
W
Fd
1
fast dead
(1.8b)

32. Example 1.2: A rig must hoist a load of 300,000 lbf. The
drawworks can provide an input power to the block and
tackle system as high as 500hp. Eight lines are strung
between the crown block and traveling block.
Calculate
(i) the static tension in the fast line when upward motion is
impending,
(ii) the maximum hook horsepower available,
(iii) the maximum hoisting speed,
(iv) the actual derrick load
(v) the maximum equivalent derrick load, and
(vi) the derrick efficiency factor.
Assume that the rig floor is arranged as shown in Fig 1.17.

33. Solution:
(i) the power efficiency of n=8 is given as 0.841 in Table
1.2. The tension in the fast line is given by Eq. 1.7.
lbf
En
W
Ff 590
,
44
)
8
(
841
.
0
000
,
300



(ii) The maximum hook horsepower available is
Ph = E.I = 0.841 (500) = 420.5 hp
(iii) The maximum hoisting speed is given by



















 


lbf
hp
lbf
ft
hp
W
P
v h
b
000
,
300
min
/
000
,
33
5
.
420
= 46.3 ft/min

34. To pull a 90-ft stand would require
min
9
.
1
min
/
3
.
46
90


ft
ft
t
(iv) The actual derrick load is given by Eq. 1.8b
W
En
En
E
Fd 




 


1
)
000
,
300
(
)
8
(
841
.
0
)
8
(
841
.
0
841
.
0
1







 

 = 382,090 lbf
(v) The maximum equivalent load is given by Eq. 1.9
lbf
W
n
n
Fde 000
,
450
)
000
,
300
(
8
4
8
4








 

(vi) The derrick efficiency factor is











000
,
450
090
,
382
de
d
d
F
F
E 0.849 or 84.9% Answer

35. Drawworks
Provide the hoisting and braking power required to
raise or lower the heavy strings of the pipe.
Principle Parts
 The drums
 The brakes
 The transmission
 The catheads

36. Main Parts:
1. Swivel
2. Kelly
3. Rotary Drive
4. Rotary Table
5. Drill Pipe
6. Drill Collar
1. Swivel:
Supports the weight of the drillstring and permits
rotation i.e. Bail and Gooseneck.
2. Kelly:
Square or Hexagonal to be gripped easily. Torque is
transmitting through kelly bushings. Kelly saver sub is
used to prevent wear on the kelly threads.
1.4 Rotary System

37. 3. Slips:
During making up a joint slips are used to prevent
drillstring from falling in hole.
4. Rotary Drive:
Provides the power to turn the rotary table.
* Power Sub: can be used to connect casing.
5. Drill Pipe:
Specified by (a) Outer Diameter
(b) Weight per foot
(c) Steel grade
(d) Range Length
Range Length (ft)
1 18 to 22
2 27 to 30
3 38 to 45
Rotary System…...

38. * Tool Joint: Female is called Box.
Male is called Pin.
* Upset : Thicker portion of the pipe.
* Internal upset: Extra thick.
* Thread Type: Round, tungsten carbide hard facing.
6. Drill Collar:
Thick walled heavy steel pipe used to apply weight to the bit.
* Stabilizer Subs : Keep drill collars centralized.
* Capacity : Volume per unit Length.
Rotary System…...
)
(
4
2
1
2
2 d
d
Aa 


)
(
4
2
2
1 d
d
As 


2
4
d
Ap

 = Capacity of pipe (1.13)
= Capacity of annulus (1.14)
= Displacement (1.15)

39. Capacity and displacement
nomenclature
Rotary System…...

42. Example 1.4: A drillstring is composed of 7,000 ft of 5-
in., 19.5-lbm/ft drillpipe and 500 ft of 8-in. OD by
2.75-in ID drill collars when drilling a 9.875-in.
borehole. Assuming that the borehole remains in
gauge, compute the number of pump cycles required
to circulate mud from the surface to the bit and from
the bottom of the hole to the surface if the pump
factor is 0.178 bbl/cycle.
Solution:
For field units of feet and barrels, Eq. 1.13 becomes
ft
bbl
d
ft
in
gal
bbl
in
gal
in
d
Ap /
4
.
029
,
1
12
42
.
231
.
4
2
3
2
2







































Rotary System…...

43. Using Table 1.5, the inner diameter of 5-in., 19.5 lbm/ft
drillpipe is 4.276 in.; thus, the capacity of the drillpipe is
ft
bbl
01766
.
0
4
.
029
,
1
276
.
4 2


And the capacity of the drill collars is
ft
bbl
00735
.
0
4
.
029
,
1
75
.
2 2


The number of pump cycles required to circulate new
mud bit is given by
  .
719
1781
.
0
)
500
(
00735
.
0
)
000
,
7
(
01776
.
0
cycles
cycle
bbl
bbl



Rotary System…...

44. Similarly, the annular capacity outside the drillpipe is
given by
ft
bbl
0704
.
0
4
.
029
,
1
5
875
.
9 2
2



And the annulus capacity outside the drill collars is
ft
bbl
0326
.
0
4
.
029
,
1
8
875
.
9 2
2



The pump cycles required to circulate mud from the bottom
of the hole to the surface is given by
  cycles
cycle
bbl
858
,
2
1781
.
0
)
500
(
0326
.
0
)
000
,
7
(
0704
.
0


 Answer
Rotary System…...

45. Components of the rotating
system

46. Components:
1. Mud Pumps
2. Mud Pits
3. Mud Mixing Equipment
4. Contaminants Removal Equipment
Pumps:
Reciprocating Positive Displacement Piston Pumps.
 Two-Cylinders - Duplex (Double Acting Forward-Backward)
 Three-Cylinders - Triplex (Forward only Single Acting)
Duplex Triplex
Heavy Light
Bulky More Compact
High Output Pressure Lower
Pulsation Without Pulsation
Require more Maint. Cheaper to Operate
Therefore majority of new pumps are Triplex.
1.5 Circulating System

47. Advantages
(1) Ability to move high solid content fluids
(2) Ability to move large particles
(3) Ease to operation and maintenance
(4) Reliability
(5) Ability to operate over wide range of pressure s and flow rates by
changing the diameters of the pump liners and pistons.
Overall Pump Efficiency =Mechanical Efficiency x Volumetric Efficiency
Em= Mechanical Efficiency ~ 90%
Ev= Volumetric Efficiency ~ 100%
Two Circulating pumps are installed on the rig.
 Shallow portion both are used.
 Deeper portion one is used.
Circulating System…...

48. Components of the circulating System.
Circulating System…...

49. Circulating System
Circulating System…...

50. Pump Displacement
(1) Double Acting
Figure 1.25 (a)
dr = Piston rod diameter
dL= Liner diameter
Ls= Stroke Length (Stroke = one complete pump revolution).
Forward Stroke Volume Displaced = (/4) dL
2 Ls
Backward Stroke Volume Displaced = (/4) (dL
2 - dr
2 ) Ls
(for one Cylinder)
Total Volume =Fp= 2 Ls(/4) (2LL
2 - Lr
2 ) . Ev (1.10)
(for two Cylinders)
Fp= Pump factor or pump displacement cycle.
Circulating System…...

52. Example 1.3: Compute the pump factor in units of
barrels per stroke for a duplex pump having 6.5-in.
liners, 2.54-in. rods, 18-in. strokes and a volumetric
efficiency of 90%?
Solution:
The pump factor for a duplex pump can be
determined using Eq 1.10:
Fp = 2 Ls(/4) (2LL
2 - Lr
2 ) . Ev
= (/2) (18) [ 2(6.5)2 - (2.5)2] . (0.9)
= 1991.2 in.3 /stroke
or = 0.2052 bbl/stroke. Answer

53. (2) Triplex Acting
Figure 1.25(b)
Fp= 2 (/4) dL
2 Ls. Ev (1.11)
q=flow rate = Fp . N
(Where N = no. of cycles per unit time)
Pumps are rated for
1. Hydraulic Power
2. Maximum Pressure
3. Maximum Flowrate
1714
q
P
PH



PH = Pump Pressure, hp
∆P = Increase in pressure, psi
q = Flow rate (gal/min)
∆P cannot more than 3500 psi
(1.12)
Circulating System…...

55. Flow conduits between pump and drill string include:
1. Surge chamber (Pulsation Damper)
2. 4 or 6 inch heavy-walled pipe connecting the pump
to a pump manifold located on the rig floor.
3. Standpipe and rotary hose.
4. Swivel
5. Kelly
Go over EXAMPLE 1.3.
Circulating System…...

56. 1. Shale shaker for coarse rock cuttings
2. Hydrocyclones and decanting centrifuge for fine particles.
3. Degasser
Gas as a drilling Fluid (Air, Natural gas)
1. Penetration rate is higher than water especially when
formation is strong and extremely low K.
2. Water flow is a problem.
3. Isolate by injecting
(a) Low Viscosity Plastic
(b) Silicon Tetrachloride
(c) Using Packers
4. Min. annular velocity is 3000 ft/min for injection pressure.
5. Use Foam.
Contaminant Removal
Circulating System…...

57. Parameters displayed
1. Depth
2. Penetration rate
3. Hook Load
4. Rotary Speed
5. Rotary Torque
6. Pump Rate
7. Pump Pressure
8. Mud Density
9. Mud Temperature
10. Mud Salinity
11. Gas content of mud
12. Hazardous gas content of air
13. Pit Level
14. Mud Flow Rate.
* Centralized well monitoring system
* Mud Logger
* Subsurface well-monitoring and data telemetry systems (mud
pulser).
1.6 Well Monitoring System

58. Function:
Prevents the uncontrolled flow of formation fluids from the
wellbore.
Kick:
Flow of formation fluids in the presence of drilling fluid
(blowout).
Uses:
1. Detect the Kick
2. Close the well at the surface.
3. Circulate the well under pressure to remove
formation fluids and increase density.
4. Move drillstring under pressure.
5. Divert flow away from rig personnel and equipment.
1.7 Well Control System

59. Kick Detection During Drilling Operation

60. Kick Detection:
a. Pit volume indicator
b. Flow indicator
c. Hole fill up indicator (during tripping)
d. Count the pump strokes.
BOP (Blow Out Preventer)
Multiple BOP’S used in series: BOP Stack
Ram Preventers Semi circular openings which
Pipe Rams match diameter of pipe
Blind Rams : Closes the hole, no pipe present.
Shear Rams: Blind rams that shear the pipe.
Working press: 2000, 5000, 10000, 15000 psig.
Annular Preventers (Bag-type): Rubber Ring
BOPE:Closed hydraulically or using screw-type locking.
Well Control System…...

61. Accumulators
High pressure hydraulic system used to close the BOP.
* Fluid Capacity : 40, 80 120 gal.
* Max. Operating Pressure : 1500-3000 psig.
* has a small pump independent of rig power.
Strip Pipe
Lower pipe with preventer closed. Must be able to vary
closing pressure using pressure regulating system.
Drilling Spool
Placed between ram preventers
(1) provide space for stripping
(2) flowline attached to it.
Well Control System…...

62. Kill Line
conduit used to pump into the annulus.
Choke Line Conduit used to release fluid
Diverter Line from the annulus.
Drilling Spools
Must be large enough to allow next casing to be put in
place without removing the BOP.
Casing Head (Braden Head)
Attached to BOP, welded to the first string of casing
cemented in the well.
Control Panel
To operate the BOP stack. RSRRS
Well Control System…...

63. Rotating Head
Seals around the kelly at top of BOP stack, used for drilling with slight
surface pressure at annulus.
Kelly Cock
Close the flow inside kelly.
Internal Blowout Preventers
Prevents flow inside drill string.
Adjustable Choke
Used during Kick circulation, controlled from a remote panel on the rig
floor.
Sufficient pressure must be held against the well by the choke so that
the bottomhole pressure in the well is maintained slightly above the
formation pressure.
* Working Press Systems: 2000,3000,5000,10000,15000 psig.
Well Control System…...