Pemex Short Course
Offshore Drilling
Lesson 1
Introduction
1
Lesson 1 - Introduction
Floating Drilling Outline
Floating Drilling Vessels
Types of Motion
Types of Waves
When is Drilling Possible (WOW)
Vessel Capacities
Movement of Liquids
2
Introduction - cont’d
Instructor: Jerome J. Schubert
Phone: 979/862-1195
E-mail: schubert@spindletop.tamu.edu
3
Introduction - cont’d
Drilling Lessons:
Can be found on the web at:
http://pumpjack.tamu.edu/~schubert/
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References
1. Floating Drilling: Equipment and its Use,
Practical Drilling Technology, Vol.2, by Riley
Sheffield, Gulf Publishing Company, Houston,
TX, 1980.
2. Applied Drilling Engineering, by Adam T.
Bourgoyne Jr., Martin E. Chenevert. Keith K.
Millheim and F.S. Young. SPE Textbook Series,
Vol. 2, Society of Petroleum Engineers,
Richardson, TX, 1991.
5
References
1. IADC Deepwater Well Control Guidelines,
Published by the International Association of
Drilling Contractors, Houston, TX, 1998.
281-578-7171
2. Design for Reliability in Deepwater
Drilling Operations, by L. M. Harris. The
Petroleum Publishing Company, Tulsa, OK,
1979.
6
References - cont’d
3. An Introduction to Marine Drilling, by
Malcolm Maclachlan. Dayton’s Oilfield
Publications Limited, P. O. Box 11, Ledbury,
Herefordshire HR8 1BN, England, 1987.
4. Drilling Engineering, A complete Well
Planning Approach, by Neal Adams and
Tommie Carrier. PennWell Publishing
Company, Tulsa, OK, 1985.
7
References - cont’d
5. Practical Well Planning and Drilling
Manual, by Steve Devereux. PennWell
Publishing Company, Tulsa, OK, 1998.
6. Oilwell Drilling Engineering, Principles
and Practice, by H. Rabia. Graham &
Trotman. Printed by The Alden Press,
Oxford, UK, 1985.
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Schedule
•Introduction to Class,
•Deepwater Platforms
•Floating Vessels,
•Types of Motion, Station Keeping
•Wellheads and BOP’s in Floating Drilling
•Drilling Risers, High Pressure Riser
•Motion Compensation
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Schedule
• Pore Pressure and Prediction
• Fracture Gradients
• LWD and Formation Test
• Special Problems in Floating Drilling
• Shallow water Flows; Hydrates
• Dual Gradient Drilling
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Schedule
SpecialApplications
Well Control
11
Drilling Rigs
Drilling Systems
Drilling Rigs
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Rotary Drilling
Drilling Team
Drilling Rigs
Rig Power System
Hoisting System
Circulating System . . .
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Rotary Drilling - cont’d
The Rotary System
The Well Control System
Well-Monitoring System
Special Marine Equipment
Drilling Cost Analysis
Examples
14
Noble
Drilling’s
Cecil
Forbes
A Jack-Up
Rig
15
Sonat’s A Semi-
George Submersible
Washington Rig
16
Zapata’s
Trader
A Drillship
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18
TENSION LEG PLATFORM
19
Shell’s
Bullwinkle
World’s tallest
offshore structure
1,353’ water
depth
Production
began in 1989
45,000 b/d
80MM scf/d
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Fig. 1.5
Classification of
rotary drilling rigs
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Drilling Operations
Field Engineers, Drilling Foremen
A. Well planning prior to SPUD
B. Monitor drilling operations
C. After drilling, review drilling results and
recommend future improvements
- prepare report.
D. General duties.
What are the well requirements?
Objectives, safety, cost
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Criteria for determining
depth limitation
Derrick
Drawworks
Mud Pumps
Drillstring
Mud System
Blowout Preventer
Power Plant
23
A Rotary Rig
Hoisting System
24
Projection of
Drilling Lines
on Rig Floor
E = efficiency = Ph/Pi = W/(n Ff ) or Ff = W/(nE)… (1.7)
TOTAL
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Load on Derrick
(considering friction in sheaves)
Derrick Load = Hook Load
+ Fast Line Load
+ Dead Line Load
Fd = W + Ff + Fs
W W 1 E En
Fd W = W
En n En
E = overall efficiency: E = en
e.g., if individual sheave efficiency = 0.98 and n = 8, then E = 0.851 26
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 500 hp.
Eight lines are strung between the crown block
and traveling block. Calculate
1. The static tension in the fast line
when upward motion is impending,
2. the maximum hook horsepower
available,
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Example 1.2, cont.
3. the maximum hoisting speed,
4. the actual derrick load,
5. the maximum equivalent derrick
load, and,
6. the derrick efficiency factor.
Assume that the rig floor is arranged as
shown in Fig. 1.17.
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Solution
1. The power efficiency for n = 8 is
given as 0.841 in Table 1.2. The tension
in the fast line is given by Eq. 1.7.
W 300,000
F 44,590 lb
E n 0.841* 8
( alternatively, E = 0.988 = 0.851 )
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Solution
2. The maximum hook horsepower
available is
Ph = Epi = 0.841(500) = 420.5 hp.
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Solution
3. The maximum hoisting speed is given by
Ph
vb
W
33,000 ft - lbf / min
420.5 hp
hp
300,000 lbf
= 46.3 ft / min
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Solution to 3., cont.
To pull a 90-ft stand would require
90 ft
t 1.9 min.
46.3 ft / min
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Solution
4. The actual derrick load is given by
Eq.1.8b:
1 E En
Fd W
En
1 + 0.841 + 0.841(8)
= (300,000)
0.841(8)
= 382,090 lbf.
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Solution
5. The maximum equivalent load is given
by Eq.1.9:
n4 8 4
Fde W * 300 ,000
n 8
Fde 450 ,000 lbf
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Solution
6. The derrick efficiency factor is:
Fd 382,090
Ed
Fde 450,000
Ed 0.849 or 84.9%
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Drillship
- moored
36
37
Heave
Surge
Sway
Roll
Pitch
Yaw
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Vessel Motions
Motions restricted to the horizontal plane
SURGE: Translation fore and aft (X-axis)
SWAY: Translation port and starboard (Y-axis)
YAW: Rotation about the Z-axis (rotation about
the moonpool)
Motions that operate in vertical planes
HEAVE: Translation up and down (Z-axis)
ROLL: Rotation about the X-axis
PITCH: Rotation about the Y-axis
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40
Wave Direction
Beam Waves
Head
Waves
Quartering Waves
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42
43
Roll vs. Significant Wave Height
Significant Wave Height, ft
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What is Significant Wave Height?
Significant wave height is the average height
of the 1/3 highest waves in a sample.
EXAMPLE The significant wave height in the
following sample is 24 ft.
7, 21, 19, 11, 18, 26, 13, 17, 25
[ Sign. WH = (21 + 26 + 25) / 3 = 24 ft ]
Avg. WH = (7, 21, 19, 11, 18, 26, 13, 17, 25) / 3 = 17.4 ft
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Heave vs. Significant Wave Height
Significant Wave Height, ft
46
Heave vs. Wave Approach Angle
BOW BEAM 47
Roll & Pitch vs. Wave Approach Angle
BOW BEAM 48
Typical Vessel Motion Limits - Criteria
Operation Wave Height Heave
ft ft
Drilling Ahead 30 10
Running and
Setting Casing 22 6
Landing BOP and Riser 15 3
Transferring Equipment 15 -
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50
SEMI
SHIP
10% vs. 1.5 %
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52
53
What is “lt” ?
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Some Definitions
Freeboard
Draft
Width
55
56
G = center of gravity. B = center of buoyancy
G is
above B!
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NOTE:
B has moved!
q
GZ =
righting
arm
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59
Dynamic Stability - for certification
60
Dynamic Stability
For adequate stability, the area under the
righting moment curve to the second
intercept or to the down-flooding angle,
whichever is less, must be a given amount
in excess of the area under the wind
heeling moment curve to the same limiting
angle. The excess of this area must be at
least 40% for shiplike vessels and 30% for
column-stabilized units (see Fig. above).
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Free Surface Effects
CG moves!
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Tall, narrow tank is more stable ...
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Effect of Fluid Level in Tank
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Effect of Partitions in Tank
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The Vessel - Classification
Three classification societies are particularly
important to offshore drilling. These societies are:
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