Pet r o l eu m En g i n eer i n g 411 Well Dr il illi ling ng
Less Le sson on 28 SMD Wel l Co n t r o l 1
Subsea Mudlift Drilling ( SMD ) Note Pump and ReturnLine 2
DESIGN PROJECT Your PETE 411 Design Project is Due in Dr. J-W’s Office by 5 p.m. on Monday, Dec. 9, 2002 Monday, Dec. 2 is set aside for you to get together with your team mates to work on the project during regular class hours. 3
Contents g
Review of Conventional Well Control
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Kick Detection in SMD
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Kick containment in SMD
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Behavior of Real Gases in SMD Wells
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Well Control in SMD 4
Kick Detection & Well Control - Review - Conventional g
Kick Indication (what is a KICK?)
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Kick Detection (confirmation)
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Kick Containment (stop flow into well)
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Circulate Kick out of hole
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Increase Mud Weight in hole (if necessary) 5
Circulate Kick out of hole Conventional Wait and Weight Method
Old Mud
Kick
Kill Mud
BHP = Constant Keep the BHP constant throughout 6
Gas Kick Behavior - Perfect Gas Maximum Choke Pressure = 1,000 psia. BHP = 6,000 psia Effect of Temperature Gradient 0
0.02 deg F/ft 2,000
0.00 deg F/ft
t f 4,000 , h t 6,000 p e D 8,000
0.01 deg F/ft
10,000 12,000 0
10
20
30
40
50
60
70
Kick Volume, bbls 7
Z-Factor - In Shallow Wells Gas Specific Gravity = 0.65
(S.G. of air = 1)
1.4 r 1.2 o t c a F 1.0 y t i ) l i r o 0.8 b i t s c s a e r F - 0.6 p Z ( m o 0.4 C s a 0.2 G
30 F 60 F 100 F 150 F 200 F 300 F 400 F
0.0 0
1,000 2,000 3,000 4,000 5,000 6,000 7,000 8,000
Pressure, psig 8
Shallow Gas Kick - Summary Effect of Temp erature and Z-Factor 0 2,000 t f 4,000 , h t 6,000 p e D 8,000
0.02 deg F/ft
Real Gas Ideal Gas PV = constant
10,000 12,000 0
10
20
30
40
50
60
70
Kick Volume, bb ls
9
Gas Kicks in Deep SMD Wells Ki ck Vol u me vs. Depth 0 5,000
MudLine
10,000
t f , h t 15,000 p e D
MudLift Pump
20,000
As expected, most of the expansion occurs in the top 3,000 ft or so
25,000 30,000 0
5
10
15
20
25
30
Kick Volum e, bb l 10
Gas Kicks in Deep SMD Wells Ki ck Vol u me vs . Dept h 0
PV = ZnRT 5,000 10,000
t f , h t 15,000 p e D
PV = constant
20,000 25,000 30,000 0
5
10
15
20
25
30
35
40
45
50
Kick Volum e, bb l
11
Gas Kick Behavior - Z-Factor Gas Specific Gravity = 0.65
(S.G. of air = 1)
3.0 ) r o t c 2.5 a F Z ( y 2.0 t i l i b i s 1.5 s e r p m o 1.0 C
30 60 100 150 200 300 400
pV=ZnRT
o
Temperature, F
0.5 0
5,000
10,000
15,000
20,000
25,000
Pressure, psig 12
Subsea Mudlift Drilling System FLOATER
Surface Pump: Constant Rate Mudlift: Const. Inlet Press. SEAFLOOR
~SEAWATER HYDROSTATIC PRESSURE BOP
10,000’
MUDLIFT
30,000’
KICK
What next?? 13
Kick Detection and Control 700 Kick Detected - - Slow d ow n Seafloo r Pump n 690 i m / l a g 680 , e t a R670 n o i t a 660 l u c r i C650
Kick begins
SEAFL OOR PUMP SURFACE PUMP
640 -30
-20
-10
0
10
20
30
Tim e, min utes 14
Kick Detection and Control
Influx has stop ped and pressur es have stabilized
A
TM
15
700 n 690 i m / l a g 680 , e t a R 670 n o i t a 660 l u c r i C 650
Kic k Detection Detected - - Slow dowControl n Seafloo r Pump Kick and
Kick b egins
SEAFL OOR PUMP SURFACE PUMP
640 -30
-20
-10
0
10
20
30
40
50
Tim e, min utes
A
TM
16
Standpipe Pressure vs. Time 5,000 i s p , e r u s s e r P
Start cir culating kick out of h ole
Conventional
4,000 Kill mud e nters to p of drillpipe
3,000 2,000
Kill mud at bit
SMD
1,000 0 0
200
400
600
800
Time, minutes 17
Surface Choke Pressure vs. Time 1,400 Top of kick at surface
1,200
Start circulating kick out
i s 1,000 p , 800 e r u 600 s s e r 400 P 200
Kill mud enters annulus
SICP SIDPP CONVENTIONAL
Kick out of return line
0 0
100
200
300
400
500
600
700
Time, minutes 18
Pit Gain vs. Time s l b b , n i a G e m u l o V t i P
70 SMD
60 50 40 30 20
Conventional
10 0 0
100
200
300
400
500
600
700
Time, minutes 19
Press ure at t h e Sea Floo r vs. Tim e 8,000 i s p , e r u s s e r P
Conventional
7,000 Kick at seafloo r
6,000
Kill mud at seafloo r
5,000 Pressure at inlet to Mudlift System
4,000
SMD
Start circul ating kick ou t
3,000 2,000
Kill mud ente rs annulus
1,000 0 0
200
400
600
800
Time, minutes 20
Kick Detection Method
Still Valid for SMD?
Pit Gain
Still valid
Flow Rate Increase (Returns)
Much Better
Well Flows With Rig Pump Off
… U-tubing ...
Fluid Fill-up on Trips
… More complicated
Increased Hook Load
Still Valid
Drop in Standpipe Pressure
Better
Drop in BHP - MWD
Still Valid
Drilling Break
Still valid
Decreased Mud Weight (Gas Cut)
Still valid 21
Well Control Summary g
Most Conventional kick detection methods are still valid
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New differential flow rate method better - use with computer monitoring
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Lower standpipe pressure makes kick detection easier and faster
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Conventional well control can be adapted with modifications 22
Well Control Summary cont’d g Not necessary to shut well in … g
Seafloor pump controls the BHP
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Surface choke pressure generally does not affect wellbore pressures
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Well control training will be essential !!
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General Summary Subsea Mudlift Drilling is a method that offers potential for lowering drilling costs in very deep waters. ( fewer casing strings, smaller rigs, less time on location, larger hole ) The method utilizes one or more small-diameter return lines from the seafloor to the surface. The drillpipe is not inside a return line. 24
Summary - cont’d A “mudlift” system is used in the return line thereby making a “dual-density” mud system possible. Wellhead pressure is maintained at seawater hydrostatic, so well is “dead” at all times Well control is quite similar to that in conventional drilling with a riser - There are some real advantages: higher margins, choke line ∆P, etc. 25
A
TM
26
U-Tubing in SMD
A
TM
FLOATER ~SEAWATER HYDROSTATIC PRESSURE
STATIC FLUID LEVEL
BOP
MUDLIFT
27
Static Pressures - SMD ANNULUS AND RETURN LINE DRILLSTRING PRESSURE SEAFLOOR
DEPTH SEA WATER HYDROSTATIC PRESSURE
PRESSURE 28
