Petroleum Engineering 411 Well Drilling

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Petroleum Engineering 411Well Drilling

• Lesson 28
• SMD Well Control

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Subsea Mudlift Drilling ( SMD )Note Pump
and ReturnLine
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DESIGN PROJECT
Your PETE 411 Design Project is Due in Dr. J-Ws
Office by 5 p.m. on Monday, Dec. 9, 2002Monday,
Dec. 2 is set aside for you to get together with
your team mates to work on the project during
regular class hours.
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Contents -

• Review of Conventional Well Control
• Kick Detection in SMD
• Kick containment in SMD
• Behavior of Real Gases in SMD Wells
• Well Control in SMD

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Kick Detection Well Control- Review -
Conventional -

• Kick Indication (what is a KICK?)
• Kick Detection (confirmation)
• Kick Containment (stop flow into well)
• Circulate Kick out of hole
• Increase Mud Weight in hole (if necessary)

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Circulate Kick out of hole
Conventional Wait and Weight Method
Old Mud
Kill Mud
Kick
BHP Constant
Keep the BHP constant throughout
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Gas Kick Behavior - Perfect Gas
Maximum Choke Pressure 1,000 psia. BHP 6,000
psia
0.02 deg F/ft
0.00 deg F/ft
0.01 deg F/ft
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Z-Factor - In Shallow Wells
Gas Specific Gravity 0.65 (S.G. of air
1)
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Shallow Gas Kick - Summary
0.02 deg F/ft
Real Gas Ideal Gas PV
constant
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Gas Kicks in Deep SMD Wells
MudLine
MudLift Pump
As expected, most of the expansion occurs in the
top 3,000 ft or so
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Gas Kicks in Deep SMD Wells
PV ZnRT
PV constant
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Gas Kick Behavior - Z-Factor
Gas Specific Gravity 0.65 (S.G. of air
1)
3.0
30
60
pVZnRT
100
150
200
2.5
300
400
2.0
Compressibility (Z-Factor)
o
Temperature,
F
1.5
1.0
0.5
0
5,000
10,000
15,000
20,000
25,000
Pressure, psig
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Subsea Mudlift Drilling System
FLOATER
Surface Pump Constant Rate Mudlift Const. Inlet
Press.
SEAWATER HYDROSTATIC PRESSURE
10,000
SEAFLOOR
BOP
MUDLIFT
30,000
KICK
What next??
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Kick Detection and Control
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Kick Detection and Control
Influx has stopped and pressures have stabilized
ATM
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Kick Detection and Control
ATM
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SICP
CONVENTIONAL
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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
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• Well Control Summary
• Most Conventional kick detection methods are
  still valid
• New differential flow rate method - better
  - use with computer monitoring
• Lower standpipe pressure makes kick detection
  easier and faster
• Conventional well control can be adapted -
  with modifications

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• Well Control Summary contd
• Not necessary to shut well in
• Seafloor pump controls the BHP
• Surface choke pressure generally does not
  affect wellbore pressures
• 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.
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Summary - contd 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 DP, etc.
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ATM
THE END
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U-Tubing in SMD
ATM
FLOATER
SEAWATER HYDROSTATIC PRESSURE
STATIC FLUID LEVEL
MUDLIFT
BOP
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Static Pressures - SMD
ANNULUS AND RETURN LINE
DRILLSTRING PRESSURE
SEAFLOOR
DEPTH
SEA WATER HYDROSTATIC PRESSURE
PRESSURE