Transcript Balanced Cement Plug - University of Stavanger

Dual Gradient Drilling
Basic Technology
by Hans C. Juvkam-Wold
Lesson 3
Wellbore Pressures
3. Wellbore Pressures
Confidential to DGD JIP
Slide 1 of 72
Contents
• Static Pressures in a conventional wellbore
• Circulating Press. in a conventional wellbore
• Static Pressures in an DGD wellbore
• Circulating Pressures in DGD wellbores,
•
•
with and without Drillstring Valve (DSV)
Pressure Profiles During a Connection
Pressure Profiles when a Kick Occurs
3. Wellbore Pressures
Confidential to DGD JIP
Slide 2 of 72
Static Pressures in a
Conventional Wellbore
0
Mud Weight = 15 lb/gal
Gradient = 0.780 psi/ft
Same inside
and outside
the wellbore
10,000
0
3. Wellbore Pressures
PRESSURE, psi
Confidential to DGD JIP
7,800
Slide 3 of 72
Static Pressures in a
Conventional Wellbore
0
Mud Weight = 15 lb/gal
Gradient = 0.780 psi/ft
Same inside
and outside
the wellbore
10,000
0
3. Wellbore Pressures
PRESSURE, psi
Confidential to DGD JIP
7,800
Depth Pressure
ft
psi
0
1
2
3
10
100
1,000
2,000
3,000
5,000
10,000
0
0.78
1.56
2.34
7.8
78
780
1,560
2,340
3,900
7,800
Slide 4 of 72
Static Pressures in a Conventional
Wellbore (alternate view)
MW = 15 lb/gal
Gradient = 0.780 psi/ft
7,800
Top of
Drillpipe
0
Drillstring
0
3. Wellbore Pressures
Top of
Annulus
Bottom
of Hole
Annulus
10,000
Distance from Standpipe, ft
Confidential to DGD JIP
20,000
Slide 5 of 72
Circulating Pressures in a
Conventional Wellbore
SPP = ?
0
Drillstring Friction = 800 psi
Pressure Across bit = 1,200 psi
Annular Friction
= 200 psi
Mud Weight
= 15 lb/gal
Drillstring
& Annulus
Static
Drillstring
Circulating
Annulus
Circulating
10,000
Bit
0
3. Wellbore Pressures
PRESSURE, psi
Confidential to DGD JIP
BHP = ?
Slide 6 of 72
Circulating Pressures in a
Conventional Wellbore
SPP = 2,200 psi
( 800 + 1,200 + 200 = 2,200 )
0
Drillstring Friction
= 800 psi
Pressure Across bit = 1,200 psi
Annular Friction (AFP) = 200 psi
Mud Weight
= 15 lb/gal
Static, DS
& Annulus
Drillstring
Annulus
Circ. BHP = DPHYDRO + AFP
= 7,800
+ 200
= 8,000 psi
10,000
0
3. Wellbore Pressures
7,800
8,000
9,200 psi
PRESSURE, psi
Confidential to DGD JIP
Slide 7 of 72
Circulating Pressures in a
Conventional Wellbore (alt. view)
MW = 15 lb/gal
9,200 psi
Bit
Circ. BHP
= 8,000 psi
7,800
Static
2,200
Annulus
Drillstring
0
0
3. Wellbore Pressures
10,000
Distance from Standpipe, ft
Confidential to DGD JIP
20,000
Slide 8 of 72
Static Pressures - DGD
Seawater
Hydrostatic
BOP
DGD Mud
Hydrostatic
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Slide 9 of 72
Static Pressures
Conventional vs. DGD
Seawater
Hydrostatic
BOP
DGD Mud
Hydrostatic
Conventional
Hydrostatic
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Slide 10 of 72
Static Pressures - DGD
No DSV
Return Line
Seawater
Drillstring Hydrostatic
BOP
DGD Mud:
Drillstring
and Annulus
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Slide 11 of 72
U-tubing
Static
Circulating
STATIC
FLUID
LEVEL
BOP
3. Wellbore Pressures
Confidential to DGD JIP
Slide 12 of 72
What is Delta MW (DMW)?
= Mud hydrostatic - Seawater hydrostatic in the water column
Seawater Hydrostatic
= 0.052 * 8.6 * 10,000 = 4,472 psi
Mud Hydrostatic in the water column
= 0.052 * 15 * 10,000 = 7,800 psi
DMW = Difference in Hydrostatic
= 7,800 - 4,472 = 3,328 psi
4,472 psi
DMW
= 3,328 psi
PRESSURE
3. Wellbore Pressures
Note that the U-Tube driving
pressure is, typically,
DMW - 50 psi
Confidential to DGD JIP
Slide 13 of 72
Static Pressures in an
DGD Wellbore
0
SW Density = 8.6 lb/gal
Mud Weight = 16 lb/gal
10,000
What is
the BHP ?
20,000
0
3. Wellbore Pressures
PRESSURE, psi
Confidential to DGD JIP
Slide 14 of 72
0
Example Calculation
SW Density = 8.6 lb/gal
Mud Weight = 16 lb/gal
10,000
What is
the BHP ?
• Seawater hydrostatic
20,000
= 0.052 * 8.6 * 10,000 = 4,472 psi
• Mud Hydrostatic
= 0.052 * 16 * 10,000 = 8,320 psi
• BHP = 4,472 + 8,320
BHP = 12,792 psi
3. Wellbore Pressures
Confidential to DGD JIP
Slide 15 of 72
Example #2
If the 20,000-ft well discussed in the
previous example were to be drilled
conventionally, what mud weight
would you use in order to achieve
the same BHP?
Hint:
Use the same mud weight from
top to bottom.
3. Wellbore Pressures
Confidential to DGD JIP
p = 12,792 psi
Slide 16 of 72
Example #2 - Solution
BHP,
p = 0.052 * MW * Depth
12,792 = 0.052 * MW * 20,000
MW = 12,792 / (0.052 * 20,000)
MW = 12.30 lb/gal
{ Note that (8.6 + 16.0) /2 = 12.30 …}
any comments?
3. Wellbore Pressures
Confidential to DGD JIP
p = 12,792 psi
Slide 17 of 72
Example #3
A new well is to be drilled
using DGD.
Water depth is 8,000 ft.
Depth BML is 19,000 ft.
BHP is expected to be
20,000 psi.
8,000’
ML
19,000’
What DGD Mud weight
will be required?
p = 20,000 psi
3. Wellbore Pressures
Confidential to DGD JIP
Slide 18 of 72
Example #3 - Solution
At ML,
p1 = 0.052 * Density * Depth
8,000’
p1 = 0.052 * 8.6 * 8,000 = 3,578 psi
ML
Hydrostatic Pressure below the ML,
p2 = 20,000 - 3,578 = 16,422 psi
19,000’
MW = 16,422 / (0.052 * 19,000)
MW = 16.62 lb/gal
p = 20,000 psi
3. Wellbore Pressures
Confidential to DGD JIP
Slide 19 of 72
Static Pressures - DGD (No DSV)
Return Line
Drillstring Hydrostatic
BOP
DGD Mud:
Drillstring
and Annulus
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Slide 20 of 72
Static Pressures in DGD Wellbore
No DSV (alternate view)
Annulus
Drillstring
BHP
Static
Fluid
Level
in DP
Bottom
of the
Hole
Static
Pressure
across
the
Mudlift
Pump
0
0
3. Wellbore Pressures
10,000
Distance from Standpipe, ft
Confidential to DGD JIP
20,000
Slide 21 of 72
Static Pressures - DGD (w / DSV)
Static Pressure across
the Mudlift Pump
Return Line
Drillstring
BOP
Annulus
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
DSV
Slide 22 of 72
Circulating Pressures
- DGD w / DSV
Return
Line
Drillstring
BOP
MLP
Annulus
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Bit +
DSV
Slide 23 of 72
Circ. Pressures in a Conventional
Wellbore (alternate view)
MW = 15 lb/gal
Drillstring
Bit
AFP
7,800
Static
Annulus
0
0
3. Wellbore Pressures
10,000
Distance from Standpipe, ft
Confidential to DGD JIP
20,000
Slide 24 of 72
Circ. Pressures in an DGD Wellbore
(alternate view)
MW = 15 lb/gal
Drillstring
Bit
AFP
7,800
Annulus
Static
Conventional
Drillstring
0
0
3. Wellbore Pressures
MLP
Annulus
10,000
Distance from Standpipe, ft
Confidential to DGD JIP
20,000
Slide 25 of 72
Factors Affecting Pressure
Profile in Wellbore
• Hydrostatics
• Friction
(mud, water, gas, cement slurry)
– Drillpipe
– Annulus
• Area Change
• Kick
(nozzle, tool joint, MWD Sub, etc.)
– Hydrostatics (kick density lower than mud density)
– Kick Intensity
3. Wellbore Pressures
Confidential to DGD JIP
Slide 26 of 72
Effect of Hydrostatics on
Wellbore Pressure Profile
0
Gas @ 1
lb/gal
Cement @
16 lb/gal
Mud @
12 lb/gal
Water @
8.6 lb/gal
10,000
0
520
4,472
6,240
8,320
Pressure, psi
3. Wellbore Pressures
Confidential to DGD JIP
Slide 27 of 72
Effect of Hydrostatics on
Wellbore Pressure Profile
Drillstring
8,320
Annulus
Mud @ 12
lb/gal
6,240
Cement @
16 lb/gal
4,472
Water @
8.6 lb/gal
520
0
Gas @
1 lb/gal
0
3. Wellbore Pressures
10,000
Distance from Standpipe, ft
Confidential to DGD JIP
20,000
Slide 28 of 72
Effect of Friction on Pressure
Profile in Conventional Wellbore
High Circ. Rate
Bit
MW = 15 lb/gal
Medium Circ. Rate
Static
Drillstring
0
0
Annulus
10,000
Distance from Standpipe, ft
3. Wellbore Pressures
Higher
circulation
Rate
means
Higher
Friction
Loss
Confidential to DGD JIP
20,000
Slide 29 of 72
“Dynamic Shut-in” of Kick
(Stop Influx while Circulating)
• When well kicks, MLP speeds up (pump is
controlled by constant pump inlet pressure)
• Change pump from pressure control to rate
control. Slow down MLP to pre-kick rate
• As a result the wellbore pressure increases
until the influx stops (PWELLBORE = PFORMATION)
• The kick is now under control
• SIDP can now be determined
3. Wellbore Pressures
Confidential to DGD JIP
Slide 30 of 72
Subsea Mudlift Drilling System
FLOATER
Surface Pump: Constant Rate
Mudlift Pump: Const. Inlet Press.
SEAFLOOR
~SEAWATER
HYDROSTATIC
PRESSURE
BOP
10,000’
MUDLIFT
30,000’
KICK
3. Wellbore Pressures
What next??
Confidential to DGD JIP
Slide 31 of 72
Kick Detection and Control
700
Circulation Rate, gal/min
Kick Detected - - Slow down Seafloor Pump
690
680
Kick begins
SEAFLOOR PUMP
670
SURFACE PUMP
660
650
640
-30
-20
-10
0
10
20
Time, minutes
3. Wellbore Pressures
Confidential to DGD JIP
Slide 32 of 72
30
Kick Detection and Control
Influx has stopped and
pressures have stabilized
TM3. Wellbore Pressures
A
Confidential to DGD JIP
Slide 33 of 72
700
Kick Detection and Control
Circulation Rate, gal/min
Kick Detected - - Slow down Seafloor Pump
690
680
Kick begins
SEAFLOOR PUMP
670
SURFACE PUMP
660
650
640
-30
-20
-10
0
10
20
30
40
T ime, minutes
TM3. Wellbore Pressures
A
Confidential to DGD JIP
Slide 34 of 72
50
Dynamic Underbalance
Dynamic Underbalance
= required increase in
BHP to stop influx
while circulating
Total Underbalance = (conventional) SIDP
= Dynamic Underbalance + AFP
AFP = Annular Friction Pressure
3. Wellbore Pressures
Confidential to DGD JIP
Slide 35 of 72
Pressure Profile in Wellbore
During a Connection (w/DSV)
• Circulating - before connection
• During Connection - Rig Pump Stopped
- Annular Friction Pressure (AFP) is lost
• During Connection
- Rig Pump Stopped
- Annular Friction Pressure (AFP) is applied
at the MLP inlet
• Circulating
3. Wellbore Pressures
- after connection
Confidential to DGD JIP
Slide 36 of 72
Circulating Pressures
Before Connection
Return Line Circulating
BOP
Annulus Circulating
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Slide 37 of 72
Static and Circulating
Pressures in DGD
Return Line Circulating
Static
BOP
Return Line Friction
Annulus Static
Annulus Circulating
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
AFP
Slide 38 of 72
Static Pressures in DGD After Rig
Pump is Stopped for Connection
Static
BOP
Return Line Friction
Annulus Static
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
AFP
Slide 39 of 72
Static Pressures in DGD After Rig
Pump is Stopped. AFP Applied at
MLP to Avoid Chance of Kick
Static
BOP
Return Line Friction
Old
Annulus
- Static
New
Annulus
- Static
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
AFP
Slide 40 of 72
Circulating Pressures in DGD.
Rig Pump is Restarted.
AFP is Removed
Return Line
- Circulating
Static
BOP
Return Line Friction
Old
Annulus
- Static
New Annulus
- Circulating
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
AFP
Slide 41 of 72
Pressure Profile in Wellbore
- Changes when a Kick Occurs
• Drilling - before kick begins
• Kick in progress - no action taken yet
• Influx is stopped - kick is still near bottom
• Kick moves up the hole
• Top of kick is at mudline
• Bottom of kick is at mudline
• Kill mud is filling annulus
• Kill mud all the way
3. Wellbore Pressures
Confidential to DGD JIP
Slide 42 of 72
Static and Circulating Pressures
in DGD - no Kick
Return Line Circulating
Static
BOP
MLP
Annulus Static
Return Line Friction
Annulus Circulating
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
AFP
Slide 43 of 72
Circulating Pressures in DGD
- Kick in Progress - no Action
MLP Speeds Up - Automatically
Return Line w/Kick
BOP
Return Line Before Kick
Extra Return Line Friction
Annulus Before Kick
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Annulus w/Kick
Kick, 2.5 ppg
Slide 44 of 72
Slow Down MLP to Stop Influx
- Kick Still Near Bottom
Kick at Bottom - 2.5 lb/gal kick fluid
Return Line
BOP
Hydrostatic Effect
of Large Kick at
Bottom
Annulus
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Kick
Slide 45 of 72
Effect of Kick Intensity Wellbore
Pressure Profile - Small Kick
Kick Intensity = 0.5 lb/gal = 0.052 * 0.5 * 10,000
= 260 psi
Return Line
BOP
8,000
Effect of Kick
Intensity Small Kick
Annulus
18,000
3. Wellbore Pressures
PRESSURE
Confidential to DGD JIP
Slide 46 of 72
Effect of Kick Size and Intensity
on Wellbore Pressures Profile
Kick still near Bottom - 2.5 lb/gal kick fluid
Return Line
BOP
Effect of Kick
Intensity and
Size
Annulus
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Kick
Slide 47 of 72
Effect of Kick Size and Intensity
on Wellbore Pressures Profile
Kick Halfway up Annulus - 2.2 lb/gal kick fluid
Return Line
Effect of Kick
Intensity and
Large Kick
BOP
Kick
Annulus
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Slide 48 of 72
Effect of Kick Size and Intensity
on Wellbore Pressures Profile
Top of Kick at Mudline
Return Line
BOP
Kick ~ 1.8 lb/gal
Annulus
Effect of Kick
Intensity
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Slide 49 of 72
Effect of Kick Size and Intensity
on Wellbore Pressures Profile
Bottom of Kick at Mudline
Return Line
Kick - 2.1 lb/gal
BOP
Effect of Kick
Intensity
Annulus
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Slide 50 of 72
Effect of Kick Size and Intensity
on Wellbore Pressures Profile
Kick is Out of Hole
Return Line
BOP
Effect of Kick
Intensity
Annulus
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Slide 51 of 72
Effect of Kill Mud on Wellbore
Pressures Profile
Kill Mud Totally Fills Hole
Return Line
- Before Kick
Effect of Kill Mud
BOP
Annulus
Effect of
Kill Mud
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Slide 52 of 72
Effect of Very Large Kick on
Wellbore Pressures Profile
Return Line
May need
Surface
Choke
BOP
Annulus
Filled
with Gas
Annulus
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
Slide 53 of 72
Pressure Profile in Wellbore
During SIDP Measurement w/DSV
• Static Conditions
• DSV Set at Exact Balance
• DSV Set ONE or TWO lb/gal above balance
• Pressure Profile when DSV opens
• How to interpret the results and determine
SIDP and Kick Intensity
3. Wellbore Pressures
Confidential to DGD JIP
Slide 54 of 72
Static Pressures - DGD (w / DSV)
Exact Balance - no Kick
Return Line
Drillstring
BOP
Annulus
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
DSV
Slide 55 of 72
Static Pressures - DGD (w / DSV)
- No Kick
0.052 * 1 * 10,000 = 520 psi
0.052 * 2 * 10,000 = 1,040 psi
Drillstring
BOP
10,000
Return Line
DSV in Balance
DSV + 1 lb/gal
DSV + 2 lb/gal
Annulus
30,000
3. Wellbore Pressures
PRESSURE
Confidential to DGD JIP
DSV
Slide 56 of 72
Static Pressures - DGD (w / DSV)
0.5 lb/gal Kick
0.052 * 0.5 * 20,000 = 520 psi
Drillstring
DSV in Balance
BOP
10,000
Return Line
w/0.5 lb/gal kick
Annulus
30,000
3. Wellbore Pressures
PRESSURE
Confidential to DGD JIP
DSV
Slide 57 of 72
Static Pressures - DGD (w / DSV)
0.5 lb/gal Kick
0.052 * 1 * 10,000 = 520 psi
0.052 * 0.6 * 20,000 = 624 psi
BOP
10,000
Return Line
Drillstring
DSV in Balance
DSV @ 1 lb/gal
DSV @ 1 lb/gal
+ 0.6 lb/gal kick
Annulus
30,000
3. Wellbore Pressures
PRESSURE
Confidential to DGD JIP
DSV
Slide 58 of 72
Measuring SIDP w/DSV
•
•
•
•
•
In the last example above, after a total shut-in, it
takes 1,144 psi to open the DSV
The DSV is set for 1 lb/gal above balance
This accounts for 520 psi
0.052 * 1 * 10,000 = 520 psi
The remaining 624 psi corresponds to a kick
intensity of 0.6 lb/gal
0.052 * 0.6 * 20,000 = 624 psi
Conclusion: SIDP = 1,144 - 520 = 624 psi
Kick Intensity = 0.6 lb/gal
Increase mud weight by 0.6 lb/gal
3. Wellbore Pressures
Confidential to DGD JIP
Slide 59 of 72
Factors Affecting Pressure
Profile in Wellbore
• Hydrostatics (mud weight) (Drillstring & Ann.)
• Friction (circulation rate)
(Drillstring & Ann.)
• Changed MLP Inlet Pressure (Drillstring & Ann.)
• Kick (Kick Intensity)
(Drillstring & Ann.
• Kick (Hydrostatics)
(Annulus)
• Area Change (e.g., nozzles) (Drillstring)
• DSV Setting
(Drillstring)
3. Wellbore Pressures
Confidential to DGD JIP
Slide 60 of 72
SUMMARY of Wellbore Pressures
- DGD (w / DSV)
Static
Circulating
BOP
Return
Line
Drillstring
Annulus
PRESSURE
3. Wellbore Pressures
Confidential to DGD JIP
DSV
Slide 61 of 72
Wellbore Pressures - Summary
Drillstring
Annulus
Return
Line
Circulating
Conventional
Circulating - DGD
- No DSV
Static DGD
Static Conventional
ML
0
3. Wellbore Pressures
ML
Distance from Standpipe
Confidential to DGD JIP
Slide 62 of 72
Questions?
• Static Pressures
• Circulating Pressures
• Kick Hydrostatic
• Kick Intensity
• Friction
• Delta MW (DMW) = ?
• Dynamic Underbalance?
3. Wellbore Pressures
Confidential to DGD JIP
Slide 63 of 72
Subsea Mudlift Drilling
Basic Technology
by Hans C. Juvkam-Wold
November 2000
The End
3. Wellbore Pressures
3. Wellbore Pressures
Confidential to DGD JIP
Slide 64 of 72