PETE 625 Well Control

1
PETE 625Well Control

• Lesson 16
• Volumetric Well Control

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Contents

• Volumetric Well Control
• Drillpipe Pressure Can be used for Pressure
  Control
• Drillpipe Pressure Cannot be used
• Lubrication
• Other Well Control Methods

3
Assignments

• HW 9 Ch 4, Problems 11- 20
• due Wednesday, July 7
• HW 10 Ch 5, Problems 1, 3, 5, 8 and 13
• due Wednesday, July 14
• Read All of Chapter 5
• QUIZ B Monday, July 12, 9-11 a.m. In
  Room 407M

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Volumetric Well Control

• Non-Circulating method of well control.
• Allows a gas bubble to migrate to the surface
  while systematically allowing the bubble to
  expand.
• It also maintains the BHP at or above formation
  pressure.
• Used whenever circulation cannot be used to
  kill the well.

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Volumetric Procedure
BHP Constant gt Formation Pressure
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Two situations can be present

• Drillpipe can be used to monitor pressure
• Drillpipe cannot be used

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Assume Drillpipe can be used to monitor
bottomhole pressure.
DPP BHP DPHSP

• DPP Drillpipe pressure (at surface)
• BHP Bottomhole Pressure
• DPHSP Drillpipe hydrostatic pressure

Thus, changes in DPP imply similar changes in BHP
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Procedure

• 1. Record SIDPP (e.g. 100 psi)
• 2. Select Safety Margin (e.g. 100 psi)
• 3. Select Working Margin (e.g. 100 psi)
• 4. Allow gas migration until drillpipe pressure
  has increased to top of working pressure range
  (to 300 psi)
• 5. Bleed off mud until DPP 200 psi

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Steps 1 through 3
psig
300
SIDPP SM WM
3
Working Margin
Drillpipe Pressure (at surface)
200
SIDPP SM
2
Safety Margin
100
SIDPP
1
0
Make sure casing seat is safe at top of WM
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Steps 1 through 5
psig
300
SIDPP SM WM
3
5
Drillpipe Pressure (at surface)
4
200
SIDPP SM
2
100
SIDPP
1
0
Time
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Procedure - contd

• 5. Bleed off mud until DDP 200 psi (to
  the top of the safety margin) This allows the
  gas to expand
• 6. Allow gas migration until drillpipe pressure
  has increased to top of working pressure range
  (to 300 psi)
• 7. Bleed off mud until DPP 200 psi
• 8 and 9. Repeat steps 6 and 7, etc.

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Steps 1 through 9 - DPPNOTE Bleed mud only, no
gas
BHP 300 DPHP
300
3
WM
5
7
9
6
8
200
2
4
Drillpipe Pressure, psi
SM
100
SIDPP
1
0
Time
BHP Form. Press. 100 DPHP
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Steps 1 through 9Example Bottomhole Pressure
4,800
3
WM
5
7
9
6
8
Bottomhole Pressure, psi
4,700
2
4
SM
4,600
BHP Form. Press.
1
Time
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Steps 1 through 9Example Casing Surface Pressures
900
9
8
800
7
6
700
3
5
Casing Pressure, psi
4
600
2
SICP
500
1
400
Time
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Steps 1 through 9Example Casing Seat Pressures
1,900
8
9
1,800
7
6
Casing Seat Pressure, psi
1,700
3
5
4
1,600
2
Kick is above casing seat
1,500
1
Make sure casing seat is safe at all times
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Volumetric Procedure
Form. Press SM BHP Form. Press SM WM
Make sure casing seat is safe at all times
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Drillpipe Pressures Steps 1 through 8
100
100 300
300 200
200 300
300 200
200 300
Kick Migration
Kick Migration
Kick Migration
5
7
4
6
8
1
2
3
Record SIDPP Select SM WM
Bleeding and Kick Expansion
Bleeding and Kick Expansion
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Drillpipe Pressures Steps 1 through 8
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Drillpipe can be used

• Detailed Procedure
• Determine a safety margin for the casing
  pressure (e.g., 100 psi above initial
  stabilized SICP and SIDPP)
• Determine working margin (e.g., 100 psi above
  safety margin)
• As bubble migrates, casing pressure will, at
  some point, reach the top of the safety margin

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Drillpipe can be used

• Detailed Procedure contd
• Allow the casing pressure to increase further,
  until it reaches the upper limit of the working
  margin
• Very slowly bleed a small volume of mud from
  the annulus (approximately 1/4 bbl) into a
  calibrated tank. Close the choke.
• Let Drillpipe pressure stabilize

21
Drillpipe can be used

• Detailed Procedure contd
• If new SIDPP gt Initial SIDPP Safety margin,
  repeat bleeding procedure.
• When the SIDPP Initial SIDPP Safety margin,
  stop bleeding and allow casing pressure to
  increase again.
• Repeat until circulation can be restored or
  bubble has reached the surface

22
Drillpipe cannot be used

• Plugged bit
• Migrating fluid is below the bit (bit off
  bottom)
• Drillpipe parted or there is a hole in
  drillpipe above the influx

23
Drillpipe cannot be used

• Well closed in on the blind rams
• Pumps are inoperable and the drillstring is not
  full of mud
• Gas has entered the drillstring

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Volumetric Procedure when drillpipe pressure
cannot be used

• 1. Record the initial SICP (e.g., 500 psig)
• 2. Allow the casing pressure to increase by the
  predetermined safety margin (to 600 psig)
• 3. Allow the casing pressure to further
  increase by the predetermined working margin
  (to 700 psig)

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Volumetric Procedure when drillpipe pressure
cannot be used

• 4. Bleed mud from the choke manifold into a
  measuring tank while maintaining a relatively
  stable casing pressure.
• 5. Continue to bleed mud until the volume in the
  measuring tank is equivalent to the muds HSP of
  the working margin buildup. The HSP is based on
  the hole dimensions at the depth of the rising
  influx.

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Volumetric Procedure Calculate Volume of Mud to
Bleed

• Dp 0.052 MW Height (MW 12 ppg)
• 100 0.052 12 Height (WM 100 psi)
• Height 100/(0.05212) 160 ft
• Annular Capacity 0.1 bbl/ft
• Volume of mud to bleed 160 ft 0.1 bbl/ft
• Volume of mud to bleed 16.0 bbl
• (modify when annular capacity changes)

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Volumetric Procedure

• 6. Repeat steps 3 through 5 until choke
  pressures stabilize, secondary control can be
  regained, or the influx surfaces.
• 7. Stop the bleed process if gas exits the
  choke. Monitor annulus pressures for further
  buildup.

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Steps 1 through 9Example Casing Surface Pressures
900
9
8
800
7
6
700
3
5
Casing Pressure, psi
4
600
2
SICP
500
1
400
Time
During step , bleed 16 bbls of mud
Same during step
5
7
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D
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pfi 1,750 psig
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17.1 bbl
16.46 bbl
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16.46 bbl of mud
Volumetric Drillers Method
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Larger Dia. Casing
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Lubrication

• Process of replacing gas at the surface of a
  wellbore with mud.
• Pump mud into the wellbore
• Let mud fall
• Bleed gas
• Repeat

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Lubrication Pump Mud - Bleed Gas
Gas is at top of annulus after Volumetric
Procedure
Pump as much mud into the top of the annulus as
the casing seat can tolerate
Allow mud to settle through gas
Bleed off a safe amount of gas, (maintaining a
safe BHP)
Repeat until all gas is removed
Top of Kick at Surface
Mud has replaced all gas in the annulus
Increased hydrostatic due to more mud allows safe
bleeding and pressure reduction
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LubricationPump Mud - Bleed Gas
Avoid Fracturing Casing SeatMaintain BHP above
Formation Pressure
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LubricationPump Mud - Bleed Gas
Pump Mud into Annulus
Pump Mud into Annulus
Kick Migrates
Bleed Gas
Top of Kick at Surface
Kick Migrates Mud Settles
Kick Compresses Pressures Rise
Pressures Drop
Kick Compresses Pressures Rise
46
Lubrication Procedure - Example Calculate casing
pressure after bleeding gas

• pcsg.new pcsg.old Dpmud_added 800 -
  Dpmud_added
• Mud added e.g., 50 bbl
• Annular Capacity 0.15 bbl/ft
• Height 50/0.15 333 ft
• Dp 0.052 12 333 208 psi
• Bleed gas until pressure drops to 592 psig

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Lubrication Procedure Calculate casing pressure
after bleeding gas

• pcsg.new pcsg.old Dpmud_added 592 -
  Dpmud_added
• Mud added e.g., 30 bbl
• Annular Capacity 0.15 bbl/ft
• Height 30/0.15 200 ft
• Dp 0.052 12 200 125 psi
• Bleed gas until pressure drops to 467 psig
• Continue until all gas is out of annulus

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D
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104.19
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1,092 psig
psia
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D
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Lubrication Procedure
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Lubrication Procedure - contd
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Off Bottom Well Control

• Volumetric
• Use same procedure as before
• Staging in the Hole
• Entails circulating mud of sufficient density
  to control BHP at the current position of the
  bit (off bottom)
• Tripping in the hole some distance
• Repeat

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SIDPP SICP
SIDPP lt SICP
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(10.2 lb/gal)
60
(maximum stage margin)


(depth of bit)
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Staging in the hole
380 psi
0 psi
10.2 lb/gal old mud
14.7 lb/gal kill mud
2,700 ft
2,700 ft
3,900 ft
3,900 ft
(11.0 lb/gal)
9,100 ft 5,203 psig
9,600 ft
9,600 ft
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Bit is at 2,700 ft
Pump 14.7 lb/gal mud to kill the well
Run pipe to bottom?
Dont exceed fracture pressure at casing seat
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Flow
NO Flow
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