PETE 411 Well Drilling

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PETE 411Well Drilling
Lesson 24 Kicks and Well Control
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Kicks and Well Control Methods

• The Anatomy of a KICK
• Kicks - Definition
• Kick Detection
• Kick Control
• (a) Dynamic Kick Control
• (b) Other Kick Control Methods
• Drillers Method
• Engineers Method

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ReadApplied Drilling Engineering, Ch.4
HW 12Casing Design due Oct. 29, 2001
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Causes of Kicks
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Causes of Kicks
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Causes of Kicks
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What?

• What is a kick?
• An unscheduled entry of formation fluid(s)
  into the wellbore

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Why?

• Why does a kick occur?
• The pressure inside the wellbore is lower
  than the formation pore pressure (in a
  permeable formation).

pw lt pf
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How?

• How can this occur?
• Mud density is too low
• Fluid level is too low - trips or lost circ.
• Swabbing on trips
• Circulation stopped - ECD too low

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What ?

• What happens if a kick is not controlled?
• BLOWOUT !!!

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Typical Kick Sequence

• 1. Kick indication
• 2. Kick detection - (confirmation)
• 3. Kick containment - (stop kick influx)
• 4. Removal of kick from wellbore
• 5. Replace old mud with kill mud (heavier)

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Kick Detection and Control
Kick Detection
Kick Control
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1. Circulate Kick out of hole
Keep the BHP constant throughout
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2. Circulate Old Mud out of hole
Keep the BHP constant throughout
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Kick Detection

• Some of the preliminary events that may be
  associated with a well-control problem, not
  necessarily in the order of occurrence, are
• 1. Pit gain
• 2. Increase in flow of mud from the well
• 3. Drilling break (sudden increase in
  drilling rate)

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Kick Detection
4. Decrease in circulating pressure

• 5. Shows of gas, oil, or salt water
• 6. Well flows after mud pump has been shut
  down
• 7. Increase in hook load
• 8. Incorrect fill-up on trips

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Dynamic Kick ControlKill well on the fly

• For use in controlling shallow gas kicks
• No competent casing seat
• No surface casing - only conductor
• Use diverter (not BOPs)
• Do not shut well in!

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Dynamic Kick Control

• 1. Keep pumping. Increase rate! (higher ECD)
• 2. Increase mud density
• 0.3 /gal per circulation
• 3. Check for flow after each complete
  circulation
• 4. If still flowing, repeat 2-4.

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Dynamic Kick Control

• Other ways that shallow gas kicks may be stopped
• 1. The well may breach with the wellbore
  essentially collapsing.
• 2. The reservoir may deplete to the point where
  flow stops.

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Conventional Kick ControlSurface Casing and BOP
Stack are in place

• Shut in well for pressure readings.
• (a) Remove kick fluid from wellbore
• (b) Replace old mud with kill weight mud
• Use choke to keep BHP constant.

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Conventional Kick Control

• 1. DRILLERS METHOD
• TWO complete circulations
• Circulate kick out of hole using old mud
• Circulate old mud out of hole using kill
  weight mud

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Conventional Kick Control

• 2. WAIT AND WEIGHT METHOD
• (Engineers Method)
• ONE complete circulation
• Circulate kick out of hole using kill weight
  mud

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Drillers Method - Constant Geometry

• Information required
• Well Data
• Depth 10,000 ft.
• Hole size 12.415 in. (constant)
• Drill Pipe 4 1/2 O.D., 16.60 /ft
• Surface Csg. 4,000 ft. of 13 3/8 O.D. 68 /ft
• (12.415 in I.D.)

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Drillers Method - Constant Geometry
Additional Information required

• Kick Data
• Original mud weight 10.0 /gal
• Shut-in annulus press. 600 psi
• Shut-in drill pipe press. 500 psi
• Kick size 30 bbl
  (pit gain)

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• Constant Annular Geometry.
• Initial conditions Kick has just entered the
  wellbore
• Pressures have stabilized

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Successful Well Control

• 1. At no time during the process of removing
  the kick fluid from the wellbore will the
  pressure exceed the pressure capability of
• the formation
• the casing
• the wellhead equipment

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Successful Well Control

• 2. When the process is complete the wellbore is
  completely filled with a fluid of sufficient
  density (kill mud) to control the formation
  pressure.
• Under these conditions the well will not flow
  when the BOPs are opened.
• 3. Keep the BHP constant throughout.

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Calculations

• From the initial shut-in data we can calculate
• Bottom hole pressure
• Casing seat pressure
• Height of kick
• Density of kick fluid

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Calculate New Bottom Hole Pressure

• PB SIDPP Hydrostatic Pressure in DP
• 500
• 0.052 10.0 10,000
• 500 5,200
• PB 5,700 psig

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Calculate Pressure at Casing Seat
P4,000 P0 DPHYDR. ANN. 0-4,000
SICP 0.052 10 4,000 600
2,080 P4,000 2,680 psig
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Calculate EMW at Casing Seat

• This corresponds to a pressure gradient of
• Equivalent Mud Weight (EMW)

( rmud 10.0 lb/gal )
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Calculate Initial Height of Kick

• Annular capacity per ft of hole

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Calculate Height of Kick
hB
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Calculate Density of Kick Fluid

• The bottom hole pressure is the pressure at the
  surface plus the total hydrostatic pressure
  between the surface and the bottom
• Annulus Drill String
• PB SICP DPMA DPKB PB SIDPP DPMD

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Density of Kick Fluid

• (must be primarily gas!)

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Circulate Kick Out of Hole

• NOTE
• The bottom hole pressure is kept constant while
  the kick fluid is circulated out of the hole!
• In this case
• BHP 5,700 psig

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• Constant Annular Geometry
• Drillers Method.
• Conditions When Top of Kick Fluid Reaches the
  Surface

BHP const.
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Top of Kick at Surface

• As the kick fluid moves up the annulus, it
  expands. If the expansion follows the gas law,
  then

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Top of Kick at Surface

• Ignoring changes due to compressibility factor
  (Z) and temperature, we get
• Since cross-sectional area constant

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Top of Kick at Surface

• We are now dealing two unknowns, P0 and h0. We
  have one equation, and need a second one.

BHP Surface Pressure Hydrostatic Head 5,700
Po DPKO DPMA 5,700 Po 20 0.052
10 (10,000 - hO ) 5,700 - 20 - 5,200 Po -
0.52
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Top of Kick at Surface
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1,200
40
50
2,000/40
2,000
800
1,100
40
1,200 800
2,000
800 / (0.052 14,000)
1.10
13.5
14.6
1,200 14.6 / 13.5
1,298 psi
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1,298
0
5
10
15
20
30
40
25
35
45
50
0
2,000
0
200
bbls
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Csg DS DS Csg
Pressure When Circulating
DrillPipe Pressure
Drillers Method
Static Pressure
First Circulation Second Circulation
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Csg DS DS Csg
Drillers Method
Casing Pressure
Drillpipe Pressure
Volume Pumped, Strokes
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1
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Engineers Method
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