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 13dc - Exponent due Nov. 6, 2002
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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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Well Control Worksheet

• Example

When circulating at a Kill Rate of 40 strokes per
minute, the circulating pressure 1,200
psi The capacity of the drillstring 2,000
strokes Mud Weight 13.5 lb/gal Well Depth
14,000 ft
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Aggie Drilling Research PRESSURE CONTROL
WORKSHEET Division of PETE Dept., TAMU DATE
College Station, TX 77843-3116 TIME WELL CLOSED
IN
1. PRE-RECORDED INFORMATION System Pressure
Loss _at_ 40 stks 1,200 psi
STROKES - Surface to Bit 2,000
stks TIME - Surface to Bit - 2,000 stks /
40 stks/min 50 min
2. MEASURE Shut-in Drill Pipe Pressure
(SIDPP) 800 psi Shut-in
Casing Pressure (SICP) 1,100
psi Pit Volume Increase (Kick Size)
40 bbl
3. CALCULATE INITIAL CIRCULATING PRESSURE
(ICP) ICP System Pressure Loss SIDPP
1,200 800 2,000 psi
4. CALCULATE KILL MUD DENSITY (New MW) Mud
Weight Increase SIDPP / (0.052 Depth)
800/(0.05214,000) 1.10 lb/gal Kill Mud
Density (New MW) Old MW MW Increase 13.5
1.10 14.6 lb/gal
5. CALCULATE FINAL CIRCULATING PRESSURE (FCP)
FCP System Pressure Loss (New MW / Old MW)
1,200 (14.6 / 13.5)
1,298 psi
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Graphical Analysis
3,000
3,000
2,000
2,000
Initial Circ. Press., ICP, psi
Final Circ. Press., FCP, psi
1,298
1,000
1,000
0
0
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Csg DS DS Csg
Pressure When Circulating
2,000
1,298
DrillPipe Pressure
Drillers Method
Static Pressure
800
2,000 stks
First Circulation Second Circulation
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Csg DS DS Csg
Drillers Method
Casing Pressure
1,100
800
0 psi
800
Drillpipe Pressure
DP Press.
0 psi
Volume Pumped, Strokes
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Engineers Method
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