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Well control adalah usaha untuk menjaga kestabilan lubang bor saat proses pemboran
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1998-99 COMPOSITE CATALOG
Well Data.xls
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WELL What Is A Kick? It Is An Influx Of Formation Fluid Into The Well.
1
WELL What Is A Blowout? An Uncontrolled Exit Of The Formation Fluids At The Surface
2
WELL What Is Formation Pressure? All Formations We Drilled Consists of Rock Grains and Pore Space. Formation Fluid Pressure Is the Pressure of the Fluids That Exist in Pore Space Pore Spaces Grains
3
WELL What Is Well Control? Preventing A Kick PRIMARY
MUD HYDROSTATIC
OR Shutting In The Well After A Kick Has Been Taken SECONDARY
BLOW OUT PREVENTERS
4
WELL What Is Formation Pressure? All Formations We Drilled Consists of Rock Grains and Pore Space. Formation Fluid Pressure Is the Pressure of the Fluids That Exist in Pore Space Pore Spaces Grains
3
WELL What Is Well Control? Preventing A Kick PRIMARY
MUD HYDROSTATIC
OR Shutting In The Well After A Kick Has Been Taken SECONDARY
BLOW OUT PREVENTERS
4
WELL Well Control?
PRIMARY PREVENTION KILL WELL
TAKE KICK
SHUT IN WELL
SECONDARY 5
WELL How Can You Prevent A Kick? KNOW WHAT CAUSES A KICK USE CORRECT RIG PRACTICES
6
WELL MUD HYDROSTATIC FALLS FORMATION PRESSURE
OR
MUD HYDROSTATIC
FORMATION PRESSURE RISES 7
WELL Causes Of Kicks Kicks Occur When “ Und Under er Bal Balanc ance e” Under Balance Is Caused by :
1. Mud Hydro Hydrost stati atic c Reducti Reduction. on. 2. Incre Increase ase in Forma Formation tion Pres Pressure sure..
8
WELL What Causes Mud Hydrostatic To Drop?
Pressure = Mud Wt X Constant X TVD
Reduce Mud Weight
Reduce Length Of Mud Column
?
?
?
?
?
?
9
WELL Mud Hydrostatic Reduction. Running Into Bubbles
10
WELL Example Hole TVD 10,000ft (81/2”) Hole cap. 0.0772 bbl/ft Dc / hole cap. 0.03 bbl/ft Mud wt. 11 ppg Formation gradient. 0.56 psi/ft Influx size 10 bbls while POOH (Swabbing) Gas gradient 0.1 psi/ft What is effect on BHP when run back to the bottom
11
WELL Mud Hydrostatic Reduction. Circulating Hole Clean
12
WELL Mud Hydrostatic Reduction. Gas in the Well Bore Drilled Gas
13
WELL Effect of Gas Expansion Example:well depth 7000’ mud wt.
11 ppg
influx (gas) volume 1 cu. Ft Calculate vol. Of gas @ 6000’, 5000’, 4000’, 3000’, 2000’, 1000’, 500’, 250’ and @ surface gas Pressure @7000’
= 11 X .052 X 7000=4000 psi
Vol. Of gas @6000’ =1.16 cu.ft @5000’ = 1.39 cu.ft
@4000’ = 1.75 cu.ft
@3000’ = 2.33 cu.ft
@2000’ = 3.5 cu.ft
@1000’ = 7.00 cu.ft
@500’ = 14.0 cu.ft
@250’ = 28.0 cu.ft
@125’ = 56.0 cu.ft
@surface = 272 cu.ft
14
WELL Mud Hydrostatic Reduction. Swabbing
15
WELL Swabbing Momentary reduction in BHP due to reduction in hydrostatic force cased by the upward suction action of the drill string, which can allow a small invasion into well bore. Main Causes: 1. Pulling Pipe Too Fast 2. High Viscosity Mud 3. Small Collar to Hole Wall Clearance 4. Balled-Up' Bit
16
WELL Mud Hydrostatic Reduction. Pumping Light Mud
psi
17
Bottom Hole Pressures
WELL What Can Reduce Mud Weight ?
Centrifuge Shakers Desilters Poor Mud/Settling
Pit Hole 18
WELL Losses
19
WELL Losses
20
WELL Mud Hydrostatic Reduction. Pull Out Without Filling The Hole
Rig Floor
Flowline
21
WELL Pressure or Level Drop Per Foot Pulled
Dry Pipe =
Mud Grad X Metal Displacement ( Casing Cap - Metal Displacement)
Wet Pipe =
Mud Grad X Metal Disp. + pipe Cap Casing Cap - Metal Disp. + Pipe Cap
Casing Cap = Annular Cap + Pipe Cap + Metal Disp. ** All Capacities In bbls/ ft.
22
WELL Example Mud Weight
= 12 ppg
Metal Disp
= .0075 bbls / ft.
Pipe Cap
= .0177 bbls / ft.
Casing Cap
= .076 bbls / ft.
Stand Length
= 93 ft.
Calculate Pressure Drop When A) Pulling One Stand Dry. B) Pulling One Stand Wet.
23
WELL Answer Dry Pipe =
Mud Grad X Metal Displacement ( Casing Cap - Metal Displacement)
12 X 0.052 X 0.0075 (0.076 - 0.0075) = 6.8 psi =
Wet Pipe =
Mud Grad X Metal Disp. + pipe Cap Casing Cap - Metal Disp. + Pipe Cap
12 X 0.052 X (0.075 + 0.0177) 0.076 - (0.075 + 0.0177) = 28.78 psi
=
24
WELL Example 720 Ft Of 8” Drill Collars. D.C. Capacity
= .0077 bbls / ft.
D.C. Displacement
= .0546 bbls / ft.
Mud Weight
= 15 ppg.
Casing Capacity
= .1497 bbls / ft.
Calculate. A. Drop in Mud Level when all collars are pulled from the hole without filling the annulus. B. Drop in Bottom Hole Pressure.
25
WELL Failure of Float collar
Rig Floor
Flowline
26
WELL Example A13 3/8 String Casing Is Run Into The Hole With Conventional Float. The Driller Did Not Fill The Casing For Fourteen 40 ft Joints. If Float Were To Fail At This Point, And Mud U-tubes Up Inside The Casing, Calculate The Effect On Bottom Hole Pressure. Data:Casing Capacity = 0.152 bbls/ft Annular Capacity = 0.1238 bbls/ft Mud Weight = 12.6 ppg Answer Hydrostatic Pressure Loss If Casing Float Fail = Mud Gradient X Casing Capacity X Differential Height (Casing Capacity + Annular Capacity) 0.665 X 0.152 X 14 X40 ( 0.152 + 0.1238)
= 205 psi
27
WELL Key Prevention Practices. Do Not R.I.H. Too Fast. Monitor Trip Tank. Always Fill Hole With Correct Mud. Monitor ECD. Keep Viscosity Down To Acceptable Level. Keep Casing Full. Know What Mud Is In Hole.
28
WELL Causes Of Abnormal Pressure Under Compaction Faulting Sand Lens Salt Dome Artesian Gas Cap Leaks Around Casing
WELL Artesian Effects Rain Underground water level
1000’
Spring
0’ 500’
Calculate Mud Weight To Balance? Formation Water = .433 psi/ft
34
WELL Gas Cap Effect
7000’
8000’
.465 psi/ft Normal Pressure 35
WELL Example Calculate the pressure at top of the reservoir Pressure at 8000’
= 8000 X .465 =
3720 psi
Height of reservoir = 8000 – 7000 =
1000’
Ph of the reservoir = 1000 X 0.1
=
100 psi
Pr at 7000’
= 3720 – 100
=
3620 psi
E.M.W. at 8000’
= 3720 / .052 / 8000/ =
8.94 ppg
E.M.W. at 7000’
= 3620 / .052 / 7000
9.94 ppg
=
In trapped gas reservoir, the highest point of the reservoir usually has the highest pressure. Due to gas less dense than formation water.
36
WELL Leaks Around Casing
37
WELL Causes Of Kicks Revision: KICKS OCCUR WHEN “ UNDERBALANCE ” UNDERBALANCE IS CAUSED BY : MUD WEIGHT REDUCTION. DROP IN MUD LEVEL. INCREASE IN FORMATION PRESSURE.
38
WELL Kick Prevention Monitor Trips - In And Out Circulate Bottoms Up If In Doubt Of Hole Condition Monitor Well At All Times Trip Carefully In And Out Pump Out If Tight Hole Circulate Through Choke If A Lot Of Gas Is Expected Keep Mud In Good Shape Always Keep Hole Full Double Check Effect Of Lightweight Mud/Pills Pump Good Cement
39
WELL What Is Warning Signs Information From the Well That Tells You That the Well May Be Getting Close to Being “Under Balanced” Your Safety Margin Is Getting Less.
40
WELL Kick Warning Signs 1. ROP Changes Overbalance Less Softer Rock 2. Hole condition Squeezing Rock Torque / Drag / Fill 3. Data from Mud Gas Cuttings Temperature
Chlorides Shale Property Trip Monitor
41
WELL Major Warning Signs Improper Fill up or Displacement During Trips Connection Gas Increased Background Gas Increased Drilling Rate Flowline Mud Temperature Increase Increased Chloride Content of Mud Increased Drill String Torque Increased Drill String Drag Increased Number and Size of Cuttings Decreasing Shale Density 42
WELL What Is a Drilling Break Sometimes Called ‘Fast Break’ A Sudden Increase in R.O.P How Much How Far to Drill ? What About a Decrease in R.O.P ?
What Affects ROP WOB
Hydraulics
RPM
Rock Type
Bit Type
Overbalance 43
WELL Increased Drilling Rate
9.00
9850’
9.15 9.30
9855’ 9860’
Increasing Drill Rate (ROP)
Geolograph Chart
44
WELL Increased Drill String Torque
45
WELL Cuttings Size and Shape
Drilled cuttings
‘Knocked Off’, Heaving Shale Cuttings
46
WELL Cause of Connection Gas Mud Static Kick Can Occur
Mud Circulating Formation Under Control Connection Gas being Circulated to Surface
0 psi
3000 psi Annular Pressure Loss = 250 psi
11 ppg mud BHP= 7114 psi
BHP= 6864 psi 12000’ 7000 psi
Formation Pressure
7000 psi
47
WELL Flow Line Temperature Graph
9500’
Normal Pressure
9600’ 9700’ 9800’
Abnormal Pressure
9900’ 10000’ 10100’ 10200’ Temperature Increase
48
WELL Shale Density Graph Abnormal Pressure Zones Exhibited a DECREASING Shale Density with DEPTH Normal Trend Line 9500’ 9600’
Shale Sand
Normal Pressure
Shale
9700’
Sand
9800’ 9900’
Shale Increasing Formation Fluid Pressure
10000’ 10100’ Sand
10200’
Increasing Shale Density
49
WELL Surface Kick Indicators Excess Flow From the Well When Tripping Return Flow Rate Increase When Pumping Pit Gain Drilling Break Decreased Pump Pressure/increased SPM Flow From Well With Pumps Off
50
WELL What Action to Take? First :
Shut the Well In
Second :
Choose and Use a Kill Method to Restore the Mud Hydrostatic Pressure to Level That Re-Establishes Primary Control
51
WELL Reason for Shut In To Prevent Blowout To Allow Pressure Reading to Be Taken for Kill Mud
Shut In Methods Hard Soft
52
WELL Shut In Practices Things That Delay Shut In. Flow / Pit Alarms Not Set (Properly) Drill Too Far After Drilling Break Lack of ‘Shut In’ Training Lack of Maintenance & Testing Waiting for Instructions Accumulator Unit Not Working Not Monitoring Trips Low Level of Crew Awareness
53
WELL Soft Method
Drilling
Line up With Remote Choke Opened. Raise Kelly/Top Drive Until Tool Joint Is Above Rotary Table Shut Down Mud Pumps Open Choke Line Valve (HCR) at Stack Check That Adjustable Choke Is Open Close Annular Preventer * Close Adjustable Choke Record Shut in Pressure and Pit Gain * API Soft Shut in States BOP (It Does Not Specify an Annular) 54
WELL Soft Method
Tripping
Line up With Remote Choke Opened. Install and make up the fully opened SAFETY VALVE in the Drill String. Close the Safety Valve Open Choke Line Valve (HCR) at Stack Check That Adjustable Choke Is Open Close Annular Preventer * Close Adjustable Choke Pick up and make up Kelly?Top Drive Open Safety Valve Record Shut in Pressures and Pit Gain * API Soft Shut in States BOP (It Does Not Specify an Annular) 55
WELL Hard Method
Drilling
Line up With Remote Choke Closed. Raise Kelly/Top Drive Until Tool Joint Is Above Rotary Table Shut Down Mud Pumps Close Ram Preventer * Open Choke Line Valve (HCR) at Stack Record Shut in Pressure and Pit Gain * API Soft Shut in States BOP (It Does Not Specify a Ram)
56
WELL Hard Method
Tripping
Line up With Remote Choke Closed. Install and make up the fully opened SAFETY VALVE in the Drill String. Close the Safety Valve Close Ram Preventer * Open Choke Line Valve (HCR) at Stack Pick up and make up Kelly?Top Drive Open Safety Valve Record Shut in Pressures and Pit Gain * API Soft Shut in States BOP (It Does Not Specify a Ram)
57
WELL Hard V’s Soft Hard Quicker Less to Remember Smaller Influx Soft Slower Checks if choke line is Clean Larger Influx Reduces Water Hammer Effect
58
WELL Top Hole Drilling Problems 1. Shallow Gas Many Rigs That Are Burned up Suffered Shallow Gas Kicks 2. Losing the Hole and a Re-drill
59
WELL Shallow Gas
Wind Direction
200 ft
60
WELL Shut in Data SIDPP SICP Pit Gain
Shut In Drill pipe Pressure Shut In Casing Pressure
SIDPP Tells You Under Balance Inside Drill String SICP Tells You Under Balance Inside Annulus Pit Gain Tells You Size of Influx at Shut in
61
WELL SIDPP V’s SICP
SIDPP
Why Are They Different?
0
psi
Pump SICP 0
psi
Choke Manifold
Mud in Annulus Is Contaminated Therefore Less Hydrostatic
Influx Height
62
WELL Pressure V’s Strokes Increase SPM = Increase PSI Approximate Effect Is : 2
= Old Pump Pressure X
63
WELL Pressure V’s Drilling Fluid Density Increase M. Wt = Increase PSI Approximate Effect Is:
= Old Pump Pressure X
64
New M.Wt Old M.Wt
WELL Kill Mud
65
WELL Initial and Final Circulating Pressure I.C.P. = Slow Circulating Pressure + SIDPP Kill M.Wt F.C.P. = Slow Circulating Pressure X
66
Old M.Wt
WELL Bottom Hole Pressure Pressure Exerted on the Bottom of the Hole. B.H.P = Mud Hydrostatic + Back Pressure Held at Remote Choke + Annular Pressure Loss (APL)
67
WELL Slow Pump Rate Normally 1/2 - 1/4 Drilling SPM Why Kill Well at Slow Rate? How Are They Taken? When Are They Taken? How Are They Used in Kill Process?
68
WELL Causes Effect the Choice of SCR
69
WELL When Should Be Taking SCR ? 1. At Beginning of Each Shift. 2. After Mud Properties Changed . 3. When Long Sections of Hole Are Drilled Rapidly (500 Ft). 4. When Returning to Drilling After Kill. 5. When Changed B.H.A (Nozzles, D.C, Motor….)
70
WELL Where To Read Standpipe Pressure. When Recording SCR SCR’ s Should Be Read On The Drill Pipe Pressure at The Remote Chock Panel. SCR’ s Should Be Taken With The Bit Near The Bottom.
71
WELL Time For Build
How Long For Shut In Pressure To Stabilize?
600
600
psi
psi
Casing Pressure
Casing Pressure
High Permeability
Low Permeability
Slow
Fast
e r u s s e r P
e r u s s e r P
Time
72
Time
WELL Gas Migration Why? Gas Is Light And Will Migrate (Percolate) Up Hole
Speed Of Migration? Depends On Mud Wt + Mud Viscosity
How Can I See Migration? Steady Rise In Surface Pressure After Initial Stabilization
73
WELL Gas Migration SIDPP or SICP
Migra tion Shut In Pressure
Time
74
WELL 600
Float in Drill String How To Find SIDPP?
psi
0
Pump Slowly Down Drill
600
Pipe And Watch Build Up psi
0
SIDPP 500
Time
SICP 600
Time
75
WELL Clean Annular
Annular Loaded With Cutting 0
0
psi
0
psi
0
76
psi
psi
WELL Bit off Bottom 0
0
psi
psi
77
WELL Packed Off 0
0
psi
78
psi
WELL Leak Off Procedure 1. Drill 10 - 15 Feet Rat Hole 2. Test Surface Equipment 3. Circulate To Condition Mud 4. Pull Inside Casing 5. Shut In Well 6. Pump 1/4 - 1/2 Bbl/Min Into Well* 7. Plot Pressure Rise 8. When Pressure Rise Slows Down Or Stops; Shut Down Pump 9. Measure Pressure Where Pressure Rise Slows Down 10. Monitor Stable Pressure Then Bleed Back Pressure * Varies With Company Policy 79
WELL How Is Formation Strength Measured? Leak Off Test (L.O.T.) Point Of Leak Off
Leak Off Pressure
Trend Line
e r u s s e r P p m u P
Volume Pumped
Fracture Pressure = Mud Hydrostatic psi + LOT psi
Formation Integrity Test Pressure Up To Agreed Pressure Without Any Leak-off 80
WELL Fracture Pressure = (Mud Wt. ppg X .052 X Shoe TVD) + L.O.T.
Fracture Mud Weight Can Be Called “ Breakdown” Or “ Max. Allowable ”
= (L.O.T ÷ Shoe TVD ÷ .052) + Mud Wt. ppg
MAASP Difference Between Pressure That Will Fracture The Rock And The Mud Hydrostatic Pressure = (Fracture Mud Wt - Current Mud Wt) X .052 X Shoe TVD
81
WELL MAASP V’s Leak Off MAASP = Leak Off At Time Of Leak Off Test If Mud Weight Is Increased The Hydrostatic On Shoe Increases Therefore Margin Between Mud Hydrostatic And Fracture Gets Less. This Margin Is Called M.A.A.S.P.
82
WELL
Drill Out The Casing Shoe And Approximately 5 – 15 Ft Into New Formation. Circulate The Mud To Get Same Weight All Way Around. Good Pressure Test Of Surface Equipment. Calibrated Pressure Gauges. Accurate T.V.D Of Casing Shoe. Accurate Volume Of Mud Pumped.
83
WELL What Exerts Pressure On The Formation? Mud Hydrostatic Friction Losses In Annulus Bridging/Packing Off In Annulus Shutting In Well With Pumps Running Kicks And The Kill Process Choke Line Friction
84
WELL What Can Increase The Risk Of Exceeding MAASP Incorrect Casing Shoe Setting Depth Unexpected High Pressure Large Kick Size Low Fracture Pressure Long Open Hole Sections Gas Migration Bad Kill Practices Too Much Safety Margin Choke Line Friction Loss 85
WELL Principle Of Kill Method Restore Primary Control How ? Clean Out Influx Replace Old Mud With Kill Mud At All Times Maintain Correct Bottom Hole Pressure. How ? Use Approved Kill Method One That Maintains Correct And Constant Bottom Hole Pressure
86
WELL Bottom Hole Pressure Pressure Exerted on the Bottom of the Hole. B.H.P = Mud Hydrostatic + Back Pressure Held at Remote Choke + Annular Pressure Loss (APL) Most Times APL Is Small And Can Be Ignored.
87
WELL Pressure Balance BHP = Hydrostatic + Back Pressure To Maintain Constant BHP!
If Fluid Hydrostatic Then Choke Back Pressure
88
WELL Role Of Choke The Choke (Remote Or Manual) Is A Device For Adjusting Back Pressure. A Kick Is Due To Lack Of Mud Hydrostatic. The Choke Provides A Back Pressure To Compensate For Lack Of Mud Hydrostatic. When Heavy Mud Is Pumped The Operator Reduces Back Pressure.
89
WELL Start up Procedure This Procedure Starts the Kill Correctly. It Ensures That B.H.P Is Correct for the Kill. It Can Be Stated That the Start up Procedure “Calibrates” the Well Kill to Correct B.H.P. How? Bring Pump Up to Speed Holding Casing Pressure Constant.
90
WELL Driller’s Method Two Circulation's 1st Clean Out Influx 2nd Circulate Kill Mud
After 1st Circulation SIDPP = SICP
91
WELL 1st Circulation Start up - Bring Pumps up to Kill Rate Holding Casing Pressure Constant When up to Speed Look at Drill Pipe Pressure. Hold It Constant at This Value For Complete Circulation On Completion of Circulation Shut Down The Reverse of Start up Procedure If Annulus Is Clean S.I.C.P Will Now Read S.I.D.P.P If Annulus Is Not Clean Then S.I.C.P Will Be Greater Than S.I.D.P.P
92
WELL 2nd Circulation Start up - Bring Pumps up to Kill Rate Holding Casing Pressure Constant When up to Speed Maintain Casing Pressure Constant Until Kill Mud Is at the Bit With Kill Mud at Bit Switch to Drill Pipe Pressure and Hold Constant Until Clean Mud Returns at Surface It May Be Preferred to Use the Wait and Weight Procedure for the 2nd Circulation. This Is in Case of Any Influx That Was Not Cleaned Out in the1st Circulation 93
WELL Wait and Weight One Circulation Pump Kill Mud From the Start Start up - Bring Pumps up to Kill Rate Holding Casing Pressure Constant Once up to Speed the Drill Pipe Pressure Should Equal I.C.P Allow Drill Pipe Pressure to Fall From I.C.P to F.C.P As Kill Mud Is Pumped to the Bit With Kill Mud at the Bit Hold Drill Pipe Pressure Constant at F.C.P Until Kill Mud Returns at Surface 94
WELL ICP = SIDPP + SCR Pressure Kill Mud FCP = SCR X Old Mud Step Down From Icp To Fcp Using Either Graph Or Chart Strokes To Bit
STKS 0 100 200 300 400 500 600 700 750
PSI 1400 1350 1300 1250 1200 1150 1100 1050 1025
ICP
FCP
PSI FCP
ICP
SIDPP
0 Strokes From Surface To Bit
Strokes From Bit To Surface
95
WELL Things To Watch Following A Choke Adjustment The Drillpipe Gauge Takes Longer To React Due To Length Of System Kill Mud Only Does Good When Going Downhole. Therefore Re-zero Stroke Counter Calculated ICP Is Only A Guideline. Actual (True) ICP Is Seen At Start Up If Actual ICP Is Different Then Recalculate Graph Or StepDown
96
WELL Comparison of Killing Methods Ease of Calculation ( Driller Method ) Lower Annulus Pressure ( Wait & Weight) Shortest Circulating Time (Wait & Weight )
97
WELL Non-Routine Techniques Drillers And Wait & Weight Only Work With Bit Below The Influx. Problems May Be:Unable To Use Pump Hole Plugged Bit Above Influx In These Situations It May Be Necessary To Use Other Well Control Techniques Volumetric Stripping Combined Volumetric/Stripping 98
WELL Volumetric Method Applications
99
WELL Volumetric Method To keep BHP constant Bleed mud through choke maintaining SIDPP constant BHP
=Ph d/p (no change) + SIDPP (constant) = Constant
Bad practice Due Hold casing Pressure Constant BHP
= Ph Ann. + SICP = Ph Ann (decrease to bleed mud) + SICP (constant) = Decrease
100
WELL Well Control Problems Indicators of Mechanical Failures Changes In Drillpipe And Casing Pressures During Well Control Variations Can Indicate Potential Mechanical Problems
