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Stuck Pipe Prevention
Prentice & Hill, LLC
Second Day
Differential StickingCauses
High Differential Pressures• Excessive Mud Weight• Drawn Down Formations• Poor Well Planning
Well Bore ContactPoor Filter CakeLittle or No Pipe Motion
Solids Induced Pack-off
Formation Loose w/ Little or No Bonding Insufficient Hydrostatic to Hold Back Formation
UNCONSOLIDATED FORMATIONS
Causes
Pack-off Due to Unconsolidated Formations
Prevention
Gel up Mud / Run Hi Vis SweepsControl DrillSpot Gel Pill Prior to TOH
Plan / Anticipate:
Solids Induced Pack-off
Increase Mud Weight, if possibleUse Under-saturated Water Base MudPump Fresh Water SweepsDesign Casing to Handle Collapse Loads
CausesMOBILE / PLASTIC FORMATIONS
Formation Extrudes Into Well Bore Due to Overburden Forces.
Prevention
Proper Well Planning:
Solids Induced Pack-off
Causes
Control Drill & Ream ConnectionsAnticipate Reaming on Trips
FRACTURED / FAULTED FORMATIONS
Prevention
Loose Chunks of Rock Fall into Well Bore
Plan / Anticipate
Solids Induced Pack-off
Causes
Raise Mud Weight, if possibleSet Casing Appropriately
OVER-PRESSURED SHALE COLLAPSE
Prevention
Shale “Pops” Off Wall Due to Pressure
Plan / Anticipate
Solids Induced Pack-off
Causes
Use Inhibited Mud SystemMinimize Exposure TimeBe Prepared for “Gumbo Attack”
REACTIVE FORMATIONS
Prevention
Mud Filtrate Reacts Chemically with Formation
Plan / Anticipate
Solids Induced Pack-off
Causes
Increase Annular VelocitiesBetter Mud Properties
Subject of another section
POOR HOLE CLEANING
PreventionNot Removing Cuttings From Well Bore
Mechanical / Wellbore Geometry Sticking Causes
KEYSEATING
Minimize Dog Leg SeverityCase Off Curves Soon After BuildingUse Keyseat WiperMake Frequent Wiper TripsBack Ream Out of Hole
• Abrupt Change in Well Bore Path (Dog Leg)• Long Hole Section Below Dog Leg
Prevention
Mechanical / Wellbore Geometry Sticking Causes
UNDERGAUGE HOLE
Always Gauge Bit & Stabilizers IN and OUTRun Gauge Protected Bits & StabilizersReam Suspected Undergauge Sections
• Undergauge Bit and/or Stabilizers• Coring (Core heads slightly U.G.)
Prevention
Mechanical / Wellbore Geometry Sticking Causes
LEDGES & DOGLEGS
Run Packed Hole AssembliesReam on Trips Through Problem Zones
• Limber BHAs• Hard - Soft Interbedded Formation
Prevention
Mechanical / Wellbore Geometry StickingCauses
SHOE JOINT BACKS OFF
Do Not Overdisplace CementThread Lock Bottom 3 Joints of CasingDrill Out Carefully
Prevention
Mechanical / Wellbore Geometry Sticking Causes JUNK
Good Housekeeping on Rig FloorKeep Hole CoveredInspect Equipment Frequently
Prevention
Something Manmade is Loose in the Hole
Mechanical / Wellbore Geometry Sticking Causes
CEMENT BLOCKS
Set All Casing As Close To TD As PossibleReam Casing Shoe & Open Hole Plugs Before Drilling Ahead
Hard Cement Falls In From Casing Shoe or FromOpen Hole Cement Plug
Prevention
Mechanical / Wellbore Geometry Sticking Causes
GREEN CEMENT
Wash Down Carefully to “Top of Cement”Pre-Treat Mud Before Drilling Green Cement
Prevention
Run BHA Into Un-set Cement
Mechanical / Wellbore Geometry Sticking Causes
LINER & SQUEEZE CEMENTING
Hazards in Liner CementingToo Much ExcessOverdisplacement
Squeeze CementingHold Pressure on Back Side, If PossibleUse Cement RetainersDO NOT Cement Up a Squeeze Packer (RTTS)
Cementing Yourself in the Hole
Trend Analysis
Plot Property -vs- Depth or Time and AnalyzeDrag on each ConnectionTorque -vs- DepthPWD -vs- TimeSoap Box
Pressure While Drilling
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40
60
80
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120
1 2 3 4 5
Time
Pres
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Pressure While Drilling
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80
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120
1 2 3 4 5Time
Pres
sure
Pressure While Drilling
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40
60
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120
1 2 3 4 5
Time
Pres
sure
Drag on Trip
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180000
200000
Weight
Depth
Recovery
Our Best Preventive Efforts Have FAILED
WE’RE STUCK !!
What Do We Do Now?
Identifying the Problem: “Why are we stuck?”
Stuck Pipe Handbook Flowcharts
Problem Diagnosis
Computer Intelligent System on Network at Cambridge FacilityCharts in Front of Sedco Forex Handbook
Solving the Problem: “What do we do now?”
First Actions
Solids Induced Stuck Pipe
Stop pumps & bleed pressure to 500 psiHold pressure & cycle drill string up to MUT with no up/down movementTry pumping if pressure bleeds offBegin working pipe up/down - max 50K overpull
Formation Movement / Poor Hole Cleaning
First Actions
Solids Induced Stuck Pipe
Do not commence jarringIncrease standpipe pressure to 1500 psiWork pipeCommence secondary procedures
Continued
First Actions
Differential Sticking
Circulate at maximum allowable rateSet compression w/ 50% MUT Pull tension w/ 50% MUTSecondary Procedures
Overbalanced, Filter Cake, Contact Area
First Actions
Mechanical Sticking
Maintain circulationJar in opposite direction of last movementLight loads (50K) w/ systematic increasesSecondary procedures
Dogleg, Keyseat, Junk, Undergauge
First Actions
Locating the Problem: “Where are we stuck?
Pipe Stretch Measurements
Pipe Stretch Equation
F
LWL
000,735
L = Length of Free Pipe (ft)L = Length of Stretch (in)F = Incremental Force (lbs)W = Weight of Drill Pipe (lb/ft)
Locating the Problem: “Where are we stuck?
Pipe Stretch Measurements
“Free Point” ToolReview Stuck Pipe Handbook Procedures
Stuck Here
Pull On DP
Measure Stretch Here
Measure StretchHere
FreePointTool
Solids Induced Stuck Pipe
JarringBack off and wash over
Secondary Procedures
Differential Sticking
Attack Filter Cake -- Spotting Fluid Spot within 4 hrs of stickingOmit after 16 hrsRule of Thumb - Soak minimum 20 hrs and a maximum 40 hrs
Secondary Procedures
Pipe Releasing AgentsSpotting Fluids
Pump “shear thinning” spacerViscosity: 100 rpm value > drilling mud50 to 100 bbl spacerCalculate volume of PRA - ExampleSpot at highest allowable pump rateWork pipe (up/down, torque) while soaking
Differential Sticking
Reduce Hydrostatic• Cut Mud Weight• “U Tube” - Kick it free• Caution - Well May Come In
Back Off and Wash Over
Secondary Procedures
Mechanical Sticking
Jar in opposite direction of last pipe movementBack Off and Wash Over
Secondary Procedures
Acid Pills
Calcium Formations, Strip Filter CakeTypically 7.5% to 15% HClCover stuck zonePump acid quickly to bitLarge water spacersWork pipe while soakingCirculate out after 5 minutes
Secondary Procedures
Fresh Water Pills
Mobile SaltCover stuck zone plus 20 bbl inside drill stringOBM - Viscous weighted spacerMaintain overpull while soakingRepeat after 2 hrs
Secondary Procedures
Drilling Jars - Benefits
Jar stuck pipe immediatelyMinimize fishing / sidetrack potentialMinimize surface loads (safety)Something to do while waiting on tools
Mechanical Jars
Most basic type of jarSliding sleeve inside shoulder sleeveHolding mechanism locks hammerOverpull stretches drill stringSudden release when holding mechanism is overcome
Mechanical Jars - Advantages
Remain locked until loadedMore freedom of placement in stringNo special tripping proceduresDo not jar unexpectedlyShort jar cycleCostAvailability
Mechanical Jars - Disadvantages
Load may not be variedJarring immediate once load is reachedLarge shock to hoisting equipmentRig may not pull over holding forceDifficult to load in deviated wellbores
Hydraulic Jars
Oil reservoir w/ orifice & bypass valveOil bleeds slowly until piston reaches bypass valveHydraulic delay
Hydraulic Jars - Advantages
Allows time to set drilling brakeNo torque needed to operateTorque does not affect loadVaried impact forceUse in deviated holes
Hydraulic Jars - Disadvantages
May jar unexpectedlyTripping more time consumingLonger jar cycleMore expensiveAvailability
Reasons Jars Fail to Fire
Incorrect weight - calculation incorrectPump open force exceeds compression forceStuck above jarJar mechanism failedJar not cockedDrag too high to load jar
Reasons Jars Fail to Fire (cont.)
Jar firing not felt at surfaceTorque trapped in mechanical jarNo patience
Accelerators - Functions
Compensate for short stringCompensate for hole drag slowing contractionAct as a reflector to jar shock waveIntensify jar blow
Jar / Accelerator PlacementConsiderations
Sticking pointJar direction requiredDifferential riskNeutral point of tension / compressionBuckling point Drag in the hole sectionDepth of hole section
Placement - Vertical Holes
Above buckling point at maximum WOBTwo DC’s above jarsNo stabilizers above jarsAccelerators needed in shallow hole sections
Placement - Deviated Holes
Do not run jars buckledAvoid tension / compression neutral pointCalculate measured weight reading requiredAccount for hole drag
Jar Placement Programs
Do not typically account for bucklingAccurately calculate and account for pump open forcesMaximize jar impact at stuck point
Example - Griffith Oil Tools
Fishing - OvershotsCatches OD of fishRight hand torque operatedAlways run a bumper subCirculating sub Basket grapple
More sturdy, Easier to releaseSpiral grapple
Stronger hold, Use in slim holeWall hooks
Fishing - Spears
Catches ID of pipeConsider stop ringRisk back off of wash pipe Rope spears
Fishing - Taps
Use when overshot or spear cannot be usedTaper Tap - Screws inside fishBox Tap - Screws over fishCannot be released & subject to breakageString shot cannot be run through taper tapExcessive torque will split box tap
Fishing - Junk
MagnetsJunk Baskets“Confusion Blocks”Mills
Pilot, Tapered, Concave, Flat-Bottom, Section, Fluted, Watermelon
Fishing - Milling
PilotTaperedConcaveFlat-BottomSectionFlutedWatermelon
Washover OperationsRun minimum size required - ¼” clearance inside, ½" clearance outsideMaximum length 600' drill pipe, 300' BHAConditioning tripEasy to differentially stickRun jars in deeper hole sectionsSteady feed when cutting formation“Jerky” feed when going over tool joints
Washover Shoes
Short tooth mills (mill tooth) for medium to hard formationsLong tooth mills for soft formations
Cut fasterHang easierHarder to get over top of fish
Flat bottom for stabilizers, reamers, tool joints, etc.
Solving the Problem: “What do we do now?”
THE OTHER OPTION:
S I D E T R A C K• Free Point and Back Off as Deep as Possible• Go Around the Fish
What Do We Do Now? Sidetrack or Fish?
It’s Purely a Matter of EconomicsSidetrack is a good choice when:
Fish Inexpensive or Recovery UnlikelyHole is Cheap (read Fast) to DrillSoft Formation - Easy to Kick OffSpread Rate (Total Daily Cost) is HIGH
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