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

Causes

MOBILE / 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

Prevention

Not 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 Cementing Too Much Excess Overdisplacement

Squeeze Cementing Hold Pressure on Back Side, If Possible Use Cement Retainers DO NOT Cement Up a Squeeze Packer (RTTS)

Cementing Yourself in the Hole

Trend Analysis

Plot Property -vs- Depth or Time and Analyze Drag on each Connection Torque -vs- Depth PWD -vs- Time Soap Box

Pressure While Drilling

0

20

40

60

80

100

120

1 2 3 4 5

Time

Pre

ssur

e

Pressure While Drilling

0

20

40

60

80

100

120

1 2 3 4 5

Time

Pre

ssu

re

Pressure While Drilling

0

20

40

60

80

100

120

1 2 3 4 5

Time

Pre

ssur

e

Drag on Trip

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

40000

60000

80000

100000

120000

140000

160000

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 Facility

Charts 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” Tool Review 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 sticking Omit after 16 hrs Rule 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 movement

Back 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 release

Spiral grapple Stronger hold, Use in slim hole

Wall 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 Operations

Run minimum size required - ¼” clearance inside, ½" clearance outside

Maximum 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 formations

Long tooth mills for soft formations Cut faster Hang easier Harder 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 Unlikely Hole is Cheap (read Fast) to Drill Soft Formation - Easy to Kick Off Spread Rate (Total Daily Cost) is HIGH