Comprehensive Stuck Pipe

8/12/2019 Comprehensive Stuck Pipe

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COMPREHENSIVE

STUCK PIPECOURSE

Suez Canal Univ.SPE studenNovember,

Cause, Solutions & Preve


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Course Instru

Name

Ahmed Mokhtar Nofal

Presenter experience

Drilling Supervisor, Agiba Pet. Co.

Rig auditor, SEPSCOConsultant

Instructor, OGSBoots & Coots

Education

ElAzhar University, Petroleum EngineeringM.Sc.

Suez Canal University, Petroleum EngineeringB.Sc.

Contacts

Cell: 002-0126885503

Mail: [email protected]


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COMPREHENSIVE

STUCK PIPECOURSE

Suez Canal Univ.SPE studenNovember,

Cause, Solutions & Preve


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Introduction - Basic knowledge


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IntroductionBasic knowled

Friction: The force resulting from the movement of one elem

another. Direction of friction is o

direction of movement

Friction can be called Drag forces


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Torque:The force to rotate the string in

bore. Torque is measured in unit of forc

(ft.lbf)

Drag: The axial resistance opposite to

movement,

it is generated due to the interaction be

(DS or Csg) and formation.

The drag is normally measured in term


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Rotating weight: The weight indicator reading which

includes the travelling equipment weight and the drag free

buoyed weight of the drill string suspended by the blocks.

Off BTM torque: The torque required to rotate the drill

string at a standard RPM without drilling torque.


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Recording off BTM torque & Rotating

weight


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Up weight: The weight indicator reading required to raise

the drillstring at a standard speed without rotation and

circulation

* Up weightRotating weight = Up drag

String tension limit: The maximum safe weight indicator

reading with no torque to avoid plastic yield (Stretching) of

the drillstring.


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Recording Up weight


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Down weight: The weight indicator reading required to

lower the drillstring at a standard speed without rotation an

circulation

String set down limit: The minimum safe weight indicatorreading with no torque to avoid plastic deformation

(buckling) of the drillstring.


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Recording Down weight


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Effect of circulating

pressure


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Effect of circulating pressure

Recording string weights

without circulation provides

actual string drag information.

Stop circulation when

recording string weight data


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IntroductionStuck pipe


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Stuck pipe:An interruption in planned operations as exces

forces prevent pulling the drillstring out of the hole.

Tight hole:A momentary interruption in planned operation

drag forces restrict drillstring movement above normal ope

conditions. The pipe is not stuck in the hole as acceptable

is still being made.


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Cause:The condition(s) responsible

for the sticking mechanism.

There are +20 causes of stuck pipe.

Mechanism:The mechanical force

sticking the drillstring in the hole.

There are only 3 mechanisms of stuck

pipe.


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Stuck pipe mechanisms


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Stuck pipe

mechanisms

Hole pack off

Differential

Well bore geo


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Differential Sticking

mechanism

Hydrostatic overbalance

pressure drives the static

drillstring into the thick filter cakeof a permeable zone.


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Well bore geometry

mechanism

Sharp changes in hole

angle/direction; an undergauge

hole diameter

or

increase in assembly stiffness

will not allow passage of the

string.


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Stuck pipe mechanism determinatio

Exercises


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Stuck pipe Causes

uc p pe causes ac


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uc p pe causes acoff/Bridge

Inadequate hole

cleaning

Settled cuttings

Well bore instability Geo-pressurized shale

Hydro-charged shale

Reactive shale

Overburden/tectonic stresses

Unconsolidated /fracturedformations

Plastic formationsCement related

Special

Cement failure

Soft cement

Junk in hole

uc p pe causes ac


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Inadequate hole cleaning

The inability to efficiently remove formation solids (cuttings, cav

wellbore.

040 degree holes > 40 deg

holes


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uc p pe causes ac


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040 degree holes

Force of Ann ular Velocity :

- The lifting force generated by the velocity of

the

fluid slipping by the cuttings (slip velocity).

- Higher annular velocity exhibits better hole

cleaning efficiency due to greater pressure drop

across the cutting.

- Annular velocity is the second greatest

uc p pe causes ac


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040 degree holes

Carry ing Capacity of Yield Poin t :

- The lifting force generated by over coming the electrical attraction of

solids(gel).

- Higher YP exhibits better hole cleaning efficiency (near vertical hole) attraction forces between the gel platelets.Suspens ion Capacity of Gel Strength:

- The ability of mud to thicken when static and to become more fluid wh

(thixotropic).

- When circulation is stopped, the electrical strength of the gels reduces

velocity of the solids.

uc p pe causes ac


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> 40 degree holes

Assis tance of Flu id Buo yancy is Lost :

In high angle holes, the force of buoyancy provides less assistance in

out of the hole.

uc p pe causes ac


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> 40 degree holes

Force From A nnular Veloc ity and YP (LSYP):

The forces generated from AV and YP push the cuttings out of the hole

"tumbling" motion

(much like wind blowing leaves across the yard). When circulation is s

cuttings sink

to the low side of the hole forming a stable cutt ings b ed (does not sl

dow n ho le).In the horizontal

section

uc p pe causes ac


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> 40 degree holes

Force From Annu lar Velocit y and YP (LSYP):

The forces from AV and YP push the cuttings out of the hole in a "short

Cuttings accumulate on the low side of the hole forming an unstable cu

(s l ides down ho le even while circulat ing ).

Fluid circulation is displaced to the top side of the hole by the higher den

settling to the low side. When circulation is stopped, the bed of cuttings

hole, eventually stabilizing at +/-65hole angle.

40 : 65 degree section Boycott effect

uc p pe causes ac


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Hole cleaning pills

Proper use of mud pills will improve hole cleaning and the pill

should be determined based on the hole size and the calculate

hydrostatic head.


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uc p pe causes ac


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Hole cleaning pills

The concept is that the low viscosity pill stirs up the cuttings fr

side of the hole and the high viscosity pill sweeps them out of

Low viscosity/High viscosity pills

Tandem Pill

uc p pe causes ac


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Hole cleaning pills

The concept is that the low viscosity pill stirs up the cuttings fr

side of the hole and the weighted pill sweeps them out of the h

Low viscosity/Weighted pills

Tandem Pill

uc p pe causes ac


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Hole cleaning pills

-2 to 3 ppg heavier than the mud

-This type of pill will aid hole cleaning by increasing the buoyanc

slightly

Weighted pills

uc p pe causes ac


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Drillstring

rotation/Reciprocation

As flow rate alone cannot always remove a cuttings bed, recipr

rotating of the drill pipe are advised whenever the hole is being

clean. This action will dramatically increase the erosion of cutti

highly deviated wells

uc p pe causes ac


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Recommended drilling

parameters

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Circulation prior to connection or tripping out of

hole

Before making a connection, the hole should be circulated at the

rate to clear the cuttings from around the BHA. Depending upon and the length of BHA, a circulation time of 5 to 10 min is often n

uc p pe causes acff/B id


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Circulation prior to connection or tripping out of

holeBefore tripping out , the hole should be circulated at the normal flow rate

shakers are clean, whilst at the same time the drill pipe should be rotate

speed / reciprocated. This may require up to 3 * bottom-ups, depending

angle and hole size



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p poff/Bridge


0:40 degree holes

cleaning summery

-High viscosity sweeps.-High RPM required.

-High AV ( 50 * Hole diameter = GPM).

-Proper Mwt.

-Proper mud reology.

Recommended

practices


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ff/B id


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off/Bridge

Well bore insta

The mechanics o

is based on the d

stresses imposedsurrounding

the wellbore


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Overburden stresses: Generated by

the force of gravity of thecombined weight of the rock and

the formation fluids overlaying a

depth of interest.

Tectonic stresses: Produced by

lateral forces (side by side) in the

Well bore instability

p poff/Bridge

Well bore stresses



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Vertical to Horizontal stresses

V:H = (Poissons ratio)/(1-)

For water in a cylinder

=0.5 V:H = 1:1

For shale in a cylinder

=0.45 V:H = 1:0.8

p poff/Bridge


Well bore stresses



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The pressure of the native fluids (Water , Oil,

Gas) within the pore space of the rock.

Normal formation pressure:

Equals to a full column (From surface to

depth of interest) of formation water.

Normal FP (psi)=

0.465 (psi/ft) * TVD (ft)


Well bore stresses

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Abnormal:Greater than normal FP

expected for depth of interest.

When permeability drops to near zero,

formation fluids becomes trapped &any other compaction will pressurize

the formation pressure over the

normal.

Subnormal:Lower than normal.

May exist regarding production depletion


Well bore stresses

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= Dewatering

Increasing Depth

and Compaction

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Well bore instabi

Well bore stresses



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Normal

Pressure

Abnormal

Normal PreWell bore instability

Well bore stresses



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Mud HP: The pressure exerted on the

wellbore regarding the drilling fluid

column at a certain depth.

The mud hydrostatic pressure value

should be between the formation

fracture pressure and the

formation pore pressure values.

HP(psi) = Mwt (ppg)x .052 x TV

- Pressure Gradient (psi/ft) = Mw

- Pressure Gradient (psi/ft) =Pre

TVD (ft)

- Mwt (ppg) = Pressure Gradien

- Mwt (ppg) = HP (psi) TVD (f


Well bore stresses

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off/Bridge



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1-Well TVD = 8000 ft. Calculate Mud Hydrostatic pressure for e

following Mud Weights.

11 ppg12 ppg14 ppg

2-What Mud Weight is required to give a pressure gradient of 0

3-Mud Hydrostatic = 3900 psi at the bottom of an 8000 ft. TVD wwould be the pressure gradient for the mud?

4-For question above what is the equivalent Mud Weight?

5-Pressure Gradient = 0.57 psi/ft. What is hydrostatic at 12000

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1-Well TVD = 8000 ft. Calculate Mud Hydrostatic pressure for each

following Mud Weights.

11 ppg12 ppg14 ppg

4576 psi4992 psi5824 psi

2-What Mud Weight is required to give a pressure gradient of 0.59

ppg

3-Mud Hydrostatic = 3900 psi at the bottom of an 8000 ft. TVD wel

be the pressure gradient for the mud? 0.49 psi/ft

4-For question above what is the equivalent Mud Weight? 9.4 ppg

5-Pressure Gradient = 0.57 psi/ft. What is hydrostatic at 12000 ft. T

off/Bridge



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off/Bridge

Well bore insta

Geo-pressurized

Curved splintery

the shale shake

blocky with the h

enlargement


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Stuck pipe causes Differen


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Stuck pipe causesDifferen

Minimize Overbalance Pressure:

Plan the casing setting depths to minimize high overbalance pressure a

zone depths.

Maintain the minimum mud weight required for well pressure control and

stability.

Control the rate of penetration to minimize mud weight and use proper h

practices.

Minimize Formation Permeability:

Use fine calcium carbonate to isolate wellbore pressure from low pressu

zones

until casing can be set. Add fine LCM to the mud system if seepage loss

Prevention



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Stuck pipe causesDifferen

Causes & pr

Contact area



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Caus

preve

Pipe

Stuck pipe freeing Differen


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Stuck depthcalculation


Stuck pipe WB Geometry


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Causes preventi

Key seat



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Causes preventi

Micro do



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Causes preventi

Ledges



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Causes preventi

Thick filt


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Causes preventi

Mobile fo


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Stuck pipeJar & Accelerat


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p p

Drilling Jars

Mechanical jar



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p p

Drilling Jars

Hydraulic jar



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p p

Drilling Jars

Pump open force

Cocking from the Ope

More difficult to cock theCocking From the Clo

Easier to cock the jar.

Jarring Up: Intensifies

up-jar blow.

Jarring Down: Dampe

the down-jar blow.

Bleed trapped pressure

pump speed when cock

the open position or wh



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p p

DrillingAcceleratorsAccelerators

types



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p p

Drilling Jars

Jar calculations



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p p

Drilling Jars

Jar Notes

-Use the largest possible size of drilling ja

will give the biggest impact )

-Do not place any stabilizers above the dr

may become stuck at a stabilizer renderin

)

- Do not place the jar next to a stabilizer. (

higher bending stress )

- Have the same diameter tubular above a

ie

the jar should not be at a transition betwee

-Have at least three drill collars or two sta

above the jar to act as an anvil



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p p

Drilling Jars

Jar Notes

- Ensure that you and the driller know :

What kind of jars are in the string

The method of operation to jar up and dow

How much pump open force to expect

- Consider the use of a jar intensifier ( acc

improve jar impact force and double impu

intensifier one stand of HWDP above the

Comprehensive Stuck Pipe

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