Fishing - Weatherford Pipe Recovery

7/30/2019 Fishing - Weatherford Pipe Recovery

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Edition 2005

Pipe Recovery Handbook



Contents

List of Tables...................................................................................................................................

4In tro d u ctio n ............................................................................................................................................ 5

Wire lin e Pip e Re co ve ry Ove rvie w ......................................................................................................... 6

W e l l C o n f ig u r a t io n a n d C o n d i ti o n s . . . .. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . .. . . . .. . . .. . . .. . . . .. . . .. . . .. . . . 7

Typ e s o f Stickin g ................................................................................................................................... 8

Sa n d Stickin g ................................................................................................................................... 1 0

Mu d Stickin g .................................................................................................................................... 1 1

Me ch a n ica l Stickin g ........................................................................................................................ 1 2

Diffe re n tia l Stickin g .......................................................................................................................... 1 3

Ke y-Se a t Stickin g......................................................................................................................

1 4Un d e rg a u g e Ho le s........................................................................................................................... 1 5

Slo u g h in g Ho le s .............................................................................................................................. 1 6

Blo wo u t Stickin g .............................................................................................................................. 1 7

Ce me n t Stickin g .............................................................................................................................. 1 8

L o st Circu la tio n ................................................................................................................................ 1 9

Fre e -Po in t Se rvice s ............................................................................................................................... 2 0

L o g g in g Se rvice s ................................................................................................................................... 2 4

Ba ckin g Off ............................................................................................................................................ 2 6

Cu ttin g th e Pip e ..................................................................................................................................... 3 2

Ch e mica l Cu tte r ............................................................................................................................... 3 3

Je t Cu tte r ......................................................................................................................................... 3 4

Ra d ia l Cu ttin g To rch ........................................................................................................................ 3 5

Sp lit Sh o t ......................................................................................................................................... 3 6

Se ve rin g To o l ................................................................................................................................... 3 7

Me ch a n ica l Cu tte r............................................................................................................................ 3 8

st

Pipe Recovery Handbook, 1 ed. July 2005.

© 2 0 0 5 We a th e rfo rd . All rig h ts re s e rv e d .

The product s in t his cat alog m ay be covered by one or m ore Unit ed St at es and/ or int ernat ional pat ent s. Please address all inquiriesconcerning int ellect ual propert y t o:

Weat herf ord I nt ernat ional Lt d.L e g a l D e p a rt m e nt515 Post Oak Blvd. , Suit e 600Houston, Texas 77027 USATel: +1-713-693-4000

3



4© 2 0 0 5 We a th e rfo rd . All rig h ts re s e rv e d .

List of Tables

Ta b le 1 —We a th e rfo rd ’s Pro ce ss fo r Estima tin g Fre e Po in t...............................................................

2 2Ta b le 2 —Bu o ya n cy Fa cto rs................................................................................................................... 2 3

Ta b le 3 —Ove rp u ll We ig h ts .................................................................................................................... 2 3

Ta b le 4 —Tig h te n in g To rq u e ................................................................................................................... 2 6

Ta b le 5 —Re ve rse To rq u e ...................................................................................................................... 2 6

Ta b le 6 —Strin g -Sh o t Stre n g th fo r Tu b in g .............................................................................................. 2 8

Ta b le 7 —Strin g -Sh o t Stre n g th fo r Drillp ip e ............................................................................................ 2 9

Ta b le 8 —Strin g -Sh o t Stre n g th fo r Drill Co lla rs ..................................................................................... 3 0

Ta b le 9 —Strin g -Sh o t Stre n g th fo r Ca sin g a n d Wa sh p ip e ..................................................................... 3 1



Introduction

5

No two sticking situations are alike. Myriad wellconfigurations, well conditions and types of stickingmean that each pipe recovery operation is unique. Allsticking situations, however, have two factors incommon: stuck pipe is always an unanticipatedproblem; and freeing stuck pipe is always an urgentrequirement.


Successful pipe recovery operations depend onexperienced crews. Experienced crews blendk n o w le d g e a n d te c h n o lo g y t o a n a l yz e s p e c if i c w e l lconfigurations and conditions, identify the cause of sticking, determine the free point, recover the pipe, andleave the fishing crew with a retrievable fish.

Te c h n ol o g y a d v a n ce s b r i n g n e w t e c h ni q u e s w h i l e e n ha n c i n g t h e o l d t o s p e e d t h e r e co v e r y o f p r o d u c ti o n .




Wireline Pipe Recovery Overview

Though each job is unique, a good operator understands the value of using a standard process toapproach each situation.

Analyze the well configuration and well conditions at the time of sticking.

Run a free-point tool to determine the uppermost stuck point.A pipe recovery log can be used to identify the amount of stuck pipe

below the uppermost stuck point.

Work the pipe and determine the estimated free point.

Select the best method and tools to separate the pipe.

B a c k o f f , c u t o r s e v e r t h e p i p e .

Remove the free portion of the pipe from the well.

Gather and analyze information about current well conditions.Gamma ray, pipe recovery, and noise/temperature logs might provide

additional relevant information.

The following flowchart illustrates Weatherford'srecommended process for pipe recovery.



7 © 2 0 0 5 We a th e rfo rd . All rig h ts re s e rv e d .

W ell Co n fig u ratio n a n d Co n ditio ns

Well ConfigurationW e l l c o n f ig u r a ti o n a n d w e l l c o n d i ti o n s a f fe c t b o t h w hyt h e pi p e is s t uc k a n d ho w i t w il l b e f re e d. T he e a si e stway to visualize the many elements of the well is tomake an annotated sketch of the well at the start of the

job, before beginning pipe recovery operations. A goodw e l l s k e t ch f a c i l i ta t e s c o m m un i c a t io n b e t w e en t h ecustomer, fishing personnel, and the Weatherford piperecovery specialist. It should include

! t o t a l d e p t h o f we l l a n d h o l e s i z e ;! a l l c a s i n g s iz e s a n d w ei g h t s;! string configuration including pipe sizes, depth,

weight, and when necessary bottomhole assembly;

! hole angle and any kickoff points;! composition and weight of the wellbore fluid;! bottomhole temperature (BHT);! surface pressure;! bottomhole pressure (BHP);! cause of sticking, when known;! record of previous pipe recovery attempts.

Well Conditions

Pipe recovery operations may be complicated bycertain challenging well conditions, including

! s h a l l o w s t r a i gh t h o l e s;! deep straight holes;! d i r e c ti o n a l ( d e v i at e d ) h o l e s ;! high temperatures;! high pressures;! multiple tubing strings;! mixed strings.



Types of Sticking


Sand Mud

Mechanical

Differential Key-Seat



Types of Sticking


Undergauge Holes Sloughing Holes

Blowout

Cement Lost Circulation



Hole in Tubing Allowing Sand to Enter Annulus

Types of Sticking

Hole

Sand Sticking

Techniques for Freeing the Pipe

Classic sand sticking occurs with tubing in a casedhole. A leaking packer or a hole in the tubing or casingcan allow sand to enter the annulus. Over time, sandcan accumulate to a level that prevents the string frombeing pulled.

! Is there a history of sand production at the surface?

Free-point operations in sand-stuck pipe can bechallenging. As the pipe is worked, small pockets, or voids, may develop at the tubing collars. These voidsa l l o w j u s t e n ou g h m o ve m e n t fo r t h e f re e - p o in t t o o l t oi n d i c a te f r ee p i p e a t p oi n t s b e l o w t h e le v e l w h e r e t h epipe can possibly be retrieved after a backoff or cut.

Using higher working weights when determining thefree point helps to obtain an accurate backoff or cuttingdepth.

Stretch readings in sand-stuck pipe are often erratic.Torque readings can generally be taken at deeper depths than stretch readings, and are usually

repeatable. Take both stretch and torque readings sothat there is a point of comparison when determiningthe free point.

When picking a backoff or cut depth in sand-stuckpipe, choose a point at some distance uphole from thestuck point, where the pipe is 100 percent free. After the pipe is backed off, the remaining fish should bewashed over to remove all remaining sand from theannulus. Pipe recovery operations can then continue.

Identification

Free-Point Tendencies




Mud Sticking in Cased Hole

Types of Sticking

Mud Sticking


Mud sticking is typically encountered in cased holes, but itcan also occur in openhole environments.

Mud sticking commonly occurs when trying to retrievetubing on a recompletion job. Wells are often completedwith mud behind the tubing above the packer. Over time,weighting materials in the drilling mud (particularly barite)may settle and collect on top of the packer. The weightingmaterials can harden and stick the pipe. Hightemperatures can accelerate the process.

In open holes, contaminants such as shale, soluble saltsand acidic gases can mix with the mud, dehydrating it and

causing the pipe to stick. Contaminants can have thesame effect in cased holes when there is a hole or leak inthe casing or tubing.

! What type of fluid is in the annulus?! H o w l o n g ha s t h e fl u i d b ee n i n th e h o l e?! When was the last time the mud was circulated?

The pipe should be worked thoroughly to free as much

pipe as possible before running the free-point indicator.W o r ki n g d o w n b e l ow t h e w e i g ht o f t h e s t r i ng u s u a l l y f r e e sthe pipe more effectively than pulling strictly above theweight of the string.

C o n t in u o u s w o rk i n g o f t h e p i p e m ay c r e a te s m a l l p o c k e tso r v o i d s a ro u n d t h e tu b i n g c o ll a r s o r t o o l j o i n t s. T h e v o i dsa l l o w j u s t e n ou g h m o ve m e n t fo r t h e f re e - p oi n t t o o l t oi n d i c a te f r e e p i p e a t p o i n t s b e l o w t h e l ev e l w h e r e t h e p ip ecan possibly be retrieved after a backoff or cut.

Using higher working weights when determining the freepoint helps to obtain an accurate backoff or cutting depth.

Perforations can be used in open holes to break up themud and encourage circulation. In cased holes where thefluid in the annulus is in a liquid or semi-liquid state to thepacker, perforating the tubing above the packer maye s t a b li s h c i r cu l a t i on a n d a l l o w t h e a s se m b l y t o b e p u l l edfrom the hole.

Identification


© 2 0 0 5 We a th e rfo rd . All rig h ts re s e rv e d .11



Types of Sticking

Mechanical StickingM e c h a ni c a l s t i c ki n g t y p i c a l l y o c c u r sin cased holes, but it may alsooccur in openhole environments.T yp e s o f m e c h a n i c al s t i c ki n ginclude:

! collapsed casing! bent pipe! stuck packers! junk in the hole! wrap-around tubing

JunkSticking may occur when a foreignobject (for example, a wrench,tong, or hammer) falls into the holeo r a p i e c e o f t h e t o ol s t r i n g b re a k soff in the hole. The junk can wedgenext to the pipe string and causethe pipe to stick.

Bent PipeSticking may also occur when thep i p e i s b e nt . B e n t pi p e i s u s u al l y aresult of dropping the pipe.

Stuck PackersWhen the release mechanism on aretrievable packer fails, the packer is stuck, preventing the tubing frombeing pulled. With permanentpackers, corrosion can formbetween the tubing and the packer,preventing the tubing from beingpulled.

Collapsed CasingCasing may collapse because of w e l l p r e s su r e s o r f o r o t h er r e a s o n s ,causing the tubing to stick.

Wrap-Around TubingWrap-around sticking can occur w h e n m u l ti p l e s t r i ng s o f t u b i n g a r erun separately instead of in dualmode, causing the tubing strings totwist and wrap around each other a s t h e y a r e r u n i n t h e h ol e .




D i f f er e n t ia l S t i c ki n g , A l s oK n o w n a s “ We l l S t i c ki n g ”

Types of Sticking

Differential StickingD i f fe r e n ti a l s t i c ki n g , a l s o c a l l e d w a ll s t ic k in g , i s acommon cause of stuck pipe in open holes. Differentialsticking occurs when the hydrostatic pressure exertedby the mud column in the wellbore is greater than theformation pressure. The pressure differential (in other words, suction) causes the drill string to stick to thewellbore. The pressure differential can also create fluidloss to a porous and permeable formation. Over time, amud-cake buildup can reinforce the sticking.

Freeing differentially stuck pipe can be difficult becauseof the strength of the hydraulic force holding the stringto the side of the wellbore. The hydraulic force may bea million pounds or more. Under such conditions, awashover might not free the pipe, a string shot mightnot result in a backoff, and jarring operations might beunsuccessful. Sticking can intensify with time;therefore, it is essential to act immediately to freed i ff e re n ti a l ly s t uc k p i p e.

Challenges

Identification


! Is the hydrostatic pressure of the mud column in thewellbore greater than the formation pressureopposite the stuck pipe interval?

! Is the formation opposite the stuck point porous andpermeable, possibly sandstone?

! W a s t he p i p e s t a t io n a r y f o r s e v er a l m i n u te s o p p o s it ea porous and permeable zone (for example, whilemaking a connection), allowing a fairly large area of the pipe to come into contact with the formation?

! Is it impossible to pull or rotate the pipe? Can thew e l l f l u i d b e c i r c u la t e d a t n o r m al p r e s su r e s a n drates?

!

Is the hole clean and in good condition?! Is the wellbore fluid clean and in good condition?

F r e e -p o i n t r e ad i n g s c a n h e l p t o i d e n t i fy d i f fe r e n ti a lsticking. When sticking is confined to a single interval,free-point readings will drop off over a very shortd i s t an c e . I f th e r e a re s e v e r al s t u c k i n t e r va l scontributing to the overall sticking, free-point readingsw i l l d r o p of f o ve r a l on g e r di s t a n ce . A g a m m a r a y l o gcan determine whether the formation has numerousporous and permeable zones.

Mud logs and temperature logs can also provideinformation that may help to pinpoint the cause of sticking and identify the best means of pipe recovery.

Rotating or applying downward movement to the pipei s m o r e l ik e l y t o b r e ak t h e m u d s ea l t h a n p u ll i n g o n t h epipe.

Lowering the mud weight may also free a differentiallystuck string. However, the mud weight should not ber e d u ce d i f w e l l c o n t ro l i s a p r ob l e m . J a r r in g o p er a t i on scan also be conducted to try to free the pipe.

If the pipe needs to be backed off or cut, free-pointreadings must be taken to establish the point at whicht h e p i pe i s c o m p l et e l y f r e e . W h e n d ea l i n g wi t hdifferentially stuck pipe, it is essential to leave sufficientpipe exposed, both to act as a guide for fishing toolsand to ensure a good reconnection. A backoff or cutclose to a casing shoe or in a washed-out area or dogleg may leave a fish top that cannot be re-engaged.





Key Seat in Deviated Hole

Types of Sticking

Key-Seat Sticking


Key seats are formed during drilling operations, whenweight is applied to the bit through the drill collars andthe drillpipe is normally in tension. If the hole isdeviated (in other words, if there is a dogleg),continuous rotation can slowly cut a groove into thehigh side of the dogleg, forming a key seat.

T h e g r oo v e ( k ey s e a t ) is s m a l l er t h a n th e m a i nborehole because it is not drilled by the bit, but worninto the formation by the smaller-diameter body of thedrillpipe. When the pipe is pulled from the hole, thel a rg e r- O D s t ab i li z e rs , d r i ll c o ll a rs a n d t o o l j o i nt s w i l l n o tp a s s t h ro u g h t he k e y s e a t .

! Did the driller encounter excessive drag at measuredt o o l j o i n t i nt e r v al s w h i l e p ul l i n g o ut o f t h e h o l e ?

! Is the pipe free to rotate and circulate?! Is it possible to work the pipe up and down, but not

possible to move it up past a certain point?! Was the pipe moving upwards when it became

stuck?

A free-point survey can help to identify key-seatsticking. To obtain stretch readings, the pipe must bepulled into the key seat and worked above the normalweight. If the pipe rotates freely, torque cannot bew o r k ed d o w n t o th e s t u c k i n t e r va l t o o b t a in t o r q u ereadings.

If the pipe has been pulled into the key seat tightlyenough to become completely stuck, the free-pointr e a d i ng s w i l l d r o p o f f ov e r a s h o r t i n te r v a l . A k e y s e a tmay be indicated if the pipe goes from completely freeto completely stuck near an OD change in the string.

The backoff point should be located several jointsabove the key seat so that the top of the fish is in themain borehole and out of the key seat. Fishing toolscan then be made up on the fish in the normal part of the hole. Coordination with the fishing tool supervisor isc r i t i ca l w h e n d e a l in g w i t h k e y s e a t s.

Identification





Formation Expansion

Bit and Stabilizer Abrasion

Types of Sticking

Undergauge Holes


Sticking can occur in open holes where the diameter of the hole is smaller than the diameter of the pipe.Undergauge holes are caused by formation expansionor by abrasion on the bit and stabilizers.

Using mud that has a lower hydrostatic pressure thanthe formation when drilling through shale with a high,expandable clay content can cause the shale to deformand the hole to close.

Drilling through a salt section using oil-based mud cancreate an undergauge hole because the weight of theoverburden may cause the salt to flow into the

borehole, shrinking the diameter.Drilling through an abrasive hole section can dull thebit and reduce the gauge (OD) of the bit ands t a b il i z e r s. O n s u b s e q ue n t t r i ps w i t h a n e w b o t t om h o l eassembly, the bit and stabilizers can become stuck.

! What was the diameter of the old bit and stabilizers?! Did the sticking occur when running a new, full-size

b o t t om h o l e a s s em b l y i n t h e h o l e ?! W e r e th e d r i l l s t r i ng a n d n e w b o t t om h o l e a ss e m b ly

rotated while tripping in the hole?

Stretch readings typically drop off over a short interval,usually near the bit. Torque readings also drop off suddenly.

If a full-gauge bit has become stuck while tripping in, jarring with an upward force will usually free the pipe. If

the bottomhole assembly is stuck below theundergauge hole, a backoff operation will be

necessary. After a backoff, it may be possible to jar thefish out of the hole. If jarring is unsuccessful, awashover operation will enable the fish to be retrieved.

Identification





Sloughing Resulting from UnstableWellbore Wall

Types of Sticking

Sloughing HolesS l o u g hi n g o c cu r s w h e n th e w a l l o f t h e we l l b o re i su n s t a bl e . T h is u n s t a bl e c o n d i ti o n c a n c a us e t h e w al l o f the wellbore to collapse, or slough, into the drilled hole,trapping the drilling assembly in place.

If improper hole conditions are present, any type of formation can slough into the wellbore and stick thedrilling assembly. A sloughing formation may occur when a shale sequence absorbs water from the drillingfluid. The water causes the shale to expand and fallinto the hole, sticking the drilling assembly.

S l o u g hi n g i s a l s o c a us e d b y

! overpressured shale sections;! steeply dipping shale beds;! t u r b ul e n t f l o w i n t h e a n n u l us ;! l e d g e s t h a t br e a k o ff ;! surge pressures;! accumulated particles in cavities.

! Before sticking occurred, were excessive amounts of shale on the shakers at bottoms up?

! Did the driller encounter hole drag?! W a s th e r e a n y f i l l o n t h e m os t r e c e nt b i t t r ip ?!

Is circulation either greatly reduced or impossible?! Were there variations in pump pressure beforesticking occurred?

! Is it possible to rotate and pump fluid into theformation with no returns?

The pipe should be worked to free it as far as possiblebefore running the free-point survey. Continuousw o r k in g o f t h e p i pe m a y c r e a te s m a l l p o c k et s , o r v o id s ,in the debris around the collars or tool joints. The voidsa l l o w j u s t e n ou g h m o ve m e n t fo r t h e f re e - p o in t t o o l t oi n d i c a te f r ee p i p e a t p oi n t s b e l o w t h e le v e l w h e r e t h e

pipe can possible be retrieved after a backoff.

Identification




A backoff operation is typically performed whensticking results from a sloughing hole. It is important toestablish a backoff point where the pipe is completelyfree. If the pipe is backed off at a depth at which itc a n n ot b e p u l l e d, a t te m p t s t o pu l l t h e pi p e wi l l l o d g ethe tool joints and collars above the pockets, making itdifficult, if not impossible, to engage the fish.



Types of Sticking

Blowout Sticking

B l o w ou t s t i c k i ng o c c u r s i n o p e n h o l e s , a n d i scharacterized by sand, shale, and other formationdebris blowing uphole, bridging over, and sticking thep i p e . Th e d e b r i s c a n a l s o b lo w i n t o a n ot h e r f or m a ti o n(an underground blowout). Pressurized fluid movementcan be to the surface or to a low-pressure formationdownhole. In these situations, there is often more thanone stuck interval.

Blowouts typically occur when the formation pressureexceeds the hydrostatic pressure of the drilling fluid.

The following conditions increase the likelihood of ablowout or pressure kick:

! insufficient mud weight resulting from

- e f fo r t s t o f r e e t h e p ip e o r a v e r t d i ff e r e nt i a l s t i c k in gby lowering the mud weight

- a l a c k o f g e o l o gi c a l d a t a a b o ut t h e f i e l d

- formation liquids and/or gases entering the mudsystem and lowering the mud weight

! f a i l u re t o k e ep t h e h ol e f u l l o f f l ui d a s a r e s ul t o f improper fluid measurement when tripping the pipe

! p u l l i n g t h e p i p e f r o m th e w e ll t o o q u i ck l y w h e n th ehydrostatic pressure of the drilling mud is almostbalanced with the formation pressure, causing a

swabbing, or piston, effect

! Where is the casing set?! Has there been an unexpected increase in the mud-

tank volume?! Has there been a kick, or are there ongoing efforts to

c o nt r ol a k i c k?

T h e f r e e -p o i n t t o ol t y p i c al l y r e g i s te r s c l e a r m o ve m e n tin the free portions of the pipe and indicates a change

from completely free to completely stuck over a fewfeet.

To r q u e r ea d i n g s m a y s h o w s o m e m o ve m e n t i n t hestuck portion of the pipe; however, movement in thestuck area will rapidly decrease with depth.

When sticking occurs because of a blowout, there istypically more than one stuck interval. Free-pointsurveys alone are generally inadequate for determiningthe safest and most economical pipe recoveryp r o c ed u r e b e c au s e t h e f r ee - p o i nt t o o l o n l y d e f i ne s t h euppermost stuck section. Logging surveys used inconjunction with the free-point survey can provideuseful information for planning subsequent fishingoperations. A pipe recovery log can provide informationabout the sticking conditions below the uppermoststuck point. Noise/temperature logs can be used toidentify the source of the blowout and to verify whether f l u i d m o v e me n t i s s t i l l o c c u r ri n g .

Identification




Blowouts can result in more than onestruck point.



Cement-stuck points occur in openand cased holes.

Types of Sticking

Cement Sticking


Cement sticking can occur in both open and casedh o l e s a n d i s u s u a l l y a r e s u lt o f o n e o f t h e f o l l o w i n g :

! a mechanical malfunction (for example, a pump truckm a l f un c t i o n o r a l e a k i n t h e p i p e s t r in g )

! miscalculation of displacement amount resulting fromhuman error or hole washout

! efforts to contain a downhole blowout or preventexcessive lost circulation

! human error

! Has cement been pumped into the well?! Did the cement job go as planned?

Stretch and torque readings will drop off over a shorti n t e r va l u n l e s s t h e c e me n t h a s n o t h a d ti m e t o se tcompletely.

A backoff or cut can be used to recover theuncemented portion of the pipe. Jarring operations will

b e s u c c es s f u l o n l y i f t h e c e me n t e d s ec t i o n i s v er yshort. If the pipe is centered in the hole, a washover can be used to free the fish. If the pipe is not centered,i t m a y be n e c e s sa r y t o m i l l u p t h e pi p e a n d ce m e n t.

When a very long interval of pipe is cemented,sidetracking or abandoning this portion of the well mayb e t h e m o s t e c o n o mi c a l s o l u t io n .

Identification





L o s t c i r cu l a t i on l e a d s t o a v a r i e t y o f sticking types.

Types of Sticking

Lost Circulation


Lost circulation most commonly occurs when thehydrostatic pressure exerted by the drilling fluid cracksor fractures shallow, unconsolidated formations,allowing the drilling fluid to flow freely into theformation.

The movement of the drilling fluid into the formationcan cause washouts, which can lead to sloughing holesticking.

If the wellbore fluid has been weighted up to drillthrough a high-pressure zone and lost circulationo c c u rs , s h al l o w g a s c a n c au s e a bl o w o ut .

Efforts to prevent lost circulation may cause cementsticking.

! Has there been a decrease in returns at the pit?

Free-point tendencies are similar to those for sloughingholes, blowout sticking, and cement sticking,d e p e n di n g o n th e t y p e o f s t i ck i n g t ha t o c c ur s a s a

result of lost circulation.

Recovery operations are dictated by the type of sticking that occurs as a result of lost circulation.

Identification





Free-Point Services

Overview

Estimating the Free Point

The free point is the deepest point at which the pipec a n b e r e c o ve r e d b y a g i v e n m e t ho d .

Most free-point tools are strain gauges. In other words,they measure the stretch or torque of the pipe betweena top anchor and a bottom anchor. Stuck pipe will notmove in response to applied stretch or torque.Because a free-point tool measures stretch or torque,a n d b e c au s e s tu c k p i p e w i ll n o t m ov e i n r e sp o n s e tosurface-applied stress, a free-point tool can determinewhether the pipe is stuck or free at a given point.

Before beginning a free-point survey, it is important totake a manual stretch reading to determine anestimated free point. Estimating the free point indicateswhich portion of the pipe string is stuck (for example,the collars, drillpipe) and helps to determine where tocalibrate the free-point tool, which will save time duringthe free-point survey. An estimated free point alsoprovides a point of comparison for the results of thefree-point survey.

T h e f r e e po i n t i s e s t i ma t e d b y a p pl y i n g o v er p u l l t o t h epipe and measuring how much the pipe stretches inresponse. To estimate the free point, first find the total

s t r i n g we i g h t . Pi p e i n a w e l l f i l l e d wi t h f l u id w i l l w e i g hless than the pipe's calculated weight in air because of t h e b uo y a n c y e f f ec t o f t h e we l l f l u i d . I f t he w e l l c o n t ai n sfluid, the weight of the pipe string must be adjusted for buoyancy. To find the appropriate buoyancy factor,refer to Table 2—Buoyancy Factors. The appropriateb u o y a nc y f a c t or c a n a l s o b e c a l c u l at e d u s i n g t h eformula below:

Buoyancy Factor = 1 (Mud Weight in lb/gal ÷ 65.63)

If the rig's weight indicator is zeroed with the block, thetotal string weight should also include the weight of theblock.

Given the total string weight, find the amount of overpull needed to stretch the pipe 3-1/2 in./1,000 ft. Tofind the overpull, refer to Table 3—Overpull Weights, or use the following formula:

Overpull = 2208.5 x Pipe Weight/ft

Free-Point Surveys

Free-Point Stretch Surveys

Free-Point Torque Surveys

A free-point survey can identify the uppermost stuckpoint in a pipe string and assess the severity of thes t i c ki n g . T h e s ur v e y h e l p s t o d e t e rm i n e w h et h e r t oback off or make a cut, and it provides essentialinformation for selecting the correct tools to use duringthe pipe recovery operation. The survey cannot providei n f o rm a t i on a b o u t c o n di t i o n s b e l o w t h e u p p e rm o s tstuck point. A pipe recovery log can give an indicationo f s t i ck i n g c o n di t i o n s be l o w t h e s t uc k p o i n t t o a ll o wbetter planning of future operations.

To obtain an accurate free-point survey, it is importantto calibrate the free-point tool's sensor(s) to the free-

point panel before beginning the survey. Calibrating thetool in free pipe provides a baseline reading—a knownamount of stretch or torque in free pipe when stress isapplied to take a free-point reading. The baselinereading serves as a point of comparison for readingstaken during the free-point survey.

Accurate free-point readings also depend on the free-point tool remaining stationary during the survey withrespect to the pipe. Using a slack joint in the free-pointt o ol s t ri n g h el p s t o k e ep t h e t oo l s t at i on a ry. A s l ac k j o in tcan take sinker bar weight and wireline weight off thef r e e -p o i n t t o o l s o t ha t t h e t o o l i s f r e e to r e s po n d t o p i p estretch or torque.

A free-point stretch survey is typically conducted whenthe free pipe is to be cut and recovered. The surveyshould be started well above the estimated free point,typically at the calibration depth. Free-point readingss h o u l d be t a k e n a t 20 0 - f t i nt e r va l s u n t i l s t u c k- p i p ec o n d i ti o n s a r e i n d i ca t e d . W he n s t u c k p i p e i s i n d i c at e d ,closely survey the interval between the stuck pipereading and the last free pipe reading to define theu p p e rm o s t s tu c k p o i n t .

A free-point torque survey is typically conducted whenthe free pipe is to be backed off and recovered. Inaddition to indicating the uppermost stuck point, a free-point torque survey also provides information about theamount of torque trapped by the hole; whether torquecan be transmitted to the depth of interest; and howmany rounds it will take to transmit torque to the pointof backoff.




Before beginning a free-point torque survey, it isimportant to tighten the free pipe fully. When torque isadded to the pipe to take a free-point reading, all theapplied torque should be released before continuingthe survey. It is not possible to recover all the appliedtorque if the pipe is loose, or if torque is being lostdownhole. It is important to work with a pipe recoveryc r e w t h a t i s a b l e t o p re v e n t tr a p p ed t o r q u e, w o r ktorque downhole, take free-point readings using bothright- and left-hand torque, and distinguish betweentorque dropoff caused by sticking and torque dropoff c au se d b y w al l d ra g.


Types of Free-Point Tools A free-point tool is run with a collar locator on single-conductor electric wireline. Most free-point tools can berun in combination with a string shot.

A free-point tool uses at least one detector to sensestretch and torque. The tool is anchored in the surveyp i p e b o t h a b o ve a n d b e l o w t h e d e t e ct o r ( s) . To o l s c a nbe anchored with bowsprings, magnets, or motorizedanchors.

Weatherford's dual-sensor free-point tool (DSFT) usesseparate sensors to measure stretch and torque, andcan directly measure left- and right-hand torque equallyw e l l . T h i s t o o l w a s s p e c i fi c a l l y d e s i g n ed to a d dr e s sdeep, hot, high-pressure wells. It can operatecontinuously at 400°F (204.4°C) and at 425°F(218.3°C) for up to two hours.

Free-Point Services



Step Acti on Exam pl e

For 13,500 ft ( 4 ,1 14 ,8 m ) of 2 3/8-in.,

8 – r o u nd t u b i n g w e i g hi n g 4 . 7 l b / f t ,

calculate the weight of the string

in air by multiplying the pipe length

b y t h e p ip e w e ig h t :

1 3 , 5 0 0 f t x 4 . 7 l b / f t = 6 3, 4 5 0 l b

Adjust the string weight for the

b u o ya n c y e f f e c t o f t h e 1 0 - l b / g alm u d b y m u l t i p l yi n g t h e s t r i ng

w e i g ht b y t h e bu o ya n c y f a c t o r o f

the mud (0.847):

6 3 ,4 5 0 lb x 0 . 84 7 = 5 3 ,7 4 2 lb

I f t h e r i g ’ s w e i g h t i n di c a t o r i s z e r o ed

with the block, add the weight of the

b l o c k t o f i n d t h e t ot a l s t r i n g we i g h t :

5 3, 74 2 l b + 1 1, 00 0 l b = 6 4, 7 42 l b

2

P i c k u p t h e t o t al s t r i n g w ei g h t

( a d j u st e d f o r b u o ya n c y a n d t he b l o c k ,

when applicable).

3 Mark the pipe at the top of the rotary.

4

Apply the overpull necessary to

s t r e t c h t he p i p e 3 . 5 i n ./ 1 , 0 0 0 f t

(88.9 mm/304.8 m ).

I n t h is e x am p l e, t h e ov e rp u ll n e ed e d t o

s t r e t c h t he p i p e i s 10 , 0 0 0 l b ( 4 , 53 5 .9 k g ).

5 Mark the pipe at the top of the rotary.

6Measure the distance between the two

m a r k s .

For the purposes of this example, assume

t h a t t he d i s t a nc e be t w e en t h e t w o m ar k s

is 29 in. ( 736.6 mm ).

7

Divide the distance by 3.5, then multiply

t h e a n s we r b y 1 , 0 0 0 t o f i n d t h e e s t i m at e d

d e p t h to t h e f r e e po i n t .

29 in. ÷ 3.5 = 8.286

8 . 2 8 6 x 1 , 0 0 0 = 8 , 28 6

I n t h i s e x a m p l e, t h e e s t i m a t ed f r e e p o i n t i s

a t 8 , 2 86 f t ( 2 , 5 25 . 6 m ) .

1 D e t e r m i ne t h e t o t a l s t r i n g w ei g h t ,

adjusted for buoyancy. Add the

weight of the block, when applicable.

Table 1—Weatherford’s Process for Estimating Free Point


Free-Point Services



Pipe OD

(in.)

Pipe

Weight

( l b / f t )

3 1/2-in.

Str etch

Tensions

1.80 4, 000

2.25 5, 000

1-1/4 2.40 5, 500

1-1/2 2.90 6, 500

2-1/16 3.40 7, 500

4.70 10,0005.30 12,000

5.95 13,000

6.50 14,000

7.90 17,000

8.70 19,000

9.30 20,000

10.30 23,000

12.95 28,000

11.00 24,000

13.40 29,000

12.75 28,000

15.50 34,000

19.20 42,000

2-3/8 6.65 15,000

2-7/8 10.40 23,000

3-1/2 13.30 30,000

4-1/2 16.60 36,000

5 19.50 43,000

5 15.00 33,000

5-1/2 17.00 38,000

6-5/8 24.00 53,000

7 35.00 77,000

7-5/8 29.70 66,000

8-5/8 40.00 88,000

9-5/8 43.50 96,000

10- 3/ 4 45.50 100,000

Casing

Tubing

Dr illpipe

1

2-3/8

2-7/8

3-1/2

4

4-1/2

Fluid

Weight

(lb/gal)

Buoyancy

Factor

8.4 0.872

8.6 0.869

8.8 0.866

9.0 0.862

9.2 0.859

9.4 0.856

9.6 0.853

9.8 0.85010. 0 0.847

10. 2 0.844

10. 4 0.841

10. 6 0.838

10. 8 0.835

11. 0 0.832

11. 2 0.829

11. 4 0.826

11. 6 0.823

11. 8 0.820

12. 0 0.817

12. 2 0.814

12. 4 0.811

12. 6 0.807

12. 8 0.804

13. 0 0.801

13. 2 0.798

13. 4 0.795

13. 6 0.792

13. 8 0.789

14. 0 0.786

14. 5 0.778

15. 0 0.771

15. 5 0.763

16. 0 0.75616. 5 0.748

17. 0 0.740

17. 5 0.733

18. 0 0.725

18. 5 0.717

19. 0 0.710

19. 5 0.702

20. 0 0.695

Tabl e 2—B uoyan cy F act ors Tab le 3—Over pu ll Wei gh ts


Free-Point Services



Logging Services

Pipe Recovery LogsIn conjunction with a free-point survey, a pipe-recoverylog can provide a complete record of all stuck intervalsand possible trouble areas in a string of stuck pipe.

The log indicates the following:

! u p p e r mo s t s tu c k p o i n t! l e n g t h o f ea c h s t uc k i n t e rv a l b e l o w t h e u p p er m o s t

stuck point! s e v e r it y o f s ti c k i n g at e a c h in t e r va l b e l o w t h e

u p p e r mo s t s tu c k p o i n t! h o w m u c h e a c h i n t e rv a l c o n t ri b u t e s t o th e t ot a l s t u c k

condition of the pipe! safest, most practical, and most economical pipe

r e c o v er y m e t h od

Weatherford's pipe recovery logging system consists of a transmitter and a receiver. The transmitter emitsrapid sonic pulses that create a continuous vibrationthrough the pipe to the receiver. As the sonic pulsetravels, it decreases at stuck intervals in proportion tothe severity of the sticking condition. The receiver measures the amplitude of the resultant sonic wave.

The logging tool is run on a single-conductor electricw i r e l in e . T h e to o l i s c a l i b ra t e d i n k n ow n f r e e pi p e ,usually near the bottom of the surface pipe or the lastcasing string. After the log is recorded, a signalattenuation scale is placed on the log. This scaleshows the severity of sticking at each interval.

Sonic pipe recovery systems cannot be used in gasenvironments or gas-cut mud. Readings in thesec o n d i ti o n s a r e e r r a ti c a n d u n r e l ia b l e .

Examples of Weatherford Pipe Recovery Logs. The log on top indicates free pipe, and the log on the bottomi n di c at e s s t uc k p i p e.




Differential Temp

(degf)

Temperature

(degf)

Collar Locator

Depth

(ft)

2000 Hz(mv)

1000 Hz

(mv)

600 Hz

(mv)

200 Hz

(mv)

-9 2

2

2

2

210

-0.5

1.2 2000

2000

2000

2000

230

0.5

X400

X450

X500

X550

X600

X650

X700

183. 5183. 5183. 6183. 6183. 7183. 8183. 8183. 8183. 8183. 8183. 9183. 9183. 9183. 9184. 0184. 0184. 0183. 2183. 7

182. 6181. 0180. 0180. 7182. 9184. 5185. 6186. 2188. 8186. 0187. 0187. 7187. 3187. 3187. 2


Gamma Ray Logs

Noise/Temperature Logs

C o ll a r L o gs

While the pipe recovery log may be run independently,Weatherford recommends running it in conjunction witha gamma ray log to correlate the stuck pipe to thef o r m at i o n . A g a m m a r a y l o g i d e n t i fi e s t h e f o r ma t i o ntype, or lithology. Information about the formation typecan help to determine the type of sticking and the mostp r a c ti c a l a n d e c o no m i c a l m e t h od o f r e c ov e r i n g th estuck pipe.

Weatherford's noise/temperature logs may be run in

combination and displayed as a single log.Noise/temperature logs identify

! lost circulation zones;! underground blowouts in source and thief zones;! d r i l l s t r i ng o r t u b i n g le a k s ;! fluid movement behind the pipe;! gas versus liquid flow.

If interpreted properly, the information gathered by thenoise/temperature logs may suggest the conditions of the borehole and the most practical, most economicalpipe recovery method.

A collar log is always recorded simultaneously withpipe recovery logs, gamma ray logs, andnoise/temperature logs. Distortions in the magneticfield set up by the collar locator are used to identify tool

joints, collars, and other points downhole. Theinformation gathered by the collar log is used for depthc o n t ro l o n s u b s e qu e n t r u n s.

E x a mp l e s o f t e m p e ra t u r e (left) and noise (right) logss h ow g a s e n tr y i n to t h e p ip e .

25

Logging Services



PipeTightening Torque

( R o u n d s p e r 1 , 0 00 f t )

Dr illp ipe 1 rou nd

T u bing 1- 1/4 to 1 -1/ 2 r oun ds

Casing 1 /8 to 1/ 4 ro un d

PipeReverse Torque

( R o u n d s p e r 1 , 0 0 0 f t )

Dr illpip e 1 /4 t o 3 /4 rou nd

Tu bin g 3/4 to 1- 1/4 ro und s

Casin g 1/ 4 r oun d

Backing Off

26

Overview

Free Pipe

Torque Considerations

A successful backoff depends on the followingconditions:

! free pipe at the point of backoff ! sufficient left-hand torque at the point of backoff ! proper weight of the pipe string at the point of backoff ! a string shot of adequate strength for the specific

pipe

It is important to interpret the results of the free-pointsurvey correctly to ensure that the pipe is completely

free at the point of backoff. Performing backoff o p e r a ti o n s i n p i p e t h at i s n o t c o mp l e t e ly f r e e c a n re s u l tin a backoff at an unplanned, undesirable depth or afailure to achieve a backoff. Backing off at a depthw h e r e p i pe m o v e m en t i s r e s tr i c t e d ( in p a r t i a ll y s t u c kpipe) or too close to a washed-out area or dogleg couldleave a fish top that cannot be re-engaged. Whenbacking off, it is essential to leave sufficient free pipeexposed, both to act as a guide for fishing tools, and toensure a good reconnection.

The pipe must be tightened completely before applyingreverse (left-hand) torque to make a backoff. Table4—Tightening Torque provides a guideline for theamount of right-hand torque needed to tighten the pipe.The actual number of rounds used to tighten the pipewill vary, depending on hole conditions and thecondition of the pipe. The amount of right-hand torqueapplied to tighten the pipe should always be greater than the amount of left-hand torque that will be used tomake the backoff.

When determining the amount of reverse torque toapply for the backoff, consider the type, size, depth,and condition of the string to be backed off. Fatiguedpipe will have lower maximum yield strength than pipein good condition. Table 5—Reverse Torque providesgeneral guidelines for the amount of reverse torqueneeded to back off the pipe. The actual number of rounds used to back off the pipe will vary depending onh o l e c o n d i ti o n s a n d t h e c o n d i ti o n o f t h e p i p e .

Table 4—Tightening Torque

Table 5—Reverse Torque

String Weight

String Shots

At the point of backoff, the pipe string should be at then e u t ra l w e i g h t. T h e n e u tr a l w e i g h t is t h e w e i gh t a twhich the threaded connection at the backoff point isneither in tension nor in compression. To determine then e u t ra l w e i g h t, i t i s n ec e s s a ry t o k no w t h e pi p e we i g h tat the backoff point, adjusted for buoyancy and thew e i g ht o f t h e b l o c k w h e n a p p l i ca b l e .

A string shot backoff relies on the impact provided bythe detonation of a string shot to loosen a pipeconnection. The string shot itself does not free pipe or unscrew a threaded connection; it simply provides

extra energy to the torqued connection, which helps tou n s c re w t h e c o n ne c t i o n. T h e e f fe c t i s s i m i l ar t o t h a t o f striking a threaded connection with a hammer whileapplying left-hand torque with wrenches. The rig-p r o v id e d t o r q ue a c t u a l ly u n s c re w s t h e p i p e ; t he s t r i n gs h o t d e t e rm i n e s w h i c h p i p e c o n n ec t i o n w i l l b eunscrewed by the torque.





String shots may also be used to! release stuck packers or fishing tools (for example,

overshots);! remove corrosion from the pipe;! clean up perforations;! jump threaded and coupled pipe connections;! r e m ov e j e t n o z zl e s f r o m d ri l l b i t s t o i n cr e a s e th e r a t e

of circulation.

A successful string shot backoff depends on thebuilding of a reliable, problem-free string shot. Stringshots must be strong enough to back off the pipewithout damaging the threaded connection or the body

of the pipe. Shot strength is expressed in grains per foot of detonating cord placed on the shot rod. Therecommended shot strength depends on

! size of the pipe to be backed off;! weight of the wellbore fluid;! depth range of the backoff.

String shot strength charts list recommended startingstrengths, which may need to be adjusted for operational conditions. Tables 6 through 9 providestring-shot strengths for tubing, drillpipe, drill collars,casing and washpipe. The recommendations listed int h e s e t ab l e s a p p l y o n l y t o w el l b o r es w i t h f l ui d t o p s

above the backoff depth.

Completing the Backoff The pipe will typically spin free after the string shot isdetonated if the neutral weight and proper amount of left-hand torque have been applied. After the stringshot is detonated, pull up on the wireline and positionthe collar locator at the next threaded connectionuphole from the backoff attempt. To verify that thebackoff was completed, pick up on the pipe whileobserving the rig's weight indicator and the wirelinecollar locator. If no additional weight is gained as thepipe is picked up, the backoff was successful. If weighti s g a i n e d a s t h e p i pe i s p i c k e d u p, t h e p i p e m i g h t no tbe unscrewed completely. Lower the pipe back down

to the neutral weight and have the rig operator applyleft-hand torque to complete the backoff.

Backing Off



28

Table 6—String-Shot Strength for Tubing

The following table lists suggested string-shot sizes in grains per ft.


Backing Off

lb/gal kg/m3

0 to

5,000

5,000 to

7,500

7,500 to

10,000

10,000 to

15,000

15,000 to

20,000

20,000 to

25,000

10 1,198

14 1,678

18 2,157 80 80 t o 160 160 t o 240 240 to 320 320 to 4 80

10 1,198 80 t o 16 0 160 to 240

14 1,678

18 2,157 80 t o 160 320 to 4 80

10 1,198 80 t o 16 0 16 t o 24 0

14 1,678 240 to 320

18 2,157 160 240 to 400 400 to 4 80

10 1,198 80 t o 16 0 160 to 240 240 to 3 20

14 1,678 160 t o 240 240 to 320 320 to 4 00

18 2,157 80 t o 16 0 160 160 to 2 40 240 t o 320 240 to 400 320 to 4 80

10 1,198 80 t o 160 80 t o 16 0 160-320

14 1,678 160 to 2 40 240-400

18 2,157 160 160 160 to 2 40 320-480 320 to 5 60

10 1,198 160 to 240

14 1,678 240 to 320

18 2,157 160 t o 2 40 160 to 240 160 to 3 20 240 t o 400 320 to 480 400 to 5 60

10 1,198 160 240 t o 320 320 to 400 480 to 5 60

14 1,678 400 to 480 560 to 6 40

18 2,157 480 to 560 560 to 7 20

40

80

80

320 to 400

320 to 400

320 to 400 400 to 4 80

320 to 480

160 to 240

160 to 320

320 to 400

240 to 320160 to 24080

160 160 to 2 40

80

80

160

80 to 160

240

80 to 160

80 to 160

160 to 240

80 to 160

160

240

Pipe

Size

(in.)

Fluid WeightD epth of B ackoff

(ft)

40 80 t o 16 0 160 to 240 240 to 3 203/4,

1 and

1-1/4

8040

1-1/2

2-1/16

3-1/2

4-1/2

2-3/8

2-7/8



lb/gal kg/m3

0 t o

5,000

5,000 t o

7,500

7,500 t o

10,000

10,000 t o

15,000

15,000 t o

20,000

20,000 t o

25,000

10 1,198 240 to 3 20 320 to 400 480 to 5 60 560 to 7 20

14 1,678 320 to 4 00 400 to 560 560 to 6 40 720 to 8 00

18 2,157 160 to 2 40 240 to 320 320 to 4 80 560 to 720 720 to 8 00 800 to 1,040

10 1,198 160 160 160 to 2 40 240 to 320 320 to 4 00 320 to 4 80

14 1,678 240 240 to 3 20 320 to 400 400 to 4 80 400 to 5 60

18 2,157 240 to 3 20 320 to 4 00 320 to 480 480 to 5 60 480 to 6 40

10 1,198 160 240 400 to 4 80 480 to 5 60

14 1,678 240 480 to 6 40 560 to 7 20

18 2,157 240 to 3 20 320 to 4 80 400 to 640 560 to 7 20 640 to 8 00

10 1,198 160 240 400 to 4 80 480 to 5 60

14 1,678 240 480 to 6 40 560 to 7 20

18 2,157 240 to 3 20 320 to 4 80 400 to 640 560 to 7 20 640 to 8 00

10 1,198 240 320 320 to 4 00 400 to 560 480 to 5 60 560 to 7 20

14 1,678 400 400 400 to 640 640 to 7 20 640 to 8 00

18 2,157 400 to 480 400 to 5 60 480 to 720 640 to 8 00 720 to 8 80

10 1,198 320 to 4 00 320 to 400 480 to 640 560 to 6 40 640 to 7 20

14 1,678 400 to 480 480 to 720 640 to 8 00 720 to 8 80

18 2,157 400 to 560 480 to 6 40 560 to 800 720 to 8 80 800 to 9 60

10 1,198 400 480 to 5 60 560 to 640 640 to 8 80 880 to 1,040

14 1,678 640 to 720 720 to 8 80 960 to 1,120

18 2,157 640 to 800 880 to 1,160 1,040 to 1,3 60

5- 9/16D P a nd

5 H W D P

Pipe

Size

( in.)

5 DP

and

4- 1/2

HWDP

4

4- 1/2

2- 7/8

3- 1/2

Fluid WeightDept h of Backof f

(ft)

2- 3/8160 160 to 240

240 to 320

240 to 320

240 to 3 20 320 to 400

240 to 320

240 to 3 20 320 to 400

320 to 400

400 to 480

400 to 480480 to 560

560 to 640

400 to 480


Table 7—String-Shot Strength for Drillpipe

The following table lists suggested string-shot sizes in grains per ft; 80-grain detonating cord is recommended.

Backing Off



lb/ga l k g/m3

0 to

5 ,0 0 0

5 ,0 0 0 to

7 ,5 0 0

7 ,5 0 0 to

1 0 ,0 0 0

1 0 ,0 0 0 to

1 5 ,0 0 0

1 5 ,0 0 0 to

2 0 ,0 0 0

2 0 ,0 0 0 to

2 5 ,0 0 0

1 0 1 , 1 9 8 1 6 0 to 3 2 0 2 4 0 to 3 2 0 2 4 0 to 4 0 0 3 2 0 t o 5 6 0 4 0 0 to 6 4 0 5 6 0 to 7 2 0

1 4 1 , 6 7 8 2 4 0 to 4 0 0 3 2 0 to 4 0 0 3 2 0 to 4 8 0 4 0 0 t o 6 4 0 4 8 0 to 7 2 0 5 6 0 to 8 0 0

1 8 2 , 1 5 7 4 0 0 to 4 8 0 4 8 0 4 8 0 to 5 6 0 5 6 0 t o 7 2 0 6 4 0 to 8 0 0 7 2 0 to 8 8 0

1 0 1 , 1 9 8 2 4 0 to 4 8 0 3 2 0 to 5 6 0 3 2 0 to 5 6 0 4 0 0 t o 6 4 0 5 6 0 to 8 0 0 6 4 0 to 8 8 0

1 4 1 , 6 7 8 3 2 0 to 6 4 0 4 0 0 to 7 2 0 4 8 0 to 8 0 0 4 8 0 t o 8 8 0 6 4 0 t o 1 , 0 4 0 8 0 0 to 1 , 2 0 0

1 8 2 , 1 5 7 4 8 0 to 7 2 0 4 8 0 to 8 0 0 5 6 0 to 8 8 0 5 6 0 t o 9 6 0 6 4 0 t o 1 , 1 2 0 8 8 0 to 1 , 3 4 0

1 0 1 , 1 9 8 4 8 0 to 5 6 0 5 6 0 to 6 4 0 5 6 0 to 7 2 0 6 4 0 t o 8 8 0 7 2 0 to 9 6 0 8 0 0 to 1 , 1 2 0

1 4 1 , 6 7 8 5 6 0 to 7 2 0 6 4 0 to 8 0 0 6 4 0 to 8 8 0 7 2 0 to 1 , 2 0 0 8 8 0 t o 1 , 4 2 0 9 6 0 to 1 , 5 0 0

1 8 2 , 1 5 7 6 4 0 to 8 0 0 6 4 0 to 8 8 0 7 2 0 to 1 1 2 0 8 0 0 to 1 , 4 4 0 9 6 0 t o 1 , 5 2 0 1 ,0 4 0 t o 1 ,7 6 0

1 0 1 , 1 9 8 6 4 0 to 8 0 0 7 2 0 to 8 8 0 8 0 0 to 9 6 0 1,040 to 1,360 1 ,2 00 to 1, 60 0 1 ,6 00 to 1, 84 0

1 4 1 , 6 7 8 8 0 0 to 9 6 0 8 8 0 to 1 , 0 4 0 9 6 0 to 1 , 2 0 0 1,200 to 1,600 1 ,4 20 to 1, 84 0 1 ,7 60 to 2, 16 0

1 8 2 , 1 5 7 8 8 0 to 1 , 2 0 0 9 6 0 to 1 , 3 6 0 1 ,0 40 t o 1 ,4 40 1 ,2 80 t o 1 ,7 60 1 ,5 20 to 2, 16 0 1 ,8 10 to 2, 32 0

1 0 1 , 1 9 8 9 6 0 t o 1 , 2 0 0 1,040 to 1,280 1,120 to 1,280 1,200 to 1,520 1 ,4 40 to 1, 84 0 1 ,8 40 to 2, 32 0

1 4 1 , 6 7 8 1,020 to 1,360 1,200 to 1,440 1,280 to 1,520 1,440 to 1,920 1 ,5 20 to 2, 00 0 2 ,0 00 to 2, 56 0

1 8 2 , 1 5 7 1,120 to 1,440 1,280 to 1,520 1,360 to 1,600 1,520 to 2,080 1 ,6 00 to 1, 56 0 2 ,1 60 to 2, 72 0

1 0 1 , 1 9 8 1,120 to 1,200 1,200 to 1,280 1,120 to 1,280 1,200 to 1,520 1 ,4 40 to 1, 84 0 1 ,8 40 to 2, 32 0

1 4 1 , 6 7 8 1,120 to 1,360 1,200 to 1,440 1,280 to 1,520 1,440 to 1,920 1 ,5 20 to 2, 00 0 2 ,0 00 to 2, 56 0

1 8 2 , 1 5 7 1,120 to 1,440 1,280 to 1,520 1,360 to 1,600 1,520 to 2,080 1 ,6 00 to 2, 56 0 2 ,1 60 to 2, 72 0

1 0 1 , 1 9 8 1,120 to 1,200 1,200 to 1,280 1,120 to 1,280 1,200 to 1,520 1 ,4 40 to 1, 84 0 1 ,8 40 to 2, 32 0

1 4 1 , 6 7 8 1,120 to 1,360 1,200 to 1,440 1,280 to 1,520 1,440 to 1,920 1 ,5 20 to 2, 00 0 2 ,0 00 to 2, 56 0

1 8 2 , 1 5 7 1,120 to 1,440 1,280 to 1,520 1,360 to 1,600 1,520 to 2,080 1 ,6 00 to 2, 56 0 2 ,1 60 to 2, 72 0

Fluid We ightDe pth of Ba c k off

( f t )

4 - 1 / 4

to

5 - 1 / 2

1 1

1 0

8 - 1 / 4

to

9

7 - 1 / 2

to

8

5 - 3 / 4

to

7

3 - 1 / 8

to

4

Pipe

Size

(in.)

30

Table 8—String-Shot Strength for Drill Collars


Not es:For large drill collars wit h H-90 or 6 5/ 8-in. regular t ool joint s, add 200 grains t o m inim um shot .

Above 10, 000 f t in f luid less t han 10 lb/ gal, do not exceed 100 grains per OD in.


Backing Off



lb/gal kg/m3

0 to

5,000

5,000 to

7,500

7,500 to

10,000

10,000 to

15,000

15,000 to

20,000

20,000 to

25,000

10 1, 198 240 t o 400

14 1, 678

18 2, 157 240 t o 320 240 to 400 400 to 5 60

10 1, 198 160 to 2 40 240 320 320 to 4 00 400 to 4 80

14 1, 678 240 480 to 5 60

18 2, 157 160 to 3 20 240 to 3 20 480 to 6 40

10 1, 198

14 1, 678

18 2, 157 160 to 3 20 320 to 4 00 400 t o 480 480 to 560 560 to 6 40 640 to 7 20

10 1, 198

14 1, 678

18 2, 157 240 to 4 00 400 to 4 80 480 t o 560 560 to 640 640 to 7 20 720 to 8 00

10 1, 198

14 1, 678

18 2, 157 240 to 4 00 400 to 4 80 480 t o 560 560 to 640 640 to 7 20 720 to 8 00

10 1, 198

14 1, 678

18 2, 157 320 to 4 00 400 to 4 80 480 t o 560 560 to 640 640 to 7 20 720 to 8 00

10 1, 198

14 1, 678

18 2, 157 400 to 4 80 480 to 5 60 560 t o 640 640 to 720 720 to 8 00 800 to 8 80

10

and

10-3/ 4

5

and

5-1/ 2

6

and

6-5/ 8

7

and7-5/ 8

8

and

8-5/ 8

9

and

9-5/ 8

4-1/ 2

Pipe

Size

(in.)

Fluid WeightD epth of B ackoff

(ft)

160 160 to 2 40240 240 to 320

320 t o 400

320 t o 480

160 t o 240

240 t o 320 320 to 400 400 to 4 80

160 to 2 40 240 to 3 20 320 t o 400 400 to 480

560 to 6 40 640 to 7 20

240 to 3 20 320 to 4 00 400 t o 480 480 to 560

480 to 5 60 560 to 6 40

560 to 6 40 640 to 7 20

560 to 6 40 640 to 7 20

240 to 3 20 320 to 4 00

240 to 3 20 320 to 4 00 400 t o 480 480 to 560

400 t o 480 480 to 560

640 to 7 20 720 to 8 00320 to 4 00 400 to 4 80 480 t o 560 560 to 640


Table 9—String-Shot Strength for Casing and Washpipe


Backing Off



Types of CuttersT h e r e a re s e v e r al c a t e go r i e s o f c u t ti n g t o o ls :

! c h e m ic a l c u t t er s! jet cutters! radial cutting torches (RCTs)! split shots! severing tools! m e c h an i c a l c u t t er s

This section describes the advantages anddisadvantages of each type of cutting device.

Cutting the Pipe

32

OverviewCutting the pipe is necessary when the geometry of thewellbore makes it impossible to transmit torque downto the point of backoff. Cutting the pipe may also be aneconomical method of pipe recovery, since it typicallytakes less time than backing off.

Various types of pipe-cutting devices are available,each with advantages and disadvantages. Todetermine the type of cutting device to use during thepipe recovery operation, the capabilities of each devicemust be considered from the point of view of thesticking situation and wellbore conditions. Anexperienced pipe recovery crew, familiar with the

advantages and limitations of a variety of cutters, canhelp to select the appropriate tool for the specificcutting operation. Manufacturers' manuals,Weatherford's sales staff, and district locations canprovide information about cutter sizes.




Cutting the Pipe

Examples of Chemically Cut Pipe

C h e mi c a l C u t te r a n d E x a m p l e C u t


Chemical Cutter Advantages

Disadvantages

! Proven, well-known and accepted technology! Provides instantaneous flare-free and burr-free cut! W i l l n o t d a m a ge a d j a c e n t p i p e s t ri n g s

! Limited use with certain pipe grades, alloys, andwellbore conditions

! Limited capability for passing through restrictions andcutting large pipe below the restriction

!

Hazardous to operate and transport! Specific safe-handling requirements! R e q u ir e s p l a c a rd e d t r a n sp o r t at i o n! Illegal to transport on passenger flights! Requires radio silence during operations! Borehole fluid limitations! Temperature and pressure limitations



Cutting the Pipe

E x a mp l e s o f J e t -C u t P i p e

34

Jet Cutter Advantages

Disadvantages

! Proven, well-known and accepted technology! Provides instantaneous cut

! Cut is often flared and sometimes split! Cut pipe may require milling and dressing before it

can be fished! M a y l e a v e d e br i s i n t h e w e l l bo r e! Limited capability for passing through restrictions and

cutting large pipe below the restriction! May damage adjacent pipe strings! H a z a rd o u s t o t r a n sp o r t! Requires placarded transportation! I l l e g al t o t r a n s p or t o n p a s s e n g e r f l i g ht s! Requires radio silence during operations




Cutting the Pipe

The Radial Cutting Torch (RCT)

Example of Pipe Cut with Radial Cutting Torch


Radial Cutting Torch (RCT)Advantages

Disadvantages

! Provides instantaneous, flare-free and burr-free cut! Leaves no debris in wellbore! Capable of cutting pipe of any alloy, plastic-lined pipe

and scaled pipe! Capable of passing through restrictions and cutting

l a r g e p i p e b e l ow t h e r e s tr i c t i on! Capable of operating at temperatures up to 500°F

(200°C) and at high pressures! Capable of operating at higher temperatures and

higher pressures than chemical cutters or jet cutters!

F e a t ur e s a n o n - e x p l o s iv e , f l a m m a bl e s o l i d! May be transported without special requirements,

also on passenger flights! High-pressure tools

! N e w, l e s s f a m i l ia r t e c h n o l o g y! Requires perforating the pipe when cutting just

above a plug

35



Cutting the Pipe

Disadvantages

! Split fish top may cause a loose collar to be left in thehole, possibly hampering milling operations

! May damage adjacent pipe strings! Requires placarded transportation! Requires radio silence during operations

Examples of Drill Collars and Pipe Cut with Split Shots

Split ShotAdvantages

! P r o d uc e s c u t s w i t h l i tt l e o r n o f l a r i n g! Capable of passing through restrictions




Cutting the Pipe

Disadvantages

! Not designed to leave a retrievable fish! L e a v es s i g n i fi c a n t a m o u nt s o f de b r i s i n th e we l l b o re! M a y o n l y b e us e d in o pe n h ol e s ; w i l l d e s t ro y a d j a c en t

pipe! Requires placarded transportation! Requires radio silence during operations

Examples of Pipe Cut with Severing ToolsSevering Tool Illustration


Severing ToolAdvantages

! Capable of separating pipe when no other cuttingd e vi c e w i l l w o rk

! Capable of separating drill collars up to 11 in.(279.4 mm)



Cutting the Pipe

E x a mp l e s o f M e c h an i c a l C u t te r s

38

Mechanical Cutter Advantages

Disadvantages

! T wo b a si c t y p e s:

- Electro-mechanical for use with electric wireline

- Mud motor-powered for use with coiled tubing andthreaded pipe

! Capable of cutting any type of pipe, in any condition! No hazardous materials! No special transportation requirements! No radio silence requirements

! S l o w c u t t in g , l a b o r -i n t e n si v e! Leaves cuttings in wellbore! Limited capability for passing through restrictions

and cutting large pipe below the restriction




Weatherford5 1 5 P t O k B l d S i t 6 0 0

SMSimply Productive

Pipe Recovery Handbook

Documents

Fishing - Weatherford Pipe Recovery