Fishing

Fishing

• What is there?

• Recovery

• Free Point and Back-off

8/25/2015 1 George E. King Engineering

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Identifying the fish

• What is it?

• Where is it?

• What is looking up?

• How damaged is it?

• Only when you know the answers to these questions can you devise a fishing attempt.


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The Importance of the “Tally Book”

• For every piece of equipment that goes in a well, you should have: – Diameter of every body, neck, shoulders, etc.

– Length of each section and the overall length.

– Thread type & if pin or box will look up at each connection (many fish are unscrewed tools).

– Break strength of all weak joints or thin tools

– Drawing or photo of all unusual tools (place a rule in the photo)


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• Keep the Tally book current – for every run, not changes.

• Successful fishermen are planners and note takers – before the fish is lost.

• Keep records of where the string drags (depth, over-pull, changes in behavior)

• Compare depth readings with profile depths

• Record all fluid levels, tight spots, and fill tags.


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• When you loose a tool (and you will if you do well work for long). – Note behavior at the separation point

– Tag down gently to see if the fish is stuck or has dropped (if there is a known tight spot, you may not want to tag)

– Pull out of the well and carefully measure and account for all the BHA that has returned, and…….


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• Check the recovered BHA and Compare the tools recovered with initial BHA from the Tally Book.

– If the BHA is unscrewed, what is thread, and is pin or box looking up? Shoulders or smooth body present?

– If BHA has broken: • Does metal near the separation indicate fatigue or corrosion?

• Do drag marks indicate pipe collapse?

• Do one-sided marks or cuts hint at low side debris?

• Does debris on the recovered section suggest bridging?


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• If wire is recovered without the rope socket, NEVER assume that the wire has pulled off at the rope socket.


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Tools for Examining the Fish

• Impression blocks (confusion blocks?)

– Flat bottom and tapered soft lead block.

– Set down just ONCE!

• Cameras

– Continuous surface readout on E-line

– Image capture (delayed updating) on E-line

– Slick line conveyed, recording cameras


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Lead impression block of an obstruction in the tubing.


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Collett bent in – perhaps from CT run?


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Camera Selection

• The continuous surface readout allows running at speed into a well (50 to 100 ft/min) – you can see what is coming.

• Image update cameras (1 to 6 seconds screen refresh) can only be run slowly if you don’t know where the fish is – you could hit the fish and destroy the down-looking camera if run too fast.

• Recording cameras, like the image update cameras, require knowledge of exactly where the fish is located.

• AND - water considerations……..


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Water for Camera Use

• If water is used in the well for the camera run: – You must be able to read a newspaper through a water

glass of the water that is to be pumped.

– Standard field brines are not suitable for camera use, even when filtered.

– A small positive water injection may be needed to sweep the wellbore during the camera run.

– If the well flows, the fluid in the wellbore will become opaque quickly.

– Camera movement will stir up some sediments from the pipe walls.


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DHVI 8/25/2015 14 George E. King Engineering

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Fishing and Tubing Repair

• Problems

• Solutions


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Typical Spear Configuration

Top connection/fishing

neck

Catch and release

mechanism

Catch spring

Adjustable stop


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Wireline Catching Tools

“Top Hat"

Internal catchers

Spear-type

wireline catchers


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Wireline grab and overshot.


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Wireline Fingers


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Overshot – note beveled guide area and inside grapple.

Release mechanism?


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Basket – used to recover small objects


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Special tool – used for odd shapes.


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Indexing system – rotates mule shoe a few degrees by pick up and set down or by pumping, depending on mechanism.


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Spear with grapple – the grapples are interchangeable


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A wireline rasp – used for removing small amounts of soft deposits. The rasp is very hard material – don’t loose this tool in the well, cannot mill it out easily.


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Swages – right: a variety of sizes, left: a fluted swage

Typical use for swages is to attempt to enlarge ovaled or partially crushed tubing. Note: the tubing can become work hardened quickly.


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Fishing With Coiled Tubing

• Load (tensile, shock, torsion?) limits

• jars

• deviation

• catch tools

• release options

• tubing cutoff


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Tools

• Overshots are primary catch tool.

• RCJB - reverse circulation junk baskets

• prongs, magnets, etc., available

• Release sub in the string

• Circulation sub

• jars and accelerators

• TV camera may be best tool of all. - Know what the fish looks like!


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Fishing For Coiled Tubing

• common causes of CT breaks

• catch tools

– continuous overshots

– others???

• release mechanisms

• engaging the fish

• deviated wells


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Simple Overshot


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Causes of CT Breaks

• previous damage (point) initiated breaks

• present damage initiation

• corrosion initiation

• collapse

• tension

• compression?


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Catch Tools

• overshots mostly - grapple?

– must deal with oval tubes as a best option

• continuous overshots - length limited

• baiting/milling efforts

– square the CT top

– open the tube • rounder = better grip

• wireline entry

• avoid spears (outward CT radial strength?)


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Fishing Flattened CT

• Baker continuous overshot for flattened CT

– accepts collapsed CT

– trap design on catch mechanism

– releasing?


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Release Options

• critical need - must be reliable!

• must be able to release

– CT limited in tension, especially in deviation

– CT jars do wear out

– release actuation mechanism: how?/possible?

• Always plan on fishing CT in stages


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Engaging the Fish

• limited push with CT

• especially limited in deviated wells

• centralization of the fish

• milling improves engagement?

– how much?

• top dressing vs length milling


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Other Problems

• Wireline!

– Removal vs mashing it down

– Condition of wireline - H2S

• Has wireline been parted or is it just stuck?

– Using CT with hook as a stiff leg to free wireline.


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Fishing Tools with Control Lines

• RISK: The hydraulic control lines may form

a birds nest in the tubing or in the BOP.

On pulling the fish through the BOP, the

control lines may peel back and jam

between the BOP stack and fish.


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• Initial Diagnosis: A tangle of cut and

broken hydraulic control lines is on top of

the tool.

• To avoid problems, a shroud was designed

as a full bore tool that would pass through

the BOP stack to centralize and contain

the control lines.

8/25/2015 41



• The shroud leading edges scooped all the debris

inside the tool body and the tool landed out on a

debris gallery on the SSTT.

• The fish was then speared through the top of the

shroud. The fish and shroud were recovered

together. The shroud gave full containment of all

debris and no further junk was added to the

hole.


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Deviated Wells

• hydraulic centralizers

• larger overshots

• motor addition to fishing BHA

– engagement potential increased?

– jarring potential decreased?

– release compromised?


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Horizontal and Deviated Well Problems

• Engaging Fish

• Pushing it to Bottom

• Retrieval - load study in stages

• Fishing under snubbing conditions


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CT Fishing in Horizontals

• Problems

– centralization

– cutting beds

– tendency to bury fish in open hole

– CT limited by buckling


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Tools for Horizontal Fishing

• most fishing tool acceptable

• horizontal centralizers

• reverse circulation and dual CT strings

• anchor and piston force tools


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Buckling/Lockup of CT

• Fcrit. = 2A((EIW sin O)/d)1/2

• where: – A = const. 0.93 for steel

– E = young’s modulus, psi

– W = buoyed pipe wt lb/ft

– O = hole inclination

– d = radial clearance between tube and csg., in

– I = moment of inertia = 0.04909 (OD2-ID2)

– OD = pipe OD (in)

– ID = pipe id, in


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Max pipe or tool length that will go through a bend

• L = 1/6 [R2 - (R - dd)]1/2

• where:

– L = maximum tool length, ft

– R = curve radius, inches

– dd = ID-ODtool


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Lockup in Vertical Wells

• Causes: – doglegs

– tight clearances

– buckled tubing/casing

• Solutions – stiffer CT

– straighteners

– cool backside???


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CT Jar Types

• Mechanical

• Hydraulic


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Jar Problems

• Drag and buckling effects lessen mechanical jar effect

• Hydraulic jars less effective because of flex of string (down-jar)


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CT Jar Considerations

• Flow through capacity

• Placement in the fishing string – above fishing tool when tool is releasable

– above hydraulic release on non releasing catch tool

• Directional (change internal component to go from up- to down jar)

• Use with accelerator and weight stem?


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Spang Jars

• Don’t work wire line on shallow problems where spangs can be across wellhead. May damage valves and if stuck, cannot close valve.


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Fishing Successes

• Cased holes - goo success – gas lift valves

– wireline

– PSI systems

– packers and plugs

– inflatables

– etc.

• Open holes - poorer record


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Fishing

• Routine Recovery: gas-lift valves, gauges, packers, plugs

• Fishing: slickline, E-line, BHA’s, debris, coiled tubing,


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Fishing with CT

• Best use: Where stiff , continuous motion and circulation are needed

• Improvements: larger CT, hydraulic jars, low-speed, high-torque motors (limits on jar action), larger injectors

• Catch tools for CT: Must take in to account the shape of the CT top (may be flattened, bent over, ovaled or necked down.


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g6.tif CT Fishing String


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g7.tif CT Fishing String

No release on catch tool, but hydraulic disconnect built in above the tool.


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g8.tif Horizontal Fishing String


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g12.tif If this string of CT was in a horizontal well, where in the wellbore would it lie?


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Best Practices

• First, run a gauge ring on slick line or CT that is slightly larger than the CT.

• Consider what happens if you get onto the fish and can’t move it - release mechanism?

• Fishing in large diameter hole or casing makes it difficult to engage the fish.


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Best Practices - Cutting CT

• If you have to cut CT when stuck, cut it in the tubing - makes it much easier to fish.

• Cut the CT with a overshot “nipper” tool that leaves a square shoulder - this allows entry into the CT.


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Deep Cuts of Stuck CT

• Cut at surface, go through CT with slickline and chemical cutter – cutter must be properly sized for CT

– CT needs to be in tension - free point?

• Don’t pull it in two with the injector if you can avoid it. – Severed edge is necked down

– Location of severed top is unpredictable


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Tools

• Overshots are primary catch tool.

• RCJB - reverse circulation junk baskets

• prongs, magnets, etc., available

• Release sub in the string

• Circulation sub

• jars and accelerators

• TV camera may be best tool of all. - Know what the fish looks like!


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Special Case of Fishing with CT

• Recovery of 9200 ft of slickline from well in Trinidad

– recovered in one piece

– recovered with CT


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Slickline Recovery

• Slickline tool stuck at 9200 ft - slickline not parted!

• Used CT - parted wire at surface and threaded it through bottom of the CT and out a side entry sub a foot above CT bottom.

• Ran CT down the well until tool was encountered, pushed it loose and reeled slickline back as CT pulled out.


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Unusual Considerations

• Large tool effects

– swab/surge

– clearances in profiles

– bending stresses and resistance

– wall drag (friction forces)


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Friction Reduction

• Friction reducer additives can result in a 15% to 17% drop in friction force.

• Use of an FR additive can drop total fraction as much at 30% when used with a CT straightener.

• Stiff, small BHA’s have been carried easier through washout and tight spots.


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CT Straightner

• Mechanical Device

– takes out residual bend in CT - lowers frictional resistance

– stresses the pipe, fatigue

– use on the end 20 to 50 ft of CT where friction needs to be cut

– use where CT must enter small diameter (close to CT diameter) profiles


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Friction Reducer Drawback

• Formation damage increased - most good friction reducers are polyacrylamides - no breaker!

• Some formations very susceptible to formation damage by any polymers or surfactants.


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CT Motors

• Power increases almost exponentially with motor size.

• Powering motors with straight nitrogen gas is often difficult - not enough lubrication.

• Volatile oils hard on stator rubbers - use of saturated nitriles helps performance.

• High temperature (400 to 500 F) motors are available.


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Motor Reliability

• Surface Test of Every Motor is HIGHLY Recommended – smaller motors - tighter clearances - tight bearing

packs

– many new motors won’t turn

– small motors are low power - 80 ft-lbs of torque?

– Surface test not an absolute guarantee of downhole performance


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Motor Stalling

• Small motors most susceptible - low torque

• Causes

– too much load on CT

– load applied too quickly - motion control on injector

– aggressive bits?


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Torsional Yield Strength

Ty = Sy(OD4 - (OD - 2 t wall-min)4)/105.86 OD

Where:

Ty = Torsional Yield Strength, lb-ft

t wall-min = thinnest wall, in

Sy = yield strength of the CT, psi

OD = CT OD

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Torque

• Usually we don’t push the torque limit in workovers

– need to rotate is limited

– smaller motors very limited in torque

• This changes in CT Drilling, especially with big motors


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Alternatives to CT for Fishing

• Wireline

– in horizontals? - yes

• Tubing or DP

– slower but more strength, control surface pressures?

• Snubbing

– slower, surface rotation


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Really Unusual Alternatives for Fishing

• junk shots

• explosives

• acids none recommended with CT


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Tractors

• Wireline tractors taking work away from CT-wireline in the North Sea area.

• One wireline tractor was stuck - another sent down to retrieve it - successful.

• SPE 38757


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Tractors

• Electric Tractors available now.

• Hydraulic CT models coming?

• Test facility in Aberdeen


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Downhole Camera view of parted pipe


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The image shows that the cones of the bit are crushed and embedded into the 9-5/8” casing at the collar. Damage to the threads where large forces were applied to move the bit can also be seen. The operator eventually milled through the bit with two concave mills

Source: DHV : Downhole Video International


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Downhole Camera view of exploded gun?


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Debris in the latch mechanism of a downhole tool.


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Depth Effects

• Fishing can be difficult at increasing depth since accelerators rely to some extent on cable/coil tension/stretch for assistance.

• The best bet in this situation is to use two accelerators with short stroke "upstroke" jars (spring type) in conjunction with a heavy duty fishing cable.


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Workover Fishing Operations

• Common Applications

• Methods

• Problems and Solutions


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Common Fishing Tools

• Magnets

• Overshots

• Spears

• Wireline grabs

• and…. – junk baskets

– bailers

– the rest of the string


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Spear Information

• Run a shoulder on all spears

• Thread on fish known? - taper taps

• Release feature on BHA?


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Oil Jars

• Weak part of wireline oil jars is the head to rod connection. Breaks often leave the rod sticking up. Compress rod back into the tool and use overshot to seize the body of the tool.


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Braided Cable

• Braided cable doesn’t fatigue as much as slickline, but has to be reheaded to prevent breakage of individual strands in the rope socket.

• Fishing with the braided cable – can’t develop as much wire speed as with slickline but can pull much harder. Use spangs and oil jars.


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Fishing – deviated wells

• Large fishing tool (overshot) problems in passing the tools around the doglegs and curves. Overshot tends to ride downward and dig out the bottom of the curve.


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Tubing Elongation

delta L = (F L)/(E An)

where:

delta L = tube stretch, inches

F = axial force on tubing, lbs

L = free length of tubing, ft

An = nom. x-sect area, in2

E = Young’s modulus, 30 x 106 for steel


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Determining Free Point - part 1

• 1. Pull pipe into tension with at least 500 lb of load over the hanging weight of tubing in the hole.

• Make a visible reference mark on the pipe

• Increase pull on the pipe in increments of 1000 lb over original tubing weight.

• Measure amount of pipe stretch (delta L)


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Free Point - part 2

• Subtract original weight reading from final pull weight (FD)

• Read Correct Free Point Constant (CFPC) from Table

• Use Equation:


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Free Point - part 3

L = delta L CFPC / FD

where:

L = minimum length of free pipe

delta L = stretch, inches

CFPC = Free Point Constant (from table)

FD = pull force, 1000 lb


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Free Point Example

• Determine the minimum length of free CT when a 10,000 ft length of 1.25”, 0.087” wall CT stretches 39 inches with an applied pull of 5000 lb over tubing weight.

• CFPC = 760 (table), FD = 5000/1000 = 5

L = delta L * CFPC / FD = 39*760/5

L = 5928 ft


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1.25” CT Stretch Tables

CT Size x-sect area CFPC

1.25 x 0.087 0.304 in2 760.0

1.25 x 0.095 0.328 in2 820.0

1.25 x 0.102 0.351 in2 877.5

1.25 x 0.109 0.374 in2 935.0

1.25 x 0.125 0.420 in2 1050.0

1.25 x 0.134 0.451 in2 1127.5

1.25 x 0.156 0.512 in2 1280.0


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1.50 x 0.095 0.399 in2 997.5

1.50 x 0.102 0.428 in2 1170.0

1.50 x 0.109 0.456 in2 1140.0

1.50 x 0.125 0.512 in2 1280.0

1.50 x 0.134 0.552 in2 1380.0

1.50 x 0.156 0.629 in2 1572.5


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1.75 x 0.109 0.538 in2 1345.0

1.75 x 0.125 0.605 in2 1512.5

1.75 x 0.134 0.652in2 1630.0

1.75 x 0.156 0.745 in2 1862.5

1.75 x 0.175 0.831 in2 2077.5


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2.00 x 0.109 0.619 in2 1547.5

2.00 x 0.125 0.698 in2 1745.0

2.00 x 0.134 0.753 in2 1882.5

2.00 x 0.156 0.861 in2 2152.5

2.00 x 0.175 0.962 in2 2405.0


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2.375 x 0.125 0.837 in2 2092.5

2.375 x 0.134 0.904 in2 2260.0

2.375 x 0.156 1.035 in2 2587.5

2.375 x 0.175 1.158 in2 2895.0

2.375 x 0.190 1.241 in2 3102.5


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Working Tensile Loads of Conveyances

Wireline Working Load Weight of Wire/Tube Running Speed

0.072 720 0.014 100-150 ft/min

0.082 930 0.018

0.092 1160 0.023

0.108 1827 0.031

CT

1.25 21900 1.332 50-100 ft/min

1.5 26600 1.623

1.75 31440 1.915

2.375 49520 3.011

Tubing

2.375 57,000 4.6 5 - 15 ft/min

2.875 79,200 6.4

3.5 119,200 9.2

3-1/2" DP 189,000 15.58/25/2015 124



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Material that can unravel can be very difficult to fish.


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Surface display of a jetting sub – the problem is that energy imparted by the jet falls off rapidly.


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The following slides are shots of fishing tools – the source of the

pictures is unknown.


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BHA 1

16” Cutlip Guide, Overshot


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BHA 2

17” Concave Mill 8/25/2015 132


BHA 3

11-3/4” Cutlip Guide, Overshot,

Short Catch Grapple 8/25/2015 133 George E. King Engineering

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BHA 5

16” Cutlip Guide, Magnet 8/25/2015 134 George E. King Engineering

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Fishing Tools

16” Cable Catcher Sub

Pre-Run Post-Run


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Fishing Tools

16” Burning Shoe 8/25/2015 136 George E. King Engineering

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Fishing Tools

8” x 2-3/4” Taper Tap 8/25/2015 137 George E. King Engineering

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Fishing Tools

5-3/4” x 2” Spear 8/25/2015 138


Fishing Tools

4-7/8” Wireline Magnet 8/25/2015 139


Documents

Fishing