coiled tubing operations

7/16/2019 Coiled Tubing Operations

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Coiled Tubing emergencyProcedures



Typical stack up

• Blind/shear

• Pipe• Slip

•

Stuffing box

• Quick connector



Emergency BOP Operation

• Stop tubing, set SLIP rams, PIPE RAMS

• Stop pumping

• Cut coil with SHEARS

• Pull above blinds (stay in stuffing box !)

• Close blinds

• Kill well down coil & / or kill line

• Fish coil out of well



BLINDS

SHEARS

PIPES

SLIPS



CT Leak At Surface

• Clear area (esp. around reel & injector)

MINOR LEAK (pinhole)

• Pull slowly on to reel while displacing to

water (minimize reel pressure)

MAJOR LEAK (large or hazardous material)

• Set SLIP & PIPE rams then check set

• Cut pipe, pull up to close BLIND rams

• Purge reel , remove failure, fish CT in

BOPs



CT Leak Below Surface

•

Loss of pump pressure or string weight• Hole or parted CT may come thru stuffing box

• Clear area and displace to water

•

Pull out at max. 20 ft/min, pumping slowly• Evaluate leak when exits stuffing box

MINOR

• Pull on to reel carefully (may break)

MAJOR (or parted coil)

• Follow Emergency BOP sequence



Stuffing Box Leak

•

Stop coil and close SLIP & PIPE rams toisolate annulus. Set manual locks.

• Place injector in neutral & engage brake.

• Bleed off pressure above pipe rams.

• Bleed off stuffing box hydraulic pressure and

replace elements. Pressurize.

• Pressure test stuffing box through kill line

(avoid collapsing CT)• Equalize pressure across BOP rams and

release manual locks.

•

Open PIPE and SLIP rams.



Surface Equipment Leaks

Rotating Joint

• Close reel isolation valve inside work reel.

•

Repair or replace joint and test.• Open isolation valve and resume operations



Surface Equipment Leaks

Leak Below BOP

• Clear area & evaluate

• Ensure coil sufficiently off bottom so it will

fall BELOW the MASTER VALVE whencut.

• Close shear/seal rams to cut and drop coil.

• Pull up coil and close blind rams.

• Close swab valve & master valve.

• Repair leak, pressure test, plan fishing

operations.



Coiled tubing injector head

• Inside tension

• Outside tension

• Load cells



Tubing Run Away (into well)

Coil is pulled into the well under its ownweight due to insufficient chain grip.

•Speed up injector to match the descendingcoil.

• Increase inside chain tension to increase

friction on coil.

• Increase stuffing box pressure to increase

friction on the coil.



Tubing Run Away (into well)

• If run away is hydraulic (not traction) reduceinjector hydraulic pressure to zero to set injector

brake.

•

If close to TD, may let fall to bottom then repairequipment and recover coil. Some may be kinked.

LAST RESORT (if insufficient coil to reach TD)

• Apply all other measures to slow the coil then closethe SLIP rams to physically grab the coiled tubing.

• Both coil and rams may be damaged.



Birdnesting



Tubing Run Away (out of well)

Upthrust due to wellbore pressure exceeds coil

weight and injector chain to coil friction.

• Speed up injector to match the coil speed.

• Increase inside chain tension to increase

friction on coil.

• Increase stuffing box pressure to increase

friction on the coil.



Tubing Run Away (out of well)

• Increase reel pressure to keep up with coil

coming out of the well.

•Prepare to close master valve if coil comes outof stuffing box.

• If coil does not stop, close the SLIP rams. Both

coil and rams may be damaged.



Tubing Pulls Out of Stuffing Box

If BHA is lost there is no external upset to tag

on the stuffing box brass inserts.

• Stop the injector to keep the coil in the chains.

• Close the blind rams to isolate the well.

•

Plan fishing operations for BHA.



Tubing Collapse At Surface

Wellbore fluids escape from stuffing box as

strippers cannot seal around collapsed coil.

Collapsed pipe may not pull through the

stuffing box brass bushings.

Injector may not be able to grip deformed coil.




WELL CONTROL

• Run back in until stuffing box seals around

coil.

• Reduce wellhead pressure by flowing the

well or stop reverse circulation.

• If seal cannot be obtained with stuffingbox, close PIPE rams to reduce leak.

• Clear the area and kill the well.




(well killed)• Clamp coil above injector head.

• Bleed off stuffing box and open pipe rams.

• Back off inside chain tension and pull the tubing

through the injector with the rig or a crane.

• Re-clamp the coil above the injector and cut off the

coil in sections.

•

Repeat until good condition coil is pulled through theinjector.

• Set slip and pipe rams, energize stripper, and make

up a dual roll on connector to the coil on the reel.



Cutting and recovering coil

Close slip ramsClose pipe ramsClose blind/shear rams




Raise the coil and kill the well




Open blind shear rams

Spear fish (difficult)or

Pull test

Open pipe and slip rams and POOH




Raise BOPs and coil

Set tubing clamp

Open pipe and slip rams




Lower BOPs to expose cut coil

Fit double end connector

Lower injector and make up

double end connector

Pull test

Remove clamp




Lower stack and make up

POOH



Tubing Breaks On Surface

Coiled tubing breaks into two sections at surface.

• Stop the injector and set the SLIP rams.

• Stop pumping operations and clear the area.

• Secure the coil to the reel and attempt to spool slack

back onto the reel.

• Remove the damaged section of pipe and reconnect thecoil with a dual roll-on connector.

• Release the slips and continue to pull out.



Tubing Breaks On Surface

• If the remaining coil cannot be spooled onto thework reel and no spare reel is available, it will be

necessary to hang off the coil in the well until a

reel is available or the well is killed.

• Close SLIP and PIPE rams then cut the coil.

• Pull up and close the blind rams.

• Once spare reel capacity is available, fish coil

from BOPs (kill well if necessary for safety).



CT Reel Drive Fails

• Stop the injector.• Ensure coil held by injector and close and lock

SLIP and TUBING rams.

•

Apply reel brake if fitted.• Repair drive and inspect coil for damage.

• If damaged, follow Leak Procedures.

• If coil is good, run in as deep as necessary to fix

the wrap on the reel. Do Not Run Kinked

Tubing Into the Well !

• If spool cannot be fixed, follow cut and fish

procedures (Leak Procedures).



Coiled Tubing Stuck In Hole

Three possible scenarios:1. The coiled tubing itself is stuck somewhere

between the BHA and the stuffing box.

2. The BHA is stuck.

3. Stuck in the stuffing box due to ballooned

coil or excess stuffing box pressure.

Coil is considered stuck if it cannot be pulled free

at the lesser of 80% of the weak link rating or 80%

of the minimum yield rating of the coiled tubing.




Three factors to consider:

1. Type of well: flowing oil or gas well,

water injection well.

2. Type of BHA on the coiled tubing.

3. Type of operation carried out when

stuck.




• Continue Pumping

• Determine stuck point and reason why.

• Pull to 80% of CT yield and hold for 10minutes.

• Observe the trend on the weight indicator

and measure the stretch in the tubing to

calculate freepoint:



Free Point Calculation

L = S( As x E)

F x 12

L = length free (ft)

S = stretch (in)

As = metal X-section area (in)E = modulus of elasticity

(30,000,000 psi for steel)

F = pull force (lbs)

= hang weight - max pull weigh



Stuck In Hole Options• Flow the well at maximum rates to remove any

debris trapping the coil downhole.

• Displace the coil to N2 to increase buoyancy.

• Underbalance the well if differentially stuck.

• Circulate acid down to remove any soluble

material holding the coil.

• Cool the well if coil is helically stuck in

corkscrewed production tubing.• Pump down the annulus to force obstruction

downhole.

• Release the BHA to be fished later.



Stuck In Hole Issues

• DO NOT work the coil violently across the coil

with frequent reversals.

•

Log the number of cycles while trying to pullfree. Do not exceed fatigue limit !

• If coil cannot be freed, hang off the coil in the

SLIP rams and close the PIPE rams.

• Kill the well then cut at free point and fish the

coil.



Chemical / Explosive Cutters

•

Determine free point and ENSURE well is dead.• Pull coil into tension so it is as straight as possible.

• Close SLIP and PIPE rams, increase stuffing box

and chain pressure, and set the reel brake.

• Monitor pressure across pipe rams for leak.

• Bleed off the coil and monitor pressure to ensure

downhole check valve and coil integrity.

• Build work platform above injector with scaffolding.




• Lay down gooseneck and cut the coil 5 feet above

the injector. Secure remaining coil at the reel.

• Straighten the coil to run wireline inside.

• Connect 2 valves, pumping “T” and wirelinelubricator and BOP to the coil to run the cutters

inside.

• Run cutter and freepoint tool to the correct depth

and cut the coil.

• COILED TUBING IS NOW OPEN TO

WELLBORE !




• With the well and coil killed, remove the

wireline equipment.

• Dress the end of the coil for a double roll-onconnector

• Open the BOP rams and pull the coil out of the

hole, spooling back on to the work reel.

• NOTE: chemical or explosive cuts may need to

be worked several times to part.



Power Pack Failure

•If the hydraulic power unit fails, injector headmotor brakes will automatically be applied.

• If in doubt, close SLIP rams and manually lock.

• Close PIPE rams and manually lock.

• Chain reel incase reel brake fails.

• Maintain circulation if required to prevent coil from

becoming stuck in the hole.

• Repair or replace powerpack, ensure BOP

accumulators are fully charged.

• Equalize BOP pressures and open rams.



Replacement Of Injector

• Close SLIP and PIPE rams, bleed off coil.

• Ensure slips are holding coil, check valves hold.

• Secure coil on either side of cut, clamp at injector.

• Cut coil above injector and secure to reel.

• Bleed off pressure above tubing rams.

• Back off inside chain tension.

• Break the union below the injector and walk up coil

with the crane, clamp coil above BOP.



Replacement Of Injector

• Back off chain tension and walk new injector

down to safety clamp on BOP

•

Clamp above, remove clamp below.• Make up union and pressure up inside chain

tension.

• Pull test before opening SLIP rams.

• Reconnect coil to reel with double roll on.



• If coil is run inside small ID tubing and BOP,

kink will be between stuffing box and chains.

• Coil run in large diameter completion will kink

at a diameter change or at the largest ID.

Tubing Kinked



Tubing Kinked - Surface

• Stop injector immediately.

• Close SLIP and PIPE rams and lock.

• Bleed off coil and ensure downhole check valves

holding.

• Cut coil at top of stuffing box to lift off injector.• Remove injector and dress coil for connector.

• Run fresh coil through stuffing box and connect

with inline connector (dual roll on).• Walk injector down to make up to BOP.

• Pull test connector then pull coil out of well.



Tubing Kinked - Downhole

Rapid weight loss in large ID may lead to kinks.

• Increase in pump pressure due to kink restriction

• Decrease in pump pressure as BHA may be brokenoff

• Loss of string weight due to parted coil

•

Increase in string weight due to drag from kink




Increase in pump pressure or string weight

• Stop pumping

• Pull out at 10 to 20 ft/min until kink tags stuffing

box• Attempt to close SLIP and PIPE rams

• If kink cannot be pulled above the BOP, run in

to good pipe then hang off and cut coil in BOP

• Kill well and fish coil (freepoint & cutters ?)




Decrease in pump pressure or loss of weight

- String parted down hole.

• Calculate remaining coil from weight• Stop pumping

• Pull out slowly until coil comes out of stuffing box

•Close blind rams then secure wellhead

coiled tubing operations

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