4- best practices f

BEST PRACTICES

• Prevention of Stuck Pipe During Routine Operations

• Preventing Drill String Failures

• Secondary Freeing Procedures

Prevention of Stuck Pipe During Routine Operations

Reaming and Backreaming

A high risk operation that accounts for a large proportion of

stuck pipe incidents.

Solids can be introduced into the circulating system faster

than the hole is being cleaned.

Results in a pack-off or potential pack-off situation.

GENERAL GUIDELINES.

PLANNING

• Have a contingency plan for possible problems.

• Always pre-plan a trip.

• Have singles ready in case a need arises to work pipe

after a connection.

Break-out stand and use singles to cock jars etc.

ORGANIZATION

• Monitor shakers and record volume of solids removed

from wellbore.

• When drilling or reaming problem area’s have two people

at the console.

• Ensure driller understands what actions to take in the

event of problems.

• Mud loggers report all parameters and report any

significant trend changes.

PARAMETERS

• Use consistent parameters for reaming operations.

• Address any parameter changes immediately.

• Circulate hole clean if indicators show the hole loading

up during reaming.

• If indications of a pack-off occur, reduce pump speed. If

after several minutes the hole does not pack-off then

return to normal parameters and be prepared to circulate

the hole clean.

• Adjust reaming speed and circulation time if cuttings

volume rate is excessive.

• Stop reaming and circulate the hole clean if, torque

becomes erratic, rotary stalls out, cave-in rate increases or

torque and pressure readings increase.

PARAMETERS CONTINUED

• Prior to heavy reaming, slow rotation <80 rpm should be

used to walk pipe past ledges.

• Reaming operations should be conducted with the

same flow rate as drilling.

• To reduce chances of sidetracking and damage to drill

string keep reaming weight and speed low.

• Maximum reaming speed should not exceed (as a rule

of thumb) four stands an hour.

• Due to large volume of settled cuttings or new

cavings introduced into the hole. It is critical that this

material be circulated out of the hole.

GENERAL OPERATION

• Follow FIRST ACTIONS for solids induced pack-off.

• When reaming problem formations, the hole may need to be

wiped at regular intervals.

• Make sure pipe is free before setting slips.

• After drilling or reaming down, circulate cuttings above BHA

prior to picking up.

• Always try to work the string past a tight spot as a first

option.

• Know and use overpull limits.

• Work overpull limit up in stages and ensure free movement in

both directions.

GENERAL OPERATION CONTINUED

• Limit overpulls to half the BHA weight.

• If a stall out occurs during reaming release the torqued up

drill string slowly.

• When back reaming, do not overpull the pipe into the slips

to connect the top drive.

• When washing in with a motor in the BHA, rotate the

entire drill string at low rpm.

Tripping in Deviated Hole

PLANNING

• Record depth of top of BHA while circulating prior to

tripping and take extreme care when the top stabilizer

reaches this point and for the following two stands. This is

the point the BHA could encounter a cuttings bed if one

exists.

• Where the well inclination is 40o-65o take care as this is the

point that cuttings will settle after avalanching down steeper

sections of the well.

PARAMETERS

• Initially do not pull more than half the BHA weight or

30,000 lbs..... when POOH.

• Note: 30,000 lb overpull rule.

Used for initial overpulls while tripping out of the hole.

Initially do not pull more than half the BHA weight or 30,000

lbs..... when POOH

• If overpulls exceed 30,000 lbs..... or half the BHA weight

then go back down one stand and circulate bottoms up at

full drilling flow rate while reciprocating and rotating the

string.

GENERAL/OPERATION

• Before tripping circulate the hole using the recommended

number of fluid circulation's.

• Reciprocate and rotate the drill string while circulating

bottoms up.

• Be aware that the BHA can become stuck in a cuttings

bed inside the casing.

• Use paper mud log model of the well and BHA to help identify

and forecast problem depths.

Connections

• Sticking problems commonly occur when making

connections.

• They can occur in all hole sizes.

• It can result in expensive side tracking.

ALL DRILLERS SHOULD BE FAMILIAR WITH

THE FOLLOWING CONNECTION PROCEDURES.

• Wipe the last joint/stand prior to making a connection.

• If erratic or high torque is experienced prior to connection

take time to ensure cuttings are above BHA.

• After connection break circulation slowly and check for

returns.

• Avoid starting/stopping pumps suddenly as shock loads may

disturb wellbore.

• Minimise time without circulation.

CONNECTION PROCEDURES

• If differential sticking is experienced.

(a) Maximise pipe motion.

(b) Consider rotating string with slips set.

• Never make a connection with overpull onto the slips.

• Set slips high enough to allow downward movement.

• If extra stick up is required take care not to bend pipe.

PLANNING

• Be ready to take survey before stopping drilling.

• Know survey times and try not to exceed. Average times are between

3-5 minutes.

• Person in charge on the rig floor must determine if the pipe is to be

moved between surveys or if another survey is to be attempted.

• Never allow the MWD operator to continue surveying without the

permission of the Driller, Directional Driller or Toolpusher.

•The following should be recorded on the rig floor.

(1) Depth or position on kelly of next survey.

(2) Last survey results.

(3) The amount of circulating and reaming prior to and during

surveys.

Surveying

GENERAL/OPERATION

• Pipe should be worked, reamed or circulated before carrying out a survey.

• The amount of presurvey working, reaming or circulating should be discussed

with the toolpusher and company rep prior to drilling the hole section.

• Ask MWD operator for rotating options during

survey.• Company rep may recommend more circulating before surveying. He may

also want to drill a few extra feet then pick back up to survey depth. These are

the sort of things that should be discussed at presection meetings.

• Do not take surveys with the kelly completely down or after a connection is

made as this may result in too little space to cock the jars and work the pipe.

• Position pipe to compensate for stretch and compression of the string so that

jars can be properly operated.

• Ensure correct handling procedures are in place when using

drillpipe screens.

(a) Drilling.

(b) Tripping.

(c) Surveying.

• If dropping a survey prior to tripping. Consider time intervals for

surveys if having to back ream through open hole section.

• Be aware of mud additives like LCM and its possible effect on

survey tools.

Drilling Parameter Trends

• Monitoring trends will give an indication of the hole condition and

provide information as to whether the hole condition is improving or

deteriorating.

• On some rigs trends may be monitored when doing drilling and

reaming operations every fifteen minutes and if significant changes

occur then corrective action should be taken immediately.

Running Casing or Liners

Steps to reduce the chances of stuck casing

• Perform Torque and Drag analysis to predict the limiting friction

factor that will still allow the casing or liner to get to bottom.

• Friction factor can be measured on the last trip out of the well, but is

best determined from experience over the duration of the well.

• If significant deviation is experienced from the predicted down

weights then remedial action can be taken before sticking occurs.

• If overpulls are experienced on the last trip out of the well, consider

performing a wiper trip. This is even more critical if the casing being

run is too heavy to be removed from the hole.

Logging

• Logging companies have their own procedures for attempting to

free a stuck logging tool. Procedures may involve opening and

closing calipers and other moving parts.

• The most common mechanisms are.

(1) Differential sticking of the cable.

(2) Mechanical sticking of formation test tools and side wall core tools.

(3) Geometrical sticking of the tool because of its shape.

(4) Keyseating of the cable.

* A procedure with recommendations for stripping in over wireline

can be found in the stuck pipe handbook .

Coring

• If the rig is fitted with a top drive it is recommended that the core is

broken every 90 ft where differential sticking is a risk.

Well Control

STUCK PIPE IS SECONDARY TO WELL CONTROL.

• Solve the well control problem first.

• Deal with the stuck pipe situation.

Lost Circulation

When intermediate to severe losses occur, cuttings can settle around

the BHA and mechanically stick the pipe. The cuttings act like a packer

and can make the losses worse.

• Try to keep the pipe moving if possible.

• Consider pulling into the shoe before pumping LCM.

• As a rule have enough open hole volume below the bit to accommodate

the whole treatment.

KEEP IN MIND:

• Reactive clays may become unstable if exposed to uninhibited fluids.

• Pressure differential in loss zones may cause differential sticking.

• Ensure any LCM is clear of pipe before pumping cement.

• Carry out pilot tests for each treatment.

Air and Foam Drilling

Although there is little reliable material available on the subject of stuck

pipe while air drilling. Problems are similar to those encountered in

conventional drilling operations.

• Differential Sticking. Unlikely to occur due to

underbalance in wellbore.

• Pack-Off. Most likely because of inadequate hole

cleaning.

• Mechanical or Geometric Sticking. May occur as in a

conventional well.


Listen to what the hole is telling you: Always Monitor

• Drag. • Torque. • Rate of return of cuttings and cavings.

Monitoring the following may indicate potential problems.

• Change in air flow rate from the compressors to the well.

• Condition of the foam.

• Small fluctuations in standpipe pressure may indicate hole cleaning

problems or mud rings forming.


When freeing the pipe always follow good drilling practices.

• In the event of mechanical sticking ALWAYS jar in the opposite direction

to the direction the pipe was travelling when it became stuck.

• In the event of a pack-off, torque made help break up the

packed material.


Good drilling practices for mud still apply with Air or Foam

• Always reciprocate, do not circulate in one place.

• The same stuck pipe indicators apply for Air or Foam as with mud.

• If problems are encountered prior to a connection, pick up a single to

work the string.

• Try to use a low energy approach with connections. No reaming or

back reaming unless absolutely necessary

• Keep drilling as low energy as possible (low rpm) to prevent pipe

lash degrading the formation integrity.

• Move the string smoothly. Remember the hole is effectively dry.


Drilling Parameters

Drilling indicators are different from those in mud.

• Torque is the primary and most reliable indicator of downhole events.

• Differential pressure gauge at the air manifold can be an excellent

indicator of what is going on downhole .

• Trends may occur over a longer period. Two or four hourly printouts

on mud loggers monitors can often identify slow building trends.

• Monitor trends in the blooey line

discharge.


Check Valves

• Drill to a maximum of 500 ft before pulling back to reposition upper

check valve.

• Use only flapper type with springs removed to allow access for wireline

tools.

• A bit float or check valve must always be run while air or foam

drilling.Air Rates

• High air rates do not usually cause erosion.

• Experience indicates the need to keep foam as dry as possible at

maximum air rates.


Casing Design

• Design casing program as usual, but be aware of collapse

considerations.Cement

• Do not use bentonite in a foam water mix if you have drilled a

cement plug. Reaction with the cement and bentonite will cause mud

rings and possible pack-off.

Communications

• Good communications between driller and air drilling contractor.

•Traffic light system or radio headsets strongly advised.

• Driller should be in a position to see blooey line. If not consider TV

camera.


Freeing Techniques

Generally different from those used in mud operations and are area

specific.

Two cardinal rules apply if sloughing, caving, tight hole, packing-off or

mud rings occur.

(1) Remember you are working with a compressible fluid. If

returns are lost do not bypass the air.

(2) Do not overpull more than 30,000 lbs..... if returns are lost

, air or foam can behave unexpectedly under such

conditions.

Overpulling will increase the tightness of the pack-off and make it more

difficult for air to percolate into it and undermine its integrity.

BE PATIENT

Drilling with Coiled Tubing

Coiled tubing cannot be rotated so differential sticking is a risk.

Working the string under pressure is a risk. (Limited number of

cycles before failure)

Usual solution is to flow the well.

POTENTIAL PROBLEMS

• High circulation

pressures.

• Large annulus.

• No rotation.

Preventing Drill String Failures

• Handle all tubulars carefully.

• Always fit thread protectors.

• Prevent slip and tong damage by correct use.

• Stab pipe with care to prevent shoulder damage.

• Follow inspection routines and make additional inspections if pipe is

subjected to heavy use.

The two most frequent causes of drill string failures are.

• BHA connection fatigue.

• drillpipe tube fatigue.


BHA Connection Fatigue Prevention

(1) Put the WOB limits used to design the BHA in the drilling program.

(2) Check bending strength ratios (BSR) of the drill collars and try to match.

(3) Use correct inspection criteria.

(4) If pin failures then BSR too high if box failures then raise BSR.

(5) Specify bore back box and stress relieve grooves in all drilling

equipment contracts.

(6) Do not allow OD change of more than 2 inches at any

one connection.


drillpipe Fatigue Prevention

(1) Use heavy-walled drillpipe as transition pipe. Do not run HWDP

buckled.

(2) Check stiffness ratio. 5.5 or less for low and less than 3.5 for high

complex wells

(3) SR = (Z lower)

(Z upper)

(4) Use correct makeup torque.

(5) Check pipe for slip damage after any rotating of pipe in slips.

(6) In slip stick situations reduce torque limit by 50%.

(7) Cycle the bottom stand of drillpipe out of the string every trip.

(8) Check for shoulder damage before making up.

(9) Minimise dog legs at shallow well depths.

(10) Rotate breaks.

Secondary Freeing Procedures

WELL CONTROL MUST BE ONE OF THE PRIMARY

CONSIDERATIONS WHEN USING PILLS OF DIFFERENT

DENSITY.

Pipe Release Agents (PRA)

Drilling Fluid and Acid suppliers must be involved in the early planning

stage.

Involves unique procedures with Technical and Environmental

considerations.

Unlike U tubing restrictions do not apply when using pipe release

agents.

Any PRA should be spotted within 4 hours of sticking for best results.

If after 16 hours the pill has not been spotted then consider another

method.


Probability of pipe freeing vs Soaking time

SOAKING TIME (hours)

0 10 20 30 40 50

90

80

70

60

50

40

30

20

10

0

%

As a rule of thumb soak for

a minimum of 20 hours and

a maximum of 40 hours.


SPOTTING A PIPE RELEASE PILL

Plan for how and where the pill will be mixed and start as

soon as possible.

Once ready displace at a continuous high flow rate.

Try and design the spacer so that turbulent flow is created across the

stuck zone.

To prevent channelling of the PRA into the drilling mud the viscosity value

of the spacer using the 100 rpm reading on a fann VG meter should be

higher.

Spacer should be between 50-100 bbls.

Include spacer and PRA formulation in the mud program

document for each well.

Pipe Release Agents (PRA)PRA PROCEDURE

(1) Volume of PRA pill should be 1.5 times larger than the volume

of the area in which the pipe is stuck.

(2) Prepare low YP spacer and check compatibility with mud and

PRA pill.

(3) Spot spacer and pill at maximum flow rate.

(4) Allow pill to soak until the pipe is free or timed out on effectiveness

of pill working.

(5) Work the pipe while the pill is soaking.

Acid Pills

HANDLING ACID CAN BE HAZARDOUS


IMPORTANT POINTS TO CONSIDER

(1) Get advice on formulation.

(2) Pump quickly with large spacers each side.

(3) Work pipe while pill is soaking.

(4) Pill should be circulated out after about 5 minutes.

(5) Separate at surface for neutralisation.

Fresh Water Pills



(1) Pill should cover zone plus 20 bbls extra in pipe to displace into annulus

during soak.

(2) Use spacer ahead of pill if using OBM (Get mud company advice).

(3) Work pipe while pill and spacer are being mixed and maximise overpull

while soaking.

(4) If not free after 2 hrs circulate out and repeat.

(SALT)

WELL CONTROL MUST BE ONE OF THE PRIMARY

CONSIDERATIONS WHEN USING PILLS OF DIFFERENT DENSITY.

Free Point Indicators

FREE-POINT DETERMINATION


• If jars are still operating, minimise stretch and torque readings

above jars to necessary calibration runs only.

• Attempt to establish free point using FPI stretch measurements

first.

• Once preliminary free point is established verify torque can be

worked down to back-off point.


FREE-POINT DETERMINATION

(1) If jars not firing then rough free-point estimated from stretch

calculations prior to wireline unit arriving on location.

(2) If jars are not stuck then fire up and uncock jars prior to RIH with

wireline tool. Do not go below weight required to recock jar during free

point determination and back off.

(3) Run FPI tool to maximum depth possible if jars are operational. If jars

are not operational 500 ft below estimated free point obtained from stretch

calculations. Run a CCL log to 500 ft above suspected stuck point.

Correlate BHA and formation depths using a paper BHA model.

(4) After CCL begin running FPI stretch tests. Initial stretch test should be

in a known free point in order to obtain baseline reading.

Procedure from stuck pipe handbook

Free Point IndicatorsFREE-POINT DETERMINATION

(5) Once preliminary free point is determined from stretch test

commence torque test procedure.

(6) After completion of tests select best back-off depth.

(7) Utilise the FPI tool to accurately determine the neutral point.

Procedure from stuck pipe

handbook


KEEP IN MIND THE FOLLOWING POINTS ABOUT

BACK-OFFS

(1) In a high proportion of wells, stuck point has always been joint of pipe

below jars.

(2) In tortuous wells torque takes time to apply and monitor.

(3) Be aware of line creep and stretch.

(4) Wireline pack-off systems allow immediate circulation after shooting.

Information Required Before Freeing

Operation Starts

• Safety- especially potential for falling objects.

• Ton miles on block line.

RIG READINESS

DRILL STRING

INFORMATION

• drillpipe:

• Yield of drillpipe tube.

• Yield of drillpipe tool joint - combined torque and pull

calculations .• Make-up torque used.

• BHA:

• Weight of BHA below jars.

• Position and formation adjacent. Paper BHA

model.

Information Required Before Freeing Operation

Starts

• Jars:

• Maximum pull while jarring with hydraulic jar.

• Jar firing force envelope.

• Time delay when firing hydraulic jars.

• Jar pump open force.

WELLBORE INFORMATION

• Formation types and characteristics.

• Hole condition.

• Up, down and free rotating weights.

• Drag chart.

4- best practices f

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