Stuck pipe prevention methods for Hole Cleaning

good presentation to reduce stuck pipe NPT

1. ميحرلا نمحرلا للها مسب

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HOLE
CLEANING
Prepared By
Eng. Nasser Hussein
Prepared by: Engineer Nasser Hussein

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Hole Cleaning
In 40-65 degree wells cuttings beds will slide down the low
side of the hole.
Prepared by: Engineer Nasser Hussein

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In deviated wells cuttings and caving settle to the low side
of the hole and form layers called solid beds or cutting
beds.
The BHA becomes stuck in the solids bed specially while
POOH.
Cuttings and caving can also slide down the annulus when
the pumps are turned off and pack-off the drill string.
This sliding can also occur while the pumps are on.
Hole Cleaning
Prepared by: Engineer Nasser Hussein

5. Hole Cleaning

6. Hole Cleaning

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PREVENTATIVE ACTION:
Maximise the annular velocity Consider using a third mud
pump. Consider using larger drill pipe.
Ensure circulation times are adequate. Consult hole cleaning
charts for confirmation & Monitor cuttings returns at shakers.
Maximise mechanical agitation of cuttings beds as Rotation &
Reciprocation.
Optimise mud properties. Increase Lsyp in 40 degree well
and above (= 1 to 1.5 * hole size).
Backream while POOH and wiper trips.
Hole Cleaning

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RIG SITE INDICATIONS:
•Over-pulls increasing while POOH.
•Erratic pump pressure.
•Poor weight transfer to bit.
•Difficult orienting tool face.
•Absence of returns at shakers.
•Presence of re-ground cuttings (LGS).
•Over-pulls inside casing.
Hole Cleaning

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DRILLER
TRENDS
DRAG TORQUE PRESSURE OTHER
DRILLING Increasing
Erratic
Increasing
Erratic
IncreasingPressure surges.
Gradual decrease in
ROP
CONNECTION Over pull off
slips
Surge to
start
circulation
Back pressure before
breaking connection
Back flow
TRIPPING OUT Increasing
Erratic
Over pull off
slips
Swabbing
TRIPPING IN Increasing set
down weight
Over pull off
slips
Begins with BHA below
depths of 35˚ hole
angle
BACK
REAMING
Over pull off
slips
Erratic over pull
Increasing
Erratic
IncreasingSurge to start
circulation. String
pistoning. Loss of fluid
is possible
PUMPING
OUT
Over pull off
slips
Increasing
Erratic
IncreasingSurge to start
circulation. String
pistoning. Loss of fluid
is possible
General signs for hole cleaning

10. Low shear yield point
LSY = 2( READING AT 3 RPM) - READING AT 6 RPM
Prepared by: Eng. Nasser Hussein10
because readings at 3 & 6 RPM reflecting
annulus condition which had cutting.

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Hole Cleaning
High Viscosity Pills
•Typically used for hole or casing sections with a deviation
less than 40°.
 
•Not recommended in highly deviated wells.
•If used regularly, will increase the Yield Point and low shear
rheology of the active system.
 
•Sweep Volume should be greater than 300 feet of annular
height.
 
•Prepare pill to a funnel vis. of 40 – 100 sec/qt over the
circulating fluid.
•mud use VG 69.

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Hole Cleaning
High Density Pills
•Highly recommended over high viscosity sweeps in deviated
and horizontal wells.
•Usually mixed at 2 - 3 ppg above circulating system mud
weight.
 
•The buoyancy effect of the higher density increases the
carrying capacity.
 
•This pill alone will have only limited effect in removing
existing cuttings beds in a horizontal wellbore unless it is
preceded by a low viscosity scouring pill in turbulent flow.
•[Do not use a high density pill alone if it is likely to cause lost
circulation. Consider formations, ECD and frac gradient.]

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Hole Cleaning
•Tandem Pill
•The most effective type of sweep in deviated wells.
•Consisting of pure base fluid of the mud (water, oil, or low vis
treated base fluid with filtrate control) calculated to fill an
annular volume of 200 – 500 ft, followed by a weighted pill
(weighted to 2 – 3 PPG over the active mud weight).
•The 2 pills together can be calculated to balance out at the
circulating fluid mud weight which will cause minimal effect on
the hydrostatic of the well.
 
•The weighted pill density should be as high as practical,
taking into consideration rig limitations and exposed
formations

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Hole Cleaning
Pills enhanced with ‘Fibers’
•Fibrous loss circulation materials effectively clean an angled
well bore by ‘lifting’ of the cuttings through mechanical
interference with the particles.
•Fiber Sweep should be used at 0.1 – 0.5 lbs/bbl mixed directly
into a pill volume of the active system mud.
•Concentration that can be pumped is dependent on the size of
circulation ports of any tools in the well.
•Directional tools are usually compatible with 0.1 – 0.15 lbs/bbl
of Fiber Sweep.
•Discuss the product application with tool company personnel
at the wellsite prior to pumping also consider reservoir
condition..

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Hole Cleaning
•Back reaming
•Back reaming should be avoided in high angle holes, but
when necessary, needs to be done carefully with appropriate
practices to minimize risks.
•If excess torque and drag are seen and it is suspected coming
from cuttings beds, back reaming can drag these cuttings up
the hole and pack off the BHA.
•Always back ream all the way to the shoe or at least to a
vertical section to avoid cuttings bed build-up.
•Adequate circulation time incorporated with sweeps should be
performed to ensure the hole is as clean as possible prior to
back reaming.

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Hole Cleaning
Back reaming
•It is important to keep the cuttings above the BHA while back
reaming.
•Prior to racking back each stand, circulate, rotate and
reciprocate the hole clean .
•If while back reaming the pipe tries to stick or the hole starts
to pack off, then attempt to lower the string back down before
trying to deal with the problem.
Never pick up. If necessary jar down, not up.

17. CCI = ( MW * AV * K ) / 400,000
Cutting Carrying Index (CCI)
If CCI is equal to 0.5 or less, the hole cleaning is poor and the
hole problem may be seen.
If CCI is equal to 1.0 or greater, it indicates that the hole
cleaning is good.
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Hole Cleaning Relation (HCR)

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FREEING:
•Depending on string movement, go
always to free area using jars.
•Pump low vis pill followed by hi-vis-pill
or weighted pill and circulate hole clean.
•Rotate pipe while circulation.
•If excessive cuttings came over shaker
when pills came out, do it periodically.
•If not pump high weighted pill.
•Back reaming trip must be considered.
Hole Cleaning

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NOTES
•Ensure maximum pump rate and maximum pipe rotation is
achieved when pumping any sweep.
•If operationally feasible reciprocating the pipe will also help in
picking up the cuttings bed while the pill is flowing across the
tandem section.
•Do not shut down the pumps while sweep is in the hole.
•Only have one sweep in the hole at a time (the tandem pill is
considered as one sweep).
•To aid in hole cleaning and solids suspension maintain low
Shear yield point rheology between 1 – 1.5 hole size.
Hole Cleaning

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NOTES
•Mud engineer should always monitor returning sweeps
and use Sweep Sheet below to track effectiveness of
sweeps and to optimize formulations and frequency
required.
•He should keep a trend chart of sweep effectiveness
relative to hook load/torque readings.
Hole Cleaning

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SWEEP SHEET
Date / Time:
Depth:
Hole angle:
Reason for sweep:
Average ROP:
Sliding / Rotation:
Active mud density:
Active mud PV/YP:
Active mud 6rpm/3rpm:
MWD tool in hole (type/company):
Circulating sub in hole (yes/no):
Pump rate during sweep:
Pipe rotation during sweep (Yes/No):
Bbls DensityPV YP
High only
High Density only
Tandem Sweep
Lo-vis
Hi-vis
Fiber-enhanced Sweep
Before After Remarks
Pump Pressure (psi)
Torque (off btm)
String Weight:
Up:
Down:
Sweep Effects: (% cuttings increase, pump pressure increase during sweep, cuttings size/appearance, etc.)

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General for hole cleaning
MINIMUM CIRCULATING CYCLES TO CLEAN HOLE
HOLE SIZE 26” 17” – 16” 12” 8”
ANGLE INTERVAL
0˚ - 35˚ 2 1.7 1.4 1.4
35˚ - 55˚ 2.5 2.5 1.8 1.6
55˚ + 3 2 1.7
GPM = 30 – 50 GPM for each inch of bit size.

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General for hole cleaning
MAXIMUM ROP VERSUS HOLE SIZE AND HOLE ANGLE
HOLE SIZE 26” 17” – 16” 12” 8”
ANGLE
INTERVAL
0˚ - 35˚ 60 ft/hr 110 ft/hr155 ft/hr240 ft/hr
35˚ - 55˚ 40 ft/hr 75 ft/hr 85 ft/hr 125 ft/hr
55˚ + 60 ft/hr 75 ft/hr 100 ft/hr