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LCM sweeps as hole cleaning treatments
25 June 2020
Hello member friends,

I hope you are doing great. I just joined SPREAD.

I would like to get your thoughts on fiber sweep or nutshell sweep as a treatment of hole cleaning in angled wells.

The basic concept behind it is that the abrasive material of this sweep will erode the beds of cuttings to some degree. But in practical terms , is it really an efficient way to serve its intended purpose ?
  • Do you have some experience with sweeps ? 
  • Are there any noteworthy steps to do while using this sweep to get better performance ? 
I would love to hear your experience about this matter.

My regards  


Baghdad, Iraq
21 answer(s)
Managing Director (
Relentless Pursuit Of Perfection Ltd.
Total Posts: 462
Join Date: 10/01/05
Dear members

In response to my question about mechanical aids such as CBI, this just in from someone with poor internet connection so he's asked me to post it:

"In my view, if you get to using cutting bed impellers or something else then you have an issue with your system - fix the issues, don't apply a band aid - gauge hole, drilling parameters/processes, mud rheology. 

You can't just run one in the hole, you need one every two or three stands maximum in the inclinations were you have cuttings bed formation. 

Have used them once many moons ago and the ECD went through the roof, added OD to the drill pipe multiple times = restrictions in the annulus = ECD increase.

You’re always going to see good runs, BUT, could the issues have been solved by fixing the basics - KISS"

I hope it helps
Lead ERD Advisor / Engineer / Instructor
Merlin ERD Limited
Total Posts: 16
Join Date: 04/05/16

I wouldn't going buying SPE Papers and posting them on a forum. You will get in a bit of copyright trouble with the SPE for that, which I am sure Dave is aware off. Purchase of papers is for sole use.

Regards, Iain
Rig_site Engineer
Total Posts: 6
Join Date: 24/06/20
Dear Dave ,
there is a bunch of papers on SPE talking about what you have mentioned . i will buy them soon and post them here so everyone here can have a look on their performance in practical terms.
my regards.
Managing Director (
Relentless Pursuit Of Perfection Ltd.
Total Posts: 462
Join Date: 10/01/05
OK folks, plenty of (great) food-for-thought.

I've been dying to ask-this-question / make-this-point.

We've heard about good drilling practices and, for the most part, we've talked about fluid (hydraulic) solutions.

What about mechanical aids, such as EPDP (Enhanced Performance Drillpipe) and CBI (Cuttings Bed Impellers) and/or any other such devices.

It would be wonderful to hear from those of you who are pushing the 'Nose-plot' envelope.  

If you're shy to use your name, or work for one of those companies who won't let you mention that you work for them ... no worries, pop me the details and I will post under my name (and look very clever!)

Thanks in advance

Note from moderator (me):

It's great to see the upsurge in activity in recent weeks!  We've "lost" (purged) another 400 members, but the site is about quality and not quantity.

We have gained about 60 great, enthusiastic new members!

Drilling Superintendent
Total Posts: 2
Join Date: 05/06/20
Based on Kerr McGee and Maersk Oil practices which worked very well in high angle:
- 6 figure reading should equal 1.2 times the hole diameter or more.
- Don't pump any sweeps they are a waste of time - the fluid velocity at the high side of the hole is twice the velocity on the low side so what do you think happens to your sweep in open hole?
Instead circulate until you see the second wave of cuttings coming up. This can be 5 or 6 or more times bottoms-up. Back ream up at 120 rpm and ream down with 40. Obviously go down a lot faster than up. 
- Be patient and while pumping as fast as you dare don't risk losses. Follow ECD from the PWD carefully.
- When drilling if ECD rises more than two points ream each stand down before the connection and control ROP to limit ECD increase.
Rig_site Engineer
Total Posts: 6
Join Date: 24/06/20
many thanks guys for your rich input i highly appreciate taking the time to answer .
Relentless Pursuit Of Perfection Ltd.
Total Posts: 5
Join Date: 15/04/13
Lots of good info and experience in the answers above. One other factor to bear in mind is an occasional reluctance from field personnel to push the mud rheology to the programmed numbers. If the programme is looking for eg 6 rpm of 21 in a 17 1/2" hole section your engineer might well take two days to get it up to about 16 then he gives up - well, we're just going to have to thin it back again at TD, right?
This is a good example of deviation between design as programmed vs design as executed. It takes a lot of product and mixing to get your rheology up right at the start of the section; fluids engineers worry that the thickened mud won't go through the screens; there just isn't enough rheology modifier on board...However if you get your rheology up straight away and manage your hole cleaning hygiene right you'll find there's no need for sweeps, which usually bring more problems than they solve. Hope that helps, John
Andy Wood
Manager of Subsurface Operations
Manage My Rocks Limited
Total Posts: 1
Join Date: 29/06/20

There is a great deal of useful advice here about general hole cleaning and the science of sweeps etc.

I would add that prevention is sometimes better than cure. Engage a good geo-mechanics company to advise on optimum MW and hole cleaning activities. If your budget allows use real time / relevant time geo-mechanical monitoring.

Good luck

Total Posts: 1
Join Date: 27/10/18
Regarding use of nutplug, apart from addressing loss circulation issues, it is not used for hole cleaning as in providing additional lift, but it acts as a good scrubber to clean up balled Bits and BHAs, when loaded in a large volume low-vis sweep, pumped at max possible pump rate and is not to be used in tandem with Hi Vis, but a HV can follow-through after spaced out with at least 15 mins of pumping regular drilling mud.
There are many techniques for pumping sweeps and combinations of sweeps, including for ERDs (despite K&M preaching against it) if done correctly and with the right choice of sweep agents, combination of weighted, or equi-weighted sweeps which can also be laced with stress caging, LCM, lubricant, etc., as required on a case by case basis.
The frequency, volume and pumping rate of sweeps (without interruptions, at least till it reaches near vertical) and spots are also important (critical in high risk wells) where inappropriate choices could compromise the well and/or string. (This is why it is critical to know what items are permissible to pass through the minimum aperture within BHA, not just for LCM pills but for sweeps and spots as well). Pills are best pre-mixed to avoid clumping and maintain a homogeneous consistency and also extend integrity and retard dispersion across the annulus (especially at higher inclinations).
It is also important to assess the results of a sweep, even if there are no visual indications at shakers of additional offloading, as other hole condition indicators need to be correlated for any improvement, deterioration or non-impact, which will determine the need and choice of the next one.
Avoid multiple sweeps entrained in the annulus, as it will mask indications of ECD flags of pack-off risks.
Sweeps in general are administered with little thought and planning, when in fact sweeping is both a science and art, that does not have any textbook silver bullets, which is unfortunately how the industry uses it and then often poorly understands when to use it and misinterprets results, usually leading to pumping away good money at best, or creating complications at a greater cost.

windy martdianzah
Drilling & Workover Engineer
Total Posts: 1
Join Date: 26/02/18
Hi Montader, 

I haven't known yet for nutplug sweep or LCM sweep main purpose for hole cleaning aid, unless there is hole stability issue like seepage loss. I had recalled in exxon mobil, they have drill and seal treatment for loss < 15 bph, to pump 40 bbl 20-25 ppb calcium carbonate sweep. 

Still the practice here for cleaning aid on low side is pumping lo vis pill to make it turbulance and disturb cutting and tandem it with Hi dense or Hivis pill (not mentioning the others most contributing factor for hole cleaning like others stated)


Mud Specialist
Medco Energi
Total Posts: 1
Join Date: 27/03/17
My experience using organic cellulose fiber sweep was not effective to removing bed cutting at high deviated well. Moreover if the mud system is NADF, it will feed the alkalinity and absorb the emulsion as organic fiber is water wet, so then will impact to reduce ES and finally increase your fluid loss. 
I suggest to use tandem sweeps instead. Combination Low-Vis & Hi-Dens or Hi-Vis will optimize to remove bed cuttings if annular velocity doesn't enough to bring cuttings up to the surface.

Documents uploaded by user:
Annular Velocity.docx
Drilling supervisor
Sonatrach Petroleum Corporation
Total Posts: 11
Join Date: 11/02/16

Dear Montader;
There are other criteria to consider while cleaning deviated wells such as the hole diameter and the deviation angle. As the LCM could plug the bit nozzles in 8 ½ and 6’’ sections and could do the same for the PDM. Therefore, attention should be paid while pumping LCM.

In low angle (<30 deg) wells:

The transport Velocity is the key

To increase cuttings removal efficiency

-       Increase Annular Velocity

-       Increase Mud Weight –If possible

-       Increase Mud Properties (YP, Gel Strength)

-       Pipe Rotation increases the annular velocity


As hole angle increases, things change; the concentration of cuttings at the low side increases. Cuttings are no longer being supported by the mud and a cuttings bed begins to form.

In high angle wells :> 30°:

-   Between 45-55°, avalanching and in the worst case pack off is highly expected in a dirty holes.

- Use tandem Pills: This consists of two pills, a low viscosity pill followed by a viscous weighted pill. The idea is that the low viscosity pill stirs up the cuttings from the low side of the hole and the viscous pill sweeps them out of the hole.

- Consider increasing the circulation rate, drill pipe rotation and reciprocating drill string for a better hole clean

You can contact me if you need some materials about stuck pipe and hole cleaning

Best ragards,

M. Boumezrag

Rig_site Engineer
Total Posts: 6
Join Date: 24/06/20
thanks gentlemen for taking the time to reply that is really kind of you . 
Rig_site Engineer
Total Posts: 6
Join Date: 24/06/20
thanks gentlemen for taking the time to rely that is really kind of you . 
Drilling Consultant
SPREAD Associates
Total Posts: 65
Join Date: 15/09/14

We did have some good result from the use of fibrous stuff which was originally used to cure minor losses, but noticed a lot of cuttings associated with the pill when it came over the shakers as well as hole drag reduced, in horizontal well. 
We had to drill with brine to reduce the "formation damage" according to Reservoir Group. Thus we could not were handicapped in mud rheology. 
But, like a couple of guys' advice, try to look into other factors such as rotary speed, mud rheology and pump rate. 
To me, a pill is like a medicine, you pump it when other parameters cannot clean the hole properly. 

Best of luck. 

Andy Pua 

(retired) Well Fluids Team leader
SPREAD Associates
Total Posts: 49
Join Date: 14/06/06

Montader,  welcome to Spread. 

Some 30 years ago when we started UK/ Norway drilling of deviated wells I did some fluid experiments with a major fluid contractor using their Perspex gravel pack simulator equipment.  You can change the fluid type pumped, see the fluid  and cuttings move, simulate deposited cuttings bed,  change fluid viscosity and change pump rate and adjust the well angle by lifting the simulator pipe etc.
We made a video of the experiments!   

What I remember was that all types of high viscosity pills actually physically compacted deposited cuttings at angle above 40 degree. Therefore viscous pills were never programmed for use in well angle sections above 40 degrees. 
These experimental results and other experiments like pulling a simulated BHA through a cuttings bed were used in putting together our ABC of hole cleaning.

You should be able to get a reasonable hole cleaning pamphlet from a mud company or a major operator. 

Enjoy you career 

Regards  Ian  


Note from moderator (Dave):

Thanks Ian!  You and your colleagues at the Production Chemistry Lab / team in Shell Expro kept us all out of trouble back in the day, when I was EE, SDE and then NSDV then DSV!  

Amongst other things (checking all cement recipes), the PC Lab also tested spacers and wellbore clean-up chemicals, saving the company a fortune compared to just pumping what the Service Companies were trying to sell.  Good days!

Drilling Specialist/Well Engineer/Training Consultant
Kingdom Drilling
Total Posts: 461
Join Date: 10/01/05

Some useful Hole cleaning movies, animations SHARED so that drilling teams can translate and sustain learning and begin that reflective journey to realise, analyse and truly investigate from where all current root cause(s), of high angle complex wells drilling, hole cleaning and associated operational failings/problems are evidently resulting from?

Enjoy this learning opportunity and wishing you well towards future improved success.

Drilling Specialist/Well Engineer/Training Consultant
Kingdom Drilling
Total Posts: 461
Join Date: 10/01/05
I agree with other comments raised in that if you are having to resort to backreaming on connections? sweeps? and fibres etc? the office and rig site team involved has simply failed on several fronts to pick up on all the early warning signs and indicators of poor hole cleaning that EVIDENTLY existed!. 

One then has to revert to response, reaction and contingent attempts loss / waste tactics to try and cure vs proactive preventative  and mitigating approach of all evident problems in the first place.

With bit bha Drilling technology that exists today, and practices ( viewed as standard practices) commonly used, it is too easy today, to simply drill yourself quickly into a Hole cleaning problem. 

Where all Have to really know and understand where your ‘drilling limits‘  are. Particularly in certain formation types / intervals. 

That must be clearly highlighted and afforded by the drilling engineers within the drilling models and Engineering programs Outputs that should exist? 

If not? most common failings are 1st, not enough energy is expended to the bit ( now cuttings are Instantly reground to start a domino effects of Several hole cleaning problem and issues that shall result). This a common problem I review. 

Secondly You are probably at times drilling the hole Far faster that thr wellbore can be cleaned in the first place. Based on max flowrate ( or limitations) that exists.. 

Mud rheology also if not addressed and maintained will add a Poor viscous couplings as another contributor 

Practices being applied ( eg backreaming all the time as a matter of course? on connections? For example again al precursor of all evident reasons things are failing that the team involved needs to Understand to address. 

Advice would be. Gather all the evidence Then try and fixes the root causes of evident problems?. Know your limitations! 

staying within the boundaries? You Will not  require sweeps,  fibres or backreaming to drill a wellbore section at optimal performance. 

That is ultimately proven when the team can Poh thr bit / bha on your well sections from td to surface on elevators only.

I’ll post a link to the two hole cleaning movies on u tube that everyone needs to watch ( several times) to to truly understand Drilling limits and best practices to safe effective and efficient  hole cleaning     

Drilling Supervisor
Total Posts: 1
Join Date: 22/10/17

I have successfully used unweighted fibre sweeps for hole cleaning in low angle drilling environments.

Have to admit I was rather sceptical about fibre when it was first proposed by the mud vendor, however, it did not disappoint, rather the opposite.

Not only are the fibre sweeps quite effective as a hole cleaning aid, but quite notably, they do so with affecting the mud's rheology, since the fibre itself does not affect fluid rheology or require any rheological adjustments, i.e. fibre sweeps are of the same rheology as the base fluid.

Fibre tends to be seen as an added cost (whereas the cost of mud thinning/viscosifying additives used for low/high viscosity sweeps, or the resulting mud treatment requirements, gets camouflaged as regular mud maintenance) but at the end of the day not having to combat undesirable rheology changes/swings can be nothing but cheaper.

On the down side, and this is just a practical aspect from personal experience, fibre sweeps can often "accelerate/consolidate" hole cleaning bringing copious amounts of cuttings that can cause the solids control system's capacity to be momentarily exceeded i.e. total mess in the shaker house!

Working principle wise, understand fibres form a mesh/net type structure that effectively catches and transports cuttings out of the hole.

My tuppence. Hope this helps.

Operations Manager / HPHT Drilling Superintendent
SPREAD Associates
Total Posts: 3
Join Date: 08/04/18
Hi Montander,

Welcome to My-Spread.

I believe it is safe to say that sweeps are the bottom of the list for managing hole cleaning in deviated wells. 'Deviated well' is a pretty broad term. There are different aspects and tactics for addressing hole cleaning in 0 - 40 degrees, 40 -60 degrees and 60 to 90 degree well sections.

There is nothing that erodes a cutting bed better than turbulent drilling fluid flow regime and appropriate pipe rotation speeds for the hole angle.

I did a Google search regarding your question toward saving me a lot of typing. It turns out I found a very good presentation that is apparently from My-Spread, been posted in this forum already. I have attached it here.

This will give you good background fundamentals on where to start for understanding and addressing hole cleaning in a deviated well. Get these right and you won't be spending a lot of time and money needlessly going down the path for what to do with sweeps.

Kind regards,
Documents uploaded by user:
Hole cleaning in directional wells.pdf
Lead ERD Advisor / Engineer / Instructor
Merlin ERD Limited
Total Posts: 16
Join Date: 04/05/16

Sweeps are a vertical section practise that made their way into dircetional wells. However, they have minimal to no impact in helping to remove cuttings beds in directional wells. Your cuttings bed is on the low side of the well and the sweep will take the easiest route - the upper annular area. Howver, it will clear the cuttings out of the near vertical section of the well, if it hasn't been strung out. You will see an increase in cuttings at the shakers and then a drop off when the sweep reaches surface. If you continue to monitor the shakers you will tend to be back to a normal cuttings level a lot sooner than bottoms up - tends to be once the volume of the low angle section fo the well has been pumped.

One other issue is the impact of the sweep on ECD as it comes to surface. If you are drilling with a narrow mud weight window you could initiate losses.

If you are going to pump a sweep you will need to maximumize flow and rotation.

It is better to focus on good drilling practices - flow, string RPM and mud rheology, and maintain a good quality wellbore (gauge hole). You are never going to stop the cuttings bed from forming. What you want to do is control the depth and then be able to efficiently clean the well bore prior to tripping. Remembering that you are going to need to circulate a minimum of 2 - 3 x bottoms up maximising RPM/Flow through-out.

You should be monitoring what's coming over your shakers all the time. Is it enough for the ROP I am drilling at. If it's not, then why not.

There's a few discussions on here re-hole cleaning practises, which would be worth your time to read up on.

Posted by

Montader Alsuhail

Rig_site Engineer


Total Posts: 6
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