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Doe's anyone have experience of using WBM or slick water during MPD operations?
21 June 2020
Good evening colleagues and greetings from Kazakhstan.

We are planning for possible MPD operations and one of the questions we have is, have MPD ops been down with WBM or slick water as the drilling fluid.

Basically we want to spot water or light annulus mud on the backside and to drill ahead with WBM in the string.

The basis for this is to reduce losses and also the cost of those losses.

At the moment this is high level planning and idea discussion, and so we would be really interested to understand the experience that others out there have and how they managed this.

12 answer(s)
Drilling/Completion/Abandonment Superintendent
Drilling Consultant
Total Posts: 8
Join Date: 05/06/20
Aword of caution on WBM if the temperature is high. We found at Maersk Oil that as soon as you close the BOP r circulation device you always had a 1000 psi due to the extremely low compressibility of water. Therefore the behaviour of the well was masked and you could not see small pressure increases because of the masking effect.
Principal Drilling Engineer
Total Posts: 21
Join Date: 04/07/08
Sounds very much like mud cap drilling of some sort, which is done relatively frequently around the world as others have already suggested. It can become very complex very quickly depending on the formations being drilled, ability of loss zone to take full or only partial injection, risk of taking gas kicks (especially if there is risk of H2S/CO2), potential for reactive or unstable formations, well location, type of rig, and whether it is a surface or subsea wellhead system.

Ensuring the pumps and circulation system and pit setup is capable of adequately managing both string and annulus fluids circulation is paramount, and that there is sufficient redundancy in case of pump failure while drilling, especially if you are looking at pressurised mud cap with potential for gas migration, and need to continuously pump to and manage annulus fluid.

Also, be aware that the drilling itself isn't always the most complex part - getting the well stable enough to come out of hole safely, and then running and properly cementing pipe without incurring losses again can be a greater challenge. Consider use of liner and tieback rather than full string of casing so that you have more flexibility to actively use the RCD and MPD system during these operations as well.

I'd suggest speaking to your MPD vendor, as the majority of them have good understanding of the technique and can assist with the specific details, particularly around defining the detailed operation procedures, and contingency planning.
SPREAD Associates
Total Posts: 6
Join Date: 18/09/07
Contact Chris Carmack (
Chris is expert on CHCD (Continuous Hole Circulation Drilling), wrt equipment and procedures. 

Chris helped set up the submersible drilling barge rig (KC Caspian Explorer) for drilling an exploration well in Northern Caspian sea with potential total losses.  We were geared up to drill with light mud, could be slick water, depending on max surface pressure you want in annulus.  

However the well did not encounter total losses, hence the developed procedures were not put to good use on this will.

Apart from the RCD rig up, and large number of full opening safety valves, rented from supplier in Kazakhstan.  

We had to modify the sea-water supply line on the barge, to ensure full continuous supply.

Note from moderator (Dave):

I have forwarded this to Chris
Albina Taganayeva
Drilling fluids engineer
NCOC North Caspian Operating Co
Total Posts: 4
Join Date: 19/06/20
Thank you Peter for such a detailed response. As I said we really are at a high level.

Your starting advice is great and we will now go back and explore the IADC selection guide as a kick off point and come back to the forum with an update.

As you said once we firm up a little more, then workshop, swot and well management plans will be key to success

thanks and regards

Albina Taganayeva
Drilling fluids engineer
NCOC North Caspian Operating Co
Total Posts: 4
Join Date: 19/06/20
David, thanks for your response and yes as others have said there seems to be a lot of floating mud cap drilling experience out their. Most likely that will be the potential solution.

now time to dig a little deeper and engage with some contractors I guess

Thanks and Regards

Albina Taganayeva
Drilling fluids engineer
NCOC North Caspian Operating Co
Total Posts: 4
Join Date: 19/06/20
Hi Cas, good to see you here on the forum. Hope you are doing well.

Yes lots of weather and sea level impacts to keep in mind here as you know!

For sure we will work with our colleagues in KPO and grab some of their experience along with the lessons learned. I guess the main difference here is that we want to use water or wbm.

Thanks and Regards

Cas Lommmers
Total Posts: 1
Join Date: 24/01/16

Hi Albina,

Please plan your operations in the summer so you have enough access to water and plan to have enough time for operational delays before the winter starts and all water around you is frozen. You can also contact KPO up north of you, they have great experience in CHCD drilling.

Drilling Specialist/Well Engineer/Training Consultant
Kingdom Drilling
Total Posts: 491
Join Date: 10/01/05

"At the moment this is high level planning and idea discussion, and so we would be really interested to understand the experience that others out there have and how they managed this."

With so little data provided we can only assist in  how to take a candidate well and work this through several base concept design options (some of that have been mentioned in other posts).  All to work toward the preferred 'Option' for all the right reasons,  to deliver a final basis of design selection ( with contingencies often needed). A safe, yet operational realistic pressure management and well control Assurance plan to dleiver outcomes and benefits desired.

To start? 

I would use of the IADC MPD candidate selection process and tools provided to us by our peers to work through all well drilling concepts on offer ie Section by section from designs to a base case design. A good comparison is always to have a standard regional well ( what you are doing now and List all current hazards/risk problems you are having) or anticipate to weigh all the 'SWOT' analysis, Strengths, Weaknesses, Opportunities and Threats that you could also conduct.

IADC Well Classification System for Underbalanced Operations and Managed Pressure Drilling
The purpose of the IADC Well Classification System is to describe the overall risk, application category and fluid system used in underbalanced operations (UBO) and managed pressure drilling (MPD). Wells are classified according to:
• Risk Level (0 to 5)
• Application Category (A, B or C)
• Fluid System (1 to 5).
This classification system provides a framework for defining minimum equipment requirements, specialized procedures, and safety management practices.

For further information? simply refer to the IADC UBO HSE Planning Guidelines and other related documents

So there is a good guide to assist.

Also Get a few specialists involved and run a on-line workshop. This would be upfront loading money well spent. 

The design hinges on whether you expect or are wanting returns or if you have a loss zone to deliver cuttings into. You have not stated this? 

With returns a light weight fluid can be used but you have to know your drilling limits as others have posted. Particularly if wellbores are large and inclined. ROP and hole cleaning in certain formation types will also have to be Strictly controlled. There are generally always operational limits and constraints that need to be well modelled and understood. Bit bha design is paramount.

if you are taking cuttings returns, You required also high efficiency solids control equipment to remove cuttings at shakers. Upgrades likely needed here? Knowing All these limits are therefore paramount and must be included in your hazard risk assessments concluded here! 

If you have a loss zone to take the cuttings then annular pressure can be maintained by using a mud cap or pressurised mud cap Systems approach as other have stated. This is commonly used in these regions and there are specialist companies that can aide and assist working you through the concepts to final design processes stages needed. You can now use a more managed pressure  just above balance drilling method to drill more effectively and efficiently yet maintain annular pressure for losses and gains etc. 

Time doing this properly is money well spent, 

The end result is that you need to assure yourself that you have enough strings of casings and sufficient drilling operating  Window margins to be able to proactively drill and mitigate to expected worst case expected conditions vs a respond and react and cure process.  

The  MPD solution selected needs to  assure that you can indeed  ‘Make Problems Disappear’  in terms of pressure management and well control assurance issues currently experienced with a solution that can safely effectively and efficiently resolves your issues. 

Lots of pre and detailed planning, getting the right people and training all involved, peer assists and reviews, right tools and equipment at the rig and downhole to best meet each section to be drilled.  Getting the numbers right first time, is paramount, truly knowing your limits , real hazard / risk management checks along the way, to result in the most practical yet evidence based and well engineered solutions are all part and parcel to achieve safe effective efficient wellbore delivery. 

If it was me assigned to this task, I would be picking up the phone and seeking specialists help and advice on all of the above.


Drilling Supt
Neptune Energy
Total Posts: 6
Join Date: 18/05/15
If you want to circulate out the cuttings you cannot use mud cap drilling as they would remain downhole injected into the loss zone probably. Using a lighter cheap fluid can be done with MPD or UBD but it will need carrying ability to lift the cuttings. With UBD you will need a separator (s) on surface to handle any hydrocarbons and a way to dispose of them. One thing to consider is wellbore stability, and wellbore quality, if you reduce the hydrostatic too much. 
Drilling Superintendent
Wild Well Control
Total Posts: 4
Join Date: 24/06/16
Offshore Malaysia we used straight sea water as the light annular fluid on many floating mud cap wells where the reservoir pressure was sub abnormal (below 8.6ppg) and in pressurized mud cap drilling when the pressure differential was within the working margin of the rotating head.   On some of the wells we used slick water to help reduce wellbore friction.     We would only weight up the light annular fluid to the weight required to get within the working margin of the rotating head.

Aberdeen Drilling Management Ltd
Total Posts: 20
Join Date: 18/08/05
Managed Pressure Drilling requires circulation so you would not have a fluid spotted in the annulus.

Agree with Steve, mud cap drilling is commonly used where total losses occur and cannot be cured.  In mud cap drilling you would use water as your drilling fluid with mud in the annulus - normally called floating mud cap drilling.  If this method is used having a way to monitor the depth to the top of the mud in the annulus is very useful.

There are also applications where you may use pressurised mud cap drilling, I have used this method in formations with massive losses which occasionally bridge off briefly with the drilled cuttings and then go back to massive losses.
Wells Mgr - Wellspec
Total Posts: 44
Join Date: 23/03/16

Slick water is used for fracture stimulation and it is basically water with chemicals added to reduce friction. 

If you are using water on the backside there is not need to design high flow operations so no need for slick water, that would only add costs.

If you have any kind of circulation you cannot keep the annulus static , the well will circulate even with losses. If you have total losses then mud cap drilling operations can be conducted. Mud cap drilling is a pretty standard operation especially in fractured carbonates.

Losses are pressure related, if you drop the pressure in the wellbore, losses will stop. If you drop the pressure too low, a kick may happen and that is the basic challenge. Look at your formations and what is causing the losses and then go from there

Let us know what kind of losses are expected and be happy to help further.
Posted by

Albina Taganayeva

Drilling fluids engineer

NCOC North Caspian Operating Co

Total Posts: 4
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