The KCL- Polymer Mud

I always imagine if that was barrells of chocolate!! oh God, I would never let it loss even one drop. haha.

I’ve worked in six different oil-wells until now. All of them used KCL-Polymer system mud. I never work with another mud system so far (High performance mud, Oil base mud, synthetic base mud, etc)… How pity I am!:mrgreen: . Well yeah, this KCl-Polymer system is still considered as a powerful mud system to combat reactive shale or clays. It’s firstly used in mid-1950 and started widely used from late 1960’s to present. So actually, this mud system is not really sophisticated:mrgreen: . But It’s inhibitive enough, tolerant of contaminants (salt, gypsum/anhydrite, and cement) and help reach high mud weight (since the KCl salt contribute to raise mud weight pretty well).  That’s why it’s been widely used all over the world.

a simplified clay structure with its charge

Now there’s might be a question comes up , why Shale or Clay must be combated? well, Because it possibly swells so badly once it is contacted to water (like a rubber when it expose to diesel oil). It’s like become 8 – 10 times bigger than its original size. It is obviously dangerous to drilling operation as It will cause some problem such as (stuck pipe, rheology problem, etc).  Another question that might be come up later is why shale/clay works that bad? because the shale has molecular structures that possibly invites water and other particle to come onto. The particle consists of 2 layers that have different charges in it. The basal plane (flat planes) is predominant of negative charges (-), and edge side is mostly positive charge (+).

Molecular structure of smectite, the least stable minerals of clays

Why it is? Hmm,,,I need separated chapter to tell it why. it’s totally chemistry🙂 , physical chemistry actually. Let’s pick up a smectite, one of the clay minerals that is considered as the least stable and the most susceptible to hydration and diagenetic alteration. Two other terms often associated with the smectites are montmorillonite and Bentonite. Since bentonite has been exposed to seawater and other sources of cations, some of the silicon and aluminium cations in the structure have been replaced. Iron and magnesium typically replace aluminum and aluminum typically replaces silicon. This replacement causes an imbalance in charges in the structure. This causes the bentonite sheet to be negatively charged. Cations (positive charged particles) are attracted to this negatively charged surface.

As time goes on, water molecules begin to seep in between the platelets. Some of the molecules of water adhere to the clay platelets and some of them go to the individual cations on the platelet surface. When a clay platelet is fully hydrated, it is surrounded by a cloud of water and hydrated ions. The Greatest concentration of water molecules and hydrated cations are near the surface of the clay. And the swelling just happened.

An inhibitive mechanism of K+ ion on Clay particle

Well, back to the KCl system. How does it work? Which of the parameter that important to monitor periodically?

Here we go! The KCl-Polymer system provides potassium ion (K+). It works strongly because particular size of the ions in relation to the clay crystal structure. The K+ ion size really fit to the shale/clay pore (10 Angstrom) once it arrived at the surface of clay or shale. Then it inhibits the water to come into it and reduce the dispersion of clays. And the swelling is just avoided. Cool right?🙂 So, things that really important to measure is the K+ concentration in a mud. There’s a couple method to measure it, but the method I ever had is the hand crank centrifuge (I’ll explain it later!).

Although, it is recognized as a powerful mud system, there’s some limitation though which are: The Toxicity of KCl—typically 3-10 % by weight concentration, disposal cost, mud system cost at hight KCl levels. But I don’t know why the HSE officer told me that the treated mud (water from mud that’s been treated) is really good for fertilizer. He dumped in a yard and the grass then grew nicely. I think it comes from the K, which accidentally has good concentration for the grass growth. kinda miracle😯

Encapsulation illustration of Clay

Anyway, the combination of KCl with the polymer will enhance its effectiveness regarding to combat shale. The polymer that used is PHPA, that’s why sometimes it called ‘ The KCl-PHPA mud”. PHPA  stands for Partially Hydrolyzed Poly Acrylamide. It was introduced by Shell Oil Co in late 1960’s. The PHPA helps to encapsulate (coats) the clays/shale surface with a protective film. This blocks or slows Base Exchange and hydration. But the poor solid control prevented wide spread use. Yep, it definitely needs a good solid control equipment (Shale shaker, etc).

a not supported solid control prevents a wide-use of PHPA

24 thoughts on “The KCL- Polymer Mud

  1. wow…you’re kind of generous and brilliant engineer, thanks for the sharing. poor me can’t (wont’) understand it😛

  2. LOL! pardon for being too technical explaining it. Actually it’s just a basic chemistry, seriously. and all mud knowledge are common senses, means u’re gonna be understand when start getting into it. btw, I’m not a good engineer if u say so :(( It is hard to understand, isn’t it? Anyway, I’ll post some less-technical later on🙂 thx for visit buds,,

  3. Its very good , But i just want to point out another use of PHPA with KCL is that PHPA encapsulate cuttings and reduce the disintergration of cuttings in the mud system so that
    we can reduce LGS in the system.

  4. if the ROP isn’t high and you have good solid control equipment, especially desander and desilter, LGS shouldn’t be a problem i guess..

    Pak Agus, what and how many materials do u use to make up 1bbls kcl-polymer?

  5. Depend on the formation that’s being drilled. commonly, KCl concentration is up to 7%. so does the polymer, it could be vary from one field to another. polymer that’s commonly used are: PAC R, PAC LV, Xantan Gum, PHPA, etc. still, all of them is depend🙂

  6. Assalamalaikum. perkenalkan saya Muhammad Irsyad mahasiswa teknik perminyakan ygsedang tugas akhir. saya ingin bertanya mas, apa sebenarnya perbedaan antara KCl-PHPA Polymer dengan KCl-Polymer? trims🙂

  7. waalaikum salam,,,,,KCl-PHPA pakai polimer namanya PHPA,,,kalau KCl-Polymer aja biasanya tidak menggunakan PHPA, hanya polymer standar saja (PAC, Xathan Gum, etc)..🙂

  8. Trima kasih Mas Agus.
    Maaf mas sebelumnya, klo boleh saya minta akun Yahoo Messenger atau email apabila ada yang ingin saya tanyakan, karena kebetulan Tugas Akhir saya ini mengenai lumpur.hehe

    Trima kasih sebelumnya Mas Agus 🙂

  9. It is actually a great and useful piece of info. I am happy that you just shared this useful info with us.
    Please stay us up to date like this. Thanks for sharing.
    regards Propolis

  10. Not bad at all, but one thing is not totally correct … the size of ions … Your asumption is valid, but you should precise it is the diameter of hydrated ions, not that of ions themselves (otherwise ranking shouldn’t be the same between Na+ and K+ for instance) …

    Good article anyway …

  11. We use polymer mud for most of our drilling well at Myanmar Oil and Gas Enterprise and observed only good for under 9000ft depth.When drilling from 9000ft to 13000ft this mud unable to control bore hole problem such as High Back Torque,stuck pipe,high temperature and difficult to drill.I would like to know,why does it cause and all mud engineer from KMC company also unable to maintain well bore stability?

  12. Basically, depends on the formation. Some are highly reactive that causing KCl-Polymer doesn’t perform as expected and needs some additional inhibitor. In some case, due to high degree of reactivity, OBM is the only mud that able to drill the formation in safe and efficient manner. And…I have no idea why certain company is like that. So many things affect the wellbore stability.

  13. Agushoe, I searched for info on KCL mud because I used it years ago and remember that it did control reactive clay pretty well. the area I am working now has clay problems and I am trying to get the operator to try KCL mud. how can I find the second article you said you posted? The forst one is very clear and informative to me so I would like to see the next one as well.



  14. Thx Robert🙂 , I’ve made several KCl-mud-related post actually. you can find one under tag “mud”. anyway, I would post some more post when possible.🙂

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