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Squeeze Cementing Principles

June 14, 2016 By Lenin Diaz 30 Comments

Squeeze Cementing Principles

Some time ago I put together a short paper about the principles of squeeze cementing. Below is an extract of this document.

Successful squeeze cementing relies mostly on selecting the correct cement slurry to form an effective cement cake or node. We base the decision shall on the injectivity test performed before the squeeze operation.

There are two main controlling variables during squeeze cementing that affect the rate of filtration. These are the fluid loss of the cement slurry and the permeability of the formation or porous media.

a) The higher the cement slurry fluid loss, the higher the amount of cement filtrate available for filtration. The fluid loss of the cement slurry is a property of the slurry that we can modify with chemicals (cement additives).

b) The higher the injectivity rate, the higher the volume of cement filtrate that the permeable media will be able to receive. Before every squeeze cementing operation, we always perform an injectivity test. This injectivity is directly proportional to the effective permeability from Darcy’s Law.

If we combine (a) and (b):

  1. High fluid loss + High Injectivity = very high rate of filtration = premature plugging. Not recommended.
  2. Medium/Low fluid loss + Medium/High Injectivity = rate of filtration controlled by cement slurry fluid loss. A margin for squeeze pressure.
  3. Medium/High fluid loss + Medium/Low injectivity = rate of filtration controlled by the permeable media. A margin for squeeze pressure.
  4. Low fluid loss + Low injectivity = very low rate of filtration = long operation. Not recommended.

2. and 3. are common scenarios for squeeze cementing with conventional slurries system, while 1. and 4. may require non-conventional slurries types or additional chemicals/materials.

More details in following posts.

 

L. Diaz

Related posts:

  1. Workover Cementing Techniques. (1) The Injectivity test
  2. Cement Slurry Laboratory Testing
  3. Suicide Squeeze Cementing: risky but valid
  4. Workover Cementing Techniques. (2) Squeeze Cementing

Filed Under: Laboratory, Remedial Cementing

Article Posted By:

Lenin Diaz is an oil industry specialist with 24 years of technical and operational expertise in fluids, cementing, water control and shut-off. A distinguished track record spanning BP, Schlumberger, and NAPESCO. Lenin lives in Tenerife, Spain and is the creator of this website. Read More…

Reader Interactions

Comments

  1. Lenin Diaz says

    June 21, 2016 at 4:29 am

    What is this groups experience with micro-fine “Matrix” cement for squeeze jobs? Is it worth the considerable additional cost, in your opinion?

    Reply
    • Lenin Diaz says

      June 21, 2016 at 5:03 am

      This was a nice question posted on linkedin group Oilfield cementing Professionals.
      These micro-cement slurries do not work on the principle I described and based on FL/filtration/filter cake/node formation. In consequence, these cement slurries have a potential application in any case where the cement slurry filtration process is not practical.
      I am of the opinion that micro-cement cement (performance will vary on particle distribution and average particle size) has an application in medium injectivity and low MASP (max. allowable surface pressure). Just to give you numbers, injectivity of 1 bpm or less and MASP of less than 1000 psi. Apart from that, a conventional slurry would do just fine.
      There is another potential application for injectivity lower than 0.5 bpm and high squeeze pressure (> 5000 psi). However in this case, knowing that to get penetration the slurry needs to displace the fluid already there, the additional friction caused by the cement slurry in addition the low injectivity would not likely permit sufficient penetration for an effective seal. It is my opinion that in this case a conventional cement slurry with medium FL (aprox. 150 to 250 ml/30min) would perform better … because it will be cement filtrate displacing the fluid in place.

      Reply
      • Kedar Sapte says

        January 17, 2017 at 2:42 pm

        Can we also say that micro-matrix cement usage shall depend on the economic factors such as purpose of squeeze and the ultimate monetary advantages of its use in special cases?

        Reply
        • Lenin Diaz says

          January 18, 2017 at 12:54 pm

          Kedar, thanks for your question. It is actually a very interesting one. Economics of remedial cementing is a tricky one, particularly if we consider new or old wells. For new wells the objective is to stop the NPT and save cost and in most cases the use of costly cement, like micro-matrix, is just a fraction of the rig time cost. In work-over, I think economics makes more sense and the use of costly cement slurries can only be justified if technically the best choice, but as you know in economics you need as well to consider the probability of not being successful in one attempt

          Reply
  2. Kedar Sapte says

    January 17, 2017 at 2:43 pm

    One more question…a rather late one….but what are the typical ranges for ‘low, medium and high’ injectivities?
    Thanks.

    Reply
    • Lenin Diaz says

      January 18, 2017 at 1:19 pm

      I developed for a field application the following flowchart some time ago. Please let me know if this helps.

      Reply
      • Kedar Sapte says

        January 30, 2017 at 6:00 am

        Thanks a lot. That was very helpful.

        Reply
      • Mohammed says

        October 6, 2019 at 9:47 am

        How Can prevent cement pluging in tubing with 200 ml/30cc

        Reply
        • Lenin Diaz says

          October 21, 2019 at 11:32 am

          Hi Mohammed, a fluid loss of 200 ml/30 min will not plug tubing or DP, but it might plug a CT which requires a max. FL of 110 ml/30min (depending on CT size)

          Cheers
          L. Diaz

          Reply
      • wellsolution says

        November 8, 2020 at 8:25 am

        please check the value of filtrate in the diagram of standard low injectivity and standard hi inj

        Reply
        • Lenin Diaz says

          November 8, 2020 at 1:11 pm

          Hi, the values provided are referential and could vary (actually they must be adjusted) for different locations (considering CT or DP deployment). Can you please share your experience ?
          Thanks
          Cheers
          L. Diaz

          Reply
  3. Thirayu Khumtong says

    January 22, 2017 at 5:24 am

    Dear Lenin Diaz, please advice regarding the right and side of the flow chart,
    1. So generally, if injectivity test result is > 3.5 bpm, can we assume that we have loss? and Thixotropic cement is neeeded?
    2. Compare between middle and on the righ where injectivity is 2.5 and 3.5 bpm, I think if injectivity is higher, the filtration rate should be lersser.

    Please advice.

    Reply
    • Lenin Diaz says

      January 24, 2017 at 12:08 pm

      Dear Thirayu, thanks a lot for your comment and for visiting my website. As I always mention I am here to help you achieving your well cementing goals.

      Now regarding point No. 1. If injectivity is as high as 3.5 bpm we are likely in a losses situation if we consider our objective is to perform a cement squeeze. My prefer way to deal with this is to use, if available, a low-density high performance cement slurry. i.e., cenospheres or a foam/nitrogen based system combining low density and high solid content to reduce the hydrostatic head during placement and have more control over the squeeze process.

      With a thixotropic cement, we are targeting an increase in friction pressure with a gel strength developing at low rates to static conditions, however thixotropic slurries density to have good characteristics are around 14 ppg which in most cases would not allow the gel strength to develop as quickly as needed in actual conditions.

      For point No. 2, as I explained in the post. High injectivity + High rate of filtration can lead to premature plugging. That is mainly valid for rates up to 2.5 rpm, but for higher injection rates up to 3.5 pm the plugging affect can be beneficial to help achieve the objective of the cement squeeze.

      Cheers
      L. Diaz

      Reply
  4. Brian says

    December 21, 2017 at 2:50 pm

    Having issues with cement retainers “washing out”. The zones are on a high vacuum and suck the tubing dry in s matter of seconds. Is there something we could pump prior to cement to slow the vacuum

    Reply
    • Lenin Diaz says

      January 28, 2018 at 1:10 pm

      Hi Brian
      Thanks for your comment. That is certainly a big issue in Low Pressure Wells or when there are total losses.
      In some parts, Shutting off intervals in Low pressure wells (Fluid level almost half way the available column) produced several solutions, they included a combination or stand alone application of nitrified fluids, modified cement slurries, a form of DOBC slurry, gels and LCM. I believe the more successful involved creating a network of LCM able to act as a filter lowering the injectivity only enough to allow filtration rather than losses.

      Cheers
      L. Diaz

      Reply
  5. Matthias Koenig says

    November 12, 2018 at 6:19 pm

    Hey Lenin!

    Good seeing you again :o) I never knew you were running this EXCELLENT webpage, but now since I’ve found let me fire away my questions:

    So we often discussed to adjust FL in order to handle different injectivities. Under what circumstances though would you modify the cement viscosity? Like if I had a very high injectivity zone, could I not leave FL but increase viscosity? Certainly not when doing a CT squeeze, but when doing a P&A operation maybe?

    Looking forward to hearing back from you,

    Cheers,
    Matt

    Reply
    • Lenin Diaz says

      November 13, 2018 at 1:03 pm

      Hi Matthias
      So great to know from you, hope all is going well !
      Please let the team know that I am surely missing our talks and work together
      And as I remember, you always asking the right question … this one is a good example
      Please keep in mind, that during squeeze we are forcing the cement filtrate (liquid phase in the cement slurry) out, and along with any liquid ahead, through a porous media (Cement Filter cake and Formation). This is why there is relationship between cement fluid loss and permeability (as related to injectivity).
      As described by Darcy’s Law viscosity plays a role (inversely proportional). In this case the viscosity of the cement filtrate.
      However, if there is very high injectivity, as you mention, and the gap is in the form of fractures big enough to allow cement slurry flow through. Then certainly a way to take advantage of the friction pressure inside the flow path is to increase the viscosity of the cementing fluids. For example, in Low Pressure wells / depleted, viscosity of the cement slurry and the fluids ahead (like gels) was a key parameter to retain some cement in the wellbore. A measure of the required viscosity (friction pressure) can be derived from the fluid level in static condition and the required pumping rate to get returns, while pumping high viscosity pills.

      Thanks for the contact and please do let me know if I can be of further support.

      Cheers
      L. Diaz

      Reply
  6. Mohammed Alkhamis says

    February 5, 2019 at 5:29 pm

    Dear Lenin Diaz, please advice regarding injectivity measurements,

    I am trying to define injectivity factor for remedial jobs. I built a setup consists of 2 ft tube (changeable to vary the diameter) and I am planning to inject cement in the tube at a constant flow rate (.25 ml/min, 1 ml/min) and record the pressures. Then I will inject different types of sealants in the tube. the main goal as I mentioned to have a reference for selecting sealant type based on injectivity factor. Do you think this is a good idea? Am I missing something important? Do I need to add fluid loss additives to the slurry?

    Thank you so much this is a great page.
    Please feel free to email me regarding my questions or if you think we can cooperate in this project.

    Reply
    • Lenin Diaz says

      February 8, 2019 at 11:58 am

      Hi Mohammed, thanks for reading my site and for your question.
      I would like to ask you first a few questions by email to better understand the context of your experimental setup.
      Cheers
      L. Diaz

      Reply
      • Lenin Diaz says

        February 21, 2019 at 2:45 pm

        Hi Mohammed,

        Following our email convesation.

        For the initial pipe setup, you will be measuring friction pressure in the pipe Vs rate. You might need to measure the position of the cement interface as it moves from the start towards the end of the pipe. Now considering the cement slurry as a suspension of particles, the slurry depending of its stability (referred to how close the slurry could behave like a homogenous liquid) and the magnitude of the friction pressure (as related to the pipe diameter and length), it would behave like a liquid (as dictated by its rheology features and flow model) until the additional friction pressure could cause the slurry to destabilize leading to the solid particles to coalesce creating internal resistance forcing the liquid phase to “filter” (like a porous media). This process might ultimately plug the pipe.
        The reason I am mentioning all this, it is an introduction to answer your question about fluid loss additive … basically this chemical would delay and make more difficult to destabilize the cement slurry. The fluid control additive increase internal adhesion and more difficult for the cement slurry to “self-filter”. Cement filtrate of the slurry could be as high as 1500 ml/30 min to <30 ml/30 min. The higher the sooner a pipe could get plugged.
        The addition of fluid loss control would also lower the plastic viscosity of the slurry, lowering your injection pressure.

        Best of luck with your experiment and in case you need any further help, please let me know

        Cheers
        L. Diaz

        Reply
  7. ragi says

    April 30, 2020 at 7:30 am

    I have a casing leak but injectivity test shows 100l with 100bar drops to 30 bar in 30 min. Is it low permeable or medium. Do anyone have injectivity standards for casing remedial cementing jobs.

    Reply
    • Lenin Diaz says

      April 30, 2020 at 3:47 pm

      Hi Ragi,
      Yes, it is low injectivity, more than that it is practically a leak. Injectivity properly implies there is a pumping rate of injection with a stable pump pressure. In your case, there is no practical sufficiently low pumping rate, so MASP is reached, pumping is shut down and leak follows. In some cases, they can eventually plug by themselves in time and it might not be possible to squeeze cement due to the difficulties to form a node.
      Cheers
      L. Diaz

      Reply
  8. Dyne Bonono says

    May 12, 2020 at 11:33 am

    Hi do you have formal references that I can use? Im a Petroleum Engineering student and is researching for references regarding squeeze cementing and the principles behind.

    Thank you.

    Reply
    • Lenin Diaz says

      May 20, 2020 at 12:55 am

      Hi Dyne, the best reference in well cementing is the Nelson book, not only because of its well-written content but also because of the tons of references included.

      Hope this helps
      L. Diaz

      Reply
  9. Dhiya Jozef says

    August 14, 2020 at 2:08 am

    Hi Lenin,

    There is a little confusion I got when read articles related to squeeze cementing, and it was about the reason behind the squeeze. Is it to establish a hydraulic seal or form cement cake / node? As per my knowledge there is a difference between the node and hydraulic seal?

    Thanks in advacne!

    Reply
    • Lenin Diaz says

      August 14, 2020 at 11:01 pm

      Hi Dhiya, Certainly there is a different. Forming nodes (in the context of squeeze cementing) doesn’t necessarily mean a seal is in place, but stablishing hydraulic seal (in the context of squeeze cementing = preventing communication between casing and formation, and vice versa, and across permeable zones) requires the creation of nodes thru filtration, if the process is completed. Refer to hesitation squeeze, in every step the permeability (fluid injection) is reduced progressively while filtration continues thru leak path where nodes are created.

      Any questions, please let me know
      Cheers
      L. Diaz

      Reply
  10. Virnando Batu says

    October 10, 2020 at 7:44 am

    Hai Mr. Lenin

    Do you have any reference to calculate volume of cement for squeeze operation?
    Is it calculate based on porosity?
    Sorry i am new in cementing
    Thank you for your help

    Reply
  11. Virnando Batu says

    October 11, 2020 at 12:36 pm

    Hi Mr. Lenin

    I’d like to ask about how to calculate volume cement for squeeze operation to plug perforation hole
    Do you have any tips for calculate the volume

    Thank you for your help
    Regards,
    Virnando

    Reply
    • Lenin Diaz says

      October 18, 2020 at 11:00 am

      Hi Virnando, thanks for your question and interest in well cementing.
      How the volume in a squeeze operation is estimated depends of several factors, starting with the placement and pumping method. For example: using a retainer or a packer; or cement plug and squeeze. For plug and squeeze, typically for low pressure squeeze (below fracture gradient), the total volume is the cement plug volume (from base to top of access path perforation or leak) + extra volume to squeeze (top of access path perforation or leak to TOC). The extra volume to squeeze depends basically on available space (like in CT placement), injectivity rate (low to very low would require less as compared to medium injectivity requiring more) and finally it would also depend, if perforations are present, on density and size of perforations. For this last, there is theory of perforation fill up (I will soon publish and make available an excel sheet) that can be used to estimate the volume of cement slurry required to filtrate and form nodes.
      For high injectivity, using tools, for example, flow behind casing, the injection test can help to determine the volume of voids behind casing. The concept is to pump a viscous fluid that creates a measurable injection pressure increase when it reaches the formation face. Monitoring the volume pumped when the pressure increase is observed provides an estimate of the void volume.
      Please let me know if you need more details
      Cheers
      L. Diaz

      Reply
    • Lenin Diaz says

      October 18, 2020 at 11:00 am

      Hi Virnando, thanks for your question and interest in well cementing.
      How the volume in a squeeze operation is estimated depends of several factors, starting with the placement and pumping method. For example: using a retainer or a packer; or cement plug and squeeze. For plug and squeeze, typically for low pressure squeeze (below fracture gradient), the total volume is the cement plug volume (from base to top of access path perforation or leak) + extra volume to squeeze (top of access path perforation or leak to TOC). The extra volume to squeeze depends basically on available space (like in CT placement), injectivity rate (low to very low would require less as compared to medium injectivity requiring more) and finally it would also depend, if perforations are present, on density and size of perforations. For this last, there is theory of perforation fill up (I will soon publish and make available an excel sheet) that can be used to estimate the volume of cement slurry required to filtrate and form nodes.
      For high injectivity, using tools, for example, flow behind casing, the injection test can help to determine the volume of voids behind casing. The concept is to pump a viscous fluid that creates a measurable injection pressure increase when it reaches the formation face. Monitoring the volume pumped when the pressure increase is observed provides an estimate of the void volume.
      Cheers,
      L. Diaz

      Reply

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