During my first years in the industry, I quickly realized the importance of proper planning and preparation before of a cementing operation. For such an important, short and intense task, being ready and organized is the most significant element to safeguard people, the well, equipment and the job objectives.
The following steps are some of the pre-job procedures I used to implement before the cement job. They don’t include, however, all the necessary preventive maintenance and required pre-operational testing of equipment.
- At the pre-job meeting, obtain all pertinent job and well information;
- Verify from records that the cementing head, casing swage, quick coupling and casing swivel have been tested. Check that the thread type is compatible with the casing or that a crossover is available; all equipment for the job must have been green tagged;
- Ensure that all other required equipment and tools to be used are in good workable condition;
- Ensure that there are sufficient sample containers;
- Check to see that all materials required for the job are loaded. Verify that the correct chemicals are used to prepare the mix water, this includes proper batch number for each chemical that will be used, as per the laboratory recipe;
- In all cases, for different blends of cement, every blend and bulk tank should be clearly identified;
- Reviews with the CUSTOMER the following job details.
- Independently calculate the required slurry and displacement volumes, using current well data. The two sets of calculations are compared to make sure all volumes are correct.
- Confirm the displacement fluid, e.g., density, drilling mud or water.
- Calculate the total water requirements and make sure is available.
- Review the maximum differential pressure at the end of the job.
- Verify the BHST and BHCT and check them against the cement-system design.
- Check on the prearranged hole conditioning and final mud density and rheology prior to cementing. Recommend additional mud conditioning if necessary and as per the job design.
- Review the number and sequence of wiper plugs.
- Verify the mixing and displacement rates, the pressure to apply when the plug lands (see Casing Pressure Limits) and how many barrels over the calculated displacement volume will be pumped if the top plug fails to bump as expected.
- Ensure that the suction rates required for the job can be achieved for both mud and water.
- Confirm the reciprocation or rotation of the casing and rate.
- Review with the team the contingency plans during the job (e.g., annulus bridges off, pipe reciprocation becomes impossible, pump failure occurs, reduced mix-water supply rate, etc.).
- Review the procedures for pressure testing the cementing and flushing lines.
- Check the mud volume on location. In case the cement job must be aborted during its execution, enough mud should be available at the surface to circulate the cement slurry out of the well;
- Verify all sensors (density, pressure, rates);
- Check pressurised mud balance for correct operation and calibration;
- Just before pre-job mud circulation is completed and check mud properties;
- Load the wiper plugs into the cementing head;
- Conduct pre-job meeting with all involved personnel. This includes the review of the material mixing and pumping sequence, pump rates, slurry densities, contingency plans, safety hazards during the pumping operation and maximum allowable pressure, name a person designated to monitor returns from the annulus, emergency procedures and escape plans;
- Key personnel should have a brief written description of the step-by-step job sequence.
As a professional cementer, you know the importance of this so if you would like to add more checks or just comments, please feel free to write them in the space below
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Cheers
L. Diaz
Hi Lenin,
Allow me please to add few more…
At the job program finalization:
Check mud properties solid, oil water content wrong data may lead to wrong BHCT
Review casing tally, actual trajectory vs planned
Check for mud compressibility and account for it during displacement.
Define minimum slurry to pump and agree prior starting the job. Cement unit may not be able to continue mixing and decision to displace or circulate out slurry must be taken.
Review mud removal with hole caliper if available.
Define contingency plan for possible QHSE event (general and specific to the job)
Always insure job objectives are define and we’ll understood by all parties and acceptance criteria Wil be met as the job design.
On the field:
Check all tank for mix fluid are properly cleaned
Check chloride content for mix water
Put aside lot number define for the job and confirm 100% Xs of lot number or check that back lot has been tested and can be use may the mix fluid need to be remixed.
Insure the mud pump PRV does not bleed into spacer or mix water pit.
Calibrate pressurized mud ballance (with distilled water)
Double check rig pump efficiency ( rig may displace)
Make sure all silo are pressurized prior the job
Define max cement to send from bulk
Insure all equipment are OK while going through their routine inspection checklist
Clearly define roles for crew members
Prepare in advance recipient to collect mix fluids samples
….
List is clearly not exhaustive
Hi Jean, Thanks for enriching this content with your contribution here. All very valid points for sure, even now the checklist is definetely not exhaustive, but it is getting better. Thanks to you all !
For loading of plugs I would add have plug loading witnessed by company rep. Would also add that equipment, iron certified and ready for job. That 100% back-up is available.
Thanks for your contribution Ben. Indeed, witnessing the plug loading in the cement head is a must.
I personally saw 3 types of human errors when loading plugs.
1) The top plug first (below);
2) Loading the plugs with one of them turned around. Yes, it happen!. It remained inside the cement head;
3) Well, this is not related to loading the plugs, but to dropping them (which needs to be witnessed as well, along with the indicator moving) … Forgetting to drop the plugs (not pulling the pins, just opening the valves).
And you wonder why sometimes we have the so-called “oilfield mysteries” … you already know what they are, don’t you?
Hello, all comments above are quite pertinent, I will also include in the list :
Discuss with the Cement Contractor Representative, the compatibilty tests results, and prepare a contingency plan in case of… .
Before preparing the mixing water( for both spacers and slurries), keep sample also of clear water.
Inspect the vent line and rock catcher on CMT line.
In advance, verify the effect of thinners on drilling mud while circulating to condition mud/hole.
The amount of spacers and slurry additives have to be stored on dedicated pallets per type of fluid to be mixed ( spacer, slurries) .
Have ready on mud pits/shale shakers and corrals, common retardant ( as Sugar, Citric Acid…) and a water hose.
Identify before starting the cement job pumping sequence a dedicated pit/corral to recover the interfaces.
By-pass not essential rig active pits to minimize the effect of potential contamination.
And aslo…..Ensure radio and battery operative!
Regards
Hi Alessandro, This is very helpful contribution here to complement this topic for our readers.
This is a great topic! A few things I can think of to add;
“Dead volumes”, or the volume that is left in a tank once the pump loses prime, is an important consideration when batching up spacer in a rig pit or tank, or when bringing your tanks up to concentration for mix water.
I was taught to always visually verify that your head pins fully retract from the bore of the head, and to count how many turns that takes, to avoid a plug hanging up on a pin after attempting to launch.
While you have the top cap of the head off, take the opportunity to make sure that you and everyone involved understands the position of the indicator when it is set/tripped, and make marks on the outside that correlate.
My career to this point has been exclusively in the arctic, and ice plugs are a common problem. This is why we send rig air down the cement line, all the way to the cement unit before flooding it with any fluid. This avoids unintended pressurizing of the line, and the possibility of freezing off more of the line.
All I’ve got for now.
Cheers!
Hi John, Nice contribution. It is good you mention an important consideration when working in low temperature zones. Blowing the water/fluid out of surface lines or Winterrising is a very importnat step.