Page 428 - Practical Well Planning and Drilling Manual

Section 3 revised 11/00/bc 1/17/01 12:00 PM Page 404

[ ] Practical Wellsite Operations
3.5.6

3. Where tank space permits, make up the mix water in advance (but
no more than 12 hours early). Run a pilot test using this mix water
and the cement (blended first if necessary) to check that the pro-
grammed pumpable time is close to that seen on your pilot test.
Use an oven to heat up the samples in a covered container, but do
not let the sample boil since this will reduce water content and
seriously affect the thickening time.
4. Ensure samples are taken of the neat mix water, mix fluid (with
additives added), spacer(s), (blended) cement, other additives, and
mud in the hole. Seal, label, put in a safe place, and keep until the
next cement job in case of later queries.
5. Take density readings of the mud with both atmospheric and pres-
surized balances on the final circulation prior to cementing. Any
difference due to aeration will affect displacement efficiency.
Consider running the degasser while circulating prior to the job.
6. Condition the mud in advance to lowest practical PV, YP, and gels.
At the end of a hole section prior to running casing, having the
mud in good shape will improve cement displacement, reduce
surge pressures, and improve the chances of successfully cement-
ing in an enlarged hole.
7. Write out your program for the job; check your calculations against
the cementers. Pass your program on to the cementer for comment.
No changes are to be made to the program issued from the drilling
office without consultation with the duty drilling manager.

During the job.

1. Follow your preplanned program during the job as closely as pos-
sible; avoid making changes “on the job” except where necessary
to meet unforeseen events.
2. Use the batch mixer for quantities of slurry above the capacity of
the recirculating mixer, and within the capacity of the batch tank
for critical slurries (small cement plugs, tail slurries).
3. When using the recirculating mixer tank to batch mix very small
slurry quantities (coiled tubing plugs, etc.), control the speed of
adding cement by restricting the cement line. This should ensure
that the correct density is obtained and avoid large slugs of cement
powder entering the mixer and only partially hydrating.

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