Page 423 - Practical Well Planning and Drilling Manual

Section 3 revised 11/00/bc 1/17/01 12:00 PM Page 399

Cementing [ ]
3.5.3

3.5.3. Preparation for Cementing

Well before the cement job, calculate the volumes of slurries
required and the materials needed to mix these. Have the cementer do
the same, then compare the calculations and sort out any discrepan-
cies. Check that all the required materials are on site or can be ordered
in time.
The cement recipe needs to be tested in town with samples of mix
water and cement from the rig. Ensure that these are sent to town in
sufficient quantity. When the bottom hole temperature is available
from the logs, check this against the assumed BHST for the slurry
design, and if there is more than 3-4° difference then mention this to
the drilling office on the next call.
About twelve hours before you anticipate the cement job will
start, have the cementer test run the pump and mixing equipment. Do
everything possible to minimize delays on the job once cement is
being mixed. When this has been done (perhaps while the casing is
being run), have a meeting with the cementer, mud technician,
drilling engineer, possibly the toolpusher, and/or any other supervi-
sors involved in the cement job. Talk through the whole program and
encourage suggestions. Then write out a procedure and give a copy to
all the supervisors. This avoids confusion during the job and leaves
you as free as possible to supervise the cementing and sort out prob-
lems as they occur. It is important to delegate tasks to the supervisors
available to you.
Make a final check that the cement plugs, etc. are on the drillfloor
ready to use, stored somewhere safe from accidental damage. Take mud
density readings with both normal and pressure balance; any difference
between the two will be due to mud aeration. You can run the degasser
if necessary to reduce this, since mud aeration will reduce pump volu-
metric efficiency.
If possible, check the volumetric efficiency of the rig pumps by
pumping from the suction tank to another tank and comparing actual
strokes with actual volume pumped (use 50 bbls or more). On a long
casing string, a difference of 0.5% on volumetric efficiency will make a
difference of more than the shoetrack volume over the full casing
capacity. To get the best chance of bumping the plug without risking
over displacement, the true volumetric efficiency of the mud pumps

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