Page 316 - Practical Well Planning and Drilling Manual

Section 2 revised 11/00/bc 1/17/01 12:04 PM Page 292

[ ] Well Programming
2.8.3

Cuttings testing. Visually examine the cuttings and cavings samples
taken by the mud loggers. Look for evidence of avoidable problems and
discuss mud treatment alternatives with the drilling supervisor before
taking action. If a test kit is available, carry out extrusion tests and/or
dispersion tests to check on mud inhibition performance.
Cavings sampling. Cavings give valuable information to optimize
mud properties and drilling practices. Analyzed after the well, they
allow better optimization of the drilling program for the next well.
While circulating with returns to surface, measure the amount of
cavings in lbs/hr coming over the shakers, estimated from a represen-
tative sample gathered from one of the shakers over a 5-minute period.
Preserve a part of the sample for later examination in the same manner
as for the washed and dried cuttings.
Note a basic description for each sample of cavings: average length
in inches, shape (e.g., splintery, blocky, evidence of rounding in the
wellbore, angular, curved), and evidence of natural fractures (e.g., car-
bonate-filled veins, clear fracture faces visible). If two distinct types of
cavings are present, estimate percentage of the total for each and give
separate descriptions. Make note of whether the source formation can
be identified by microscope examination and comparison with earlier
cuttings samples. Inform the drilling supervisor of any significant
change to the amount or appearance of cavings.
Preservation of shale formation samples for drilling department shale
analysis. Oven drying samples has a great effect on the reactivity to
drilling muds, which will affect analyses to be done in the lab. For
shale samples (cuttings and cavings) required for shale analysis, rinse
the samples in the base brine of the mud (mud liquid phase), then blot
dry. Loosely fill an airtight jar, label with date and time of sampling,
and bit depth. Store in a cool place until transporting it to the lab.
Avoid rough handling.

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