Page 317 - Practical Well Planning and Drilling Manual

Section 2 revised 11/00/bc 1/17/01 12:04 PM Page 293

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2.9

Drilling Problems--
Avoidance Planning

Many well plans seemed to be designed to get the rig into trouble.
This section will look at borehole stability, losses, stuck pipe, etc., from
the viewpoint of planning to avoid the problem or to mitigate the effect
of it if it occurs.

2.9.1. Wellbore Stability

The following information comes from personal experience and
from interesting lunches and E-mails with knowledgeable industry fig-
ures, especially Dr. Fersheed Mody of Baroid and Dr. Eric van Oort of
Shell. Some of the following is based on a presentation by Dr. Mody at
the AADE-Houston Chapter Drilling Fluids Conference and Exhibition.
Every drilling program should be written with wellbore stability in
mind. An understanding of the mechanisms, which cause and acceler-
ate instability leading to knowledge of what can be done to avoid it, is
essential for all drilling engineers.
Shale comprises over 75% of drilled rock and causes over 90% of
wellbore instability problems, ranging from washout to complete col-

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