Page 181 - Practical Well Planning and Drilling Manual

Section 2 revised 11/00/bc 1/17/01 12:04 PM Page 157

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2.3

Directional Planning

In Section 1, “Well Design,” the various options for planning the
wellpath were covered. It was necessary to do this at the well design
stage rather than the drilling program stage since it impacts the casing
design. Having already defined the surface location, targets, and pre-
ferred wellpath in this section, the drilling program must show how the
wellpath will be drilled to within an acceptable level of positional accu-
racy. Practical directional considerations will be covered in Section 3,
“Practical Wellsite Operations and Reporting.”

2.3.1. Downhole Tools Affecting Directional Control

The fundamental factor controlling directional performance is the
design of the bottom hole assembly. Design in the context of direction-
al drilling means the configuration and spacing of the bit, drill collars,
full-gauge and undergauge supporting tools (stabilizers and roller
reamers), sideforce generating tools (rebel tool and dynamic stabiliz-
er), and downhole motors including turbines that can affect the direc-

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