Page 182 - Drilling Technology in Nontechnical Language

8

DIRECTIONAL AND

HORIZONTAL DRILLING

Overview

Directional drilling—the process of accurately guiding a well through

a predefined target or targets—is a source of great interest for many

people outside the drilling industry. This chapter will first give some of the
reasons for drilling directional wells and will look at how the desired well
path is designed. The tools and techniques for deviating the wellbore will
be described. Accurate navigation is a prerequisite to drilling directional
wells, and the navigational tools available to the driller, along with their
advantages and limitations, will be covered. Deviated wells have their own
special problems, which will be examined. Finally, this chapter will discuss
some specifics concerning drilling horizontal and multilateral wells.

Why Drill Directional Wells?

Drilling a deviated well to a target that is not vertically below the rig
location will always cost more than drilling to the same target vertically.

The justification for spending that extra money comes down to the total
cost of achieving the well objectives being lower by drilling a directional
rather than a vertical well. Some of the particular reasons could include
the following:

▪ Single surface location for multiple wells. To effectively drain

a reservoir requires wells flowing from different parts of the
reservoir. If all those wells come together to the same surface
location, all the production facilities can be at that location,
which may be cheaper than connecting wells from many surface
locations. The production staff need only to work on one location,

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