# Directional Drilling

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Petroleum Engineering 406
Lesson 18
Directional Drilling

Lesson 10 - Directional Drilling
4 When is it used?
4 Type I Wells (build and hold)
4 Ty
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4 Type III Wells (build)
4 Directional Well Planning & Design
4 Survey Calculation Methods

Homework:
Ch. 8, pp. 351-363
REF. API Bulletin D20, “Directional Drilling
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Terminology”

What is Directional Drilling?
Directional Drilling is the process of
directing a wellbore along some trajectory
to a predetermined target.
Basically it refers to drilling in a non-vertical
direction. Even “vertical” hole sometimes
require directional drilling techniques.
Examples: Slanted holes, high angle holes (far from vertical), and Horizontal holes.

Non-Vertical
θ, α
or I
Wellbore
Inclination Angle
Z Axis (True Vertical
Depth)
No
N rth
Direction
Angle

φ, ε
or A
Direction Plane X

Lease Boundary
Surface
Surface Location for Well No. 1
Location for
Well No. 2
Bottom Hole Location for Well 2
Houses
Figure 8.2 - Plan view of a typical oil and gas structure under a lake showing how
directional wells could be used to develop it. Best locations? Drill from lake?

Top View
NOTE: All the
wells are
5 - 50 wells
directional
per p
latform
Figure 8.3 - Typical offshore development platform
with directional wells.

Drilling Rig Inside Building
Figure 8.4 - Developing a field under a city
using directionally drilled wells.

Why not
drill from
Maximum
top of
lateral
mo
m untain?
displ.?
Fig. 8.5 - Drilling of directional wells where the
reservoir is beneath a major surface obstruction.

Fish Lost in Hole and
Cement Plug
Unable to Recover
Si
S detracked H
o
H le
Around Fish
Figure 8.6 -
Sidetracking
around a fish.