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PETE 411

Well Drilling

Lesson 33

Directional Drilling

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Directional Drilling

When is it used?

Type I Wells

Type II Wells

Type III Wells

Directional Well Planning & Design

Survey Calculation Methods

Build and Hold

Build-Hold and Drop

ContinuousBuild

KOP

EOC

I II III

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Read ADE Ch.8 (Reference)

HW #17 due 11-27-02HW #18 due 12-06-02

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Inclination Angle, I

Direction Angle, A

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6

Max.Horiz.

Depart.?

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8

9

10

11

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Type I Type II Type III

Build and Hold

Build-Hold and Drop

ContinuousBuild

KOP

EOC

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x

y

I

I

r

rL

In the BUILDSection

x = r (1 - cos I)

y = r sin I

L = r rad

degI r180

= L

BUR*

000,18r

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Fig. 8.11

42131 xrr and xr

1642131 xrr and xr

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N18E

N55WS20W

S23E

Azimuth

Angle

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Example 1: Design of Directional Well

Design a directional well with the following restrictions:

• Total horizontal departure = 4,500 ft

• True vertical depth (TVD) = 12,500 ft

• Depth to kickoff point (KOP) = 2,500 ft

• Rate of build of hole angle = 1.5 deg/100 ft

• Type I well (build and hold)

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Example 1: Design of Directional Well

(i) What is the maximum hole angle required.

(ii) What is the total measured depth (MD)?

(MD = well depth measured along the wellbore,

not the vertical depth)

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(i) Maximum Inclination

Angle

ft820,35.1

000,18r1

0r2

ft000,10

500,2500,12

DD 14

ft500,4x4

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(i) Maximum Inclination Angle

500,4)820,3(2

500,4)820,3(2000,10500,4000,10tan 2

221-

3.26max

421

4212

1424141

max x)rr(2

x)rr(2)DD(xDDtan2

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(ii) Measured Depth of Well

ft 395

)26.3 cos-3,820(1

)cos1(rx 1Build

ft 4,105

395500,4xHold

ft 265,9L

105,4sinL

Hold

Hold

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(ii) Measured Depth of Well

Holdrad11 LrDMD

ft 518,13MD

265,9180

26.33,8202,500

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* The actual well path hardly ever coincides with the planned trajectory

* Important: Hit target within specified radius

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What is known?I1 , I2 , A1 , A2 ,

L=MD1-2

Calculate = dogleg angle

DLS =L

DLS = dogleg severity

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