Prepared by

Y. MADI

The present document is devised for non

experienced engineers acting in drilling

field engineering.

The course is composed on sequences

related to drilling operations in order to

make hole, to stabilize the wall formations

and to keep under control oil wells.

As the completion of the program, the

engineers will be able to understand:

Well planning

Drill String

Casing design

Cementing job

Wellheads and BOP

Well Control

FOREWORD

WELL PLANNING

Geophysic Studies (Logging) Geology Studies Reserve Estimation

Well Implantation

Well Coordinates

Preparation of the Rig site

PRELIMINARY STUDIES

Well Planning is defined as the drilling program to

drill a well from the rig site to the target. This

program is also called "Architecture". It includes all

operations involved to build the well such as casing,

cementing, well control and safety.

Well Planner Engineers are responsible to elaborate

the drilling program taking into account the cost, the

duration with the respect of the environment.

To perform this task, they need to gather many

informations and work with a team composed by

Geologists, Log engineers, Reservoir engineers,

Production engineers, Drillers, Mud engineers

The main required data is the Lithology that shows

all formations to be drilled from the surface to the

target.

Based on this lithology, the team work is able to:

Identify the nature of formation (sand, clay, sandstone, dolomite.)

Estimate the thickness of layers Estimate the Dip of layers Detect weak zones Presence of undesirable fluids contained in the formation

Detect faults, anticlines..

WELL PLANNING

The total depth to reach the target is required to plan the well path.

The size of the tubing needed to produce the oil is very important data

given by the Production Department.

The drilling program permits to determine

:

The number of drilling sections

The depth of each section

The diameters of bits

The diameters of casings

The type and properties of the drilling

fluid

Based on the oilfield experience, the

drilling program is composed from 3 to 5

sections.

Exploration : sections

Development : 4 sections

WELL PLANNING

Ho

le D

epth

x 1

00

0 f

t

Mud Weight ppg

Casing Formations

CASING PROGRAM

Data

Lithology Total Depth Production diameter

Example : Drilling program

of 4 sections

How to elaborate Well Planning

Start from the last section where the production diameter is given

(known). This diameter is C4 (Casing diameter)

To drill the section, the drilling bit

diameter is D4 (Drilling diameter)

J1 J1

4th Section

Clearance

D4

C4

Clearance

J1 : Clearance between the bit

diameter and the outside diameter

casing in the same section.

This clearance vary from 11/2 to 4"

J2 : Clearance between the inside

diameter casing and the bit diameter

for the next section. The minimum

clearance may be :

1/8 " casings 41/2 to 85/8

5/32 " casings 95/8 to 133/8

3/16 " casings 16" to 20"

D4 = C4 + 2 J1

3rd Section :

ic3 = D4 + 2 J2 where :

ic3 inside diameter casing

ec3 = ic3 + 2 e where

e : outside diameter casing

and

e : wall thickness of the

casing

D4= ec3 + 2 J1

J1 J1

J2 J2

4th Section

3rd Section

2nd Section :

iC2 = D3 + 2 J2

eC2 = iC2 + 2 e

D2 = eC2 + 2 J1

J1 J1

J1

J1

J1

J1

J2 J2

J2 J2

4th

section

3rd

section

2nd

section

1st section :

iC1 = D2 + 2 J2

eC1 = iC1 + 2 e

D1 = eC1 + 2 J1

Well Planning

Drilling Casing Depth (ft)

26" 185/8 1200

16" 133/8 4500

121/4 95/8 8700

81/2 7'' 13500

6" 41/2 15200

Example of Well

Planning

18"5/8 Casing shoe @ 464m

26" Hole @ 465m

13 3/8 " Casing Shoe @ 2392m

16" Hole @ 2393m

9 5/8 " Casing Shoe @ 3345m 121/4" Hole @ 3346m

7" Casing Shoe @ 3404m K.O.P @ 3060m

8 3/8" Hole @ 3405m

6" O-Hole

Drilling / Casing Program

Surface Casing

Intermediate

Casing

Intermediate

Casing

Production

Casing

Drilling Casing Cement