1. 2014
Drilling Bit Selection
By
Karim Ahmed Shawky
Presented to :Dr: Taher El Faherny
A Dissertation Submitted to the Faculty of Engineering. The British University in Egypt.
In partial
Fulfillment of
The Requirements for the Bachelor Degree in petroleum engineering
June 2014

2. 2014
Drilling Bit Selection
Dissertation Approved:
Dr. Taher El Faherny
Dissertation Adviser
Committee Member Name Here
Committee Member Name Here
Dean Faculty of Engineering

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2014
Declaration of Originality
This is to certify that the work is completely my own and not of any other person,
unless explicitly acknowledged ( Including citation of published and unpublished
sources).
The work has not previously been submitted in any form to the British University
in Egypt or to any other institution for assessment for any purpose.
Signed: Karim Ahmed Shwaky
Date: 17 of June 2014

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Acknowledgements
I would like to express my sincere appreciation to my advisor, Dr.Taher El Fahareny, at the
Department of Petroleum Engineering at The British University in Egypt (BUE) for his
continuous technical and mental support as well as insights toward the completion of this work.
Undoubtedly, this work could not be possibly completed without such help.
I would especially like to thank Eng: Mohmoud Fathy for their generous support, coaching and
companionship during my Research Project shared their expertise with me very generously and I
have learned a lot from him. My thanks and appreciation also to (BUE) staff for willing to help
us, and above all to your good companionship.
My special thanks go to all my family members particularly, my parents for their unconditional
support, prayers, and love.
Karim Ahmed Shawky Mohmed , June 2014
Abstract
The drill bit represents the core of the drilling operation. The drill bit cut the rock by crushing
and gauging the cutting up to the annulus. The proper design for drill bit saves time and cost of
drilling the well. The drill bit may be rock bit or roller cone bit. Rock bit cut rock by shearing
action while the roller cone bit cut rock by gouging and scraping action. Selection of drill bit is

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affected by various criteria such as formation type, formation strength, cost per foot, and section
to be drilled (footage).
The design of drill bit includes:
- The design for the bit body
- The cutter structure and density
- The design of special feature such as back ream cutters in PDC bit
To have an effective rate of penetration using drill bit, bit hydraulics must be optimized for
effective rate of penetration using:
- Maximum hydraulic horse force
- Maximum impact force
Then the selection of proper nozzles sizes that achieve the hydraulic optimization is calculated
from the hydraulics.
Drill bit plays an important role in rate of penetration through two criteria; maximum hydraulic
horse power and maximum impact force. Optimization in these two criterions will give a
relationship between surface pressure Ps and Pbit that will enhance rate of penetration and hole
cleaning.
After drill bit has been used, bit dullness is performed to diagnose the condition of bit and
analyze the wear in the drill bit. Bit dullness is consisted of eight characters that represent the
overall condition of the bit.
Many factors in drilling operation will affect rate of penetration such as hole cleaning issues,
flow rate, hole deviation, drilling practices, drill bit type….etc.
Drill bit type, features will affect ROP as using the proper type of the bit and suitable features
that will increase bit life and bit efficiency. The drill is a bio-link in drilling cost estimation sheet
as the selection of the proper bit can save time and cost for the operator company.