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CHAPTER TWO

Mud Hydraulics Fundamentals

Contents
2.1 Introduction 19
2.2 Characterization of Drilling Mud 19
2.2.1 Drilling Mud Classifications 20
2.2.2 Rheological Models 21
2.2.3 Measurements of Rheological Properties 23
2.3 Hydraulics Models 26
2.3.1 Flow Regimes 27
2.3.2 Pressure Loss 35
2.3.3 Surge and Swab Pressure 49
2.3.4 Pressure Drop at the Bit 52
2.3.5 The Cuttings-Carrying Capacity of Mud 54
Summary 57

2.1 INTRODUCTION

Mud hydraulics is considered one of the most important factors
affecting mud drilling performance. The rate of penetration can be signif-
icantly increased using state-of-the-art techniques for hydraulics optimiza-
tion to minimize drilling operation costs. The goal of the optimization is
to make the maximum usage of a pump’s power to help the bit to drill
at maximum efficiency. This goal is achieved by minimizing the energy
loss due to friction in the circulating system and using the saved energy
to improve bit hydraulics. This chapter provides drilling engineers the
essential fundamentals of mud hydraulics for pump selection (Chapter 3)
and hydraulics optimization (Chapter 4).

2.2 CHARACTERIZATION OF DRILLING MUD

Different types of drilling mud are used in drilling operations based
on their rheological behavior. This section describes the classification,
rheology, and measurements of the properties of drilling mud used in the
oil and gas industries.

Applied Drilling Circulation Systems. DOI: 10.1016/B978-0-12-381957-4.00002-4
© 2011 Elsevier Inc. All rights reserved. 19