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CHAPTER FOUR

Mud Hydraulics Optimization

Contents
4.1 Introduction 81
4.2 The Criteria of Hydraulics Optimization 81
4.2.1 The Maximum Bit Hydraulic Horsepower Criterion 82
4.2.2 The Maximum Jet Impact Force Criterion 83
4.2.3 The Maximum Nozzle Velocity Criterion 84
4.2.4 Bit Hydraulics 84
4.2.5 Economical Bit Hydraulics 85
4.3 The Optimum Design of a Hydraulics Program 86
4.3.1 Selecting the Liner Size 86
4.3.2 Selecting the Flow Rate and the Bit Nozzle Size 89
4.3.3 Application Examples 91
4.3.4 Analyzing Trip Operations 98
Summary 104

4.1 INTRODUCTION
Drilling hydraulics is considered the most important factor in drilling
performance. The rate of penetration can be significantly increased using state-
of-the-art techniques for hydraulics optimization to minimize drilling cost. The
goal of the optimization is to make the maximum usage of the pump’spowerto
help the bit to drill at maximum efficiency. This is achieved by minimizing the
energy loss due to friction in the circulating system and use the saved energy to
improve bit hydraulics. Starting with fluid rheology basics, this chapter provides
drilling engineers with a practical approach to optimizing drilling hydraulics.

4.2 THE CRITERIA OF HYDRAULICS OPTIMIZATION

An operator’s primary concern with drilling fluid hydraulics is achieving
adequate hole cleaning below the bit. This is important for the following reasons:
• The rate of penetration (ROP) depends on hole cleaning below the bit.
• Some bits can be damaged due to overheating if cuttings accumulate
below them.

Applied Drilling Circulation Systems. DOI: 10.1016/B978-0-12-381957-4.00004-8
© 2011 Elsevier Inc. All rights reserved. 81