Measurement While Drilling (MWD) Signal Analysis, Optimization and Design

382 Pages·2014·7.56 MB·English

by  Wilson C. Chin

Measurement While Drilling (MWD)
Signal Analysis, Optimization
and Design
Scrivener Publishing
100 Cummings Center, Suite 541J
Beverly, MA 01915-6106
Publishers at Scrivener
Martin Scrivener ([email protected])
Phillip Carmical ([email protected])
Measurement While
Drilling (MWD) Signal
Analysis, Optimization
and Design
by
Wilson C. Chin, Ph.D., M.I.T.
Stratamagnetic Soft ware, LLC, Houston, Texas
Yinao Su, Limin Sheng, Lin Li,
Hailong Bian and Rong Shi
China National Petroleum Corporation
(CNPC), Beijing, China
Copyright © 2014 by Scrivener Publishing LLC. All rights reserved.
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Cover design by Kris Hackerott
Library of Congr ess Cataloging-in-Publication Data:
ISBN 978-1-118-83168-7
Printed in the United States of America
10 9 8 7 6 5 4 3 2 1
Contents
Opening Message xiii
Preface xv
Acknowledgements xix
1 Stories from the Field, Fundamental Questions and Solutions 1
1.1 Mysteries, Clues and Possibilities 1
1.2 Paper No. AADE-11-NTCE-74, “High-Data-Rate
Measurement-While-Drilling System for Very Deep
Wells,” updated 10
1.2.1 Abstract 10
1.2.2 Introduction 10
1.2.3 MWD telemetry basis 12
1.2.4 New telemetry approach 13
1.2.5 New technology elements 15
1.2.5.1 Downhole source and signal optimization 15
1.2.5.2 Surface signal processing and noise
removal 18
1.2.5.3 Pressure, torque and erosion computer
modeling 19
1.2.5.4 Wind tunnel analysis: studying
new approaches 22
1.2.5.5 Example test results 41
1.2.6 Conclusions 44
1.2.7 Acknowledgements 45
1.2.8 References 45
1.3 References 46
v
vi Contents
2 Harmonic Analysis: Six-Segment Downhole Acoustic
Waveguide 47
2.1 MWD Fundamentals 48
2.2 MWD Telemetry Concepts Re-examined 49
2.2.1 Conventional pulser ideas explained 49
2.2.2 Acoustics at higher data rates 50
2.2.3 High-data-rate continuous wave telemetry 52
2.2.4 Drillbit as a refl ector 53
2.2.5 Source modeling subtleties and errors 54
2.2.6 Flow loop and fi eld test subtleties 56
2.2.7 Wind tunnel testing comments 58
2.3 Downhole Wave Propagation Subtleties 58
2.3.1 Th ree distinct physical problems 59
2.3.2 Downhole source problem 60
2.4 Six-Segment Downhole Waveguide Model 62
2.4.1 Nomenclature 64
2.4.2 Mathematical formulation 66
2.4.2.1 Dipole source, drill collar modeling 66
2.4.2.2 Harmonic analysis 68
2.4.2.3 Governing partial diff erential equations 69
2.4.2.4 Matching conditions at impedance junctions 71
2.4.2.5 Matrix formulation 72
2.4.2.6 Matrix inversion 74
2.4.2.7 Final data analysis 75
2.5 An Example: Optimizing Pulser Signal Strength 77
2.5.1 Problem defi nition and results 77
2.5.2 User interface 80
2.5.3 Constructive interference at high frequencies 81
2.6 Additional Engineering Conclusions 83
2.7 References 85
3 Harmonic Analysis: Elementary Pipe and Collar Models 86
3.1 Constant area drillpipe wave models 86
3.1.1 Case (a), infi nite system, both directions 87
3.1.2 Case (b), drillbit as a solid refl ector 88
3.1.3 Case (c), drillbit as open-ended refl ector 88
3.1.4 Case (d), “fi nite-fi nite” waveguide of length 2L 89
3.1.5 Physical Interpretation 89
Contents vii
3.2 Variable area collar-pipe wave models 92
3.2.1 Mathematical formulation 92
3.2.2 Example calculations 94
3.3 References 96
4 Transient Constant Area Surface and Downhole Wave Models 97
4.1 Method 4-1. Upgoing wave refl ection at solid boundary,
single transducer deconvolution using delay equation,
no mud pump noise 99
4.1.1 Physical problem 99
4.1.2 Th eory 100
4.1.3 Run 1. Wide signal – low data rate 101
4.1.4 Run 2. Narrow pulse width – high data rate 103
4.1.5 Run 3. Phase-shift keying or PSK 104
4.1.6 Runs 4, 5. Phase-shift keying or PSK, very high
data rate 107
4.2 Method 4-2. Upgoing wave refl ection at solid boundary,
single transducer deconvolution using delay equation,
with mud pump noise 108
4.2.1 Physical Problem 108
4.2.2 Soft ware note 109
4.2.3 Th eory 109
4.2.4 Run 1. 12 Hz PSK, plus pump noise with S/N = 0.25 110
4.2.5 Run 2. 24 Hz PSK, plus pump noise with S/N = 0.25 111
4.3 Method 4-3. Directional fi ltering – diff erence equation
method requiring two transducers 112
4.3.1 Physical problem 112
4.3.2 Th eory 113
4.3.3 Run 1. Single narrow pulse, S/N = 1, approximately 114
4.3.4 Run 2. Very noisy environment 116
4.3.5 Run 3. Very, very noisy environment 117
4.3.6 Run 4. Very, very, very noisy environment 118
4.3.7 Run 5. Non-periodic background noise 119
4.4 Method 4-4. Directional fi ltering – diff erential equation
method requiring two transducers 120
4.4.1 Physical problem 120
4.4.2 Th eory 121
4.4.3 Run 1. Validation analysis 122
viii Contents
4.4.4 Run 2. A very, very noisy example 124
4.4.5 Note on multiple-transducer methods 125
4.5 Method 4-5. Downhole refl ection and deconvolution at
the bit, waves created by MWD dipole source, bit assumed
as perfect solid refl ector 126
4.5.1 Soft ware note 126
4.5.2 Physical problem 127
4.5.3 On solid and open refl ectors 127
4.5.4 Th eory 128
4.5.5 Run 1. Long, low data rate pulse 130
4.5.6 Run 2. Higher data rate, faster valve action 130
4.5.7 Run 3. PSK example, 12 Hz frequency 131
4.5.8 Run 4. 24 Hz, Coarse sampling time 132
4.6 Method 4-6. Downhole refl ection and deconvolution at
the bit, waves created by MWD dipole source, bit assumed
as perfect open end or zero acoustic pressure refl ector 133
4.6.1 Soft ware note 133
4.6.2 Physical problem 133
4.6.3 Th eory 134
4.6.4 Run 1. Low data rate run 135
4.6.5 Run 2. Higher data rate 136
4.6.6 Run 3. Phase-shift -keying, 12 Hz carrier wave 137
4.6.7 Run 4. Phase-shift -keying, 24 Hz carrier wave 137
4.6.8 Run 5. Phase-shift -keying, 48 Hz carrier 138
4.7 References 139
5 Transient Variable Area Downhole Inverse Models 140
5.1 Method 5-1. Problems with acoustic impedance mismatch
due to collar-drillpipe area discontinuity, with drillbit
assumed as open-end refl ector 142
5.1.1 Physical problem 142
5.1.2 Th eory 143
5.1.3 Run 1. Phase-shift -keying, 12 Hz carrier wave 147
5.1.4 Run 2. Phase-shift -keying, 24 Hz carrier wave 147
5.1.5 Run 3. Phase-shift -keying, 96 Hz carrier wave 148
5.1.6 Run 4. Short rectangular pulse with rounded edges 149