MWD Signal Analysis,
Optimization and Design
Second Edition, 2018
by
Wilson C. Chin, Ph.D., M.I.T.
Stratamagnetic Software, LLC, Houston, Texas
Table of Contents
Preface, xii
Acknowledgements, xv
1. Stories from the Field, Fundamental Questions and Solutions, 1
1.2.1 Abstract, 11
1.2.2 Introduction, 11
1.2.3 MWD telemetry basics, 13
1.2.4 New telemetry approach, 14
1.2.5 New technology elements, 16
1.2.5.1 Downhole source and signal optimization, 16
1.2.5.2 Surface signal processing and noise removal, 19
1.2.5.3 Pressure, torque and erosion computer modeling, 20
1.2.5.4 Wind tunnel analysis: studying new approaches, 23
1.2.5.5 Example test results, 42
1.2.6 Conclusions, 45
1.2.7 Acknowledgements, 46
1.2.8 Credits, 46
1.2.9 Paper references, 47
1.3 References, 48
2. Harmonic Analysis: Six-Segment Downhole Acoustic Waveguide, 49
2.1 MWD Fundamentals, 50
2.2 MWD Telemetry Concepts Re-examined, 51
2.2.1 Conventional pulser ideas explained, 51
2.2.2 Acoustics at higher data rates, 52
2.2.3 High-data-rate continuous wave telemetry, 54
2.2.4 Drillbit as a reflector, 55
2.2.5 Source modeling subtleties and errors, 56
2.2.6 Flow loop and field test subtleties, 58
2.2.7 Wind tunnel testing comments, 60
2.3 Downhole Wave Propagation Subtleties, 60
2.3.1 Three distinct physical problems, 61
2.3.2 Downhole source problem, 62
2.4 Six-Segment Downhole Waveguide Model, 64
2.4.1 Nomenclature, 66
2.4.2 Mathematical formulation, 68
2.4.2.1 Dipole source, drill collar modeling, 68
2.4.2.2 Harmonic analysis, 70
2.4.2.3 Governing partial differential equations, 71
2.4.2.4 Matching conditions at impedance junctions, 73
2.4.2.5 Matrix formulation, 74
2.4.2.6 Matrix inversion, 76
2.4.2.7 Final data analysis, 75
2.5 An Example: Optimizing Pulser Signal Strength, 79
2.5.1 Problem definition and results, 79
2.5.2 User interface, 82
2.5.3 Constructive interference at high frequencies, 83
2.6 Additional Engineering Conclusions, 85
2.7 References, 87
3. Harmonic Analysis: Elementary Pipe and Collar Models, 88
3.1 Constant area drillpipe wave models, 88
3.1.1 Case (a), infinite system, both directions, 89
3.1.2 Case (b), drillbit as a solid reflector, 90
3.1.3 Case (c), drillbit as open-ended reflector, 90
3.1.4 Case (d), "finite-finite" waveguide of length 2L, 91
3.1.5 Physical Interpretation, 91
3.2 Variable area collar-pipe wave models, 94
3.2.1 Mathematical formulation, 94
3.2.2 Example calculations, 96
3.3 References, 98
4. Transient Constant Area Surface and Downhole Wave Models, 97
Overview, 99
4.1 Method 4-1. Upgoing wave reflection at solid boundary,
single transducer deconvolution using delay equation, no
mud pump noise, 101
4.1.1 Physical problem, 101
4.1.2 Theory, 102
4.1.3 Run 1. Wide signal – low data rate, 103
4.1.4 Run 2. Narrow pulse width – high data rate, 105
4.1.5 Run 3. Phase-shift keying or PSK, 106
4.1.6 Runs 4, 5. Phase-shift keying or PSK, very high data rate, 109
4.2 Method 4-2. Upgoing wave reflection at solid boundary,
single transducer deconvolution using delay equation, with
mud pump noise, 110
4.2.1 Physical Problem, 110
4.2.2 Software note, 111
4.2.3 Theory, 111
4.2.4 Run 1. 12 Hz PSK, plus pump noise with S/N = 0.25, 112
4.2.5 Run 2. 24 Hz PSK, plus pump noise with S/N = 0.25, 113
4.3 Method 4-3. Directional filtering – difference equation method
requiring two transducers, 114
4.3.1 Physical problem, 114
4.3.2 Theory, 115
4.3.3 Run 1. Single narrow pulse, S/N = 1, approximately, 116
4.3.4 Run 2. Very noisy environment, 118
4.3.5 Run 3. Very, very noisy environment, 119
4.3.6 Run 4. Very, very, very noisy environment, 120
4.3.7 Run 5. Non-periodic background noise, 121
4.4 Method 4-4. Directional filtering – differential equation
method requiring two transducers, 122
4.4.1 Physical problem, 122
4.4.2 Theory, 123
4.4.3 Run 1. Validation analysis, 124
4.4.4 Run 2. A very, very noisy example, 126
4.4.5 Note on multiple-transducer methods, 127
4.5 Method 4-5. Downhole reflection and deconvolution at
the bit, waves created by MWD dipole source, bit assumed as
perfect solid reflector, 128
4.5.1 Software note, 128
4.5.2 Physical problem, 129
4.5.3 On solid and open reflectors, 129
4.5.4 Theory, 130
4.5.5 Run 1. Long, low data rate pulse, 132
4.5.6 Run 2. Higher data rate, faster valve action, 132
4.5.7 Run 3. PSK example, 12 Hz frequency, 133
4.5.8 Run 4. 24 Hz, Coarse sampling time, 134
4.6 Method 4-6. Downhole reflection and deconvolution at
the bit, waves created by MWD dipole source, bit assumed as
perfect open end or zero acoustic pressure reflector, 135
4.6.1 Software note, 135
4.6.2 Physical problem, 135
4.6.3 Theory, 136
4.6.4 Run 1. Low data rate run, 137
4.6.5 Run 2. Higher data rate, 138
4.6.6 Run 3. Phase-shift-keying, 12 Hz carrier wave, 139
4.6.7 Run 4. Phase-shift-keying, 24 Hz carrier wave, 139
4.6.8 Run 5. Phase-shift-keying, 48 Hz carrier, 140
4.7 References, 141
5. Transient Variable Area Downhole Inverse Models, 142
5.1 Method 5-1. Problems with acoustic impedance mismatch
due to collar-drillpipe area discontinuity, with drillbit
assumed as open-end reflector, 144
5.1.1 Physical problem, 144
5.1.2 Theory, 145
5.1.3 Run 1. Phase-shift-keying, 12 Hz carrier wave, 149
5.1.4 Run 2. Phase-shift-keying, 24 Hz carrier wave, 149
5.1.5 Run 3. Phase-shift-keying, 96 Hz carrier wave, 150
5.1.6 Run 4. Short rectangular pulse with rounded edges, 151
5.2 Method 5-2. Problems with collar-drillpipe area discontinuity,
with drillbit assumed as closed end, solid drillbit reflector, 152
5.2.1 Theory, 152
5.2.2 Run 1. Phase-shift-keying, 12 Hz carrier wave, 152
5.2.3 Run 2. Phase-shift-keying, 24 Hz carrier wave, 153
5.2.4 Run 3. Phase-shift-keying, 96 Hz carrier wave, 153
5.2.5 Run 4. Short rectangular pulse with rounded edges, 153
5.3 References, 154
6.1 Desurger Distortion, 156
6.1.1 Low-frequency positive pulsers, 158
6.1.2 Higher frequency mud sirens, 159
6.2 Downhole Drilling Noise, 162
6.2.1 Positive displacement motors, 163
6.2.2 Turbodrill motors, 164
6.2.3 Drillstring vibrations, 164
6.3. Attenuation Mechanisms, 166
6.3.1 Newtonian model, 166
6.3.2 Non-Newtonian fluids, 167
6.4 Drillpipe Attenuation and Mudpump Reflection 169
6.4.1 Low-data-rate physics, 170
6.4.2 High data rate effects, 171
6.5 Applications to Negative Pulser Design in Fluid Flows and to
Elastic Wave Telemetry Analysis in Drillpipe Systems, 172
6.6 LMS Adaptive and Savitzky-Golay Smoothing Filters, 174
6.7 Low Pass Butterworth, Low Pass FFT and Notch Filters, 176
6.8 Typical Frequency Spectra and MWD Signal Strength Properties, 177
6.9 References, 178
7. Mud Siren Torque and Erosion Analysis, 179
7.1 The Physical Problem, 179
7.1.1 Stable-closed designs, 181
7.1.2 Previous solutions, 181
7.1.3 Stable-opened designs, 183
7.1.4 Torque and its importance, 184
7.1.5 Numerical modeling, 185
7.2 Mathematical Approach, 185
7.2.1 Inviscid aerodynamic model, 187
7.2.2 Simplified boundary conditions, 188
7.3 Mud Siren Formulation, 190
7.3.1 Differential equation, 190
7.3.2 Pressure integral, 191
7.3.3 Upstream and annular boundary condition, 192
7.3.4 Radial variations, 194
7.3.5 Downstream flow deflection, 195
7.3.6 Lobe tangency conditions, 196
7.3.7 Numerical solution, 196
7.3.8 Interpreting torque computations, 197
7.3.9 Streamline tracing, 198
7.4 Typical Computed Results and Practical Applications, 200
7.4.1 Detailed engineering design suite, 200
7.5 Conclusions, 206
7.5.1 Software reference, 206
7.6 References, 207
8. Downhole Turbine Design and Short Wind Tunnel Testing, 208
8.1 Turbine Design Issues, 208
8.2 Why Wind Tunnels Work, 210
8.3 Turbine Model Development, 213
8.4 Software Reference, 217
8.5 Erosion and Power Evaluation, 222
8.6 Simplified Testing, 225
8.7 References, 228
9. Siren Design and Evaluation in Mud Flow Loops and Wind Tunnels, 229
9.1 Early Wind Tunnel and Modern Test Facilities, 230
9.1.1 Basic ideas, 231
9.1.2 Three types of wind tunnels, 232
9.1.3 Background, early short wind tunnel, 233
9.1.4 Modern short and long wind tunnel system, 234
9.1.5 Frequently asked questions, 237
9.2 Short wind tunnel design, 240
9.2.1 Siren torque testing in short wind tunnel, 244
9.2.2 Siren static torque testing procedure, 247
9.2.3 Erosion considerations, 250
9.3 Intermediate Wind Tunnel for Signal Strength Measurement, 251
9.3.1 Analytical acoustic model, 252
9.3.2 Single transducer test using speaker source, 255
9.3.3 Siren
transducers, 255
9.3.4 Intermediate wind tunnel test procedure, 257
9.3.5 Predicting mud flow
Dp’s from wind tunnel data, 2619.4 Long Wind Tunnel for Telemetry Modeling, 263
9.4.1 Early construction approach - basic ideas, 263
9.4.2 Evaluating new telemetry concepts, 268
9.5 Water and Mud Flow Loop Testing, 268
9.5.1 Real-world flow loops, 269
9.5.2 Solid reflectors, 271
9.5.3 Drillbit nozzles, 272
9.5.4 Erosion testing, 273
9.5.5 Attenuation testing, 274
9.5.6 The way forward, 275
9.6 References, 276
10.1 Overall Telemetry Summary, 278
10.1.1 Optimal pulser placement for wave interference, 278
10.1.2 Telemetry design using FSK, 281
10.1.3 Sirens in tandem or "sirens in series," 283
10.1.4 Attenuation misinterpretation, 284
10.1.5 Surface signal processing, 288
10.1.6 Attenuation, distance and frequency, 291
10.1.7 Ghost signals and echoes, 294
10.2 Sirens, Turbines and Batteries, 295
10.2.1 Siren drive, 295
10.2.2 Turbine-alternator system, 295
10.2.3 Batteries, 296
10.2.4 Tool requirements, 297
10.2.5 Design trade-offs, 298
10.3 References, 299
12.1 DRGDS Near-bit Geosteering Drilling System, 318
12.1.1 Overview, 318
12.1.2 DRGDS tool architecture, 319
12.1.3 Functions of DRGDS, 327
12.2 DRGRT Natural Azi-Gamma Ray Measurement, 332
12.3 DRNBLog Geological Log, 336
12.4 DRMPR Electromagnetic Wave Resistivity, 338
12.5 DRNP Neutron Porosity, 339
12.6 DRMWD Positive Mud Pulser, 343
12.7 DREMWD Electromagnetic MWD, 344
12.8 DRPWD Pressure While Drilling, 347
12.9 Automatic Vertical Drilling System – DRVDS-1, 350
12.10 Automatic Vertical Drilling System – DRVDS-2, 354
13.1 Engineering and Design Highlights, 356
13.2 Credits, 364
14.1 Short and Long Wind Tunnel Facilities, 366
14.2 Credits, 375
15.1 Recent Patent Publications, 377
15.2 Credits, 391
15.3 References, 391
16. MWD Turbosiren - Principles, Design and Development, 392
16.1 Background and Motivation, 392
16.1.1 Mud siren background, 393
16.1.2 Enter the turbosiren, 398
16.1.3 General unanswered questions, 404
16.2 Prototype Turbosirens and Experimental Notes, 405
16.2.1 Single-stage turbosiren, 405
16.2.2 Basic measurements, 406
16.2. 3 Dual-stage turbosiren, 409
16.2.4 Three-stage turbosiren, 410
16.2.5 Complementary reference turbine, 411
16.2.6 Turbosiren assemblies, 412
16.2.7 Turbosiren fabrication, 414
16.2.8 Test matrix, changing lobe number and taper, 415
16.3 Pressure Measurement - Subtleties and Ideas, 416
16.3.1 Physical discussion, 416
16.3.2 Test Series A - "Sirens in series" signal augmentation, 419
16.3.3 Test Series B - Rotor taper effects on RPM and Delta-P, 423
16.3.4 Test Series C - Reference axial turbine, 429
16.4 Credits, 438
16.5 References, 439
17. Design of Miniature Sirens,440
17.1 Siren flowmeter applications, 441
17.2 Mini-siren prototypes, 442
17.3 Cardboard test prototyping, 448
17.4 Credits, 450
18. Wave-Based Directional Filtering, 451
18.1 Background, 451
18.2 Theory and Difference-Delay Equations, 452
18.3 Calculated Results, 455
18.3.1 Method 4-3, Difference equation
(Software reference, 2XDCR07D.FOR), 456
18.3.2 Method 4-3, Difference equation
(Software reference, 2XDCR07E.FOR), 460
18.3.3 Method 4-3, Difference equation
(Software reference, 2XDCR07F.FOR), 463
18.3.4 Method 4-4, Differential equation (Software reference,
SAS14D.FOR Option 3 identical to SIGPROC-1.FOR), 466
18.4 Conclusions, 472
18.5 References, 472
Cumulative References, 473
Index, 478
About the Author, 489