Measurement While Drilling (2^nd Ed.) Signal Analysis, Optimization and Design

Trade magazines and review articles describe MWD in casual terms, e.g., positive versus negative pulsers, continuous wave systems, drilling channel noise and attenuation, in very simple terms absent of technical rigor. However, few truly scientific discussions are available on existing methods, let alone the advances necessary for high-data-rate telemetry. Without a strong foundation building on solid acoustic principles, rigorous mathematics, and of course, fast, inexpensive and efficient testing of mechanical designs, low data rates will impose unacceptable quality issues to real-time formation evaluation for years to come.

This all-new revised second edition of an instant classic promises to change all of this. The lead author and M.I.T.-educated scientist, Wilson Chin, has written the only book available that develops mud pulse telemetry from first principles, adapting sound acoustic principles to rigorous signal processing and efficient wind tunnel testing. In fact, the methods and telemetry principles developed in the book were recently adopted by one of the world's largest industrial corporations in its mission to redefine the face of MWD.

The entire engineering history for continuous wave telemetry is covered: anecdotal stories and their fallacies, original hardware problems and their solutions, different noise mechanisms and their signal processing solutions, apparent paradoxes encountered in field tests and simple explanations to complicated questions, and so on, are discussed in complete "tell all" detail for students, research professors and professional engineers alike. These include signal processing algorithms, signal enhancement methods, and highly efficient "short" and "long wind tunnel" test methods, whose results can be dynamically re-scaled to real muds flowing at any speed. A must read for all petroleum engineering professionals!

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 MWD System for Very Deep Wells” significantly expanded with additional photographs and detailed annotations 11

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 Flowloop 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

2.5 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 99

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 and 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 Signal Processor Design and Additional Noise Models 155

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 Δp procedure using single and differential transducers 255

9.3.4 Intermediate wind tunnel test procedure 257

9.3.5 Predicting mud flow Δp’s from wind tunnel data 261

9.4 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

9.6 References 276

10 Advanced System Summary and Modern MWD Developments 277

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

10.3 References 299

11 MWD Signal Processing in China 300

12 Sensor Developments in China 318

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 Sinopec MWD Research 355

13.1 Engineering and Design Highlights 356

13.2 Credits 364

14 Gyrodata MWD Research 365

14.1 Short and Long Wind Tunnel Facilities 366

14.2 Credits 375

15 GE Oil & Gas MWD Developments (BakerHughes, a GE Company) 376

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

16.5 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

Wilson Chin earned his Ph.D. at the Massachusetts Institute of Technology and his M.Sc. at the California Institute of Technology, majoring in aerospace engineering and wave propagation before refocusing his interests toward petroleum exploration. His work in fluid mechanics, electromagnetics, formation testing and reservoir characterization is well known, forming the basis for twenty research monographs, about one hundred papers and fifty domestic and international patents. Wilson's current interests address high speed mud pulse telemetry in Measurement While Drilling (MWD) applications.