Multiprobe Pressure Analysis and Interpretation

A popular 1990s formation tester with a single "pumping" probe and one passive "observation port" displaced 180 deg away, designed to measure pressures at two locations for permeability prediction, encounters well known detection problems at low mobilities. This book, using aerodynamics methods, explains why and also reveals the existence of a wide stagnation zone that hides critical formation details. And it does much more.  An exact analytical solution is used to validate a new transient, three-dimensional, finite difference model for more general testers, one that guides new hardware designs with independent azimuthally displaced probes having with different rates, flow schedules and nozzle geometries, supports interpretation and formation evaluation, and assists with job planning at the rigsite. The methods also apply to conventional tools, allowing comparisons between older and newer technologies. Importantly, the authors introduce a completely new three-probe design with independently operable active elements that eliminate all older tool deficiencies.

Numerous subjects are discussed, such as pressure transient analyses with multiple operating probes, supercharge analysis with invasion and mudcake buildup, accurate and rapid calculations that allow more than 1,000 simulations per minute, extremely rapid batch mode calculations using convergence acceleration methods, rapid fluid withdrawal with minimal dissolved gas release, dip angle, heterogeneity and anisotropy evaluation, and many other topics.  In addition, tool operation sequences, detailed engineering and design functions, field test procedures and laboratory facilities, are discussed and illustrated in photographs that go "behind the scenes" at one of the world’s largest international oil service companies. The book hopes to educate new engineers and veteran engineers alike in hardware and software design at a time when increasing efficiency is crucial and "doing more with less" represents the new norm.

Wilson Chin earned his PhD from M.I.T. and his M.Sc. from Caltech. He has authored over twenty books with Wiley-Scrivener and other major scientific publishers, has more than four dozen domestic and international patents to his credit, and has published over one hundred journal articles, in the areas of reservoir engineering, formation testing, well logging, Measurement While Drilling, and drilling and cementing rheology. Inquiries: wilsonchin@aol.com.

Tao Lu, PhD, Vice President, China Oilfield Services Limited, leads the company's logging and directional well R&D activities, also heading its formation testing research, applications and marketing efforts. Mr. Lu is recipient of numerous awards, including the National Technology Development Medal, National Engineering Talent and State Council Awards, and several COSL technology innovation prizes.

Minggao Zhou, Senior Mechanical Engineer at COSL’s Oil Field Technology Research Institute, holds a Master's Degree in Engineering and leads the company's formation testing project team. He has worked extensively in research and development over the past two decades and has participated in several National Five Year Programs. His professional interests span a wide range of well logging instruments, presently focusingon formation testing design and interpretation.

Yongren Feng is a Professor Level Senior Engineer and Chief Engineer at the Oilfield Technology Research Institute of China Oilfield Services Limited. He has been engaged in the research and development of offshore oil logging instruments for three decades, mainly responsible for wireline formation testing technology, electric core sampling methods and formation testing while drilling (FTWD) tool development.

Yuqing Yang, PhD, Chief Engineer and Professor, Technology and Exploration, with China Oilfield Services Limited, is engaged in the research and management of geological applications of logging data. He has published several books, ten patents and sixty articles, winning a COSL Science and Technology Progress Award.

Preface xi

Acknowledgements xv

1 Formation Testing – Background, Perspectives and New Industry Requirements 1

1.1 Formation Testing – A Brief Introduction 1

1.2 Conventional Formation Testing Concepts 6

1.3 A New Triple Probe Tool – Design Concepts and Well Logging Advantages 7

1.3.1 Azimuthal flow signal strength (circumferential probes) 9

1.3.2 Axial signal strength (centerline oriented dual probes) 14

1.3.3 Hardware and software considerations simulation considerations 21

1.3.4 Closing remarks 24

1.4 References 24

2 Visual Tour in Formation Testing, Design and Manufacturing 25

2.1 Detailed Mechanical CAD Animation 26

2.2 From Drawing Board to Engineering Prototyping 35

2.3 Manufacturing Highlights and Production 39

2.4 Laboratory Facilities with Formation Testing Fixtures 40

2.5 Beijing Test Well and Logging Facilities 42

2.6 Tool Positioning in Beijing Test Well 44

2.7 Field Operations – Bohai Bay and Middle East 45

2.8 Closing Remarks 48

2.9 References 48

3 Triple Probe Formation Tester – from Idea to Design to Field Evaluation 49

3.1 Laboratory Highlights – Triple Probe Formation Tester 50

3.2 Triple Probe Close-ups in Field Test 53

3.3 Positioning the Tool in the Well 56

3.4 Example Pressure Testing Well Logs 59

3.5 References 61

4 Project Background – Analysis, Modeling and Interpretation 62

4.1 Well Logging Advantages 64

4.2 Math Model Perspectives 65

4.3 Related Formation Testing Literature 68

4.4 Background Schlumberger Results 71

4.5 Analysis of MDT Pressure Data 73

4.6 References 74

5 Dual Probe Analysis for Thamama Formation 76

5.1 Thamama Formation Problem Definition 76

5.2 FT-Multiprobe Simulation 78

5.3 FT-00 Forward Simulation 87

5.4 FT-01 Inverse Analysis 89

5.5 References 91

6 Dual Probe Application for Wara Formation 92

6.1 Wave Formation Data Description 92

6.2 FT-Multiprobe History Matching 93

6.3 FT-00 and FT-01 Analysis for Sink and Vertical Probe Data 100

6.4 References 103

7 Multiprobe Flow Modeling Strategies 104

7.1 Triple-probe Formation Testing Instrument 104

7.1.1 Background remarks 104

7.1.2 Multiprobe tool introduction 106

7.2 Dual and Triple-probe Steady Flow Modeling 112

7.2.1 Background – Sources, sinks, doublets and more 112

7.2.2 Modeling hierarchies 112

7.2.3 Exact steady flow pressure analysis 114

7.2.4 Exact streamline tracing and geometric analysis 117

7.2.5 Unbalanced doublet flows – a new approach 118

7.3 Transient Numerical Model 123

7.3.1 Simulator overview 123

7.3.2 Computational details 125

7.3.3 Flowline volume storage modeling 125

7.3.4 Active flowline volume coupling at observation probes 126

7.3.5 Mud filtrate invasion and supercharging, and underbalanced drilling 126

7.3.6 Periodicity conditions in flows from circular wells 127

7.4 References 130

8 Multiprobe Applications – Detailed Examples and Assessment 132

8.1 Drawdown for Round and Slot Nozzles With and Without Mud Filtrate Migration Through the  Sandface 134

Example 1. Simple drawdown, round nozzle, no invasion 134

Example 2. Simple drawdown, round nozzle, invasion with supercharging, 200 psi overbalance 143

Example 3. Simple drawdown, round nozzle, invasion with strong supercharging, 2,000 psi overbalance 147

Example 4. Simple drawdown, round nozzle, underbalanced drilling, 100 psi underbalance 149

Example 5. Simple drawdown, slot nozzle, no invasion 151

Example 6. Simple drawdown, three pumping slot nozzles, no invasion 156

8.2 Highly Transient Applications, Drawdown and Buildup, Multiple Round or Slot Nozzles, No Invasion 160

Example 7. Simple drawdown and buildup, single round nozzle 160

Example 8. Three round nozzles executing drawdown and buildup simultaneously and independently, no invasion 165

Example 9. Two round nozzles, one withdrawing fluid, the second simultaneously injecting, no invasion 170

Example 10. Invasion or supercharge characterization in transient problems 174

8.3 Additional Topics 178

Example 11. A complicated simulation, effect of pore pressure in output displays 178

Example 12. Batch processing capabilities 183

Example 13. Spherical flow evaluation and geometric factors 191

viii Contents

Example 14. Pressure behavior at permeability extremes 194

Example 15. Comparing problems with and without supercharge 197

9 Special Topics – Gas Release, Convergence Acceleration, Big Data and Inverse Methods 200

9.1 Suppressing Dissolved Gas Release 201

Bubble point considerations 201

Example 1. Undesirable dissolved gas release 202

Example 2. Dissolved gas remains in solution 207

9.2 Steady Flow Convergence Acceleration for Interpretation Applications 212

Interpretation applications 213

Validating convergence accelerations 214

Big data inverse applications 219

9.3 Heterogeneity and Dip Detection Using Multiple Firings 219

9.4 Triple Probe Tools with Different Nozzle Geometries 225

9.5 Inverse Problems for Azimuthal and Axial Probe Applications 229

9.5.1 Azimuthal inverse problem 229

Steady flow forward calculations 231

Limited (kh,kv) range example 231

Inverse permeability predictions 241

Algorithm analysis 241

Wider (kh,kv) permeability example 247

Inverse method recapitulation 251

Data integrity in “big data” implementation 254

Azimuthal inverse strategies 256

9.5.2 Axial inverse problem for any dip angle 257

9.5.2.1 Dual probe anisotropy inverse analysis 257

Existing source model simulators 258

9.5.2.2 Supercharging – Effects of nonuniform initial pressure 267

Conventional zero supercharge model 268

Supercharge “Fast Forward” solver 269

9.5.2.3 Multiprobe “DOI,” inverse and barrier analysis 275

9.6 Closing Remarks 282

9.7 References 283

Contents ix

10 Integrated Multiprobe Modeling System 284

Section 1 – General transient 3D simulator 286

10.1 Overall Capabilities and Enhancements 286

10.2 The “Steady” Check-box Option for Low and High Permeability Flows 291

10.3 Flows with Mixed Nozzle Designs and Different Pumping Schedules 294

Run 1. All round nozzles with staggered flow rates 294

Run 2. All slotted nozzles with staggered flow rates 296

Run 3. All slotted nozzles with identical flow rates 297

Run 4. Slot, round, slot combination with identical flow rates 300

Run 5. Round, slot, round combination with identical flow rates 301

10.4 Geometric Factor Role in Model and Tool Calibration 303

10.4.1 Model calibration 303

10.4.2 Tool and software calibration 306

10.5 Pad Nozzles with Different Orifice Sizes and Shapes 307

10.6 Pore Pressure Determination with Triple Probe Tool and Effects of Supercharge 309

Section 2 – Steady Simulator and Inverse Applications 312

10.7 Software Reference Overview 312

10.8 General Transient 3D Simulator in Batch Mode 315

10.9 Rapid Steady 3D Simulator in Batch Mode 319

10.10 Big Data Inverse Approach and Examples 333

10.10.1 Run 1. Center pumping probe, two observation probes with a first viscosity guess 333

10.10.2 Run 2. Center pumping probe, two observation probes with a second viscosity guess 348

10.10.3 Run 3. Three pumping probes in drawdown mode 350

10.10.4 Run 4. Two pumping probes in drawdown mode 359

10.11 Closing Remarks 361

Cumulative References 362

Index 377

About the Authors 387

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