Wilson C. Chin, author, scientist and software developer, earned his Ph.D. from M.I.T. and M.Sc. at Caltech. He has published 30 books, 50 patents and 100 papers. His petroleum geoscience interests focus on MWD design, managed pressure drilling, reservoir engineering, formation testing, electromagnetic logging, and drilling and cementing rheology. Wilson's work in advanced aerodynamics, computational biology and medical imaging have attracted strong interest and venture capital awards.

Mr. Chin is recipient to 5 awards from the U.S. Department of Energy. In 2023, he was Baker Hughes' nominee to the U.S. National Academy of Engineering. Stratamagnetic Software LLC (1997) has provided math modeling and simulation services to companies worldwide. In 2024, Mr. Chin founded Hong Kong's iSyringe Imaging Technologies Limited to develop a novel medical imaging instrument. Advanced aerodyamic design methods for Sixth Generation bombers and drones, developed over two decades and summarized here, are now offered to the aerospace community.

All techniques, methods and algorithms in our publications are developed for the general public interest and are not subject to patent restrictions unless noted otherwise. Comments, questions and contributions from all readers are welcome.

Advanced Aerodynamic Models for Sixth Generation Aircraft Design. Modern bombers and drones fly with delta and lambda planforms, blended fuselages and flapless wings in ground proximity to avoid detection. Transonic flows are common with strong background shears over land, on aircraft carrier take-off or landing. Euler and Navier-Stokes methods are non-standard, slow and inaccurate.

Forward problems determine pressures when shapes are given, subject to Kutta's condition. For irrotational, incompressible 2D flow, velocity potentials F(x,y) satisfy Fxx + Fyy = 0. What if, assuming background shear velocities U(y), Fxx + Fyy - 2U'(y)/U(y) Fy = 0 suffices? And extensions to 3D transonic flow with shocks are possible? Solutions in minutes?

Inverse problems determine shapes when pressures are given, subject to trailing edge constraints. Flapless wings require opened edges with specified mass efflux for navigation control. For 2D irrotational, incompressible flow, streamfunctions S(x,y) satisfy Sxx + Syy = 0. What if, for horizontal shears, Sxx + Syy = U"(y)/U(y) S holds, with simple Kutta-like conditions used for edge control? You're taught that S is a (bold) vector S in 3D, that simply adding Szz is wrong. But rigorous streamfunction-like approaches do lead to Sxx + Syy + Szz = U"(y)/U(y) S, also readily extended for transonic effects. Boundary conditions take a form Sy(x,y=0,z) + C*S = -1/2 Cp(x,z) similar to tangency conditions in forward potential flow.

In short, forward and inverse problems can be solved by modifying available potential flow codes. We've developed general theories, robust and rapid algorithms validated with dozens of applications. Executables and source code are available for immediately productivity. Deepseek-R1, our partner in discovery, describes these paradigm shifts. And yes, we'll share our open source AI/ML LLM thinking transcripts and source code with the aerospace community.

For more information, click Preface or Table of Contents. Pre-publication 2027 book copies at Highlights (150 pages, all applications examples) or Complete manuscript (400 pages) .

Multiprobe Pressure Testing and Reservoir Characterization (Wiley, 2024). In the early 1990s, a novel formation tester introduced by a major oil service company was innovative in two respects. The tool, consisting of an active "sink" probe and a passive "horizontal" observation probe displaced azimuthally 180 deg from the sink, would offer predictions for both kh and kv permeabilities. However, at low mobilities, pressure drops at the latter were significantly less than those at the sink. The same was true for the "vertical" probe, located several feet away, coincident with the sink azimuth. These limitations reduced the versatility and usefulness of the multiprobe design, substantially decreasing accuracy behind many tester predictions.

This book introduces a new approach to formation testing and multiprobe design. Single, dual, triple and four-probes are studied azimuthally using advanced finite difference methods for single-phase liquid and gas as well as contaminated multiphase flows. Probes may be operated in any combination, while probe pump rates and geometries may be chosen selectively, e.g., round, oval or slot nozzle. The models developed are useful for pressure transient analysis, say heteregeneity and anisotropy mapping as well as tool hardware design. User friendly software is now offered to the industry and collaborations are strongly welcome.

For more information, click Preface or Table of Contents.

Biofluids Modeling: Methods, Perspectives and Solutions (Wiley, 2023). Twenty-twenty (2020) was our defining year - Our year of living dangerously. Covid-19 unexpectedly struck. Flights worldwide were cancelled. Borders were shut. Lives were turned upside-down. Deaths mounted. Unpredictability became the only predictable norm. The first author, after one long, long flight, would find himself immobile from "DVT" or "Deep Vein Thrombosis." Not just in one leg, but blood clots in both.

But months visiting hospital after hospital led to unpredictably good results, not only healthwise. In my delirium and disorientation, I envisioned the human body as a petroleum reservoir, with tissue representing formations of unknown properties, populated by veins (production wells) and arteries (injection wells) of all sizes and shapes. Formation testers, which withdraw oil and gas from unknown rock, are important in reservoir characterization. Pressure transients are interrogated using advanced Darcy math models to predict downhole properties for their economic potential.

And so, the Intelligent iSyringe was born. A simple, miniature formation tester, useful for convenient, real-time, inexpensive human and animal tissue imaging that provides quantitative local results for permeability, anisotropy, compressibility and more. Physicians could now describe anomalies in quantitative terms, supplementing X-ray, ultrasound, Catscan and MRI images. So far, we've published Biofluids Modeling, two papers in J. Pharmaceutical Technology and J. Radiology, filed patent applications, won venture capital awards and founded iSyringe Imaging Technologies Limited in Hong Kong.

For more information, click Preface or Table of Contents.

Quantitative Methods in Reservoir Engineering, Chinese Edition (Elsevier, 2021). Most reservoir flow books provide basic equations like Darcy’s law, single-phase radial solutions, simple well test models, and simplified discussions on relative permeability and capillary pressure. Then elementary concepts on finite differences and modeling are summarized, and commercial simulators and case studies are quickly offered. Unfortunately, many such models are incorrect. The author would develop truly rigorous models that were rapid, stable and simple to use, leading to his 1990 BP Chairman's Innovation Award and several derivative book publications. The present book is a Chinese translation for the Second Edition English book (below) of the same name. It is intended for Chinese language readers, a growing audience given the increasing importance of oil and gas in Asia. For questions and comments, please feel free to contact Xiaoying "Jenny" Zhuang, Asia Marketing Manager.

For more information, click Preface or Table of Contents.

Multiprobe Pressure Analysis and Interpretation (Wiley, 2021). Oilfield manufacturers have developed invaluable and versatile dual or multiprobe formation testers consisting of axially displaced pumping and observation probes. Single probe tools pump and measure spherical permeability, while dual probe devices offer kh and kv using data from a single azimuth. In the early 1990s, a multiprobe tester was introduced by a service company that was innovative for its time. This tool, consisting of an active "sink probe" and a passive "horizontal" observation probe displaced 180 deg from the sink would offer kh and kv predictions. However, at low mobilities, measured pressure drops at the latter were significantly less than those at the sink. The same was true for its "vertical" probe, located several feet away. These limitations significantly reduced the tool's usefulness for reservoir characterization.

Several high risk formation testing projects were recently undertaken at China Oilfield Services Limited. Its engineers raised interesting questions. What if three azimuthally displaced probes, each separated by 120 deg from the others, were used? What if each probe in the triple combination, possibly equipped with different nozzle sizes and shapes, were capable of operating independently from the others, and at different rates or depths of investigation? How would such an instrument be used in detailed heterogeneity and anisotropy mapping? These questions, and many more, are answered in this ground-breaking volume. The entire technology is now available to the petroleum community. The authors welcome questions and collaborations.

For more information, click Preface or Table of Contents.

Supercharge Invasion and Mudcake Growth in Downhole Applications (Wiley, 2021). This important volume complements COSL's above Multiprobe Pressure Analysis in many ways. These include pressure transient analysis, forward and inverse modeling, supercharge, mudcake growth and fluid invasion formulations, plus contamination and multiphase cleaning methods - and all during the past two decades by the present authors. While China Oilfield Services Limited does manufacture its own conventional single, dual and multiprobe tools, it is the availability of our complete suite of physics-based software models and "Job Planning System" that allows these and its newer generation of formation testers to be used in many more innovative ways. How is supercharge handled in pressure interpretation? What length of time is required before contaminant mud filtrate is absent from collected samples? What is the so-called inverse problem and how is its solution applied in field practice? These questions and many more are considered in the present volume.

For more information, click Preface or Table of Contents.

Reservoir Simulation and Well Interference: Parent-Child, Multilateral Well and Fracture Interactions (Wiley, 2020). This volume addresses the most pressing problems confronting modern oil and gas production - well spacing and topology decisions, hydraulic fracturing effects, and challenging transient, 3D real-world simulations performed rapidly using rigorous models.

Co-written by a world-renowned petroleum engineer, this breakthrough new volume teaches engineers how to configure, place and produce horizontal and multilateral wells in geologically complicated reservoirs, select optimal well spacings and fracture separations, and how to manage factors influencing well productivity using proven cost-effective and user-friendly simulation methods.

Charged in the 1990s with solving some of petroleum engineering's biggest problems that the industry deemed unsolvable, the authors of this innovative new volume solved those problems, not just using a well-published math model, but one optimized to run rapidly, the first time, every time. This not only provides numerical output, but production curves and color pressure plots automatically. And each in a single hour of desk time.

Using their Multisim software featured in this volume, secondary school students at the Aldine Independent School District delivered professional quality simulations in a training program funded by some of the largest energy companies in the world. Think what you, as a professional engineer, could do in your daily work. Valuable with or without the software, this volume is the cutting-edge of reservoir engineering today, prefacing each chapter with a trade journal summary followed by hands-on details, allowing readers to replicate and extend results for their own applications. This volume covers Parent-Child, Multilateral Well and Fracture Flow Interactions, reservoir flow analysis, many other issues involving fluid flow, fracturing, and many other common unsolvable problems that engineers encounter every day. It is a must-have for every engineer's bookshelf.

This groundbreaking new volume presents simulation, explained in simple terms, focusing on strengths in the present formulation and limitations behind industry models. Introduces a reservoir simulator, developed in earlier books and used at multiple companies, incorporating smart menus for interactive computing requiring minimal training. Goes through six challenging problems with complicated geologies and multilateral well systems defined and solved, each in one hour of desk time, with integrated graphics producing production histories and 3D color pressure plots. Covers pressure and rate constraints, levels and type changeable at any time, how new wells may be added, and existing wells shortened, lengthened or redirected during simulations, how multilaterals and fracture systems may assume arbitrary geometries, dozens of farfield drive models, liquids and gases supported; and, finally, program architecture that supports multiple what-if analyses in same work session.

For more information, click Preface or Table of Contents.

Formation Testing: Supercharge, Pressure Testing and Contamination Models (Wiley, 2019). The Halliburton paper, "A New Hostile Environment Wireline Formation Testing Tool: Case Study from the Gulf of Thailand," by Rourke et al., SPWLA 47th Annual Logging Symposium, Veracruz, Mexico, June 4-7, 2006, cites numerous field examples where overbalance pressures exceed 2,000 psi - not a typographical error.

Supercharging has long disrupted pressure transient interpretation in logging operations. Real-time prediction methods, e.g., Halliburton's GeoTap^TM due to Proett and Chin for tight zone applications, or Chin's later rational polynomial approach, apply only to problems with identical initial and farfield pressures. Long wait times are typically required before high pressure borehole effects dissipate.

We've developed supercharge models with overbalanced initial pressures plus exact analytical solutions for both forward and inverse problems. Now, accurately predict pore pressure, mobility and compressibility from any three (time, pressure) points, rapidly without waiting. What's more, we can handle inverse problems with multiple flow rates (positive or negative, in any order) for standard logging and analyze-inject-analyze formation treatment applications. And again, low mobility, with flowline volume distortion, rapidly without waiting. For more information, click Preface or Table of Contents.

Modern Aerodynamic Methods for Direct and Inverse Applications (Wiley, 2019). An important volume describing modern methods for aerodynamic design in subsonic, transonic and supersonic flow. Special techniques include: (1) Exact drag calculations for nonplanar supersonic bodies, (2) Nonlinear oscillations in low frequency transonic flow, (3) Hydrodynamic stability of shear flows past flexible surfaces, (4) Actuator disk simulation for jet engine power addition, (5) Engine and airframe integration, (6) Type-independent methods for supercritical transonic flow calculation, (7) Shear flow analysis without Euler equation approaches, and more. Importantly, the inverse problem is solved with a new Neumann formulation that rapidly calculates airfoil shapes which induce prescribed pressure distributions. An analogous Kutta-type condition related to opened edges with prescribed mass efflux is introduced in this award-winning book - an important development which will prove useful in flapless wing design for military aircraft in the 2020s time frame.

For more information, click Preface or Table of Contents.

Measurement While Drilling: Signal Analysis, Optimization and Design, 2nd Edition (Wiley, 2018). This long awaited update to our best-selling 2014 MWD book takes you behind the scenes, introducing you to the latest developmental efforts at leading international corporations like Sinopec, CNPC, Gyrodata, and GE Oil & Gas. New "out of box" designs are profiled, together with experimental results, and detailed color photographs of prototypes and test fixtures are offered. In particular, we cover high signal strength, rapid self-spinning "sirens in series" that rotate under minimal power, drawing only on the kinetic energy of the flowing mud. We cover miniature, low torque sirens that rotate in narrow conduits, driven by flow rates as low as those from simple hair dryers. We also demonstrate how special rotor tapers can significantly affect siren torque - increasing values so much that jamming is unlikely and trapped debris are rapidly destroyed. Detailed numerical studies are also offered showing how signal reflections from pump pistons and desurgers, and strong mudpump noise, are both effortlessly filtered and removed using cleverly designed transducer arrays and signal processing.

Managed Pressure Drilling: Modeling, Strategy and Planning (Elsevier, 2012). Non-Newtonian flow models for drilling and cementing are developed for arbitrary flow schedules, where different fluids with contrasting rates are pumped for different durations. Steady, transient and multiphase flows are supported - general time-varying rotation rates, axial movements and pressure gradients. Realistic annuli include eccentric circles with cuttings beds, washouts and fractures. The book, which discusses pressure prediction along the entire borehole, also considers hole cleaning strategies important to horizontal drilling. Flow assurance and wax deposition models critical to subsea pipeline operations are additionally covered.

We are pleased to offer the recently published Managed Pressure Drilling (Chinese, 2016) from Elsevier, introducing our unique approaches to Asia. The book is must reading at China National Petroleum Corporation (CNPC), China National Offshore Oil Corporation (CNOOC), China Oilfield Services Limited (COSL), China Petroleum and Chemical Corporation (Sinopec) and other leading oil companies. This book may be purchased from www.amazon.cn or other authorized resellers (ISBN 9787518311729).

The author, key developer to Halliburton's OptiCem, Displace3D and iCem products, wrote Computational Rheology and Borehole Flow Modeling (described below). The present work in drilling and cementing rheology was supported by the United States Department of Energy's Ultra-Deepwater Program during 2009-2011.

For more information, click Preface or Table of Contents. An additional volume, Modern Borehole Analytics (Wiley, 2017), also described below, expands upon our MPD applications to include the role of formation pore pressure, mudcake dynamics and growth models.

Modern Borehole Analytics for Annular Flow, Hole Cleaning and Pressure Control (Wiley, 2017). This new book on drilling and cementing rheology expands upon Managed Pressure Drilling: Modeling, Strategy and Planning (Elsevier, 2014, 2017), providing additional solved problems focusing on practical applications. Importantly, the integrity of the mudcake (separating borehole from reservoir events) is addressed. Does it really seal the formation to provide smooth annular flow? Is it thin or thick? What is its growth rate and how does this control influx into the matrix rock? Related topics like pore pressure determination in tight zones, necessary to understanding blowout prevention and modeling, are considered, drawing on recent advances in formation testing. This book is a "must have" addition to every engineer's library.

For more information, click Preface or Table of Contents.

Measurement While Drilling Signal Analysis, Optimization and Design, First Edition (Wiley, 2014). Key issues in MWD telemetry - desurger distortions, signal enhancement by constructive wave interference, multiple transducer echo cancellation and pump noise removal methods are considered. Siren hardware and turbine design are discussed, as are innovative test approaches.

The author's extremely rapid and accurate wind tunnel methods, used at Schlumberger, Halliburton, CNPC, Gyrodata, Sinopec, GE Oil & Gas and others, are industry standards. Numerous signal processing algorithms and mud pulse design methods are offered. The author holds multiple patents in MWD telemetry and has consulted widely. The fundamental principles and methods developed in this volume laid the groundwork for very high data rate MWD systems proposed in multiple 2024-25 publications.

For more information, click Preface or Table of Contents.

And finally, the long awaited 2nd Edition (with numerous surprises) went to press and published during Summer 2018.

Reservoir Engineering in Modern Oilfields: Vertical, Deviated, Horizontal and Multilateral Well Systems (Wiley, 2016). Mr. Chin earned the British Petroleum Chairman's Innovation Award for reservoir engineering in 1990. This book describes rapid, accurate and stable methods for Darcy flow simulation of systems of vertical, deviated, horizontal and multilateral wells in 3D layered, heterogeneous and anisotropic formations. Wells are sketched on computer screens, constraints are specified (that may change during simulation), new laterals drilled or old ones extended, and farfield drives are defined for steady or transient analysis. Detailed results completed within minutes, with color plots and reports generated. Extremely fast graphics and numerical engines, plus a user-friendly interface, support field optimization and infill drilling needs. Special graphics boards or hardware accelerators not required to operate Windows software.

For more information, click Preface or Table of Contents.

Quantitative Methods in Reservoir Engineering, Second Edition (Elsevier, 2016). This new book updates our successful First Edition with latest developments in formation testing (exact and numerical forward simulation methods, inverse approaches for permeability prediction in high and low mobility environments, surveys of modern tools and their capabilities) and multilateral well design for enhanced production in layered, anisotropic and heterogeneous reservoirs. These two areas augment the extensive collection of math models presented in the predecessor book (described below). In addition, many concepts new to formation testing pressure transient interpretation, complex invasion and "Time Lapse Logging" are introduced.

For more information, click Preface or Table of Contents.

Quantitative Methods in Reservoir Engineering, First Edition (Elsevier, 2002). This monograph, an outgrowth of Modern Reservoir Flow, presents exact models for Darcy flows from fractures and shales, provides rigorous solutions for formation invasion with mudcake buildup, develops reservoir flow simulators on curvilinear grids, explains streamline tracing algorithms in complex reservoirs, and so on. These latter topics, covered in highly specialized courses, are presented in a "plain English, down to earth" manner requiring no more than a basic calculus background.

The author previously won the Chairman's Innovation Award at British Petroleum for reservoir engineering. Models described here have been commercialized over the years with success. Content included in Quantitative Methods in Reservoir Engineering, Second Edition (see above).

Formation Testing: Pressure Transient and Contamination Modeling (Wiley, 2014). The first industry book devoted to formation testing - the author, who developed Halliburton's GeoTap algorithms for real-time permeability in tight formations, presents exact forward and inverse methods supported by two prestigious Small Business Innovation Research (SBIR) awards from the U.S. Department of Energy. Pressure transient interpretation methods are developed from first principles. "Time to clean" multiphase models support strategies needed to pump clean in-situ oil samples. The book (co-authored with CNOOC) presents a "behind the scenes" tool design tour at Asia's largest oil service company. The novel algorithms developed would later form the basis for pressure interpretation behind the Intelligent iSyringe medical imaging device described in our 2023 book Biofluids Modeling.

For more information, click Preface or Table of Contents.

Formation Testing: Low Mobility Pressure Transient Analysis (Wiley, 2015). One year after Formation Testing: Pressure Transient and Contamination Modeling appeared, major breakthroughs in real-time permeability prediction in tight zones were announced for pressure transient data with strong flowline storage effects. Such applications are particularly important to well logging in the post 1990s time frame, as highly mobile formations have become rarer in geological discovery.

A new "rational polynomial" scheme requires only three data points, versus ten in competitor schemes and provides answers in seconds. Phase delay approaches (analogous to resistivity logging) extrapolate anisotropic permeability from time differences between "transmitter" (pumping probe) and "receivers" (observation pressure transducers). This volume is must reading for log analysts and tool developers.

For more information, click Preface or Table of Contents.

Electromagnetic Well Logging: Models for MWD/LWD Interpretation and Tool Design (Wiley, 2014). Electromagnetic tools measure phase differences and amplitude ratios between coil transmitters and receivers. Resistivities are inferred from Maxwell's equations, but analytical difficulties preclude accurate analysis - dipole, integral equation and Born approximations are not helpful because large coil fields near drill collars are complicated to model. Further, tools may reside across multiple anisotropic layers, where interfacial charge creation leads to uncertainty in relating measurements to fluid saturations. The author, who specialized in electrodynamics at M.I.T.'s renowned physics department, solves the complete problem using a new and fast approach. Accurate 3D methods such as those proposed and solved in this book would prove extremely useful to modern logging, still mired in limiting dipole models after decades of use. Unlike available models, the present complex elliptic equations are solved with modern "relaxation" methods which promise solutions within seconds in typical computers.

For more information, click Preface or Table of Contents.

Resistivity Modeling: Propagation, Laterolog and Micro-Pad Analysis (Wiley, 2016). Whereas Electromagnetic Well Logging addresses diffusive wave propagation associated with alternating currents in 3D, this volume focuses on subjects central to resistivity logging. In particular, axisymmetric A/C coil fields with multiple horizontal and radial layers, "time lapse logging" where formation properties are inferred from resistitivy changes, plus D/C design methods for laterolog and pad resistivity tools. Voltage field calculations in anisotropic media are discussed as is streamline analysis for current flow.

Our mathematical formulations are clearly stated and solved, so that engineers and physicists unambiguously understand the implicit assumptions used. What does your data "really" see in vertical versus horizontal wells? Finally, Archie's well known law is extended to field-wide interpretation as opposed to core-level applications.

For more information, click Preface or Table of Contents.

Wave Propagation in Drilling, Well Logging and Reservoir Applications (Wiley, 2014). Starting with a survey of wave propagation math methods, we delve into practical petroleum applications. Half of the book is devoted to drillstring vibrations, axial models with bit bounce and drill ahead, rock-bit interaction, stick-slip effects in torsional displacements, and coupled axial, torsional and lateral vibrations.

Additional subjects include ocean waves, acoustic propagation for mud pulse MWD, Maxwell's equations in resistivity logging, permeability prediction from Stoneley wave measurements, and eccentric hole approaches to borehole seismics. Throughout the book, mathematical formulations are emphaiszed, but presented with a clarity focused on higher level undergraduate study. Solution methods are particularly emphasized. Wave propagation is especially interesting to the author, who earned his M.I.T. Ph.D. in this area.

For more information, click Preface or Table of Contents.

EARLIER BOOKS

Borehole Flow Modeling in Horizontal, Deviated and Vertical Wells (Elsevier, 1991). This first book written by the author in 1991 rigorously models non-Newtonian flows in eccentric annuli using advanced curvilinear boundary-conforming mesh systems. The model shows why viscous stress controls hole cleaning in horizontal wells, how vertical velocity is similarly important in vertical wells and explains apparent viscosity's role in freeing stuck pipe. Models for barite sag (density stratification) correctly predict the recirculating vortex flows observed experimentally.

The curvilinear grids used model off-centered circles containing cuttings beds, washouts and fractures, producing accurate numerical solutions within seconds on typical Windows platforms. Consistency with a University of Tulsa experimental database validated the now popular approach to hole cleaning and pressure prediction. The methods have been licensed by leading companies like Baker Hughes and Hlliburton Energy Services. Content offered in this book is now included in Managed Pressure Drilling described above.

Modern Reservoir Flow and Well Transient Analysis (Elsevier, 1993). This classic book adapted solutions from theoretical aerodynamics and elasticity to reservoir simulation, for example, flows past fractures, boreholes with intersecting fractures, shales and shale arrays. Exact methods for streamline analysis are presented, as are curvilinear grid approaches to modeling irregular reservoir boundaries. Steady and transient analyses are developed for well topologies from vertical, to horizontal, to multilateral.

The content here is now included in Quantitative Methods in Reservoir Engineering, Second Edition in both English and Chinese editions. The Multisim reservoir simulator used builds on an earlier prototype that led to the British Petroleum 1990 Chairman's Innovation Award and a unit mobility solver licensed to Halliburton Landmark Graphics.

Wave Propagation in Petroleum Engineering (Elsevier, 1994). This work combined drillstring vibrations of advanced axial, torsional and lateral vibrations in a single model that explained numerous field observations. For example, axial models included "displacement sources" that simulated roller cone motions, while bit-bounce and rate-of-penetration effects were enabled using lab defined rock-bit interaction results. Torsional stick-slip and reversals were obtained by coupling with axial vibrations. Out-of-plane lateral displacements were simulated by including torsion (integration with axial model provided a comprehensive description for observed phenomena).

"Why Drillstrings Fail at the Neutral Point," a key World Oil publication from the 1980s, explained with our methods why catastrophic downhole vibrations strong enough to destroy drill collars could not be detected from surface measurements. Using analytical "group velocity" ideas from classical physics, we demonstrated how the neutral point acted as a "black hole" (yes, as in relativity) that absorbed transverse energy converted from longitudinal vibrations in real-time. The solutions demonstrated the role of mode coupling in downhole oscillations. How is this useful practically? One might, for example, control damaging transverse modes by changing the seemingly unrelated weight-on-bit. Original content is now included in a revised Wave Propagation above.

Computational Rheology for Pipeline and Annular Flow (Elsevier, 2001). The pioneering approaches in Borehole Flow Modeling were extended in several directions. New topics included (1) pipe flow modeling in general ducts, (2) coupled velocity and temperature in bundled pipelines, (3) solids deposition modeling, (4) wax buildup in subsea pipelines, hydrate control, pipe bends, secondary flows and others.

Content is now incorporated in Managed Pressure Drilling (above) which extends our capabilities to applications with rotation, reciprocation, pump transients, plug flow and multiphase effects. The curvilinear grid methods developed here and in Borehole Flow Modeling would eventually find applications in modeling clogged artery and vein flows in the human body. These models are treated above in Biofluids Modeling.

Formation Invasion, with Applications to MWD, Time Lapse Analysis and Formation Damage (Elsevier, 1995). That mudcake grows with "the square root of time" is assumed in drilling and well logging. But this is generally untrue. Rigorous math models, together with validating Catscan experiments in linear and radial flow vessels, reveal the effects of borehole curvature, formation permeability, mudcake composition, pressure compaction and so on. The square root model holds only for large diameter boreholes.

New radial models are formulated and solved to predict "time to plug" in slim holes and erosive effects in dynamic filtration. Importantly, fluid based "time lapse logging" methods are developed for porosity, viscosity and pore pressure prediction using resistivities found at different instants in time. Content is now included in Quantitative Methods, Second Edition (above).