The 9th RPI for January-February 2017

Bill Goodway - Independent Consultant in Geophysics, Calgary, Canada

About Bill Goodway

I grew up and was educated in the UK near London. My early introduction to science came at Brentwood School, a 550-year-old boarding school in County Essex, just east of London where two imaginative teachers made physics, astronomy and geology the most compelling and interesting areas of study that shaped my future. I must admit that my passion for physics lead to the exclusion of many other subjects during those early years and later on in my choice and decision to pursue a career in geophysics.

Following this I gained entry into University College London to pursue a degree in either geology or physics, as a major in geophysics was not offered at a B.Sc. level. I chose geology but was destined to end up working in geophysics through an enduring love of physics. Later in life being dissatisfied with a geology degree while impersonating a geophysicist, I returned to university obtaining a geophysics M.Sc. from the University of Calgary.

My career started in seismic acquisition in the North Sea leading eventually to a transfer to Calgary in the early 80’s. Soon after arriving in Calgary I joined PanCanadian Petroleum as a geophysicist that progressed to being the team lead of the Seismic Analysis Group. This was a considerable stroke of luck as the company had job stability and through a very supportive management encouraged me and my colleagues to accomplish some interesting, even ground breaking applied seismology. Following the PanCanadian and AEC merger to form EnCana in 2002, I became Advisor for Seismic Analysis within the Frontier and New Ventures Group. After having sold off all the lucrative PanCanadian offshore oil discoveries such as Buzzard in the N Sea, I moved to a domestic business unit where through some enlightened collaboration I initiated and subsequently developed new applications of seismic to EnCana’s overwhelming pursuit of unconventional gas shale development.

In 2010 I ended my career with EnCana to join Apache as Manager of Geophysics (Canada) and Advisor Senior Staff in the Exploration and Production Technology group based in Houston. This role involved leading a small group of specialists working primarily on acquisition design and processing interaction for improved Quantitative Interpretation (QI) applied to both conventional exploration and unconventional play development throughout the Apache regions.

I have presented and co-authored numerous papers at CSEG, EAGE and SEG conventions on seismic acquisition and processing, borehole geophysics, anisotropy, multicomponent recording and AVO inversion/QI.

For my work and through considerable encouragement and collaboration from my colleagues, I received four of the CSEG’s annual Best Paper Awards between 1994 and 1997, was awarded the CSEG Medal in 2008 and in 2009 was selected as the SEG’s Honorary Lecturer for North America.

In 2013 I was the honoree for the 2nd CSEG Annual Symposium and in 2016 I was recognized by the SEG with the Reginald Fessenden Award for my development and promotion of lambda-rho-mu inversion technology that has become a valuable exploration tool resulting in documented cases of improved drilling success.

I am a member of the CSEG, SEG and APEGGA as well as a past member of the SEG Research Committee and TLE editorial board. In addition I was elected President of the CSEG for the 2002/2003 term.

Your secret recipe and pathway for success in becoming a well-known name in the rock physics community

I am not certain that my name is that well known amongst those in the rock physics community. However I am known, maybe somewhat controversially for my introduction of LMR (Lambda-Mu-Rho) in the broader community of QI that includes rock physicists.

My pathway to success as a geophysicist followed an erratic path as I started from a geological background that is considerably less quantitatively mathematical and I feel that I may have progressed faster and achieved more by following a deeper foundation in physics in my pursuit of a geophysical career. However once I had embarked on my geophysics career I decided that I need to be at the forefront of the exploration drill-bit in an E&P organization, where the application of seismic methods play a central and critical part to reducing risk in describing and predicting hydrocarbon reservoirs.

For me the problems posed by having to explore, delineate and characterize conventional and unconventional reservoirs remain the most interesting as you can test the validity of your ideas, hypotheses and methods in a real earth setting for the ultimate goal in the production of hydrocarbons. Furthermore the challenges that I encountered in my career of having to successfully predict exploration drilling locations were so diverse that my effort and focus was forced into areas of interest that required me to rapidly augment my technical knowledge and understanding.

In recent years, by necessity, I have had to adapt geophysical theory to become relevant in the O&G industry’s concentration on unconventional resources in shale formations. Well established conventional methods based on rock physics and QI/AVO inversion have had to catch up and become a routine part of enhancing the engineering advances in horizontal drilling and hydraulic fracturing. But I have found that this change from exploring for the proverbial “needle in a haystack” conventional hydrocarbon reservoir to characterizing the far more ubiquitous background source rock for its producibility, to be refreshingly less stressful and more satisfying as a controlled technical experiment.

Challenges you see in moving rock physics to the next level

First I must start with a brief preamble to excuse my lack of rock physics expertise. Early in my career my geophysical background and experience was in the technically controlled and measurably precise world of seismic acquisition and processing. However as I became more involved with the challenge to create high fidelity noise free data that accurately represented the subsurface I realized that the ultimate goal for seismic imaging was to describe and characterize the hydrocarbon bearing rock formations that we need to successfully exploit. As a result I was drawn into applying AVO based methods, specifically AVO inversion for moduli that have direct relationships to rock physics. This forced me to embrace and become familiar with the science of modeling, describing, measuring and understanding the physics of rocks at the very smallest of scales. This effort required a change in acquisition design and processing interaction to produce more robust, high density and better quality seismic data, that would allow for pre-stack Quantitative Interpretation (QI) applied to both conventional exploration and unconventional play development.

My involvement and motivation for introducing a specific AVO/QI based method termed LMR back in the 90’s has endured I believe, due to the insight and improved understanding of extrinsic velocity or impedance measurements afforded by recasting these quantities in more intuitive and intrinsic rock physics parameters. These parameters consisting of density (ρ) and the orthogonal Lamé moduli terms of shear rigidity mu (μ) and incompressibility lambda (λ) (or kappa (k) can be estimated from seismic data thereby enabling a joint analysis and description of the subsurface from a rock physics basis. This brings me to the first of my points around what I see as a challenge in the bigger perspective of using rock physics to calibrate, characterize and validate the results of QI analysis.

Seismic data is a depressingly over determined and woefully under resolved blunt tool with limited degrees of freedom. By comparison rock physics has an overwhelming and diverse quantity of complex theories and measurements that facilitate precise, descriptive and predictive relationships from the very finest of scales in the laboratory, all the way to the seismic wavelength. More effort to bridge this gap in the “measurement accuracy scale” is crucial in reducing the risk and failure that currently plagues drilling predictions and success rates based on QI.

In the relatively recent paradigm of horizontal well hydro-fracture stimulation of fully charged tight reservoirs with low porosity, the application of AVO/QI methods is simplified to primarily extracting lithology and mechanical properties from seismic data. Consequently the scope rock physics has expanded to include the rock-mechanics and petro-physics used in adapting conventional methods to map shale lithology, porosity, OOIP/OGIP and brittleness.

However this has created some significant challenges or shortcomings in applying rock physics to unconventional reservoirs as we don’t have any log measurements from the stimulated reservoir as logging is done prior to completions and production. Consequently unlike conventional clastic reservoirs, there is no information post hydraulic-fracturing from which we can obtain actual rock physics measurements of producing unconventional reservoirs for theoretical model validation of permeability and porosity within these formations. As a result we don’t really know the connection between porosity/TOC /quartz content on common seismically derived attributes such brittleness estimates of frack-ability.

A related more tractable challenge is to better understand what is meant by the brittleness index (increasing Young’s modulus with decreasing Poisson ratio) that has been added to the cornucopia of QI attributes from the world of completions engineering. Brittleness is an elastic property of an unbound rock (both Young’s modulus and Poisson ratio are unbound quantities i.e. not in-situ) that in some way represents how the rock will fail in the confined subsurface. This would appear to be a very problematic connection to make as it is essentially empirical and requires a more rigorous rock physics analysis to confirm, reject or at least show where the relationship might hold. In fact there is some compelling contradictory evidence from log data and related rock physics modelling, which suggests an increase in penny shaped TOC rich micro-fractures actually increases Poisson’s ratio and hence is at odds or even opposed to the prediction of frack-ability from the brittleness index.

Lastly given the importance of in-situ stresses to the success or failure of hydro-fracture stimulation, 3D Amplitude Variation with Azimuth (AVAZ) inversion is routinely applied to estimate the orientation and intensity of anisotropy due to in-situ stress or fractures. However I believe these methods face a serious challenge in being accepted across the disciplines of geology and engineering as they assume simplistic models based on long wavelength anisotropic seismic wave propagation and rarely incorporate geo-mechanics or the rock physics of fractured shales. For example at what scale does the anisotropy we measure manifest itself as aligned heterogeneity and is this a consistent quantity at all scales? Is the “true anisotropy” measured at the laboratory/log scale or the borehole and surface seismic scale? In some cases these measurements of anisotropy at different scales are so diverse that they have opposed signs. Even within the simplifying anisotropic assumptions of seismically derived VTI or HTI stiffness tensor, there are challenges in usefully applying our understanding to completions engineering as it is well known that VTI increases the minimum closure stress gradient while the fact that HTI decreases the stress gradient is almost totally unknown. This is an added benefit of fractures that might benefit from more detailed rock physics measurements and analysis.

Advice for early career scientists (rock physicists, geophysicists, etc.)

It is essential to establish a goal even if this changes over time. This ensures that the pursuit of knowledge, understanding and enlightenment to achieve the goal is focussed and compelling. However having a goal is not in itself enough to ensure success. One must have a driving passion to achieve the goal and the good fortune to have a supportive organization with enlightened management supervision and thought provoking colleagues. These last few points are beyond one’s complete control but you must strive to position yourself for such an opportunity as they are infrequent and difficult to come by. As I noted in my career history I had the considerable good fortune over a period of nearly 20 years to enjoy relatively robust job stability and an extremely supportive management that encouraged me and my colleagues to pursue our wildest ideas to accomplish some interesting, even ground breaking applied seismology. The best working environment is one that that encourages experimentation and backs it up with flexibility and money; an environment that allows the joy of thinking freely and brainstorming with colleagues.

Always look for a better way to solve a problem, and don’t feel the need to use existing tools; if you don’t see the best tool in the toolbox then invent new tools.

Always look at the big picture. Try to adapt and combine seismic rock physics theory and methods with techniques from geology, engineering and other disciplines to corroborate and characterize the subsurface so as to efficiently exploit the extraction of hydrocarbon resources. This helps to gauge whether we are fooling ourselves or making reasonable predictions.

Always maintain and grow your computer literacy and expertise as well as ensuring your programming skills are at the forefront of your skill set.

And finally allow your imagination to roam over as wide a range of possibilities that your stamina and passion can reasonably explore in the development of new concepts and solutions.

We thank Bill for his continuous contributions to the rock physics community.

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