Partha S. Routh obtained a B.Sc. with honors (1991) and an M.S. in Exploration Geophysics (1993) from the Indian Institute of Technology, in Kharagpur, and a Ph.D. (1999) from the University of British Columbia (UBC), Canada, with a focus on electromagnetic inversion problems. After a postdoctoral position at UBC–Geophysical Inversion Facility, he joined Conoco Upstream Technology in Oklahoma.
After a post-doc at the UBC-Geophysical Inversion Facility, he joined ConocoPhillips Upstream Technology where he conducted research on pre-stack seismic inversion and imaging and potential field applications. In 2002, he joined the geophysics faculty at Boise State University with a research focus in near-surface environmental geophysics and geothermal applications. He received tenure in 2006.
He has been with ExxonMobil for the past 13 years mostly involved with full waveform inversion (FWI) research and applications through a variety of roles mostly in research and exploration. Over the years, he gained valuable experience applying FWI and imaging in various basins in the world. Currently, he is the Elastic FWI Technology Coordinator in ExxonMobil Technology Company. His primary interests are in area of inverse problems, and their application to seismic using wave equation as well time-lapse. He is active in FWI for imaging, reservoir characterization and monitoring. Partha has authored and co-authored more than 50 publications and 15patents. He is currently an Associate Editor of Geophysics and past-chair of SEG Research committee and past-president of SEG near surface society.
2023 SEG Distinguished Lecturer
New frontiers in full wave-field inversion: Journey towards elastic FWI and direct use of raw seismic data
In this talk we strive to move closer to the vision of extracting full value from seismic data proposed by Tarantola in 1986 where the goal is inferring elastic properties of the subsurface via full physics driven solution - elastic full-wavefield inversion (eFWI). Over the past two decades, tremendous progress has been made in FWI and its application to many datasets from various geological basins in the world. The progress has mostly focused on acoustic FWI to determine high resolution velocity models of the subsurface to improve imaging either via ray based and/or wave-based imaging algorithms. In geologically complex areas, FWI can capture velocity variations at a scale useful for both imaging and acoustic property inversion, beyond what can be obtained with conventional methods. In a strongly elastic medium, acoustic physics can fall short in explaining the data and introduce errors in the results that can be difficult to quantify. Therefore, to fully explain the amplitudes of seismic data from near to far offsets elastic physics is necessary. The cost of solving eFWI is much more compared to acoustic FWI and for a 3D field scale application it would be not possible without significant advancements and investment in computer hardware and algorithms.
Elastic property inversion typically relies on post-migrated gathers or angle stacks to infer AVO (amplitude versus offset) information. Bandlimited P-impedance (Ip), Vp/Vs are routinely inverted from angle gathers with an estimated wavelet derived from available well. Data required for such inversions depend on several processing steps to preserve primary only reflection. These processing steps enable convolution physics to be applied in a local window where the wavelet is stationary. If processing can mitigate non-primary noise, and elastic contrasts are weak, convolution approach works well. In complex geological setting, such as hard/strong contrasts such as presence of sharp geological boundaries, the presence of non-primary reflection modes in the data (e.g., refractions, converted waves, internal multiples, and diffracted multiples) and varying illumination it can be challenging for processing steps to mitigate such effects completely.
This DL talk is a broad overview of elastic FWI technology mostly aimed at non-experts, with the goal of discussing the benefits and challenges of eFWI and some of the practical insights into integrating with conventional seismic imaging, geological information, rock properties, to extract the maximum value. Figure 1 shows the differences between conventional inversion approach and eFWI. In conventional approach the data are increasingly simplified to conform to convolution physics whereas in eFWI the shot data are directly inverted via anisotropic visco-elastic physics to produce 3D elastic properties of subsurface. Like acoustic FWI, acquisition details are an important consideration for successful application of eFWI. I will also discuss the use of raw data after nav-merge directly in the eFWI framework that requires very minimal to no processing with the potential to accelerate extraction of subsurface information faster. Using examples from exploration and development settings, I will present the value eFWI brings to the upstream decision-making process and discuss future areas of improvements.
A recording of the lecture is available.
2022 SEG Honorary Lecturer, North America
Full wave-field inversion: Journey towards practical applications
The vision of extracting the full value from seismic data via full-wavefield inversion (FWI) has been around since the inception of the method in the early 1980’s. Over the past two decades, tremendous progress has been made in addressing FWI’s technical challenges and moving the technology closer to realizing its ultimate vision. Key hallmarks of this technology range from rapidly creating significantly improved velocity models for imaging purposes, to obtaining subsurface physical properties directly from seismic data. In geologically complex areas FWI can capture velocity variations at a scale useful for both imaging and property inversion, beyond what can be done with conventional methods. None of these advances would be possible without significant improvements and investment in computer hardware and algorithms.
This HL talk is a broad overview of FWI technology mostly aimed at non-experts, with the goal of discussing the impactful vision of FWI, its early challenges, advancements in methodologies to solve large scale ill-posed inverse problem with practical insights into integrating FWI with conventional approaches to extract maximum value. Figure 1 shows the differences and synergy between conventional seismic data processing and FWI. As expected, the reliability of the results is dependent on the input data, therefore acquisition details are an important consideration for successful application of FWI. Thus, FWI has been a key influence on the advancement of acquisition technology, in particular acquiring long offsets and low frequencies.
The issues associated with FWI are complex and rich. For this talk, I will mostly focus on acoustic physics in an attenuative and anisotropic setting. Addressing these pressing technical challenges requires ideas that are a mix of algorithm innovation, computational advancements, and problem-dependent workflows to move toward the goal of providing high-quality subsurface images at a resolution and scale that provides value to our business. Using examples from exploration and development settings, I will present the value FWI brings to the upstream decision-making process. I will end the talk with a discussion on the choice of physics. In a strongly elastic medium, acoustic physics can fall short in explaining the data and introduce errors in the results. In a future DL talk, I will expand on the elastic aspect of FWI and discuss the opportunity and associated challenges when higher level of physics is introduced.
A recording of the lecture is available.
SEG Best Paper Presented at the Annual Meeting Award 2012 
Partha S. Routh, Gopal Palacharla, Ivan Chikichev, Spyros Lazaratos received 2012 SEG Best Paper Presented at the Annual Meeting Award for their paper Full wavefield inversion of time-lapse data for improved imaging and reservoir characterization.
- Honors and Awards Program 2013 SEG Annual meeting, 4:30–5:30 p.m., Sunday 22 September 2013 George R. Brown Convention Centerm Level 3, George Bush Grand Ballroom, Houston, Texas USA p. 43