Michael Hoversten

Chevron (Netherlands)

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Erika Gasperikova

Lawrence Berkeley National Laboratory

H. F. Morrison

University of California, Berkeley

Gregory A. Newman

Lawrence Berkeley National Laboratory

David Alumbaugh

Lawrence Berkeley National Laboratory

Jinsong Chen

National Engineering Research Center of Electromagnetic Radiation Control Materials

C. Riveros

Gary L. Oppliger

University of Nevada, Reno

N.E. Goldstein

Lawrence Berkeley National Laboratory

David Pardo

University of the Basque Country

Tage Røsten

Equinor (Norway)

Cooperative Institutions

Chevron (United States)

University of California, Berkeley

Chevron (Netherlands)

Lawrence Berkeley National Laboratory

Schlumberger (United States)

NASA Earth Science

Schlumberger (United Kingdom)

Chevron (China)

Schlumberger (British Virgin Islands)

Schlumberger (Norway)

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Simulation of marine controlled source electromagnetic measurements using a parallel fourier hp-finite element method

Computational Geosciences (2010)

David Pardo Myung Jin Nam Carlos Torres‐Verdín Michael Hoversten Iñaki Garay

10.1007/s10596-010-9195-1

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Citations (26)

Sharp boundary inversion of 2D magnetotelluric data

Geophysical Prospecting (1999)

Torquil Smith Michael Hoversten Erika Gasperikova Frank Morrison

We consider 2D earth models consisting of laterally variable layers. Boundaries between layers are described by their depths at a set of nodes and interpolated laterally between nodes. Conductivity within each layer is described by values at a set of nodes fixed within each layer, and is interpolated laterally within each layer. Within the set of possible models of this sort, we iteratively invert magnetotelluric data for models minimizing the lateral roughness of the layer boundaries, and the lateral roughness of conductivities within layers, for a given level of data misfit. This stabilizes the inverse problem and avoids superfluous detail. This approach allows the determination of boundary positions between geological units with sharp discontinuities in properties across boundaries, while sharing the stability features of recent smooth conductivity distribution inversions. We compare sharp boundary inversion results with smooth conductivity distribution inversion results on a numerical example, and on inversion of field data from the Columbia River flood basalts of Washington State. In the synthetic example, where true positions and resistivities are known, sharp boundary inversion results determine both layer boundary locations and layer resistivities accurately. In inversion of Columbia flood basalt data, sharp boundary inversion recovers a model with substantially less internal variation within units, and less ambiguity in both the depth to base of the basalts and depth to resistive basement.

Magnetotellurics

Classification of discontinuities

10.1046/j.1365-2478.1999.00145.x

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Citations (98)

Description, field test and data analysis of a control-source EM system (EM-60). [Grass Valley]

H. F. Morrison N.E. Goldstein Michael Hoversten Gary L. Oppliger C. Riveros

Good results with electromagnetic (EM) systems led to the development of the EM-60 system, the number related to the 60 kW output of the motor generator used. The transmitter, the receiver, and data interpretations for the Grass Valley field test are described. (MHR)

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Stochastic full-waveform inversion (SWI) of seismic data for FWI starting models

Jinsong Chen Uwe Albertin Kurt T. Nihei Sam T. Kaplan Michael Hoversten

Current approaches for FWI based on a waveform misfit objective function have been demonstrated to be effective for high-fidelity imaging of acoustic and elastic properties, when starting from velocity models that are within the basin of attraction of the true velocity model. Such initial models need to include the long-wavelength structure sufficiently and accurately so that the synthetic and observed data misfit is less than half of a wavelength. If this condition is violated, gradient-based optimization methods can converge to a local rather than the desired global solution. Over the past several years, a clear focus of FWI research has been centered on finding new cycle-skip immune approaches for FWI by using a range of data, image and modeling domain objective functions. In this study, we develop a stochastic full waveform inversion (SWI) approach within a Bayesian framework to estimate the long wavelength starting model for FWI. We use Markov Chain Monte Carlo (MCMC) methods to draw many samples from model space described by sparse and smooth Gaussian radial basis functions (RBF). We demonstrate the effectiveness of SWI using a 2D marine synthetic salt model. Starting from a water bottom over half space model, SWI recovers a long wavelength starting model that allows standard least-squares FWI to correctly recover the true structure of the salt. Presentation Date: Tuesday, October 13, 2020 Session Start Time: 1:50 PM Presentation Time: 3:30 PM Location: Poster Station 3 Presentation Type: Poster

10.1190/segam2020-3418905.1

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A sampling-based Bayesian model for gas saturation estimationusing seismic AVA and marine CSEM data

Geophysics (2006)

Jinsong Chen Michael Hoversten D. W. Vasco Yoram Rubin Zhangshuan Hou

We develop a sampling-based Bayesian model to jointly invertseismic amplitude versus angles (AVA) and marine controlled-sourceelectromagnetic (CSEM) data for layered reservoir models. The porosityand fluid saturation in each layer of the reservoir, the seismic P- andS-wave velocity and density in the layers below and above the reservoir,and the electrical conductivity of the overburden are considered asrandom variables. Pre-stack seismic AVA data in a selected time windowand real and quadrature components of the recorded electrical field areconsidered as data. We use Markov chain Monte Carlo (MCMC) samplingmethods to obtain a large number of samples from the joint posteriordistribution function. Using those samples, we obtain not only estimatesof each unknown variable, but also its uncertainty information. Thedeveloped method is applied to both synthetic and field data to explorethe combined use of seismic AVA and EM data for gas saturationestimation. Results show that the developed method is effective for jointinversion, and the incorporation of CSEM data reduces uncertainty influid saturation estimation, when compared to results from inversion ofAVA data only.

Overburden

Seismic to simulation

Amplitude versus offset

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Reservoir characterization using crosswell EM inversion: A feasibility study for the Snorre Field, North Sea

Geophysics (1999)

Michael Hoversten Gregory A. Newman H. F. Morrison Erika Gasperikova Jr Berg

North sea

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3D Magnetotelluric characterization of the COSO GeothermalField

Gregory A. Newman Michael Hoversten Erika Gasperikova Philip E. Wannamaker

Knowledge of the subsurface electrical resistivity/conductivity can contribute to a better understanding of complex hydrothermal systems, typified by Coso geothermal field, through mapping the geometry (bounds and controlling structures) over existing production. Three-dimensional magnetotelluric (MT) inversion is now an emerging technology for characterizing the resistivity structures of complex geothermal systems. The method appears to hold great promise, but histories exploiting truly 3D inversion that demonstrate the advantages that can be gained by acquiring and analyzing MT data in three dimensions are still few in number. This project will address said issue, by applying 3D MT forward modeling and inversion to a MT data set acquired over the Coso geothermal field. The goal of the project is to provide the capability to image large geothermal reservoirs in a single self-consistent model. Initial analysis of the Coso MT data has been carried out using 2D MT imaging technology to construct an initial 3D resistivity model from a series of 2D resistivity images obtained using the inline electric field measurements (Zxy impedance elements) along different measurement transects. This model will be subsequently refined through a 3D inversion process. The initial 3D resistivity model clearly shows the controlling geological structures possibly influencing well production at Coso. The field data however, also show clear three dimensionality below 1 Hz, demonstrating the limitations of 2D resistivity imaging. The 3D MT predicted data arising from this starting model show good correspondence in dominant components of the impedance tensor (Zxy and Zyx) above 1Hz. Below 1 Hz there is significant differences between the field data and the 2D model data.

Magnetotellurics

Electrical Resistivity Tomography

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Model Reduction via Principe Component Analysis and Markov Chain Monte Carlo (MCMC) Methods

AGUFM (2011)

Ruoting Gong J. Chen Michael Hoversten Jingru Luo

Component (thermodynamics)

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Analysis of 3d Magnetotelluric Measurements Over the Coso Geothermal Field

AGUFM (2007)

Gregory A. Newman Erika Gasperikova Michael Hoversten

Magnetotellurics

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A 3D model study to investigate EM imaging of sub-basalt structures in a deepwater environment

David Alumbaugh Michael Hoversten Joseph P. Stefani Catherine Thacher

A modeling study has been undertaken to investigate the resolution and accuracy of marine magnetotelluric (MT) and controlled source electromagnetic (CSEM) data to image the base of basalt and sediments in an environment representative of the North Atlantic Margin. The three dimensional (3D) model was constructed using regional well logs, seismic and geologic data to create a cube of porosity and saturation that is 32 km long, 16 km wide and 5 km deep. The porosity and water saturations were then converted to resistivity using well log-derived relationships in the sediments above the basalt, three different volcanic units, sub-volcanic sediments, and flat lying basement. Transverse anisotropy was incorporated in most of the units by making the vertical resistivity more resistive than the horizontal, while the flow basalts were made tridiagonally anisotropic to account for lower resistivities along strike caused by faulting, and higher vertical resistivities caused by the flow structures. Simulated MT and CSEM data were computed using a 3D finite difference algorithm. A two-dimensional (2D) pixilated inversion algorithm was used to produce images of the synthetic MT and CSEM data along lines that were roughly perpendicular to the regional strike of the basalt structure. The images show that the MT data by themselves lack resolution to warrant use alone, but help to constrain the inversion process when jointly inverted with CSEM data. Constraints in the form of a discontinuity at the top of the basalt further enhance image resolution.

10.1190/segam2013-0251.1

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Citations (4)