G. Michael Hoversten

Employment History

9/98 - present, Staff Scientist Lawrence Berkeley National Laboratory

Initiated a project to use surface and borehole electromagnetic (EM) methods for near surface characterization at the DOE Hanford site. Work over the last two years has focused on experiments to image subsurface flow of waste using EM, one at a surface leak test and another at a mock storage tank site where crosswell EM is being used to image small amounts of leaking tank waste. A second on going project is a collaborative effort with Sandia National Laboratories to develop innovative new three dimensional surface EM imaging systems and algorithms. The systems and algorithms are being deployed to image clastic dike structures at potential new waste storage installations at Hanford.

Developed a research program in integrated seismic & cross well electromagnetics for reservoir monitoring funded by the DOE Oil and Gas Partnership, industry partners include Chevron, Texaco, EMI and TomoSeis. Current areas of active research are 1) integrated geophysical modeling for petroleum exploration and reservoir monitoring, 2) joint inversion of geophysical data. In support of the integrated geophysical modeling an extensive Motif based modeling system has been developed that is linked to underlying forward and inverse modeling codes for 3D gravity, gravity-gradients, 2&3D elastic seismic, 2&3D electromagnetic, 2&3D magnetotellurics and 2&3D reservoir simulation (VIP Therm & Tough2). The modeling system allows the user to construct and visualize 3D models that simultaneously carry porosity, Sw, Sg, temperature, pressure, Vp, Vs, density and electrical resistivity. From the interface 3D models can be built starting from seismic data surfaces and well logs or from reservoir simulation runs. The system is currently being used to quantify the time-lapse effects on surface seismic, gravity and crosswell EM during water, steam and CO₂ flood of reservoirs.

Joint inversion work has concentrated on algorithm development for jointly inverting gravity and magnetotelluric data (in support of our previously Marine Magnetotellurics for base salt mapping consortium) for a model with common structure with resistivity and density linked via log derived constitutive relations. New work is concentrating on joint acoustic impedance - gravity inversion as well as joint electromagnetic Ð full waveform seismic inversion.

9/93 - 9/98, Research Geophysicist, University of California, Berkeley

Developed a research program, funded by a consortium of major oil companies, for electromagnetic imaging of salt structures in the Gulf of Mexico and for the development of new joint inversion techniques to accommodate seismic, potential fields and electromagnetic data. Developed a research program with SAGA Petroleum for a numerical feasibility study of the application of cross-well electromagnetics for monitoring reservoir water flooding. Developed Unix Motif based graphical user interfaces for geophysical numerical modeling codes under a project for the USGS to enhance geophysical capabilities in environmental site characterization. Developed new 3D numerical modeling code for simulating the EM response of thin conductive 3D sheets buried within a layered earth. Developed a 3D EM modeling package which is linked to a 3D reservoir simulator in order to simulate the time varying response of borehole logging systems to reservoir treatments such as steam flood and water injection.

Extensive development of Motif based electromagnetic data interpretation systems. One package is for 1,2 & 3 dimensional forward and inverse modeling of MT data named ÒMTWORKSÓ MTWORKS is distributed worldwide by the Engineering Geoscience group to mining and petroleum companies. A second major package is for 2 and 3D forward and inverse modeling of finite source EM data, ÒEM3DÓ which includes airborne, surface and cross well capability. The development of EM3D represents a collaborative effort with Sandia National Laboratory making use of the algorithm development by Newman & Alumbaugh.

3/92 - 9/98, Pinecrest Geophysical Software (consulting)

Established PGS as a geophysical consulting and custom geophysical software development firm. PGS specialized in graphical user interfaces for geophysical modeling packages developed by industry and academia. Consulting clients include; BP America, BP Research Sunbury, BHP Petroleum, Chevron Overseas Petroleum, Geothermex, Mt. Isia Minning, Sandia National Laboratory.

8/83 - 2/92, Sr. Geophysicist, British Petroleum

Exploration and Production Research Division, BP Research Sunbury England

Research the practical application of EM exploration techniques to the problems encountered in petroleum exploration. Enhanced existing university EM modeling codes for use by geophysical interpreters. Developed an interactive version of a two dimensional MT inversion algorithm. The interactive 2D inverse package became the primary MT interpretation tool for BP's exploration efforts in Papua New Guinea (PNG). Performed detailed 2 and 3 dimensional interpretations of PNG data that led to an invited paper at the 1992 EAEG in Paris on the use of MT in Papua New Guinea. Applied DC resistivity modeling and inversion algorithms to the sea floor mapping of carbonate deposits caused by hydrocarbon seepage. Successfully demonstrated the potential of using sea floor EM techniques for mapping the base of salt in the Gulf of Mexico where seismic imaging fails.

Interactive Processing/Prestack Interpretation Workstation Development

Group leader for interactive processing/prestack interpretation workstation. Responsible for software design of post and prestack seismic data interpretation system including seismic and well log database. Responsible for work planning for 4 geophysical programmers, production of 2 year work plan with man-month development estimates and quarterly goals. The system was written in FORTRAN and C using VAX UIS graphics primitives. The system was delivered on time with all production goals met. Geophysical analysis provided to BP Exploration operating divisions. Perform specialized seismic inversion analysis in difficult areas to evaluate the potential of using seismic trace inversion to estimate net pay in reservoir intervals.

BP Geophysical Research & Technical Service, London

Special assignment for development work on the seismic exploration workstation. Developed new exploration software including: Log manipulation and editing, calibration, wavelet extraction, synthetic seismogram generation, various CMP trace inversion techniques.

Seismic Interpretation/Software Development Group

Development team member for BP's interactive 2D & 3D seismic interpretation workstation. Interactive applications developed: menu driven 1D & 2D seismic modeling codes, stereo imaging of 3D seismic data with stereo digitizing of 3D horizons, CMP inversion using trace integration, constrained least squares and linear programming. Directed pre-drilling reservoir evaluation, including sand/shale thickness and sand porosity maps generated from inversion, modeling and well log correlations. Performed amplitude versus offset processing and modeling for interpretation. Use 3D finite-element and ray trace forward modeling to verify interpretations. Perform structural and stratigraphic interpretation of 2D and 3D seismic land (north slope, mid-continent) and sea (gulf of Mexico, Arabian gulf, North Sea) data.

Geophysical Special Projects (Electrical and Gravity Group)

Responsible for electrical and electromagnetic (EM) modeling codes. Directed EM modeling and inversion code development by University and private contractors. Developed interpretation schemes for finite source time domain EM and induced polarization (IP) data, including criteria for the appropriate use of multi-dimensional modeling codes for interpretation of field data. Produced 2D structural models subsequently confirmed by drilling using IP, and magnetotelluric data in seismic "bad data" areas. Performed numerical model studies to assess spatial resolution of 2D inverse models for MT data in overthrust geology's. Performed data interpretation and prepared reports on MT, TDEM, and IP survey data for a wide range of geologic settings.

2/81 - 7/83, Post Doctoral Fellow, University of California, Berkeley

Assisted development of 3D integral equation and 2D hybrid finite element-integral equation EM modeling codes. Optimized computing time of CPU intensive finite element codes. Performed resolution study of inversion results for conductive targets beneath conductive overburden. Produced catalogs of responses for currently popular EM prospecting methods.