Theoretical Developments in Electromagnetic Induction Geophysics with Selected Applications in the Near Surface

Near-surface applied electromagnetic geophysics is experiencing an explosive period of growth with many innovative techniques and applications presently emergent and others certain to be forthcoming. An attempt is made here to bring together and describe some of the most notable advances. This is a difficult task since papers describing electromagnetic induction methods are widely dispersed throughout the scientific literature. The traditional topics discussed herein include modeling, inversion, heterogeneity, anisotropy, target recognition, logging, and airborne electromagnetics (EM). Several new or emerging techniques are introduced including landmine detection, biogeophysics, interferometry, shallow-water electromagnetics, radiomagnetotellurics, and airborne unexploded ordnance (UXO) discrimination. Representative case histories that illustrate the range of exciting new geoscience that has been enabled by the developing techniques are presented from important application areas such as hydrogeology, contamination, UXO and landmines, soils and agriculture, archeology, and hazards and climat

Finite Element Time-Domain Body-of-Revolution Maxwell Solver based on Discrete Exterior Calculus

We present a finite-element time-domain (FETD) Maxwell solver for the analysis of body-of-revolution (BOR) geometries based on discrete exterior calculus (DEC) of differential forms and transformation optics (TO) concepts. We explore TO principles to map the original 3-D BOR problem to a 2-D one in the meridian plane based on a Cartesian coordinate system where the cylindrical metric is fully embedded into the constitutive properties of an effective inhomogeneous and anisotropic medium that fills the domain. The proposed solver uses a TE/TM field decomposition and an appropriate set of DEC-based basis functions on an irregular grid discretizing the meridian plane. A symplectic time discretization based on a leap-frog scheme is applied to obtain the full-discrete marching-on-time algorithm. We validate the algorithm by comparing the numerical results against analytical solutions for resonant fields in cylindrical cavities and against pseudo-analytical solutions for fields radiated by cylindrically symmetric antennas in layered media. We also illustrate the application of the algorithm for a particle-in-cell (PIC) simulation of beam-wave interactions inside a high-power backward-wave oscillator.Comment: 42 pages, 19 figure

Technology Survey to Support Revision to the Remedial Investigation/Feasibility Study Work Plan for the 200­-SW­-2 Operable Unit at the U.S. Department of Energy’s Hanford Site

A survey of technologies was conducted to provide information for a Data Quality Objectives process being conducted to support revision of the Remedial Investigation/Feasibility Study Work Plan for the 200-SW-2 Operable Unit. The technology survey considered remediation and characterization technologies. This effort was conducted to address, in part, comments on the previous version of the Remedial Investigation/Feasibility Study Work Plan for the 200-SW-2 Operable Unit as documented in 200­SW­1 and 200­SW­2 Collaborative Workshops―Agreement, Completion Matrix, and Supporting Documentation. By providing a thorough survey of remediation and characterization options, this report is intended to enable the subsequent data quality objectives and work plan revision processes to consider the full range of potential alternatives for planning of the Remedial Investigation/Feasibility Study activities

Casing structural integrity and failure modes in a range of well types: a review.

This paper focus on factors attributing to casing failure, their failure mechanism and the resulting failure mode. The casing is a critical component in a well and the main mechanical structural barrier element that provide conduits and avenue for oil and gas production over the well lifecycle and beyond. The casings are normally subjected to material degradation, varying local loads, induced stresses during stimulation, natural fractures, slip and shear during their installation and operation leading to different kinds of casing failure modes. The review paper also covers recent developments in casing integrity assessment techniques and their respective limitations. The taxonomy of the major causes and cases of casing failure in different well types is covered. In addition, an overview of casing trend utilisation and failure mix by grades is provided. The trend of casing utilisation in different wells examined show deep-water and shale gas horizontal wells employing higher tensile grades (P110 & Q125) due to their characteristics. Additionally, this review presents casing failure mixed by grades, with P110 recording the highest failure cases owing to its stiffness, high application in injection wells, shale gas, deep-water and high temperature and high temperature (HPHT) wells with high failure probability. A summary of existing tools used for the assessment of well integrity issues and their respective limitations is provided and conclusions drawn

A Comparative Overview of Geophysical Methods

This report was prepared with support from the Air Force Research Laboratory, under contract FA8718-07-C-0021.The shallow subsurface structure of the Earth is important to understand for many economic and safety reasons. The problem is usually difficult due to complexity of the earth’s subsurface processes especially near the surface. A number of geophysical methods are used for this purpose using different physical characteristics of the Earth materials. A particular geophysical method illuminates part of the problem, but a reliable solution can only be found by combining results of different methods. In order to synthesize information from different geophysical methods, it is important to understand their similarities and differences. The aim of this study is to correlate the basic principles of geophysical methods side-by-side starting from fundamental equations. This study reveals that many analogies exist among these methods both in their mathematical formulation, and sometimes, in ways they are used in the geophysical applications