中文的技术文献
自然场技术论文
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自然场技术论文
应用实例
索引
- Investigations of Different Survey Techniques and Inversion Strategies For Detecting Water-Bearing Structures with TDEM
March 2017. R.W.Groom and Lei Yang. 2017 SAGEEP Annual Symposium, Denver, Colorado. - EMIT Maxwell Comparisons to PEI Freespace Plate
Nov 2016. R.W.Groom and Bob Lo. - Discussions on Resolution of Different TDEM
Survey Techniques for Detecting Water-Bearing
Structures
June 2016. Lei Yang and R.W.Groom. 7th International Conference on Environmental and Engineering Geophysics, Beijing, China. - Application of 3D CSAMT Inversion to Various Data Components and its Enhancement
March 2013. Ruizhong Jia and R.W.Groom. 2013 SAGEEP Annual Symposium, Denver, Colorado. - Investigation of gold-bearing veins using magnetics and time domain electromagnetics
Dec 2012. L.J Davis and R.W.Groom. 45th AGU Fall Meeting, San Francisco, California. - Investigation of gold-bearing veins in Charters Towers, Australia using magnetics and TEM
Apr 2012. L.J Davis and R.W.Groom. Internal Report. - A Comparison of Airborne and Ground EM Data at a Calibration Site near the Grand Canyon
Nov 2011. Laura Davis, Ruizhong Jia and Ross Groom. 10th CIGEW Workshop, Nanchang, China. - 1D-Time Domain Inversion Incorporating Various Data Strategies with a Trust-Region Method
Nov 2011.Ruizhong Jia, L.J. Davis and R.W. Groom. 10th China International Geo-Electromagnetic Workshop, Nanchang, China - Preliminary Modeling of the Magnetic Effects of Steel Casings
May 2011. L.J. Davis and R.W. Groom. Internal Report. - X-Hole Tomography.
2011. R.W. Groom. Internal Report - Crosshole Radio Imaging Tomography
2011. R.W.Groom. Internal Report - Deep, Accurate Structural Interpretations through Time Domain EM Techniques
May 2010. L.J. Davis and R.W. Groom. GeoCanada 2010 Conference, Calgary, Canada. - Calibration of Airborne TEM with Ground TEM. Two Case Studies in Arizona.
April 2010. L.J. Davis. Workshop on Airborne EM, 2010 SAGEEP Annual Symposium, Keystone, Colorado. - A Comparison of airborne and ground Electromagnetic data near the Grand Canyon
Feb 2010. L.J. Davis and R.W. Groom. Internal Report. - Inference of lithologic distributions in an alluvial aquifer using airborne transient electromagnetic surveys
2009. Jesse E. Dickinson, D.R. Pool, R.W. Groom, and L.J. Davis. Accepted with minor revisions, Geophysics. - Some issues on 1d-TEM inversion utilizing various multiple data strategies
Oct 2009. Ruizhong Jia, L.J. Davis, and R.W. Groom. 79th SEG Conference, Houston, Texas. - A comparison of airborne and ground electromagnetic data near the Grand Canyon
Oct 2009. L.J. Davis and R.W. Groom. 79th SEG Conference, Houston, Texas. - New Approaches To Topographic Gravity Corrections
April 2009. Ruizhong Jia, Laura Davis and R.W. Groom. 2009 SAGEEP Annual Symposium, Fort Worth, Texas. - Airborne - EM Hydrocarbon Mapping In Mozambique
Feb 2009. Andreas Pfaffling, Ståle Monstad, Ross W. Groom and Jonathan Rudd.
21st ASEG-PESA Conference, Sydney, Australia. - Traditional EM & onshore hydrocarbon exploration
Oct 2008. Andi Pfaffling and Ross W. Groom. EAGE Non-Seismic Workshop, Manama, Bahrain. - Processing gradients of magnetic data utilizing an equivalent source technique
Sept 2007. Ruizhong Jia and R.W. Groom. 77th SEG Conference, San Antonio, Texas. - Airborne EM Data Comparisons in a Sedimentary Basin
Sept 2007. Laura Davis and Ross Groom. Exploration 2007, Toronto, Canada. - Enhancing Model Reliability from TEM Data Utilizing Various Multiple Data Strategies
April 2007. Ruizhong Jia and R.W. Groom. 2007 SAGEEP Annual Symposium, Denver, Colorado. - Enhancing Model Reliability from TEM Data Utilizing Various Multiple Data Strategies
2007. Ruizhong Jia and R.W. Groom. KEGS Symposium, Toronto, Canada. - Vertical Spatial Sensitivity and Exploration Depth of Low-Induction-Number Electromagnetic-Induction Instruments
2007. James B. Callegary, Ty P.A. Ferré and R.W. Groom. Vadose Zone Journal 6:158-167. - Aerial Transient Electromagnetic Surveys of Alluvial Aquifers in Rural Watersheds of Arizona, United States
2006. Pool, Callegary and Groom. 2006 AGU Fall Meeting, San Francisco, California. - Processing gradients of magnetic data utilizing an equivalent technique.
Ruizhong Jia and R.W. Groom. - Magnetic Case Study: Raglan Mine
2006. Laura Davis. Internal Report. - Geophysical case study of the Iso and New Insco deposits, Québec, Canada: Part II, modeling and interpretation
2006. Li Zhen Cheng. Reviewed Draft. Exploration and Mining Geology, January 2006, vol. 15, no. 1-2, p. 65-74. - Comparison of Theoretical and Physical Model Studies of the Responses of Moving Source and Fixed Loop Electromagnetic Exploration Systems
2005. K. Duckworth. Pure and Applied Geophysics, December 2005, vol. 162, no. 12, p. 2505-2521. - Inversion of Ground Gravity and Airborne Gradient Data
Nov 2005. Ruizhong Jia, Ross Groom and Bob Lo. 75th SEG Conference, Houston, Texas. - On some issues regarding 3D-gravity inversion
Nov 2005. Ruizhong Jia and R.W. Groom. 75th SEG Conference, Houston, Texas. - 3-D sensitivity distribution of low-induction-number frequency-domain electromagnetic instruments
2005. James B. Callegary, Ty P.A. Ferré and R.W. Groom. 2005 AGU Fall Meeting, San Francisco, California. - On Time-Domain Transient Electromagnetic Soundings, Extended Abstract
2005. Ruizhong Jia and Ross Groom. 2005 SAGEEP Annual Symposium, Atlanta, Georgia. - Final Report On Improved Aeromagnetic Compensation: A New Aircraft Compensation System for Magnetic Terrains
2004. John Jia, Bob Lo and Ross Groom. OMET Report. - The Use of GPS Sensors and Numerical Improvements in Aeromagnetic Compensation. Extended Abstract
2004. Ruizhong Jia, R.W. Groom and Bob Lo. SEG. 74th SEG Conference, Denver, USA. - Magnetic Compensation of magnetic noise related to aircraft's maneuvers in airborne survey. Extended Abstract
2004. R.W. Groom, Ruizhong Jia and Bob Lo. 2004 SAGEEP Annual Symposium, Colorado Springs, Colorado. - Exploring for Groundwater with Electromagnetic Methods
2004. Ross Groom. Internal Report. - Coal Authority Phase 2: Theoretical Modelling Study
April 2004. R.W.Groom. UK Coal Authority. - On Inversion of Gradient Magnetic Data for Detection of Multiple Buried Metallic Objectives. Extended Abstract
2004. Ruizhong Jia and R.W. Groom. 2004 SAGEEP Annual Symposium, Colorado Springs, Colorado. - Inversion of Magnetic and Gradient Magnetic Data For Detection and Discrimination of Metallic Objects
2003. Ross Groom. EAGE, 9th European Meeting, Prague, Czech Republic. - Investigations into Inversion of Magnetic and Gradient Magnetic Data for Detection and Discrimination of Metallic Objects. Extended Abstract
2003. R.W. Groom, Ruizhong Jia and C. Alvarez. 2003 SAGEEP Annual Symposium, San Antonio, Texas. - UXO Applications for Geophysics
2002. PetRos EiKon. Internal Report. - 3D EM Modelling - Application of the Localized Non-Linear Approximator to Near Surface Applications. Extended Abstract
2002. R. Groom and C. Alvarez. 2002 SAGEEP Annual Symposium, Las Vegas, Nevada. - Some Pitfalls in Gradient Magnetic Processing or Why Rotate Gradients
2002. R.W. Groom and Bob Lo. KEGS Symposium, Toronto, Canada. - Improved Depth Distributions by Inversion of Magnetic Surveys Collected at Different Survey Heights
2002. Bob Lo and R.W. Groom. KEGS Symposium, Toronto, Canada. - An Inverse Magnetic Problem
2002. Ruizhong Jia. Internal Report. - 3D Modelling of Near Surface Problems
2002. PetRos EiKon. Internal Report. - Development in a normal mode helical electrical antennae crosshole instrumentation and integrated interpretation system. Extended Abstract
2001. R.W. Groom and C. Candy.
2001 Symposium on the Application of Geophysics to Environmental and Engineering Problems, Denver, Colorado. - X-hole Tomography. A New Frontier in Equipment and Software
2001. R.W. Groom and C. Candy. KEGS Symposium, Toronto, Canada. - Mag 3D Inversion
2000. PetRos EiKon. Internal Report. - An Interpretation Study of Pulse EM Reconnaissance Data from the Raglan Belt of Northern Canada, Extended Abstracts
1999. Groom, R.W., Murray, Alvarez, C. and North, J. 3D Symposium, Salt Lake City, Utah. - Modelling of complex electromagnetic targets using advanced non-linear approximator techniques, Extended Abstracts
1999. Murray, I. R., Alvarez, C. and Groom, R.W. 69th SEG Conference, Houston, Texas. - On Extending the Localized Non-Linear Approximation to Inductive Modes Extended Abstracts
1997. Murray, I.R. F004, 59th EAGE Conference, Geneva, Switzerland. - A case study on the application of the EMIGMA modelling package to Crone data over the SOQUEM Lac Volant Region, Sept-Îles, Québec, Extended Abstracts
1996. Parker, D.H, Boivin, M., Murray, I. R and Groom, R.W. 67th SEG Conference, Dallas, Texas. - A case study of the application of the EMIGMA modelling package in interpretation of UTEM data over the Cominco Cerattepe deposit in Turkey, Extended Abstracts
1996. Groom, R.W., Hyde, C.H. and Lajoie, J. 66th SEG Conference, Denver, Colorado. - Beyond the Born and Rytov Approximations: A Nonlinear Approach to Electromagnetic Scattering
1993. Habashy T. M, Groom, R.W. and Spies. B.R. Journal of Geophysical Research, 98, no. B2, p. 1759-1775.
Full Listing
- Title:
- Investigations of Different Survey Techniques and Inversion Strategies For Detecting Water-Bearing Structures with TDEM
- By:
- March 2017. R.W.Groom and Lei Yang. 2017 SAGEEP Annual Symposium, Denver, Colorado.
- Description:
- In the last decade, the CNNC has performed many kilometers of ground time domain measurements in the basins of northwest China. These measurements have all been made at the centre of a small loop which is moved in short loop-size steps along survey lines. In this environment, for several hundred meters in depth, there are alternating clay and sandstone layers both of fairly low resistivity. One relatively deep sandstone structure is water bearing and where it thins, water is trapped. These traps are utilized to recover water for drinking and irrigation but are also possible locations of roll-front uranium deposit and thus the principle aim of the surveys is to map this water bearing sandstone. Beginning in 2012, we have been carrying out experiments in survey and inversion techniques to understand how to more accurately resolve shallow strata.
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- Title:
- EMIT Maxwell Comparisons to PEI Freespace Plate
- By:
- Nov 2016. R.W.Groom and Bob Lo.
- Description:
- It is our understanding that the Maxwell algorithm is derived from the MultiLoop 1 formulation of Lamontagne Geophysics. PEI freespace plate (EikPlate FS) is based on the basic mathematical formulation of P.Annan in his PhD Thesis (1974). The derivation of the algorithm is a completely new implementation and does not follow the older UofT Plate algorithm of A.Dyck (1980's) or the later version by R.Groom (1994).
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- Title:
- Discussions on Resolution of Different TDEM Survey Techniques for Detecting Water-Bearing Structures
- By:
- June 2016. Lei Yang and R.W.Groom. 7th International Conference on Environmental and Engineering Geophysics, Beijing, China.
- Description:
- It is common when using TDEM to measure only inside the transmitter loop. In groundwater and environmental applications, this is almost ubiquitous. This situation arose, historically, as inversion applications only were available for central loop readings (Anderson, 1993) and geoscientists thought of such readings as soundings similar to resistivity sounding applications. But, should we consider TDEM data as analogous to reflection data and measure proximate to the source or as analogous to refraction data and measure away from the source? In mining applications, three-dimensional modeling has long been available and the use of multiple measurements inside and outside loops has been common for three decades. In this paper, we examine several misunderstandings and problems associated with inloop approaches by comparing results from different TDEM survey techniques. We utilize both synthetic and field data for our studies.
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- Title:
- Application of 3D CSAMT Inversion to Various Data Components and its Enhancement
- By:
- March 2013. Ruizhong Jia and R.W.Groom. 2013 SAGEEP Annual Symposium, Denver, Colorado.
- Description:
- We have developed a 3D inversion algorithm for CSAMT data incorporating a constrained trust-region technique. The algorithm is not limited by assumption regarding the farfield as we utilize a controlled source approach utilizing the specifics of the grounded transmitter incorporating not only the injected currents but also the induced fields from the transmitted magnetic fields. The inversion technique can be termed a quasi-Newton method with a fast convergence rate. The inversion algorithm can invert the electric fields, magnetic fields and/or impedance data to obtain a 3D resistivity distribution. We first utilize a synthetic example to demonstrate inverting the electric field data and impedance data.
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- Title:
- Investigation of gold-bearing veins using magnetics and time domain electromagnetics
- By:
- Dec 2012. L.J Davis and R.W.Groom. 45th AGU Fall Meeting, San Francisco, California.
- Description:
- Gold-bearing quartz-sulfide veins have been mined near Charters Towers, Queensland, Australia for over a century. The gold is occurs in very small lenses that are difficult to find by drilling and standard geophysical techniques. In such granitic environments, the typical technique is IP but here we try different methods. Ground TEM data were collected at a site at which there are two known gold-bearing structures. Airborne magnetic data at the site are also available. The purpose of our studies was to determine if these geophysical methods could locate the known structures and to better understand their geometry and thus assist in detecting the small lode structures. Modeling of the TEM data indicates that the structures which include the mineralized veins are weakly conductive and are actually composed of multiple structures in close proximity. The TEM structural interpretation has a close correlation to linear anomalies in the magnetic data caused by low-susceptibility material. These anomaly types correlate not only at the known gold-bearing structures, but also at new structures. A summary of the exploration process to-date is presented.
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- Title:
- Investigation of gold-bearing veins in Charters Towers, Australia using magnetics and TEM
- By:
- Apr 2012. L.J Davis and R.W.Groom. Internal Report.
- Description:
- Gold-bearing fractures have been mined near Charters Towers, Queensland, Australia for over a century. Sulfides and high concentrations of gold are precipitated from fluids in very small lenses that are difficult to find by drilling and standard geophysical techniques. While ground timedomain electromagnetic (TEM) is normally used in mining for exploring for strong conductors, this paper demonstrates that precise knowledge of the equipment characteristics and accurate 3D modeling can allow accurate exploration for weak conductors. Ground TEM data were collected at a site at which there are two known gold-bearing structures. Airborne magnetic data at the site are also available. The purpose our studies was to determine if these geophysical methods could locate the known structures and to better understand their geometry. Such knowledge would assist in detecting the small lode structures.
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- Title:
- A Comparison of Airborne and Ground EM Data at a Calibration Site near the Grand Canyon
- By:
- Nov 2011. Laura Davis, Ruizhong Jia and Ross Groom. 10th CIGEW Workshop, Nanchang, China.
- Description:
- Airborne time-domain electromagnetics (TEM) is a popular geophysical method in mineral exploration, allowing large areas to be surveyed. The objective of our study is to determine if airborne TEM can to be used for quantitative interpretation in sedimentary environments by using ground TEM as the basis for calibration of the airborne data. Our calibration site is located near the Grand Canyon, a region that is actively being explored for breccia pipe uranium deposits.
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- Title:
- 1D-Time Domain Inversion Incorporating Various Data Strategies with a Trust-Region Method
- By:
- Nov 2011.Ruizhong Jia, L.J. Davis and R.W. Groom. 10th China International Geo-Electromagnetic Workshop, Nanchang, China
- Description:
- For many years since the early 1980's, in-loop time domain inversions were not only performed but recommended by manufacturers of such equipment including the use of smooth over-parametrized models. For various reasons, we have opposed this simplistic approach and have sought more precise techniques to provide higher resolution models with appropriate physical constraints. In previous research, we have studied the importance of correct system representation and how to provide more precise under-parametrized and geologically constrained models. In this paper, we have developed a constrained trust-region method to jointly invert the data of multiple stations and multiple components so as to explore the importance of utilizing multiple data elements to provide accurate and reliable results. This method has a fast convergence rate and can incorporate known geological information.
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- Title:
- Preliminary Modeling of the Magnetic Effects of Steel Casings
- By:
- May 2011. L.J. Davis and R.W. Groom. Internal Report.
- Description:
- To study the effects of a steel casing and to verify the accuracy of our specialized algorithms for modeling such structures, we initially carried out synthetic data studies over planes at various depths below the surface.
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- Title:
- X-Hole Tomography.
- By:
- 2011. R.W. Groom. Internal Report
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- Title:
- Crosshole Radio Imaging Tomography
- By:
- 2011. R.W.Groom. Internal Report
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- Title:
- Deep, Accurate Structural Interpretations through Time Domain EM Techniques
- By:
- May 2010. L.J. Davis and R.W. Groom. GeoCanada 2010 Conference, Calgary, Canada.
- Description:
- Inversion techniques are frequently used by geophysicists when interpreting airborne and ground time-domain electromagnetic data. Here, we examined critical factors for obtaining satisfactory inversion results in deep sedimentary environments. In particular, it was found that a precise knowledge of system parameters is essential, and that seemingly small errors in these parameters may cause misleading inversion results. However, with accurate information of the system parameters exceptionally accurate structural interpretations can be made. We also demonstrate the ability of wide-offset ground TEM to resolve deep structure.
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- Title:
- Calibration of Airborne TEM with Ground TEM. Two Case Studies in Arizona.
- By:
- April 2010. L.J. Davis. Workshop on Airborne EM, 2010 SAGEEP Annual Symposium, Keystone, Colorado.
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- Title:
- A Comparison of airborne and ground Electromagnetic data near the Grand Canyon
- By:
- Feb 2010. L.J. Davis and R.W. Groom. Internal Report.
- Description:
- Airborne time-domain electromagnetics (TEM) is used extensively in mineral exploration for locating conductors. In this study, we examine to what extent airborne TEM may also be used for quantitative geological interpretation, the resolution capabilities of various airborne TEM systems and the comparison of the resolved structures to ground EM data.
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- Title:
- Inference of lithologic distributions in an alluvial aquifer using airborne transient electromagnetic surveys
- By:
- 2009. Jesse E. Dickinson, D.R. Pool, R.W. Groom, and L.J. Davis. Accepted with minor revisions, Geophysics.
- Description:
- Uncertainty in predicting the potential responses of groundwater systems to hydrologic stresses is related to unknown aquifer extent and properties. Much of this uncertainty is related to sparse well data, especially in alluvial aquifer systems typical of the southwestern United States. Significant lithologic distributions in alluvial aquifers can be inferred from resistivity distributions. An airborne TEM survey was completed along 628 km of flight lines in the Upper San Pedro Basin in southeastern Arizona using the GEOTEM system (Fugro Airborne Surveys, Ottawa, Ontario, Canada) for the purpose of mapping resistivity distributions within the alluvial aquifer.
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- Title:
- Some issues on 1d-TEM inversion utilizing various multiple data strategies
- By:
- Oct 2009. Ruizhong Jia, L.J. Davis, and R.W. Groom. 79th SEG Conference, Houston, Texas.
- Description:
- For many years since the early 1980's, inloop TEM inversions were not only performed but recommended by manufacturers of such equipment including the use of smooth over-parametrized models. For various reasons, we have opposed this simplistic approach and have sought more precise techniques to provide higher resolution models with appropriate physical constraints. In previous research, we have studied the importance of correct system representation and how to provide more precise underparametrized and geologically constrained models. Now we have begun exploring the importance of utilizing multiple data elements to provide accurate results.
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- Title:
- A comparison of airborne and ground electromagnetic data near the Grand Canyon
- By:
- Oct 2009. L.J. Davis and R.W. Groom. 79th SEG Conference, Houston, Texas.
- Description:
- In 2007, three time-domain electromagnetic (TEM) airborne surveys were flown for Uranium One in northern Arizona over thick, generally flat-lying sedimentary sequences. Each survey was flown with a different system (MegaTEM, GeoTEM, and VTEM), and data was also collected with each system over a test area for calibration. Ground TEM data was later collected at this site in 2008. The availability of data from three airborne TEM surveys at the test area allows for a unique opportunity for a comparison between these systems and with TEM ground methods. The purpose of our study was to determine whether a single 1D model could be found that is consistent with all of the EM data available at the test area and geological data, as well as to understand the differences in resolution between the different systems.
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- Title:
- New Approaches To Topographic Gravity Corrections
- By:
- April 2009. Ruizhong Jia, Laura Davis and R.W. Groom. 2009 SAGEEP Annual Symposium, Fort Worth, Texas.
- Description:
- The conventional approach of computing a gravity topographic correction from digital elevation models (DEM) involves creating a correction grid at a station by means of interpolation. Obviously, the interpolation process introduces errors in the estimated elevation of the grid points that result in noise of the computed topographic correction. We have developed a new technique to compute the topographic correction by directly utilizing a DEM without creating a grid at each station. Our method avoids the noise introduced in the interpolated elevation of each grid point. Based on a real survey in an area of high relief, we utilized both our technique and the conventional approach to compute the regional topographic corrections with a GTOPO30 DEM produced by the U.S. Geological Survey. The discrepancies between the results of our method and the results generated with the conventional method are partly attributed to the noise introduced in the estimated elevations at the grid points by interpolation. It is shown that the conventional method is dependent upon the grid setting. Our technique does not involve preparing a correction grid at a station and therefore avoids this difficulty. Our method is more efficient because no additional correction grids need to be created by interpolation.
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- Title:
- Airborne - EM Hydrocarbon Mapping In Mozambique
- By:
- Feb 2009. Andreas Pfaffling, Ståle Monstad, Ross W. Groom and Jonathan Rudd.
21st ASEG-PESA Conference, Sydney, Australia. - Description:
- We lay out a case history of a multi-method airborne geophysical survey to assist a hydrocarbon exploration project in central Mozambique. The dedicated targets of the survey are near surface resistivity anomalies caused by hydrocarbon seepage plumes. The geophysical survey concept includes the use of time-domain electromagnetics, magnetometry and gamma-spectrometry applied from rotary and fixed wing aircraft. Preliminary data interpretation, closely tied to 2D seismic information and the regional geological understanding, indicates a successful delineation of a seepage alteration zone just one month after survey completion.
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- Title:
- Traditional EM & onshore hydrocarbon exploration
- By:
- Oct 2008. Andi Pfaffling and Ross W. Groom. EAGE Non-Seismic Workshop, Manama, Bahrain.
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- Title:
- Processing gradients of magnetic data utilizing an equivalent source technique
- By:
- Sept 2007. Ruizhong Jia and R.W. Groom. 77th SEG Conference, San Antonio, Texas.
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- Title:
- Airborne EM Data Comparisons in a Sedimentary Basin
- By:
- Sept 2007. Laura Davis and Ross Groom. Exploration 2007, Toronto, Canada.
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- Title:
- Enhancing Model Reliability from TEM Data Utilizing Various Multiple Data Strategies
- By:
- April 2007. Ruizhong Jia and R.W. Groom. 2007 SAGEEP Annual Symposium, Denver, Colorado.
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- Title:
- Enhancing Model Reliability from TEM Data Utilizing Various Multiple Data Strategies
- By:
- 2007. Ruizhong Jia and R.W. Groom. KEGS Symposium, Toronto, Canada.
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- Title:
- Vertical Spatial Sensitivity and Exploration Depth of Low-Induction-Number Electromagnetic-Induction Instruments
- By:
- 2007. James B. Callegary, Ty P.A. Ferré and R.W. Groom. Vadose Zone Journal 6:158-167.
- Description:
- Vertical spatial sensitivity and effective depth of exploration (de) of low-induction-number (LIN) frequency-domain electromagnetic-induction instruments over a layered soil were evaluated using a complete numerical solution to Maxwell's equations. Previous studies using approximate mathematical solutions predicted a vertical spatial sensitivity for instruments operating under LIN conditions that, for a given transmitter-receiver coil-separation (s), coil orientation and transmitter frequency (ω), should depend solely on depth below the land surface. When not operating under LIN conditions, vertical spatial sensitivity and de also depend on apparent soil electrical conductivity (σa) and therefore the induction number (β) which is directly proportional to σa. In this new evaluation, we determine the range of σa and β values for which the LIN conditions hold and how de changes when they do not.
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- Title:
- Aerial Transient Electromagnetic Surveys of Alluvial Aquifers in Rural Watersheds of Arizona, United States
- By:
- 2006. Pool, Callegary and Groom. 2006 AGU Fall Meeting, San Francisco, California.
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- Title:
- Processing gradients of magnetic data utilizing an equivalent technique.
- By:
- Ruizhong Jia and R.W. Groom.
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- Title:
- Magnetic Case Study: Raglan Mine
- By:
- 2006. Laura Davis. Internal Report.
- Description:
- The objective of this study was to test the tools available in EMIGMA (PetRos Eikon) for their utility in analyzing magnetic data in terms of the usefulness and efficiency of available algorithms and the ease of using the interface. Many different types of tools were used together to get a clear understanding of the geophysics of the problem, and what the geophysics means for the structure of the subsurface. For the purpose of this testing, field data from a portion of the Raglan Mine site was examined.
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- Title:
- Geophysical case study of the Iso and New Insco deposits, Québec, Canada: Part II, modeling and interpretation
- By:
- 2006. Li Zhen Cheng. Reviewed Draft. Exploration and Mining Geology, January 2006, vol. 15, no. 1-2, p. 65-74.
- Description:
- The MEGATEMII data collected over the Iso and New Insco bodies have been modelled using three modeling packages. The EMQ package is a quick inversion tool which indicates that the Iso body is a dipping plate-like body. The New Insco body is inferred to have a geometry somewhere between a dipping plate and a sphere. The Maxwell package was used to refine the properties of the plate-like body at Iso. The EMIGMA package was able to identify which parts of the New Insco orebody were more conductive. It was observed that the most conductive parts correspond to the copper-rich zones and the next most conductive to the pyrite-rich zone. The EMIGMA package was also used to show that a thick-prism model might be a more appropriate model for the New Insco ore body.
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- Title:
- Comparison of Theoretical and Physical Model Studies of the Responses of Moving Source and Fixed Loop Electromagnetic Exploration Systems
- By:
- 2005. K. Duckworth. Pure and Applied Geophysics, December 2005, vol. 162, no. 12, p. 2505-2521.
- Description:
- Theoretical and physical scale model responses for moving source and fixed loop electromagnetic exploration systems are presented for the case of a vertical, thin, plate conductor located first in free-space and then in a conductive host. The results are presented in the form of anomaly index diagrams plotted in complex space. The two modeling approaches show general agreement on the behavior of the current gathering effect that operates when the conductive host is present. Both approaches show an onset of a strong positive effect at higher frequencies in the responses provided by both horizontal coplanar coil systems and by fixed loop systems. Agreement is also shown on an unanticipated negative effect that a conductive host causes in the responses provided by the vertical coplanar coincident coil system. Both modeling approaches demonstrate that the responses provided by fixed loop systems are predominantly caused by the current gathering effect. The extent of this effect for fixed loop systems depends on the size of the transmitter loop with respect to the target and on the depth of the target. The theoretical modeling demonstrates that both moving source and fixed loop systems operated over a target located in a conductive host, provide responses that become almost identical and independent of the conductance of the target at high frequency.
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- Title:
- Inversion of Ground Gravity and Airborne Gradient Data
- By:
- Nov 2005. Ruizhong Jia, Ross Groom and Bob Lo. 75th SEG Conference, Houston, Texas.
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- Title:
- On some issues regarding 3D-gravity inversion
- By:
- Nov 2005. Ruizhong Jia and R.W. Groom. 75th SEG Conference, Houston, Texas.
- Description:
- We used our forward simulation algorithms to generate the vertical component of gravity field (Gz) on the ground surface and the airborne data Gzz which is the spatial vertical derivative of Gz. We applied our inversion technique to synthetic ground data and airborne data. The results of this work demonstrates that in some cases the Euler deconvolution technique plays important role in enhancing our 3D-gravity inversion.
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- Title:
- 3-D sensitivity distribution of low-induction-number frequency-domain electromagnetic instruments
- By:
- 2005. James B. Callegary, Ty P.A. Ferré and R.W. Groom. 2005 AGU Fall Meeting, San Francisco, California.
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- Title:
- On Time-Domain Transient Electromagnetic Soundings, Extended Abstract
- By:
- 2005. Ruizhong Jia and Ross Groom. 2005 SAGEEP Annual Symposium, Atlanta, Georgia.
- Description:
- Some issues in modelliing TEM responses and their relevance to real-world systems and geology.
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- Title:
- Final Report On Improved Aeromagnetic Compensation: A New Aircraft Compensation System for Magnetic Terrains
- By:
- 2004. John Jia, Bob Lo and Ross Groom. OMET Report.
- Description:
- Leliak's system of equations, first published over 30 years ago for served magnetometers, remains today the standard for aeromagnetic compensation using multiple strapdown sensors. This project examines the fundamentals of Leliak's system of equations to gain understanding into aeromagnetic compensation.
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- Title:
- The Use of GPS Sensors and Numerical Improvements in Aeromagnetic Compensation. Extended Abstract
- By:
- 2004. Ruizhong Jia, R.W. Groom and Bob Lo. SEG. 74th SEG Conference, Denver, USA.
- Description:
- The results of this work demonstrate that it is possible to use three well-spaced GPS receivers on an aircraft to measure the aircraft attitude to the precision required to compensate for the aircraft effects. The experiments with the different highpass filters used on the data and with the different solvers indicate that with the proper selection of filters and solvers, better compensation results can be obtained.
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- Title:
- Magnetic Compensation of magnetic noise related to aircraft's maneuvers in airborne survey. Extended Abstract
- By:
- 2004. R.W. Groom, Ruizhong Jia and Bob Lo. 2004 SAGEEP Annual Symposium, Colorado Springs, Colorado.
- Description:
- An aircraft or helicopter emanates magnetic signals. These signals owe to a number of factors including induced fields due to magnetically susceptible and permanent magnetic materials on the platforms as well as both induced electromagnetic signals and electromagnetic signals generated either by electrical systems or moving parts such as rotors. This paper discusses the problems and techniques related to removing the effects of the moving platform and makes an attempt to study the subject with the use of simulated data.
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- Title:
- Exploring for Groundwater with Electromagnetic Methods
- By:
- 2004. Ross Groom. Internal Report.
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- Title:
- Coal Authority Phase 2: Theoretical Modelling Study
- By:
- April 2004. R.W.Groom. UK Coal Authority.
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- Title:
- On Inversion of Gradient Magnetic Data for Detection of Multiple Buried Metallic Objectives. Extended Abstract
- By:
- 2004. Ruizhong Jia and R.W. Groom. 2004 SAGEEP Annual Symposium, Colorado Springs, Colorado.
- Description:
- In previous works, the authors developed algorithms to implement an Euler depth estimator as well as an inversion algorithm for detecting a simple dipole, which is often a suitable model for UXO applications. These algorithms worked independently with a single anomaly. In the present paper, a combination of these algorithms is used to determine the locations and the internal magnetization vectors of multiple buried objects in a practical field survey.
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- Title:
- Inversion of Magnetic and Gradient Magnetic Data For Detection and Discrimination of Metallic Objects
- By:
- 2003. Ross Groom. EAGE, 9th European Meeting, Prague, Czech Republic.
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- Title:
- Investigations into Inversion of Magnetic and Gradient Magnetic Data for Detection and Discrimination of Metallic Objects. Extended Abstract
- By:
- 2003. R.W. Groom, Ruizhong Jia and C. Alvarez. 2003 SAGEEP Annual Symposium, San Antonio, Texas.
- Description:
- Three-dimensional magnetic modeling capabilities have been extended to simulate TMI, magnetic vector and gradient measurements for both permanent magnetization and strong induced effects. It is possible now to model quite general 3D shapes including conical and cylindrical objects both solid and hollow. These general shapes can be combined to represent projectile shells with quite general shapes having varying internal magnetic properties. Based on these simulation capabilities, the use of inversion algorithms is investigated for determining the internal magnetization vector of buried objects.
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- Title:
- UXO Applications for Geophysics
- By:
- 2002. PetRos EiKon. Internal Report.
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- Title:
- 3D EM Modelling - Application of the Localized Non-Linear Approximator to Near Surface Applications. Extended Abstract
- By:
- 2002. R. Groom and C. Alvarez. 2002 SAGEEP Annual Symposium, Las Vegas, Nevada.
- Description:
- Rapid O(N) numerical techniques were initially developed for hydrocarbon reservoir characterization and later for mineral exploration. Now they are proving useful for near-surface environmental and geotechnical applications. The general formulation of the techniques provides extensions to simulation problems of specific interest for near-surface EM, such as the simulation of induction effects due to contrasts solely in induced magnetization and the combined response due to contrasts in resistivity and magnetization. The use of the original techniques as well as research into new extensions as they pertain to near-surface applications is discussed
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- Title:
- Some Pitfalls in Gradient Magnetic Processing or Why Rotate Gradients
- By:
- 2002. R.W. Groom and Bob Lo. KEGS Symposium, Toronto, Canada.
- Description:
- A number of gradient derivation examples are considered: (1) derivation of TMI gradients in three-sensor magnetic processing; (2) generation of analytic gradients for benchmarking from fully synthetic data; (3) gradient derivation from simulated data with true flight and orientation information, and (4) gradient derivation from real data.
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- Title:
- Improved Depth Distributions by Inversion of Magnetic Surveys Collected at Different Survey Heights
- By:
- 2002. Bob Lo and R.W. Groom. KEGS Symposium, Toronto, Canada.
- Description:
- The presentation describes the ability of EMIGMA to use in inversions data from different elevations. This feature seems to improve the distribution of magnetic material in the models providing a more accurate estimation of the depth to top and bottom.
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- Title:
- An Inverse Magnetic Problem
- By:
- 2002. Ruizhong Jia. Internal Report.
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- Title:
- 3D Modelling of Near Surface Problems
- By:
- 2002. PetRos EiKon. Internal Report.
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- Title:
- Development in a normal mode helical electrical antennae crosshole instrumentation and integrated interpretation system. Extended Abstract
- By:
- 2001. R.W. Groom and C. Candy.
2001 Symposium on the Application of Geophysics to Environmental and Engineering Problems, Denver, Colorado. - Description:
- New instrumentation including a single-antenna NMHA system and a compact downhole device is offered for effective multi-frequency investigation of different environments. Simulation capabilities developed both for the antennae radiation pattern and electromagnetic wave scattering in a three-dimensional environment provide for contrasts in resistivity, electrical permittivity and magnetic permeability. Suggested tomographic techniques allow for near-field scattering and curved boreholes. Data are presented from a calibration site with detailed logs, a landfill site with leachate contamination, an industrial site with industrial cleaning solution contamination, and a survey to study groundwater geometry in a glacial till environment.
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- Title:
- X-hole Tomography. A New Frontier in Equipment and Software
- By:
- 2001. R.W. Groom and C. Candy. KEGS Symposium, Toronto, Canada.
- Description:
- The X-hole tomography instrumentation and data interpretation methods are described. Survey test results are presented for glacio-fluvial environment, a municipal landfill test site, earthen dam and mine settings.
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- Title:
- Mag 3D Inversion
- By:
- 2000. PetRos EiKon. Internal Report.
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- Title:
- An Interpretation Study of Pulse EM Reconnaissance Data from the Raglan Belt of Northern Canada, Extended Abstracts
- By:
- 1999. Groom, R.W., Murray, Alvarez, C. and North, J. 3D Symposium, Salt Lake City, Utah.
- Description:
- Several stages of interpretation of pulse EM data over a relatively complex geological setting are presented. Simulation of the electromagnetic data was critical to understanding the electromagnetic data. This simulation required the accurate reproduction of several physical mechanisms not to our knowledge previously available. These studies led to a better understanding of some basic physical responses potentially present in many data scenarios.
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- Title:
- Modelling of complex electromagnetic targets using advanced non-linear approximator techniques, Extended Abstracts
- By:
- 1999. Murray, I. R., Alvarez, C. and Groom, R.W. 69th SEG Conference, Houston, Texas.
- Description:
- The development of rapid O(N) numerical techniques, initiated by the pioneering of the Localized Non-Linear (LN) Approximator in 1993, offers many possibilities for the simulation of realistic electromagnetic situations for a wide range of applications. Very rapid calculation times combined with minimal memory requirements offer the potential to simulate more complex and thus more geologically meaningful models. This paper summarizes experiments with many developments in LN techniques, including extensions to inductive modes, multi-body problems, time-varying magnetic effects and polyhedral primitives.
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- Title:
- On Extending the Localized Non-Linear Approximation to Inductive Modes Extended Abstracts
- By:
- 1997. Murray, I.R. F004, 59th EAGE Conference, Geneva, Switzerland.
- Description:
- A large loop inductive excitation is modeled to illustrate the use of approximate methods for simulating complex physical models in small geophysical environments where computing resources are limited. Comparisons with other existing scattering algorithms have shown the technique to be very effective at modeling inductive response, with computation times being significantly faster than those of the algorithms lately designed specifically for speed. In addition, there is no breakdown of the solution in the near-field as is often the case for techniques of traditional design utilizing polynomial basis functions, since the new theory uses no explicit basis to represent the current density.
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- Title:
- A case study on the application of the EMIGMA modelling package to Crone data over the SOQUEM Lac Volant Region, Sept-Îles, Québec, Extended Abstracts
- By:
- 1996. Parker, D.H, Boivin, M., Murray, I. R and Groom, R.W. 67th SEG Conference, Dallas, Texas.
- Description:
- This paper is part of an interpretation of Crone and Max-Min data collected at the Lac Volant property in Sept-Îles, Québec during the fall of 1996. Two conductive targets were delineated. It is shown that the use of electromagnetic modelling can enhance the comprehension of the relation between the data and the geological structure and so affect drilling decisions. In this case, the Lac Volant anomaly was determined to represent a spatially limited massive sulphide target despite the significant base metal values and the hope generated by the discovery.
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- Title:
- A case study of the application of the EMIGMA modelling package in interpretation of UTEM data over the Cominco Cerattepe deposit in Turkey, Extended Abstracts
- By:
- 1996. Groom, R.W., Hyde, C.H. and Lajoie, J. 66th SEG Conference, Denver, Colorado.
- Description:
- This paper is part of an interpretation of UTEM data collected at the Cerattepe property in northeastern Turkey during 1992 and 1993. Three exploration targets were delineated during the survey, namely the Cerattepe main zone, the Cerattepe north zone, and the Kardalen target. It is shown that the use of electromagnetic modelling can significantly enhance the comprehension of the relation between the data and the geological structure and so affect drilling decisions.
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- Title:
- Beyond the Born and Rytov Approximations: A Nonlinear Approach to Electromagnetic Scattering
- By:
- 1993. Habashy T. M, Groom, R.W. and Spies. B.R. Journal of Geophysical Research, 98, no. B2, p. 1759-1775.
- Description:
- Four new, relatively simple nonlinear estimators presented in this paper can be used for rapid electromagnetic modeling in geophysical applications where conductivity can vary over many orders of magnitude. The first, the static localized nonlinear approximation, is designed specifically to correct the magnitude of the electric field internal to the scatterer. The second, the localized nonlinear approximation, improves the estimate of the phase of the scattered field and includes some of the cross-polarization effects due to full wave scattering. The third and the forth based on the Rytov transformation are designed to further improve the estimation of the phase of the scattered field, especially at high frequency and for larger size scatterers. The enhanced accuracy of the new estimators makes them potentially useful for the solution of low-frequency three-dimensional inverse problems in electromagnetics.
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