Interpretation of the magnetic anomaly over the Omaha Oil Field, Gallatin County, Illinois

Geophysics ◽  
1994 ◽  
Vol 59 (7) ◽  
pp. 1092-1099 ◽  
Author(s):  
Mark A. Sparlin ◽  
Richard D. Lewis
Keyword(s):  
Magnetic Anomaly ◽  
Primary Source ◽  
Oil Field ◽  
Magnetic Feature ◽  
Magnetic Survey ◽  
Aeromagnetic Survey ◽  
Data Set ◽  
Interesting Possibility ◽  
Ground Magnetic ◽  
Structural Closure

A 40 nanoTesla (nT) magnetic anomaly identified in an aeromagnetic survey over southern Illinois contours as a localized magnetic high on the west flank of a regional magnetic low. This magnetic anomaly is generally coincident with the Omaha Oil Field in northwest Gallatin County, Illinois. It was initially assumed that cultural sources of steel associated with this oil field were the primary source of the magnetic feature; however, similar oil fields overflown by the survey do not exhibit magnetic anomalies in the data set. The Luther Rister et ux ♯1 well, drilled near the apex of the Omaha structural dome, encountered two zones of ultramafic intrusive rock containing 9.0 percent by volume magnetite. These intrusives were identified to be alnöites which are a class of mantle‐derived ultramafic rock that can be associated with the incipient stages of crustal rifting. A ground magnetic survey verified the presence of the anomaly, and provided detailed data for 3-D modeling of the source. Petrophysical evaluations, magnetic susceptibility measurements and thin section modal analysis were made on drill cuttings from the ultramafic intrusives encountered in the Luther Rister ♯1 well. These measurements were made to constrain the 3-D magnetic modeling by the petrophysical characteristics of the source. After removal of the regional magnetic field, the resulting 140 nT residual magnetic anomaly was successfully modeled using two ultramafic sills with an igneous feeder plug. The two igneous sills adequately account for the structural closure exhibited in the Omaha Oil Field and raise the interesting possibility of other hydrocarbon trapping structures generated by intrusives emplaced into the sedimentary section.

Analysis of the Czech magnetic anomaly data obtained by ground-based and airborne magnetic surveys

2020 ◽  
Author(s):  
Pavel Hejda ◽  
Dana Čápová ◽  
Eva Hudečková ◽  
Vladimír Kolejka
Keyword(s):  
Magnetic Anomaly ◽  
Magnetic Anomalies ◽  
Data File ◽  
Ore Deposits ◽  
Substantial Contribution ◽  
Magnetic Survey ◽  
Contour Maps ◽  
Anomaly Map ◽  
Ground Magnetic ◽  
Airborne Survey

<p>The modern epoch of ground magnetic surveying activity on the Czech territory was started by the Institute of Geophysics by setting up a fundamental network of the 1<sup>st</sup> order in 1957-58. It consists of 199 points and was reoccupied in 1976-78 and 1994-96. The anomaly maps were constructed by subtraction of the IGRF model.</p><p>Extensive aeromagnetic measurements have been performed from 1959 to 1972 by permalloy probe of Soviet provenience. The accuracy of the instrumentation was about (and often above) 10 nT. The second period of airborne survey started in 1976. Thanks to the deployment of proton precession magnetometer, the accuracy improved to ~ 2 nT. Since 2004 the measurements were carried out by caesium magnetometer. The data were digitized, known anthropogenic anomalies were cleared away and data were transformed to the regular grid with step 250 m. The final data file of magnetic anomalies ΔT, administered by the Czech Geological Survey, represents a substantial contribution to the exploration of ore deposits and to the structure geology in general.</p><p>In view of the fact that data file of magnetic anomalies was compiled from data acquired by heterogeneous methods in the course of more than 50 years, our recent study is aimed at looking into the homogeneity of the data by comparison them with ground-based magnetic survey. A simple comparison of the contour maps showed good similarity of the large regional anomalies. For more detailed analysis, the variation of ΔT in the neighbourhood of all points of the fundamental network was inspected and the basic statistic characteristics were computed. Summary results as well as several examples will be presented accordingly as the INSPIRE compliant services and eventually as the user-friendly web map application and made available on the CGS Portal http://mapy.geology.cz/ and on the updated web of the CzechGeo/EPOS consortium www.czechgeo.cz. Incorporating the map into the World Digital Magnetic Anomaly Map (WDMAM – IAGA) is also under consideration. This data will also be interesting for the EPOS.</p>

Magnetic survey – ground technology, aeromagnetic survey on aircraft and unmanned aerial vehicles: a comparative analysis of the results (on the example of Eastern Transbaikalia)

2020 ◽  
Vol 26 (8) ◽  
pp. 6-15
Author(s):  
R. Gruzdev ◽  
Keyword(s):  
Unmanned Aerial Vehicles ◽  
Geophysical Methods ◽  
Work Productivity ◽  
Field Work ◽  
Magnetic Survey ◽  
Aeromagnetic Survey ◽  
Aerial Vehicles ◽  
Eastern Transbaikalia ◽  
Actual Material ◽  
Ground Magnetic

The use of unmanned aerial vehicles (UAVs) in geophysical work is becoming a very popular area in the field of modern geological exploration. The advantage of unmanned systems is the optimal ratio of the quality of research results with a significant increase in work productivity and a decrease in cost. In this regard, the improvement of field techniques and the processing of UAV materials is of particular interest for exploration. On the subject, there are a number of unresolved issues that have been revealed to some extent as a result of the author’s comparison of ground-based magnetic exploration and aeromagnetic survey data. The purpose of the study was to assess the possibility of a full-fledged replacement of ground magnetic exploration work for aeromagnetic survey using unmanned aerial vehicles. The comparison of different types of magnetic survey is relevant, since on the basis of the actual material, the possibility of using an alternative more productive method – aeromagnetic survey using modern UAVs – instead of traditional expensive ground-based magnetic exploration works is analyzed. To compare the results of the studies, actual material obtained from field work on an area of 13,4 km2 was used. Based on the databases, maps of anomalous magnetic field and graphs on several geophysical profiles are built. Results of magnetic survey in air and ground versions are analyzed; correlation relationships between data of ground pedestrian magnetic survey and aeromagnetic system on An-3 and UAV aircraft are established. Based on the results of the study, correlation and determination coefficients were obtained, which indicate that geophysical methods on UAVs adequately occupy their place between classical aerogeophysics and ground-based pedestrian survey. Moreover, aeromagnetic survey using UAVs is able to replace pedestrian magnetic exploration during work at the same heights. Based on the results of the study, methodological recommendations for the production of aeromagnetic survey on UAVs were compiled

scholarly journals The Magnetometry—A Primary Tool in the Prospection of Underground Water

2020 ◽  
Author(s):  
Héctor López Loera
Keyword(s):  
High Probability ◽  
Underground Water ◽  
Arid Zones ◽  
Magnetic Survey ◽  
Aeromagnetic Survey ◽  
Electrical Sounding ◽  
Electrical Methods ◽  
Ground Magnetic ◽  
The One ◽  
Semi Arid

One of the most important problems in arid and semi-arid zones in the Mexican Mesa Central is the one related to the exploration and exploitation of groundwater. It is found at depths over 200 m, and movement is primarily through fractures. This work presents a geophysical methodology, which shows the potential of combining natural and induced methods to locate confined aquifers in fault zones. The study begins by interpreting the aeromagnetic survey, mainly by searching alignments associated with low magnetic anomalies, which are correlated with faults zones, and/or fractures and/or geologic contacts where ferromagnetic minerals have undergone oxidation due to their association with recharged zones. These aeromagnetic alignments are confirmed on land by a ground magnetic survey. Based on these interpretations, electrical methods include sections and vertical electrical sounding are used to verify if the zones are correlated to the underground moisture. If both permeability and moisture are met together, then they considered as zones with a high probability of locating ground water in the Mexican Mesa Central.

Airborne geophysical surveys in Greenland – 1996 update

1997 ◽  
pp. 75-79
Author(s):  
Robert W. Stemp
Keyword(s):  
Mineral Exploration ◽  
Geological Mapping ◽  
Digital Data ◽  
Magnetic Survey ◽  
Aeromagnetic Survey ◽  
West Greenland ◽  
South West ◽  
Geophysical Surveys ◽  
The Government ◽  
Airborne Geophysical Data

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stemp, R. W. (1997). Airborne geophysical surveys in Greenland – 1996 update. Geology of Greenland Survey Bulletin, 176, 75-79. https://doi.org/10.34194/ggub.v176.5069 _______________ Two major airborne geophysical surveys were carried out in 1996, the third year of a planned five-year electromagnetic and magnetic survey programme (project AEM Greenland 1994–1998) financed by the Government of Greenland, and the second year of an aeromagnetic survey programme (project Aeromag) jointly financed by the governments of Denmark and Greenland; both projects are managed by the Geological Survey of Denmark and Greenland (GEUS). The two 1996 surveys were: 1) Project Aeromag 1996 in South-West and southern West Greenland;2) Project AEM Greenland 1996 in South-West Greenland. All areas surveyed and planned for future surveys as of March 1997 are shown in Figure 1. Results of both the 1996 surveys were released in March 1997, as a continuation of a major effort to make high quality airborne geophysical data available for both mineral exploration and geological mapping purposes. The data acquired are included in geoscientific databases at GEUS for public use; digital data and maps may be purchased from the Survey. The main results from the 1996 surveys are described in Thorning & Stemp (1997) and Stemp (1997). Two further new airborne surveys have already been approved for data acquisition during the 1997 field season, with subsequent data release in March 1998. A summary of all surveys completed, in progress or planned since the formal inception of project AEM Greenland 1994–1998 is given in Table 1. The programme was expanded to include a separate regional aeromagnetic survey in 1995, provisionally for 1995–1996, with extension subject to annual confirmation and funding.

Ground magnetic survey for the investigation of magnetic minerals at Iboro Village, Abeokuta, south-western Nigeria

2021 ◽  
Vol 20 (2) ◽  
pp. 99-106
Author(s):  
O.I. Popoola ◽  
O.A. Adenuga ◽  
E.O. Joshua
Keyword(s):  
Magnetic Anomalies ◽  
Geological Structure ◽  
Magnetic Survey ◽  
Magnetic Minerals ◽  
Contour Maps ◽  
Ogun State ◽  
Geological Map ◽  
Regional Gradient ◽  
Ground Magnetic ◽  
Iron Ore Deposit

The geological map of the old western region of Nigeria indicates the presence of iron ore deposit at Iboro village Ogun state (7.9983o - 7.99933o N, 3.5790o - 3.5890o E). Hence a ground magnetic survey was carried out at a location at Iboro village so as to delineate the subsurface magnetic anomalies and to know whether the anomalies favour accumulation of magnetic minerals. The survey was carried out using high resolution proton precession magnetometer model G-856X. Eight traverses were run at 5m separations and earth magnetic intensity values were measured at 10m intervals along each traverse; the acquired data were corrected for drift. The residual anomalies obtained by removal of regional gradient from observed data using trend analysis were presented as profiles and maps. The treated data were qualitatively and quantitatively interpreted and the results gave values for the total ground magnetic anomalies that varied between a minimum and maximum peak values of about -33.0 and 30.6nT respectively. Depth to the basement rock was estimated using Peter’s half slope method which gave a maximum depth of about 13m. The contour maps and the total relative graphs present the subsurface picture of the geological structure that is assumed to harbour the metallic minerals through the action of the field towards the concentration of anomalies. It was suspected that the overburden was relatively thin in the study area and the minerals were at a shallow depth.

Resolving Optimum Magnetic Signatures for Drill-Hole Targeting in Gold Exploration – A Case Study for Mbudzane in Gwanda, Zimbabwe

2013 ◽  
Vol 3 (1) ◽  
pp. 9-29
Author(s):  
Dumisani John Hlatywayo ◽  
Emmanuel Sakala
Keyword(s):  
Drill Hole ◽  
Magnetic Survey ◽  
Gold Exploration ◽  
Rock Formations ◽  
Induced Polarisation ◽  
Line Spacing ◽  
Magnetic Signatures ◽  
Ground Magnetic ◽  
Tilt Derivative ◽  
Resistivity Image

Optimum magnetic signatures for drill-hole targeting in gold exploration in Mbudzane were resolved from induced polarisation-resistivity and magnetic anomalies. Total magnetic field and a gold-in-soil map showed the area is magnetically quiet with high anomalous values along old gold workings. Induced polarisation was carried out along a grid for lines of 500m length, 50m separation and a baseline oriented at 330˚. The survey comprised a gradient array and three real sections. The magnetic survey was conducted over the same grid as the induced polarisation. Stations were set at 5m intervals for a line spacing of 50m. The results show intense anomalies that suggest different degrees of magnetic alteration and a set of conjugate lineaments and faults that possibly control the mineralisation in Mbudzane. The tilt derivative of the reduced-to-pole image resolves the separation between anomalies, giving information on the faulting. High chargeability is confined to the sheared and silicified mafic schist. The gradient resistivity image revealed contact between rock formations. Real section IP shows coincident low chargeability – low resistivity anomalies close to the surface. Chargeability intensity increases with depth, suggesting incipient development of disseminated sulphide replacement zones. A strong correlation between ground magnetic inferred contacts and apparent resistivity-chargeability anomalies forms the basis for suggesting a new drill-hole targeting. They dictate both the depth and angle at which drilling should be carried out. These results should be applicable to any region where drill-hole targeting in gold exploration may be required.

scholarly journals Productivity in the US Housing Industry: Total Factor and Public Firms

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Michael S. Puddicombe
Keyword(s):  
Primary Source ◽  
Basic Question ◽  
Wealth Accumulation ◽  
Single Family ◽  
Time Series Regression ◽  
Data Set ◽  
Public Firms ◽  
The Us ◽  
Home Sales ◽  
Housing Industry

Productivity is widely recognized as one of the main contributors to increased economic and societal wellbeing. Unfortunately, productivity has been extremely difficult to operationalize in a repeatable context in the construction sector. The result is a lack of consensus on the basic question of whether there has been improvement or decline in the productivity of the sector. This study focuses on productivity in the housing industry. Productivity is especially important in this industry, as in addition to providing shelter, the housing market is the primary source of wealth accumulation in the US. An individual’s ability to enter this market will be a function of affordability which will be effected by the productivity of the industry. The combination of academic and societal impacts suggests that there is a need to address a fundamental question: what is the status of productivity in the housing industry. In order to address this question a data base was compiled from the 10-Ks of the largest, long lived, US companies in the single family housing industry. The result is a panel data set that consists of information on 11 firms over a 15-year period. These 11 firms were responsible for approximately 25% of all new home sales in any given year. The data set was analysed with random effects GLS time series regression. The results indicate that, at best, the housing industry has seen negligible total productivity growth.

The Use of Euler Deconvolution Technique in the Estimation of Depth to Magnetic Source Bodies around the Schist Belt Parts of Kano State, Nigeria

2021 ◽  
Vol 14 (1) ◽  
pp. 19-23
Keyword(s):  
Depth Estimation ◽  
Magnetic Survey ◽  
Schist Belt ◽  
Euler Deconvolution ◽  
Depth Estimate ◽  
Paper Detail ◽  
Magnetic Source ◽  
Deconvolution Technique ◽  
Proton Precession Magnetometer ◽  
Ground Magnetic

Abstract: Depth estimation of magnetic source bodies in parts of the Schist Belt of Kano, using Euler Deconvolution is presented in this paper. Detail ground magnetic survey was carried out using SCINTREX proton precession magnetometer to produce the Total Magnetic Intensity (TMI) map and consequently the residual map. The TMI ranges from 34,261 nT to 34,365 nT, while the residual field ranges from -160 nT to 115 nT. The depth estimate for contacts ranges from 6.5 m to 39.8 m, while that of dyke ranges from 8.9 m to 51.3 m. The depth estimation presented in this work is compared with the results of aeromagnetic study carried out in the same area and found to agree fairly well. Further, this also ensures the validity of aeromagnetic investigation in such applications. Keywords: Contacts, Dykes, Euler Deconvolution, Schist Belt. PACS: 91.25.F and 91.25.Rt.

Applications of Artificial Neural Networks for Seismic Facies Classification

2021 ◽  
Vol 73 (02) ◽  
pp. 68-69
Author(s):  
Chris Carpenter
Keyword(s):  
Neural Network ◽  
Seismic Data ◽  
Reservoir Characterization ◽  
Probabilistic Neural Network ◽  
Oil Field ◽  
Seismic Facies ◽  
Data Set ◽  
Full Field ◽  
Facies Classification

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 200577, “Applications of Artificial Neural Networks for Seismic Facies Classification: A Case Study From the Mid-Cretaceous Reservoir in a Supergiant Oil Field,” by Ali Al-Ali, Karl Stephen, SPE, and Asghar Shams, Heriot-Watt University, prepared for the 2020 SPE Europec featured at the 82nd EAGE Conference and Exhibition, originally scheduled to be held in Amsterdam, 1-3 December. The paper has not been peer reviewed. Facies classification using data from sources such as wells and outcrops cannot capture all reservoir characterization in the interwell region. Therefore, as an alternative approach, seismic facies classification schemes are applied to reduce the uncertainties in the reservoir model. In this study, a machine-learning neural network was introduced to predict the lithology required for building a full-field Earth model for carbonate reservoirs in southern Iraq. The work and the methodology provide a significant improvement in facies classification and reveal the capability of a probabilistic neural network technique. Introduction The use of machine learning in seismic facies classification has increased gradually during the past decade in the interpretation of 3D and 4D seismic volumes and reservoir characterization work flows. The complete paper provides a literature review regarding this topic. Previously, seismic reservoir characterization has revealed the heterogeneity of the Mishrif reservoir and its distribution in terms of the pore system and the structural model. However, the main objective of this work is to classify and predict the heterogeneous facies of the carbonate Mishrif reservoir in a giant oil field using a multilayer feed-forward network (MLFN) and a probabilistic neural network (PNN) in nonlinear facies classification techniques. A related objective was to find any domain-specific causal relationships among input and output variables. These two methods have been applied to classify and predict the presence of different facies in Mishrif reservoir rock types. Case Study Reservoir and Data Set Description. The West Qurna field is a giant, multibillion-barrel oil field in the southern Mesopotamian Basin with multiple carbonate and clastic reservoirs. The overall structure of the field is a north/south trending anticline steep on the western flank and gentle on the eastern flank. Many producing reservoirs developed in this oil field; however, the Mid- Cretaceous Mishrif reservoir is the main producing reservoir. The reservoir consists of thick carbonate strata (roughly 250 m) deposited on a shallow water platform adjacent to more-distal, deeper-water nonreservoir carbonate facies developing into three stratigraphic sequence units in the second order. Mishrif facies are characterized by a porosity greater than 20% and large permeability contrast from grainstones to microporosity (10-1000 md). The first full-field 3D seismic data set was achieved over 500 km2 during 2012 and 2013 in order to plan the development of all field reservoirs. A de-tailed description of the reservoir has been determined from well logs and core and seismic data. This study is mainly based on facies log (22 wells) and high-resolution 3D seismic volume to generate seismic attributes as the input data for the training of the neural network model. The model is used to evaluate lithofacies in wells without core data but with appropriate facies logs. Also, testing was carried out in parallel with the core data to verify the results of facies classification.

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