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Jeffrey J. Daniels

Publications and source records attributed to Jeffrey J. Daniels.

17 recordsLinked to original sources
USGS1985

TRENDS IN BOREHOLE GEOPHYSICS FOR MINERAL EXPLORATION: ASSAYING AND REMOTE DETECTION.

Several borehole geophysical techniques have been developed in recent years. Assaying technique development has been concentrated on nuclear methods, with some progress being made on using electrical and magnetic properties for mineral identification. Adaptation of conventional surface geophysical techniques to the borehole for locating near-misses of mineralized zones has led to the development of borehole resistivity, electromagnetic (EM), gravity and magnetic methods to the borehole environment. This paper discusses some of the applications and pitfalls of these new techniques.

Conference Paper↗
USGS1984

BROADBAND DIGITAL GEOPHYSICAL TELEMETRY SYSTEM.

A system has been developed to simultaneously sample and transmit digital data from five remote geophysical data receiver stations to a control station that processes, displays, and stores the data. A microprocessor in each remote station receives commands from the control station over a single telemetry channel.

Conference Paper↗
USGS1980

Borehole geophysical measurements for hole UE25-3, Nevada Test Site, Nuclear Waste Isolation Program

Borehole geophysical measurements made in drill hole UE25a-3 with a U.S. Geological Survey research well-logging truck are presented in this paper. The purpose of these logging measurements is to provide in-situ physical properties information that is not commercially available on drill hole UE25a-3. Well logs are presented in this paper for dual-detector density, normal resistivity, gamma-ray, neutron-neutron, induced polarization, and magnetic susceptibility measurements. These data are analyzed for correlations with the core lithology. Hole-to-surface measurements made from drill hole UE25a-3 indicate the presence of two resistive bodies at depth. The deeper resistive anomaly may be related to a granitic intrusion.

Nevada↗
USGS1980

Analysis of borehole geophysical data in an evaporite sequence at Salt Valley, Utah

Interpretation of the lithology of an interbed sequence (thin-bedded sediments between thick layers of salt) is often difficult due to the presence of dolomitic sandstones and halite inclusions. The most useful well logging measurements in an evaporite sequence are gamma-ray, neutron-neutron, density, and acoustic velocity. The high resistivity of salt and the low resistivity of commonly used drilling fluids (brine muds) make it difficult to obtain measurements of electrical properties in an evaporite sequence. Tests of a single-coil induction probe at Salt Valley show good resolution of the interbed lithologies and may be useful in determining moisture in the halite. Complex structural features (faulting and folding) are difficult to interpret with individual well logs. Interpretation of complex folding can be aided by plotting the percent frequency of occurrence of well log response values for the interbeds. Limbs of a fold that intersect the drill hole at different dip angles yield similar distribution patterns on these percent-frequency plots.

Utah↗
USGS1980

Hole-to-surface resistivity measurements at Salt Valley, Utah

Evaporites are an important potential medium for the storage of radioactive wastes. In order to ascertain the viability of a proposed waste isolation site, it is necessary to study its geology without extensive drilling that might destroy its structural integrity. Hole-to-surface and hole-to-hole geophysical measurements can be useful in supplementing geologic data obtained from a few drill holes and can be used to aid the interpretation of surface geophysical measurements. The study presented in this paper was conducted at Salt Valley, Utah to test the feasibility of using hole-to-surface direct-current resistivity measurements to detect geologic inhomogeneities in evaporites. These measurements show the following: (1) It is feasible to make hole-to-surface resistivity measurements over evaporites. However, near-surface steel casing can make it difficult to quantitatively analyze the field data with present interpretation techniques. Future investigations should include theoretical studies to solve interpretation problems when steel casing is in the hole and the mud is a high-conductivity brine. (2) A comparison of measurements made from the three different source drill holes shows that the halite acts as an electrical insulator and most of the current emitted from the source is contained in the caprock. (3) A comparison of measurements made parallel and perpendicular to the valley walls shows that there are more variations in the halitecaprock interface perpendicular than parallel to the axis of the Salt Valley anticline. (4) Structurally complex interbeds within the salt may cause differences in the current distribution measured at the surface from current sources buried at different depths. (5) Total field mapping would be more useful than the single-component data that were collected in this study.

Utah↗
USGS1979

Analysis of borehole geophysical information across a uranium deposit in the Jackson Group, Karnes County, Texas

Borehole geophysical studies across a uranium deposit in the Jackson Group, South Texas, show the three geochemical environments often associated with uranium roll-type deposits: an altered (oxidized) zone, an ore zone, and an unaltered (reduced) zone. Mineralogic analysis of the total sulfides contained in the drill core shows only slight changes in the total sulfide content among the three geochemical regimes. However, induced polarization measurements on the core samples indicate that samples obtained from the reduced side of the ore zone are more electrically polarizable than those from the oxidized side of the ore zone, and therefore probably contain more pyrite. Analysis of the clay-size fraction in core samples indicates that montmorillonite is the dominant clay mineral. High resistivity values within the ore zone indicate the presence of calcite cement concentrations that are higher than those seen outside of the ore zone. Between-hole resistivity and induced polarization measurements show the presence of an extensive zone of calcite cement within the ore zone, and electrical polarizable material (such as pyrite) within and on the reduced side of the ore zone. A quantitative analysis of the between-hole resistivity data, using a layered-earth model, and a qualitative analysis of the between-hole induced polarization measurements showed that mineralogic variations among the three geochemical environments were more pronounced than were indicated by the geophysical and geologic well logs. Uranium exploration in the South Texas Coastal Plain area has focused chiefly in three geologic units: the Oakville Sandstone, the Catahoula Tuff, and the Jackson Group. The Oakville Sandstone and the Catahoula Tuff are of Miocene age, and the Jackson Group is of Eocene age (Eargle and others, 1971). Most of the uranium mineralization in these formations is low grade (often less than 0.02 percent U3O8) and occurs in shallow deposits that are found by concentrated exploratory drilling programs. The sporadic occurrence of these deposits makes it desirable to develop borehole geophysical techniques that will help to define the depositional environments of the uranium ore, which is characterized by geochemical changes near the uranium deposits. Geochemical changes are accompanied by changes in the physical characteristics of the rocks that can be detected with borehole geophysical tools. This study is concerned with a uranium deposit within the Jackson Group that is located just east of Karnes City, Tex. Five holes were drilled on this property to obtain borehole geophysical data and cores. The cores were analyzed for mineralogic and electrical properties. The borehole geophysical information at this property included induced polarization, resistivity, gamma-gamma density, neutron-neutron, gamma-ray, caliper, and single-point-resistance logs. Between-hole resistivity and induced polarization measurements were made between hole pairs across the ore deposit and off the ore deposit.

Open-File Report↗
USGS1977

A computer program to calculate the resistivity and induced polarization response for a three-dimensional body in the presence of buried electrodes

Three-dimensional induced polarization and resistivity modeling for buried electrode configurations can be achieved by adapting surface integral techniques for surface electrode configurations to buried electrodes. Modification of. the surface technique is accomplished by considering the additional mathematical terms required to express-the changes in the electrical potential and geometry caused by placing the source and receiver electrodes below the surface. This report presents a listing of a computer program to calculate the resistivity and induced polarization response from a three-dimensional body for buried electrode configurations. The program is designed to calculate the response for the following electrode configurations: (1) hole-to-surface array with a buried bipole source and a surface bipole receiver, (2) hole-to-surface array with a buried pole source and a surface bipole receiver, (3) hole-to-hole array with a buried, fixed pole source and a moving bipole receiver, (4) surface-to-hole array with a fixed pole source on the surface and a moving bipole receiver in the borehole, (5) hole-to-hole array with a buried, fixed bipole source and a buried, moving bipole receiver, (6) hole-to-hole array with a buried, moving bipole source and a buried, moving bipole receiver, and (7) single-hole, buried bipole-bipole array. Input and output examples are given for each of the arrays.

Open-File Report↗
USGS1976

Non-radiometric borehole geophysical detection of geochemical halos surrounding sedimentary uranium deposits

Roll-type uranium deposits are formed by the concentration of uranium by ground water in geochemical cells. Non-uranium minerals having different solubilities may be deposited ahead of or behind the uranium minerals, forming halos that surround the ore. In addition, oxidizing and reducing environmental conditions may cause zones of mineral alteration to develop beyond the limits of the uranium deposit. Certain physical property anomalies that are commonly associated with halos can be detected by relatively fast and inexpensive borehole geophysical measurements made either in individual holes, or between two adjacent holes. Borehole measurements that have been found to be useful include electrical resistivity, induced polarization, and magnetic susceptibility. Electrical resistivity is increased by the presence of calcite and other cementing minerals that sometimes create permeability barriers in the neighborhood of uranium deposits. Induced polarization (IP) response is increased by sulfide and clay minerals that are commonly found in anomalous concentrations near roll-type deposits. Magnetic susceptibility is usually decreased by the oxidation of magnetite to hematite or limonite in the zone of chemical alteration that is left as a trail behind roll fronts. Borehole measurements of electrical resistivity, induced polarization and magnetic susceptibility were made in the vicinity of a uranium roll-type deposit in south Texas. Results indicate that mineral halos can be detected by borehole measurements made. in wide-spaced drill holes, and that the total amount of drilling needed to find a deposit can be reduced substantially by this exploration approach.

Open-File Report↗