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At least 631 records · Page 35Linked to original sources
USGS2012

Scientific basis for safely shutting in the Macondo Well after the April 20, 2010 Deepwater Horizon blowout

As part of the government response to the Deepwater Horizon blowout, a Well Integrity Team evaluated the geologic hazards of shutting in the Macondo Well at the seafloor and determined the conditions under which it could safely be undertaken. Of particular concern was the possibility that, under the anticipated high shut-in pressures, oil could leak out of the well casing below the seafloor. Such a leak could lead to new geologic pathways for hydrocarbon release to the Gulf of Mexico. Evaluating this hazard required analyses of 2D and 3D seismic surveys, seafloor bathymetry, sediment properties, geophysical well logs, and drilling data to assess the geological, hydrological, and geomechanical conditions around the Macondo Well. After the well was successfully capped and shut in on July 15, 2010, a variety of monitoring activities were used to assess subsurface well integrity. These activities included acquisition of wellhead pressure data, marine multichannel seismic profiles, seafloor and water-column sonar surveys, and wellhead visual/acoustic monitoring. These data showed that the Macondo Well was not leaking after shut in, and therefore, it could remain safely shut until reservoir pressures were suppressed (killed) with heavy drilling mud and the well was sealed with cement.

Gulf of Mexico↗
USGS1988

Geologic logs for selected deep wells in parts of Oklahoma, Texas, and New Mexico

A computerized data base of geologic logs for selected deep wells in parts of Oklahoma, Texas, and New Mexico was prepared by the U.S. Geological Survey as part of the Central Midwest Regional Aquifer-System Analysis. At least one well per county in the study area was selected, and the geologic logs for the wells were entered into the data base. Summaries of the geologic logs are presented in this report. Geophysical logs were used for interpretation of the geologic logs, and a list of these geophysical logs also is presented. These geophysical logs are available for inspection at the U.S. Geological Survey office in Oklahoma City, Oklahoma.

Open-File Report↗
USGS2021

Alaska natural gas hydrate production testing: Test site selection, characterization and testing operations

This Interagency Agreement supports the U.S. Department of Energy (DOE) and its research partners in understanding, predicting, and testing the recoverability and potential production characteristics of onshore natural gas hydrate in the Greater Prudhoe Bay area on the Alaska North Slope (ANS: Prudhoe Bay, Kuparuk River, and Milne Point areas) or other areas deemed suitable by DOE and USGS for potential long-term production testing of gas hydrate. Researchers will accomplish these tasks by evaluating the occurrence and resource potential of the known gas hydrate accumulations in the Eileen trend. Geologic, geochemical, and geophysical (2-D and 3-D seismic surveys) data from northern Alaska and other data sources, including wireline and mud log surveys of wells of opportunity, will be used to assess the occurrence and nature of the known gas hydrate accumulations. The project involves two primary areas of effort: the geologic and engineering assessment of the Eileen gas-hydrate accumulation and support of DOE and its industry partners in evaluating, planning, and preparing for drilling and testing gas hydrate research wells in northern Alaska.

Alaska↗
USGS1981

Airborne electromagnetic and magnetic survey of parts of the Upper Peninsula of Michigan and Northern Wisconsin

The data presented in this report is from an airborne electromagnetic INPUT (Registered trademark of Barringer Research Ltd.) and total field magnetic survey conducted by Geoterrex Limited of Ottawa Canada. The survey is located in eight areas in the Upper Peninsula of Michigan and one area in Northern Wisconsin. The accompanying report describes the basic parameters for the areas surveyed (figure 1). All of the areas except area E (figure 1) are within the Iron River 2° quadrangle. This quadrangle is being studied as part of the U.S. Geological Survey (USGS) CUSMAP (Conterminous United States Mineral Appraisal Program) project. The survey was done in order to provide geophysical information which will aid in the integrated geological assessment of the Iron River 2° quadrangle.

Michigan, Wisconsin↗
USGS2006

Geologic interpretation and multibeam bathymetry of the sea floor in southeastern Long Island Sound

Digital terrain models (DTMs) produced from multibeam echosounder (MBES) bathymetric data provide valuable base maps for marine geological interpretations (e.g. Todd and others, 1999; Mosher and Thomson, 2002; ten Brink and others, 2004; Poppe and others, 2006a,b). These maps help define the geological variability of the sea floor (one of the primary controls of benthic habitat diversity); improve our understanding of the processes that control the distribution and transport of bottom sediments, the distribution of benthic habitats and associated infaunal community structures; and provide a detailed framework for future research, monitoring, and management activities. The bathymetric survey interpreted herein (National Oceanic and Atmospheric Administration (NOAA) survey H11255) covers roughly 95 km? of sea floor in southeastern Long Island Sound (fig. 1). This bathymetry has been examined in relation to seismic reflection data collected concurrently, as well as archived seismic profiles acquired as part of a long-standing geologic mapping partnership between the State of Connecticut and the U.S. Geological Survey (USGS). The objective of this work was to use these geophysical data sets to interpret geomorphological attributes of the sea floor in terms of the Quaternary geologic history and modern sedimentary processes within Long Island Sound.

Open-File Report↗
USGS1982

Geology of areas marked by geophysical anomalies (B-35 and B-34), Wadi Bidah District, Kingdom of Saudi Arabia

Geophysical surveys in the Wadi Bidah district, in the southwestern part of the Kingdom of Saudi Arabia, have revealed anomalies of the type that may be caused by deposits of massive sulfides. Accordingly, a study was undertaken to investigate the geologic environment associated with the geophysical anomalies and to determine whether mineral exploration of the anomalous areas might be warranted. An extensive geochemical sampling program did not disclose any evidence of ore mineral concentrations in the rocks. Detailed geologic mapping shows the anomalous areas to be underlain by Precambrian carbonaceous graywacke, the outcrop patterns of which closely fit the anomaly patterns. Field evidence and petrologic studies indicate that carbonaceous material in the rocks is the cause of the geophysical anomalies. Nothing was found in the anomalous areas that suggests the presence of mineral deposits of commercial grade, and further mineral investigations or exploration in the areas is not recommended.

Open-File Report↗
USGS2007

Geophysical delineation of the freshwater/saline-water transition zone in the Barton Springs segment of the Edwards Aquifer, Travis and Hays Counties, Texas, September 2006

During September 2006, the U.S. Geological Survey, in cooperation with the Barton Springs/Edwards Aquifer Conservation District, conducted a geophysical pilot study to determine whether time-domain electromagnetic (TDEM) sounding could be used to delineate the freshwater/saline-water transition zone in the Barton Springs segment of the Edwards aquifer in Travis and Hays Counties, Texas. There was uncertainty regarding the application of TDEM sounding for this purpose because of the depth of the aquifer (200-500 feet to the top of the aquifer) and the relatively low-resistivity clayey units in the upper confining unit. Twenty-five TDEM soundings were made along four 2-3-mile-long profiles in a study area overlying the transition zone near the Travis-Hays County boundary. The soundings yield measurements of subsurface electrical resistivity, the variations in which were correlated with hydrogeologic and stratigraphic units, and then with dissolved solids concentrations in the aquifer. Geonics Protem 47 and 57 systems with 492-foot and 328-foot transmitter-loop sizes were used to collect the TDEM soundings. A smooth model (vertical delineation of calculated apparent resistivity that represents an estimate [non-unique] of the true resistivity) for each sounding site was created using an iterative software program for inverse modeling. The effectiveness of using TDEM soundings to delineate the transition zone was indicated by comparing the distribution of resistivity in the aquifer with the distribution of dissolved solids concentrations in the aquifer along the profiles. TDEM sounding data show that, in general, the Edwards aquifer in the study area is characterized by a sharp change in resistivity from west to east. The western part of the Edwards aquifer in the study area shows higher resistivity than the eastern part. The higher resistivity regions correspond to lower dissolved solids concentrations (freshwater), and the lower resistivity regions correspond to higher dissolved solids concentrations (saline water). On the basis of reasonably close matches between the inferred locations of the freshwater/saline-water transition zone in the Edwards aquifer in the study area from resistivities and from dissolved solids concentrations in three of the four profiles, TDEM sounding appears to be a suitable tool for delineating the transition zone.

Texas↗
USGS2014

Archive of digital chirp subbottom profile data collected during USGS Cruise 13GFP01, Brownlee Dam and Hells Canyon Reservoir, Idaho and Oregon, 2013

From March 16 - 31, 2013, the U.S. Geological Survey in cooperation with the Idaho Power Company conducted a geophysical survey to investigate sediment deposits and long-term sediment transport within the Snake River from Brownlee Dam to Hells Canyon Reservoir, along the Idaho and Oregon border; this effort will help the USGS to better understand geologic processes. This report serves as an archive of unprocessed digital chirp subbottom data, trackline maps, navigation files, Geographic Information System (GIS) files, Field Activity Collection System (FACS) logs, and formal Federal Geographic Data Committee (FGDC) metadata. Gained (showing a relative increase in signal amplitude) digital images of the seismic profiles are also provided. Refer to the Acronyms page for expansions of acronyms and abbreviations used in this report.

Idaho;Oregon↗
USGS2016

Archive of bathymetry and backscatter data collected in 2014 nearshore Breton and Gosier Islands, Breton National Wildlife Refuge, Louisiana

As part of the Barrier Island Monitoring Project, scientists from the U.S. Geological Survey (USGS) St. Petersburg Coastal and Marine Science Center conducted nearshore geophysical surveys off Breton and Gosier Islands, Louisiana, in July and August of 2014. To assist the United States Fish and Wildlife Service (USFWS) with restoration planning efforts, the USGS was tasked with answering fundamental questions about the physical environment of the southern Chandeleur Islands, including the geology, morphology, and oceanography. Baseline data needed to answer these questions were either insufficient or missing. The USGS conducted a comprehensive geologic investigation in the summer of 2014, collecting geophysical and sedimentological data. Breton Island, located at the southern end of the Chandeleur Island chain in southeastern Louisiana, was recognized as a natural, globally significant nesting sanctuary for several bird species and was established as the Breton National Wildlife Refuge (NWR) in 1904. The areal extent of Breton Island has diminished 90 percent since 1920. Land loss is attributed to ongoing relative sea-level rise, diminished sediment supply, and storm impacts. The bird population on Breton Island has also declined over the years, most notably after Hurricane George in 1998 and after Hurricane Katrina in 2015; the latter completely submerged the island. Despite decreasing habitable acreage, migratory seabirds continue to return and nest on Breton Island. To prevent the island from being submerged in the future, and to protect, stabilize, and provide more nesting and foraging areas for the bird population, the USFWS proposed a restoration effort to rebuild Breton Island to its pre-Katrina footprint. This data series serves as an archive of processed interferometric swath and single-beam bathymetry data, and side-scan sonar data, collected in the nearshore of Breton and Gosier Islands, NWR, Louisiana. The data were collected during two USGS cruises (USGS Field Activity Numbers 2014-314-FA and 2014-317-FA) in July and August 2014. Geographic information system data products include a 100-meter-cell-size interpolated bathymetry grid, trackline maps, and point data files. Additional files include error analysis maps, Field Activity Collection System logs, and formal Federal Geographic Data Committee metadata. NOTE: These data are scientific in nature and are not to be used for navigation. Any use of trade names is for descriptive purposes only and does not imply endorsement by the U.S. Government.

Louisiana↗
USGS2009

Integrated Geophysical Investigation of Preferential Flow Paths at the Former Tyson Valley Powder Farm near Eureka, Missouri, May 2006

In May 2006, the U.S. Geological Survey, in cooperation with the U.S. Army Corps of Engineers, conducted surface and borehole geophysical surveys at the former Tyson Valley Powder Farm near Eureka, Mo., to identify preferential pathways for potential contaminant transport along the bedrock surface and into dissolution-enhanced fractures. The Tyson Valley Powder Farm was formerly used as a munitions storage and disposal facility in the 1940s and 1950s, and the site at which the surveys were performed was a disposal area for munitions and waste solvents such as trichloroethylene and dichloroethylene. Direct-current resistivity and seismic refraction data were acquired on the surface; gamma, electromagnetic induction, and full waveform sonic logs were acquired in accessible boreholes. Through the combined interpretation of the seismic refraction tomographic and resistivity inversion results and borehole logs, inconsistencies in the bedrock surface were identified that may provide horizontal preferential flow paths for dense nonaqueous phase liquid contaminants. These results, interpreted and displayed in georeferenced three-dimensional space, should help to establish more effective monitoring and remediation strategies.

Scientific Investigations Report↗
USGS2002

Cooperative investigation of precision and accuracy in chemical analysis of silicate rocks

This is the preliminary report of the first extensive program ever organized to study the analysis of igneous rocks, a study sponsored by the United States Geological Survey, the Massachusetts Institute of Technology, and the Geophysical Laboratory of the Carnegie Institution of Washington. Large samples of two typical igneous rocks, a granite and a diabase, were carefully prepared and divided. Small samples (about 70 grams) of each were sent to 25 rock-analysis laboratories throughout the world; analyses of one or both samples were reported by 34 analysts in these laboratories. The results, which showed rather large discrepancies, are presented in histograms. The great discordance in results reflects the present unsatisfactory state of rock analysis. It is hoped that the ultimate establishment of standard samples and procedures will contribute to the improvement of quality of analyses. The two rock samples have also been thoroughly studied spectrographically and petrographically. Detailed reports of all the studies will be published.

Analytical Chemistry↗
USGS2018

Determination of δ13C, δ15N, or δ34S by isotope-ratio-monitoring mass spectrometry using an elemental analyzer

This report describes procedures used in the Geology, Geophysics, and Geochemistry Science Center of the U.S. Geological Survey in Denver, Colorado, to determine the stable-isotope ratios 13 C/ 12 C, 15 N/ 14 N, and 34 S/ 32 S in solid materials. The procedures use elemental analyzers connected directly to gas-source isotope-ratio mass spectrometers. A different elemental–analyzer–mass-spectrometer system is used for 13 C/ 12 C and 15 N/ 14 N than is used for 34 S/ 32 S to accommodate differences in reagents, catalysts, and instrument settings.

Techniques and Methods↗
USGS2009

Detailed Geophysical Fault Characterization in Yucca Flat, Nevada Test Site, Nevada

Yucca Flat is a topographic and structural basin in the northeastern part of the Nevada Test Site (NTS) in Nye County, Nevada. Between the years 1951 and 1992, 659 underground nuclear tests took place in Yucca Flat; most were conducted in large, vertical excavations that penetrated alluvium and the underlying Cenozoic volcanic rocks. Radioactive and other potential chemical contaminants at the NTS are the subject of a long-term program of investigation and remediation by the U.S. Department of Energy (DOE), National Nuclear Security Administration, Nevada Site Office, under its Environmental Restoration Program. As part of the program, the DOE seeks to assess the extent of contamination and to evaluate the potential risks to humans and the environment from byproducts of weapons testing. To accomplish this objective, the DOE Environmental Restoration Program is constructing and calibrating a ground-water flow model to predict hydrologic flow in Yucca Flat as part of an effort to quantify the subsurface hydrology of the Nevada Test Site. A necessary part of calibrating and evaluating a model of the flow system is an understanding of the location and characteristics of faults that may influence ground-water flow. In addition, knowledge of fault-zone architecture and physical properties is a fundamental component of the containment of the contamination from underground nuclear tests, should such testing ever resume at the Nevada Test Site. The goal of the present investigation is to develop a detailed understanding of the geometry and physical properties of fault zones in Yucca Flat. This study was designed to investigate faults in greater detail and to characterize fault geometry, the presence of fault splays, and the fault-zone width. Integrated geological and geophysical studies have been designed and implemented to work toward this goal. This report describes the geophysical surveys conducted near two drill holes in Yucca Flat, the data analyses performed, and the integrated interpretations developed from the suite of geophysical methodologies utilized in this investigation. Data collection for this activity started in the spring of 2005 and continued into 2006. A suite of electrical geophysical surveys were run in combination with ground magnetic surveys; these surveys resulted in high-resolution subsurface data that portray subsurface fault geometry at the two sites and have identified structures not readily apparent from surface geologic mapping, potential field geophysical data, or surface effects fracture maps.

Open-File Report↗
USGS2011

Geophysical logging data from the Mills Gap Road area near Asheville, North Carolina

In September 2009, the U.S. Geological Survey (USGS) was requested to assist the Environmental Protection Agency (EPA) Region 4 Superfund Section in the development of a conceptual groundwater flow model in the area of the Mills Gap Road contaminant investigation near Asheville, North Carolina (Site ID A4P5) through an Interagency Grant and work authorization IAD DW number 14946085. The USGS approach included the application of established and state-of-the-science borehole geophysical tools and methods used to delineate and characterize fracture zones in the regolith-fractured bedrock groundwater system. Borehole geophysical logs were collected in eight wells in the Mills Gap Road project area from January through June 2010. These subsurface data were compared to local surface geologic mapping data collected by the North Carolina Geological Survey (NCGS) from January through May 2010.

North Carolina↗
USGS2001

Geophysical investigations of well fields to characterize fractured-bedrock aquifers in southern New Hampshire

Bedrock-fracture zones near high-yield bedrock wells in southern New Hampshire well fields were located and characterized using seven surface and six borehole geophysical survey methods. Detailed surveys of six sites with various methods provide an opportunity to integrate and compare survey results. Borehole geophysical surveys were conducted at three of the sites to confirm subsurface features. Hydrogeologic settings, including a variety of bedrock and surface geologic materials, were sought to gain an insight into the usefulness of the methods in varied terrains. Results from 15 survey lines, 8 arrays, and 3 boreholes were processed and interpreted from the 6 sites. The surface geophysical methods used provided physical properties of fractured bedrock. Seismic refraction and ground-penetrating radar (GPR) primarily were used to characterize the overburden materials, but in a few cases indicated bedrock-fracture zones. Magnetometer surveys were used to obtain background information about the bedrock to compare with other results, and to search for magnetic lows, which may result from weathered fractured rock. Electromagnetic terrain conductivity surveys (EM) and very-low-frequency electromagnetic surveys (VLF) were used as rapid reconnaissance techniques with the primary purpose of identifying electrical anomalies, indicating potential fracture zones in bedrock. Direct-current (dc) resistivity methods were used to gather detailed subsurface information about fracture depth and orientation. Two-dimensional (2-D) dc-resistivity surveys using dipole-dipole and Schlumberger arrays located and characterized the overburden, bedrock, and bedrock-fracture zones through analysis of data inversions. Azimuthal square array dc-resistivity survey results indicated orientations of conductive steep-dipping bedrock-fracture zones that were located and characterized by previously applied geophysical methods. Various available data sets were used for site selection, characterizations, and interpretations. Lineament data, developed as a part of a statewide and regional scale investigation of the bedrock aquifer, were available to identify potential near-vertical fracture zones. Geophysical surveys indicated fracture zones coincident with lineaments at 4 of the sites. Geologic data collected as a part of the regional scale investigation provided outcrop fracture measurements, ductile fabric, and contact information. Dominant fracture trends correspond to the trends of geophysical anomalies at 4 of the sites. Water-well drillers? logs from water supply and environmental data sets also were used where available to characterize sites. Regional overburden information was compiled from stratified-drift aquifer maps and surficial-geological maps.

Water-Resources Investigations Report↗
USGS2025

Airborne geophysical efforts for critical mineral systems mapping in the southern Midcontinent, USA

The increasing global demand for critical minerals to support energy and technological advancement has accelerated exploration and research efforts for these essential resources. Since 2019, the United States Geological Survey (USGS) Earth Mapping Resources Initiative (EMRI) has worked to modernize geologic mapping of the Nation to better understand its critical mineral resources. To further this initiative, the USGS has flown a series of high-resolution airborne magnetic and radiometric surveys over large areas of the southern Midcontinent. The surveys cover known critical mineral deposits and areas with the potential to host additional critical minerals based on the presence of one or more overlapping mineral systems. One aspect of EMRI emphasizes close collaboration between the USGS and the Association of American State Geologists, as well as other government and industry partners to leverage geophysical, geological, and geochemical expertise on both regional and local scales. The EMRI high-resolution airborne survey data provide new insights into the geophysical framework of the southern Midcontinent and its critical mineral endowment. Additionally, discoveries made from the data have directed new studies for critical mineral exploration.

southern Midcontinent↗
USGS2011

Enhancement of USGS scientific investigations in Texas by using geophysical techniques, 2005-10

Geophysical techniques are an increasingly important tool for scientific investigations, environmental planning, and resource management. During 2005-10 the U.S. Geological Survey Texas Water Science Center greatly expanded its capabilities of using surface and borehole geophysical techniques to gain insights into how groundwater systems work and the occurrence and distribution of certain contaminants. Geophysical techniques provide a relatively quick and inexpensive means to characterize the subsurface hydrology and lithology.

Fact Sheet↗