Geology Reports⌕ Search

SEARCH · Geology Reports

Results for “Energy Economics”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources

Reconnaissance of ground-water resources in the Mountain Home plateau area, southwest Idaho

The Mountain Home plateau area occupies approximately 1,220 square miles of the western Snake River Plain in southwestern Idaho. About 40,000 acres are presently (1977) irrigated with ground water, about 30,000 acres with surface water. An estimated 450,000 acres are potentially irrigable, if water is available. Development of ground-water re- sources has caused water-level declines in several places. Largest declines are south of Mountain Home, where water levels dropped more than 20 feet in the last 9 years. Ground water in the area occurs primarily under water-table conditions. Perched-water zones are present in several locations. The most productive aquifer in the eastern part of the plateau is basalt of the Bureau Formation of the Idaho Group. In the western part, the most productive aquifers are sand and gravel of the older terrace gravel lithologic unit and the Idaho Group. Recharge to the ground-water system is water from the Boise River drainage basin, precipitation on the plateau and adjacent mountains, and leakage from irrigation structures. Ground-water movement is generally south or southwest. Natural ground-water discharge from the plateau is about 18,000 acre-feet annually. The chemical composition of the ground water generally reflects water characteristics in the area of the source of recharge and, for the most part, is good. Deuterium and oxygen-18 isotope analyses suggest that the water at the lower end of the ground-water flow system underlying the plateau was recharged a long time ago, although climatic conditions then were similar to current conditions in the Boise River basin. Additional large-scale ground-water development will probably result in economically prohibitive pumping lifts, which also would consume excessive amounts of energy. Therefore, large-scale new agricultural development would depend heavily on the availability of surface water. However, one or several deep test holes, in selected places, could help answer some questions about the occurrence of ground water and perhaps encourage further exploration for untapped deep artesian aquifers. The occurrence of perched-water zones beneath lands irrigated by surface water suggests that more zones of this type could develop if water is imported into the area to irrigate additional lands, and if the efficiency of the present distribution systems remains unchanged.

Idaho↗

Chapter 10: Occurrence of non-native invasive plants: The role of anthropogenic features

The invasion of non-native plants in the Wyoming Basins Ecoregional Assessment (WBEA) area is a major economic and ecological stress, with invasions thought to be hastened by energy developments. Given the potential impacts of nonnative invasive plants and the rapid changes in land use in the WBEA, broad-scale assessments and predictive models of nonnative invasive plant distribution are needed. Using this information, the current extent of populations for targeting treatment and monitoring can be identified, the habitat affinities for forecasting where weeds may establish next determined, and the responses to individual human disturbances (such as energy developments) predicted. To address these needs, we conducted vegetation surveys across the WBEA area at 317 individual survey blocks (five plots per survey block) during the summers of 2005 and 2006. Survey blocks were stratified by both human disturbance and habitat productivity; in each of five plots per survey block the occurrence of 23 common nonnative invasive plants was recorded during early and late season surveys. Here, we report on the four most common invasive plants, crested wheatgrass ( Agropyron cristatum ), cheatgrass ( Bromus tectorum ), halogeton ( Halogeton glomeratus ), and Russian thistle ( Salsola spp. ). Occurrence models were generated for each species using random-effects logistic regression to account for nesting of plots within sample sites. Predictors of occupancy included local habitat, abiotic condition, and distance to anthropogenic features. Although occurrences of all four invasive plants were affected by habitat, abiotic, and anthropogenic factors, cheatgrass and Russian thistle were most strongly associated with anthropogenic disturbance, primarily major roads and energy well sites. We assessed relationships between environmental and anthropogenic predictors and species occurrences to identify the major factors affecting current species distribution, examined shape of the response in occurrence in relation to proximity to individual anthropogenic disturbances, and provided spatial predictions of the locations where invasive plants are most likely to occur.

Wyoming↗

Overview of future USGS Gulf of Mexico buoyant storage assessment project

The United States Geological Survey (USGS) is a member of a U.S. Department of Energy-funded partnership headed by the University of Texas Bureau of Economic Geology that is working to assess the feasibility of offshore geologic carbon dioxide (CO2) storage in the Gulf of Mexico. The role of the USGS is to assess the buoyant geologic CO2 storage resource of the western half of the offshore Gulf of Mexico (GoM). Buoyant CO2 storage is the CO2 held in place by a top and lateral seal (either a sealing formation or a sealing fault), that creates a column of CO2 in communication across pore space in a geologic reservoir. This assessment will be similar to the USGS assessment of onshore buoyant geologic CO2 storage [1] and will employ a modified version of existing USGS methodology [2] to assess the buoyant CO2 storage capacity in the GoM.

Gulf of Mexico↗

Terrestrial ecological risk analysis via dietary exposure at uranium mine sites in the Grand Canyon watershed (Arizona, USA)

The U.S. Department of the Interior recently included uranium (U) on a list of mineral commodities that are considered critical to economic and national security. The uses of U for commercial and residential energy production, defense applications, medical device technologies, and energy generation for space vehicles and satellites are known, but the environmental impacts of uranium extraction are not always well quantified. We conducted a screening-level ecological risk analysis based on exposure to mining-related elements via diets and incidental soil ingestion for terrestrial biota to provide context to chemical characterization and exposures at breccia pipe U mines in northern Arizona. Relative risks, calculated as hazard quotients (HQs), were generally low for all biological receptor models. Our models screened for risk to omnivores and insectivores (HQs>1) but not herbivores and carnivores. Uranium was not the driver of ecological risk; arsenic, cadmium, copper, and zinc were of concern for biota consuming ground-dwelling invertebrates. Invertebrate species composition should be considered when applying these models to other mining locations or future sampling at the breccia pipe mine sites. Dietary concentration thresholds (DCTs) were also calculated to understand food concentrations that may lead to ecological risk. The DCTs indicated that critical concentrations were not approached in our model scenarios, as evident in the very low HQs for most models. The DCTs may be used by natural resource and land managers as well as mine operators to screen or monitor for potential risk to terrestrial receptors as mine sites are developed and remediated in the future.

Arizona↗

Geology and mineral resources of the North Absaroka Wilderness and vicinity, Park County, Wyoming, with sections on mineralization of the Sunlight mining region and geology and mineralization of the Cooke City mining district, and a section on aeromagnetic interpretation

SUMMARY The North Absaroka Wilderness is approximately 560 square miles (1,450 km 2 ) of rugged scenic mountainous terrain that adjoins the eastern boundary of Yellowstone National Park in northwestern Wyoming. The area was studied during 1970, 1971, and 1972 by personnel of the U. S. Geological Survey and the U. S. Bureau of Mines to evaluate its mineral-resource potential as required by the Wilderness Act of 1964. This evaluation is based on a search of the literature courthouse and production records, geologic field mapping, field inspection of claims and prospects, analyses of bedrock and stream-sediment samples, and an aeromagnetic survey. The North Absaroka Wilderness is underlain almost entirely by andesitic and basaltic volcanic rocks of Eocene age. These volcanics rest on deformed sedimentary rocks of Paleozoic and, locally, of Mesozoic age that are exposed at places along the northern and eastern edges of the wilderness. Dikes and other igneous intrusive bodies cut both the volcanic and sedimentary rocks. A nearly flat detachment fault, the Heart Mountain fault, and a related steep break-away fault have displaced middle and upper Paleozoic rocks and some of the older part of the volcanic sequence to the southeast. A much greater thickness of volcanic rocks was found to be involved in Heart Mountain faulting than had previously been recognized; however, most of the volcanic rocks and many of the intrusives were emplaced after Heart Mountain faulting. Local folding and high-angle faulting in mid-Eocene time have deformed all but the youngest part of the volcanic sequence in the southeastern part of the wilderness. This deformation is interpreted as the last pulse of Laramide orogeny. The results of this study indicate that the mineral-resource potential of the wilderness is minimal. Bentonite, petroleum, low-quality coal, and localized deposits of uranium and chromite have been produced in the surrounding region from rocks that underlie the volcanic rocks; but such deposits, if present in the wilderness, would be too deeply buried, too small, or too sporadically distributed to be profitably located and exploited. Copper and gold mines and prospects are present on the fringes of the wilderness, but otherwise the area seems to be devoid of economically valuable concentrations of metallic minerals. No surface evidence of geothermal-energy potential was found. Known mineral deposits in the vicinity of the North Absaroka Wilderness are associated with intrusive rocks. From the Cooke City mining district, just north of the wilderness, replacement deposits in Upper Cambrian carbonate rocks may extend a short distance into the north edge of the wilderness, In the Sunlight mining region, an enclave nearly surrounded by the wilderness, mineralization occurs in veins and is disseminated in volcanic and plutonic rocks. Richer concentrations of metallic minerals may occur in carbonate rocks adjacent to intrusive bodies at depth beneath the volcanic rocks in the Sunlight region. A few small intrusive bodies occur in the wilderness, but no significant associated mineralization was detected. Aeromagnetic data indicate that other intrusives not exposed by erosion may occur in the wilderness; however, no significant metamorphism or alteration is evident at the surface to indicate their presence. Although most of the rocks of the wilderness are of igneous origin, they are all so old (Eocene) that it is unlikely that they retain any original heat. The Pleistocene rhyolitic ash-flow tuffs in the southwestern part of the wilderness were erupted from sources in Yellowstone National Park just to the west; however, in the wilderness these tuffs are too thin to contain any residual heat.

Wyoming↗

Managing the water-energy-food nexus: Opportunities in Central Asia

This article examines impacts of infrastructure development and climate variability on economic outcomes for the Amu Darya Basin in Central Asia. It aims to identify the most economically productive mix of expanded reservoir storage for economic benefit sharing to occur, in which economic welfare of all riparians is improved. Policies examined include four combinations of storage infrastructure for each of two climate futures. An empirical optimization model is developed and applied to identify opportunities for improving the welfare of Tajikistan, Uzbekistan, Afghanistan, and Turkmenistan. The analysis 1) characterizes politically constrained and economically optimized water-use patterns for these combinations of expanded reservoir storage capacity, 2) describes Pareto-Improving packages of expanded storage capacity that could raise economic welfare for all four riparians, and accounts for impacts for each of two climate scenarios. Results indicate that a combination of targeted water storage infrastructure and efficient water allocation could produce outcomes for which the discounted net present value of benefits are favorable for each riparian. Results identify a framework to provide economic motivation for all riparians to cooperate through development of water storage infrastructure. Our findings illustrate the principle that development of water infrastructure can expand the negotiation space by which all communities can gain economic benefits in the face of limited water supply. Still, despite our optimistic findings, patient and deliberate negotiation will be required to transform potential improvements into actual gains.

Journal of Hydrology↗

Coal-to-liquids: Potential impact on U.S. coal reserves

The production of liquid fuels from coal will very likely become an important part of the hydrocarbon energy mix of the future, provided that technical and environmental obstacles are overcome economically. The coal industry should be able to handle a coal-to-liquids (CTL) industry of modest size, using 60-70 million short tons or 54-64 million metric tonnes of coal per annum, without premature depletion of the country's coal reserves. However, attempts to use CTL technology to replace all petroleum imports would deplete the nation's coal reserves by the end of the century. ?? 2009 U.S. Government.

Natural Resources Research↗

Storm-influenced deltaic deposits of the Middle Jurassic Gaikema Sandstone in a measured section on the northern Iniskin Peninsula, Cook Inlet basin, Alaska

Middle Jurassic strata of the Gaikema Sandstone were deposited about 170 million years ago on a delta that was located on the western shoreline of the Cook Inlet basin (Detterman and Hartsock, 1966; LePain and others, 2011, 2013). The delta was built by swift, sediment-laden rivers that flowed southeastward from a mountainous volcanic terrane west of the Bruin Bay fault (fig. 6-1). Upon reaching the edge of the Jurassic sea, the rivers dumped abundant sand, gravel, and mud into a depocenter on the northern Iniskin Peninsula, about 240 km southwest of Anchorage (figs. 6-1, 6-2). This report provides a preliminary description and interpretation of a detailed, 34-m-thick measured section in the Gaikema Sandstone on the south shore of Chinitna Bay at latitude 59.816°N, longitude 153.168°W (figs. 6-1–6-3). The sandstone in this measured section exhibits hummocky cross lamination and other features suggestive of storm-influenced deposition on the shallow-marine, seaward margin of the Gaikema delta. Our field studies of the Gaikema Sandstone were conducted during 2013 and 2014 as part of a collaborative effort by the Alaska Division of Geological & Geophysical Surveys (DGGS), Alaska Division of Oil and Gas (DOG), and U.S. Geological Survey (USGS) to provide the public with reliable information on the geologic framework and petroleum resource potential of Cook Inlet basin (Gillis, 2013, 2014). Jurassic rocks in Cook Inlet, including the Gaikema Sandstone, are of economic interest because they could contain significant undiscovered petroleum resources (Bureau of Ocean Energy Management, 2011; Stanley and others, 2011a, 2011b, 2013a; LePain and others, 2013).

Alaska↗

Evaluating the potential of co-located non-petroleum energy resources in the Gulf Coast using play fairwayaAnalysis

Geological resources critical to the energy transition, such as sedimentary geothermal, carbon storage potential, and lithium in brines, commonly struggle for economic feasibility as stand-alone developments but can have greater viability when the potential for more than one of these resources exist within the same reservoir or stacked in different stratigraphic intervals. There may also be instances where development of one resource inhibits development of others and decisions need to be made on how to best prioritize the use of those resources in the subsurface. Subsurface data sets were analyzed and integrated to evaluate the distribution of non-petroleum energy and related resources in the onshore and nearshore U.S. Gulf Coast. Temperature, pressure, brine composition (lithium content), and reservoir quality data for thirty-four depositional units have been compiled and visualized to high-grade areas where multiple resource opportunities likely coexist. For sedimentary geothermal, possible resource areas are defined as low potential (<90°C), moderate potential (90–150°C), and high potential (>150°C). For CO 2 storage, high potential areas exhibit supercritical CO 2 conditions less than 80% of the fracture gradient. Areas with pore pressure between 80% and 100% of the fracture gradient are considered to exhibit moderate potential and areas where the fracture gradient is equal to or greater than 100% are assigned low potential. Lithium resources in brines were defined by lithium concentrations as low potential (<100ppm), moderate potential (100-200ppm), or high potential (>200ppm). Reservoir quality affects the viability of all three of these resources and is evaluated using depositional environment maps of each unit. The resulting play fairway maps can be used for regional scale screening evaluations of these resources and to identify areas of interest where more detailed, prospect-scale studies can be undertaken.

Gulf Coast↗

Earth and water resources and hazards in Central America

Long-range economic development in Central America will depend in large part on production of indigenous mineral, energy, and water resources and on mitigation of the disastrous effects of geologic and hydrologic hazards such as landslides, earthquakes, volcanic eruptions, and floods. The region has six world-class metal mines at present as well as additional evidence of widespread mineralization. Systematic investigations using modern mineral exploration techniques should reveal more mineral deposits suitable for development. Widespread evidence of lignite and geothermal resources suggests that intensive studies could identify producible energy sources in most Central American countries. Water supply and water quality vary greatly from country to country. Local problems of ground- and surface-water availability and of contamination create a need for systematic programs to provide better hydrologic data, capital improvements, and management. Disastrous earthquakes have destroyed or severely damaged many cities in Central America. Volcanic eruptions, landslides, mudflows, and floods have devastated most of the Pacific side of Central America at one time or another. A regional approach to earthquake, volcano, and flood-risk analysis and monitoring, using modern technology and concepts, would provide the facilities and means for acquiring knowledge necessary to reduce future losses. All Central American countries need to strengthen institutions and programs dealing with earth and water resources and natural hazards. Some of these needs may be satisfied through existing or pending projects and technical and economic assistance from U.S. or other sources. The need for a comprehensive study of the natural resources of Central America and the requirements for their development is evident. The U.S. Caribbean Basin Initiative offers both an excellent opportunity for a regional approach to these pervasive problems and an opportunity for international cooperation.

Circular↗

Critical analysis of world uranium resources

The U.S. Department of Energy, Energy Information Administration (EIA) joined with the U.S. Department of the Interior, U.S. Geological Survey (USGS) to analyze the world uranium supply and demand balance. To evaluate short-term primary supply (0–15 years), the analysis focused on Reasonably Assured Resources (RAR), which are resources projected with a high degree of geologic assurance and considered to be economically feasible to mine. Such resources include uranium resources from mines currently in production as well as resources that are in the stages of feasibility or of being permitted. Sources of secondary supply for uranium, such as stockpiles and reprocessed fuel, were also examined. To evaluate long-term primary supply, estimates of uranium from unconventional and from undiscovered resources were analyzed. At 2010 rates of consumption, uranium resources identified in operating or developing mines would fuel the world nuclear fleet for about 30 years. However, projections currently predict an increase in uranium requirements tied to expansion of nuclear energy worldwide. Under a low-demand scenario, requirements through the period ending in 2035 are about 2.1 million tU. In the low demand case, uranium identified in existing and developing mines is adequate to supply requirements. However, whether or not these identified resources will be developed rapidly enough to provide an uninterrupted fuel supply to expanded nuclear facilities could not be determined. On the basis of a scenario of high demand through 2035, 2.6 million tU is required and identified resources in operating or developing mines is inadequate. Beyond 2035, when requirements could exceed resources in these developing properties, other sources will need to be developed from less well-assured resources, deposits not yet at the prefeasibility stage, resources that are currently subeconomic, secondary sources, undiscovered conventional resources, and unconventional uranium supplies. This report’s analysis of 141 mines that are operating or are being actively developed identifies 2.7 million tU of in-situ uranium resources worldwide, approximately 2.1 million tU recoverable after mining and milling losses were deducted. Sixty-four operating mines report a total of 1.4 million tU of in-situ RAR (about 1 million tU recoverable). Seventy-seven developing mines/production centers report 1.3 million tU in-situ Reasonably Assured Resources (RAR) (about 1.1 million tU recoverable), which have a reasonable chance of producing uranium within 5 years. Most of the production is projected to come from conventional underground or open pit mines as opposed to in-situ leach mines. Production capacity in operating mines is about 76,000 tU/yr, and in developing mines is estimated at greater than 52,000 tU/yr. Production capacity in operating mines should be considered a maximum as mines seldom produce up to licensed capacity due to operational difficulties. In 2010, worldwide mines operated at 70 percent of licensed capacity, and production has never exceeded 89 percent of capacity. The capacity in developing mines is not always reported. In this study 35 percent of developing mines did not report a target licensed capacity, so estimates of future capacity may be too low. The Organisation for Economic Co-operation and Development’s Nuclear Energy Agency (NEA) and International Atomic Energy Agency (IAEA) estimate an additional 1.4 million tU economically recoverable resources, beyond that identified in operating or developing mines identified in this report. As well, 0.5 million tU in subeconomic resources, and 2.3 million tU in the geologically less certain inferred category are identified worldwide. These agencies estimate 2.2 million tU in secondary sources such as government and commercial stockpiles and re-enriched uranium tails. They also estimate that unconventional uranium supplies (uraniferous phosphate and black shale deposits) may contain up to 7.6 million tU. Although unconventional resources are currently subeconomic, the improvement of extraction techniques or the production of coproducts may make extraction of uranium from these types of deposits profitable. A large undiscovered resource base is reported by these agencies, however this class of resource should be considered speculative and will require intensive exploration programs to adequately define them as mineable. These resources may all contribute to uranium supply that would fuel the world nuclear fleet well beyond that calculated in this report. Production of resources in both operating and developing uranium mines is subject to uncertainties caused by technical, legal, regulatory, and financial challenges that combined to create long timelines between deposit discovery and mine production. This analysis indicates that mine development is proceeding too slowly to fully meet requirements for an expanded nuclear power reactor fleet in the near future (to 2035), and unless adequate secondary or unconventional resources can be identified, imbalances in supply and demand may occur.

Scientific Investigations Report↗

A two-stage step-wise framework for fast optimization of well placement in coalbed methane reservoirs

Coalbed methane (CBM) has emerged as a clean energy resource in the global energy mix, especially in countries such as Australia, China, India and the USA. The economical and successful development of CBM requires a thorough evaluation and optimization of well placement prior to field-scale exploitation. This paper presents a two-stage, step-wise optimization framework to obtain the optimal placement of wells for large-scale development of CBM reservoirs. In the first stage, an optimal uniform well pattern is obtained by optimizing well pattern description parameters with the particle swarm optimization (PSO) algorithm. Subsequently, the location and status (active/inactive) of each well are perturbed and optimized within the patterns through the integration of the generalized pattern search (GPS) algorithm and a quality map (QM) representing the production potential. This framework was tested in a synthetic anthracite CBM reservoir in the Qinshui basin (with high gas content and low permeability) and a real field high volatile bituminous reservoir in the Illinois basin (with low gas content and high permeability). The results show that: (i) significant variations in the net present value (NPV) exist with respect to different uniform well patterns (even for cases where the total number of wells are identical), the optima of which can be efficiently determined by the PSO within 100 numerical simulation runs; (ii) the optimization of well perturbations by the GPS results in a more noticeable improvement in NPVs for the synthetic (12.3%) than for the real field model (4.6%); (iii) for the low permeable synthetic model with narrow optimal well spacings (320 m × 200 m), the contribution of the optimization of well perturbation to the NPV increment is heavily dependent on the uniform well placement solution; (iv) for the high permeable real field model with large optimal well spacings (1300 m × 1300 m), the initial uniform well placement has a very minor effect on the subsequent well perturbation solutions in terms of NPV; (v) the proposed framework significantly outperforms the conventional well-by-well concatenation procedure in terms of computational efficiency, robustness and optimal criteria set for production potential.

International Journal of Coal Geology↗

Review of lignite resources of western Tennessee and the Jackson Purchase area, western Kentucky

Introduction: This review of the lignite deposits of western Tennessee and the Jackson Purchase area in western Kentucky (Fig. 1) is a preliminary report on part of the U.S. Geological Survey's National Coal Resource Assessment of the Gulf Coastal Plain Coal Province. Lignite deposits of western Kentucky and Tennessee are an extension of the Gulf Coastal Plain Coal Province (Cushing and others, 1964), and currently are not economic to mine. These deposits have not been extensively investigated or developed as an energy resource. This review includes a description of the geology of the lignite-bearing units, a discussion of the available coal quality data, and information on organic petrology. Palynological data for lignite samples collected in Kentucky and Tennessee as part of this work are presented in an Appendix.

Open-File Report↗

A review of lignite resources of western Tennessee and the Jackson Purchase area, western Kentucky

This review of the lignite deposits of western Tennessee and the Jackson Purchase area in western Kentucky (Figure 1) is an updated report on part of the U.S. Geological Survey's National Coal Resource Assessment of the Gulf Coastal Plain Coal Province (see Ruppert et al., 2002; Hackley et al., 2006; Dennen, 2009; and other chapters of this publication). Lignite deposits of western Kentucky and Tennessee are an extension of the Gulf Coastal Plain Coal Province (Cushing et al., 1964), and currently are not economic to mine. These deposits have not been extensively investigated or developed as an energy resource. This review includes a description of the geology of the lignite-bearing units, a discussion of the available coal quality data, and information on organic petrology. Palynological data for lignite samples collected in Kentucky and Tennessee as part of this work are presented in Table 1. Lignite trace element data originally presented in Hackley et al. (2006) are not included in this report due to potential laboratory quality control issues during the time the samples were analyzed (U.S. Geological Survey Energy Resources Program, 2010).

Kentucky, Tennessee↗

Landscape-scale wildlife species richness metrics to inform wind and solar energy facility siting: An Arizona case study

The juxtaposition of wildlife and wind or solar energy facility infrastructure can present problems for developers, planners, policy makers, and management agencies. Guidance on siting of these renewable energy facilities may help identify potential wildlife-facility conflicts with species of regulatory or economic concern. However, existing spatial guidance usually does not consider all wildlife that might use a potential facility location or corridors for its servicing infrastructure. We illustrate an approach toward assessing potential wildlife-facility conflicts using readily available vertebrate habitat models. The U.S. Geological Survey's Gap Analysis Program (GAP) has developed spatial models of potential habitat for vertebrate species across the entire nation. To illustrate their applicability, we used GAP models to estimate richness of all native, terrestrial vertebrates within Arizona and for those vertebrates grouped by class or by sensitivity to the type of facility infrastructure. We examined the spatial overlap of high species richness of each group with agency-developed guidance used to inform facility-siting decisions and found that GAP-based richness mappings augmented existing guidance. As the GAP vertebrate habitat models are publicly available for the entire USA, use of these data can provide a coarse view of potential wildlife-facility conflicts and inform facility planning early in the process.

Arizona↗

Hydraulic properties of sediments from the GC955 gas hydrate reservoir in the Gulf of Mexico

The economic feasibility of gas production from hydrate deposits is critical for hydrate to become an energy resource. Permeability in hydrate-bearing sediments dictates gas and water flow rates and needs to be accurately evaluated. Published permeability studies of hydrate-bearing sediments mostly quantify vertical permeability; however, the flow is mainly horizontal during gas production in layered reservoirs. Additionally, ASTM standards require a hydraulic gradient of 10–30 to be used during laboratory permeability measurements, but the gradient is much higher in the field, particularly near a production well. To address these issues, this study focuses on the hydraulic properties of a sandy silt subsample of the hydrate reservoir and a clayey silt subsample of the fine-grained, hydrate-free interbed recovered from a GC955 deep-water Gulf of Mexico gas hydrate reservoir. We characterize the sediment pore space with water retention curves for both hydrate-free and hydrate-bearing samples (hydrate saturation, S h =80 %). Vertical deformation with increasing stress is also quantified while consolidating the samples to the 4 MPa in situ vertical effective stress. The customized permeameter measures both the horizontal and vertical permeability with increasing stress. Results show that high hydraulic gradients lower permeability in the flow direction, possibly due to increased flow tortuosity and local sediment compaction from the high seepage force. Assuming a single permeability value, even though hydraulic gradients decrease with distance from the well, is not realistic for field estimations. The results highlight that permeability anisotropy, hydrate saturation, stress conditions, and hydraulic gradient all substantially impact reservoir permeability during production.

Geomechanics for Energy and the Environment↗

Tapping methane hydrates for unconventional natural gas

Methane hydrate is an icelike form of concentrated methane and water found in the sediments of permafrost regions and marine continental margins at depths far shallower than conventional oil and gas. Despite their relative accessibility and widespread occurrence, methane hydrates have never been tapped to meet increasing global energy demands. With rising natural gas prices, production from these unconventional gas deposits is becoming economically viable, particularly in permafrost areas already being exploited for conventional oil and gas. This article provides an overview of gas hydrate occurrence, resource assessment, exploration, production technologies, renewability, and future challenges.

Elements↗

Great Lakes spatial priorities study

Spatial data about the bathymetry, habitat characteristics, underlying geology, and other features of the ocean and inland seas are essential for decision-making. Marine research and management organizations use these data to help ensure safe navigation, promote sustainable fisheries, extract energy, and protect marine habitats in the coastal and ocean waters of the U.S. Exclusive Economic Zone (EEZ) and Laurentian Great Lakes. Many of these organizations may have overlapping or shared mapping interests without knowing it. In a multi-jurisdictional planning environment, it can be challenging and cumbersome to determine where other entities have shared or overlapping mapping interests, especially across a transnational region such as the Great Lakes. State and provincial governments, federal governments, academia, tribes and First Nations, and other stakeholders from both the U.S. and Canada all have mapping interests across Great Lakes waters. Identifying and communicating target geographies for new data collection that are shared among multiple organizations can both help to avoid redundancy of new mapping efforts, and create opportunities for greater efficiency through collaboration. To address this issue, a spatial priorities study was conducted using a geospatial tool developed by the National Ocean Services National Centers for Coastal and Ocean Science (NCCOS). The tool provided an easy-to-use online interface in which programs can identify their priorities in a simple and straightforward way. This study asked representatives of Great Lakes management and science organizations to identify the areas for which they needed maps of lakebed features on a near-term, mid-term, and long-term timeframe, and why. Then, the responses were analyzed and overlaid to determine areas of shared mapping need and opportunity and to determine the types of map products needed. The analysis revealed high interest among multiple organizations in discrete geographies including the Minnesota and Wisconsin shoreline from Duluth to the eastern extent of the Bayfield Peninsula, Green Bay in Lake Michigan, and the southern coastlines of Lake Erie and Lake Ontario, the St. Marys River, and the northern Lake Superior coastal waters near Grand Portage, MN. Lower priority mapping interest were distributed widely across all lakes, but tended to be concentrated in nearshore areas (<30 m depth). The analysis also indicated that the top mapping justifications were Habitat/biota/natural area, Benthic exploration, Commercial and recreational fishing, and Scientific research. The top desired map product types were Elevation, Substrate/sub-bottom geologic characterization, and Habitat map/characterization, although participants on some lakes noted other less prevalent product types. Following from previously conducted NOAA and non-NOAA Federal spatial prioritization exercises, the results of this regional focus can help mapping organizations better understand how their priorities align with the needs of regional organizations, allow for more efficient coordination and funding, and enable partners to leverage assets and resources to fill their most pressing data and information gaps across Great Lakes waters. The U.S. Mapping Coordination Site hosts the results of this study and other spatial prioritization studies. Through this website, one can interact with the study results along with recent and planned mapping efforts. NOAA intends to update their spatial priorities on a three- to five-year basis. Future studies should strive to expand participation of federal agencies, state and local governments, federally-recognized tribes, academia, and private industry (among other stakeholders) to seek out ocean mapping partnerships in conjunction with the National Ocean Mapping, Exploration and Characterization (NOMEC) goals map once, use many times.”

Great Lakes↗