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At least 55 records · Page 3

Correction and Geological Analysis of Lunar 3.8 Cm Radar Data

Earth based radar observations of the Moon have been taken at many wavelengths during the last ten years -- at 3.8, 70 cm, and most recently, 7.5 cm. Radar returns have been collected in both polarized and depolarized form so that is possible to derive both topographic and local surface roughness from the data. Until recently, work with 3.8 cm radar data had consisted of qualitative correlation of photographic and thermal IR data with individual depolarized radar data frames (local surface roughness) at different wavelengths. These studies provided results which demonstrated that the relationships between surface roughness (measured by either thermal emission or radar reflectivity) at different wavelengths can be used as an index of a crater's state of degradation (age). However, systematic studies of craters, or other local terrain features, as well as regional or global studies of major terrains (involving a number of data frames), cannot be done until individual frames are calibrated, geometric distortion is removed, and corrected frames are mosaicked.

Clark, P. E.↗

Optimizing space radars for geological analysis in tropical environments

A swath along the Motagua Fault in northeastern Guatemala was imaged with the AN/APS-94D airborne and the SIR-A Space Shuttle-borne radars with a difference in look direction on the order of ten degrees. Imagery of the Panama Canal Zone, overlapping in coverage but with diverse look directions was produced by the AN/APQ-97 and GEMS airborne radars and SIR-A. Taking into account the diversity of system and operational parameters, comparative analysis of the images well documented that the increased data content of the airborne radar imagery was due to the high look angles at which these systems operate.

Dellwig, L. F.↗

Preliminary spectral and geologic analysis of Landsat-4 Thematic Mapper data, Wind River Basin area, Wyoming

A Landsat-4 Thematic Mapper (TM) image of the Wind River Basin area in Wyoming is currently under analysis for stratigraphic and structural mapping and for assessment of spectral and spatial characteristics using visible, near infrared, and short wavelength infrared bands. To estimate the equivalent Lambertian surface reflectance, TM radiance data were calibrated to remove atmospheric and instrumental effects. Reflectance measurements for homogeneous natural and cultural targets were acquired about one year after data acquisition. Calibration data obtained during the analysis were used to calculate new gains and offsets to improve scanner response for earth science applications. It is shown that the principal component images calculated from the TM data were the result of linear transformations of ground reflectance. In images prepared from this transform, the separation of spectral classes was independent of systematic atmospheric and instrumental factors. Several examples of the processed images are provided.

Conel, J. E.↗

Comparing Geologic Data Sets Collected by Planetary Analog Traverses and by Standard Geologic Field Mapping: Desert Rats Data Analysis

Geologic mapping involves interpreting relationships between identifiable units and landforms to understand the formative history of a region. Traditional field techniques are used to accomplish this on Earth. Mapping proves more challenging for other planets, which are studied primarily by orbital remote sensing and, less frequently, by robotic and human surface exploration. Systematic comparative assessments of geologic maps created by traditional mapping versus photogeology together with data from planned traverses are limited. The objective of this project is to produce a geologic map from data collected on the Desert Research and Technology Studies (RATS) 2010 analog mission using Apollo-style traverses in conjunction with remote sensing data. This map is compared with a geologic map produced using standard field techniques.

Feng, Wanda↗

Identification of potential CO 2 leakage pathways and mechanisms in oil reservoirs using fault tree analysis

Geological storage of CO 2 technologies has become an important and effective way to reduce the greenhouse gas emissions, especially when it is combined with CO 2 enhanced oil recovery (EOR), which can not only trap CO 2 but also enhance oil recovery. However, the risk of CO 2 leakage has always been a prominent issue. In this paper, the mechanisms and pathways of CO 2 leakage during geological storage in oil reservoirs were analyzed using fault tree analysis (FTR). Besides, monitoring technologies were discussed and deployed in a CO 2 EOR demonstration project. The analysis results showed that the sealing failures of oil producer and CO2 injector wells, like well cement failure and casing failure, are the main reasons for the CO 2 leakage, which has been observed in the oil field monitoring project. The monitoring results indicated that there is no large-scale CO 2 leakage, while relatively high and abnormal CO 2 concentration in soil gas near some wellbores are observed, which indicates there is some leakage of CO 2 through incomplete cement ring and well casing string. FTR results provide guidelines for monitoring and preventing of CO 2 leakage during geological storage in oil reservoirs. Finally, the near-surface monitoring methods, especially the soil gas monitoring technologies, can effectively detect the leakage of CO 2 , and are a proper method for CO 2 leakage monitoring.

58 GEOSCIENCES↗

Spaceborne radar observations: A guide for Magellan radar-image analysis

Geologic analyses of spaceborne radar images of Earth are reviewed and summarized with respect to detecting, mapping, and interpreting impact craters, volcanic landforms, eolian and subsurface features, and tectonic landforms. Interpretations are illustrated mostly with Seasat synthetic aperture radar and shuttle-imaging-radar images. Analogies are drawn for the potential interpretation of radar images of Venus, with emphasis on the effects of variation in Magellan look angle with Venusian latitude. In each landform category, differences in feature perception and interpretive capability are related to variations in imaging geometry, spatial resolution, and wavelength of the imaging radar systems. Impact craters and other radially symmetrical features may show apparent bilateral symmetry parallel to the illumination vector at low look angles. The styles of eruption and the emplacement of major and minor volcanic constructs can be interpreted from morphological features observed in images. Radar responses that are governed by small-scale surface roughness may serve to distinguish flow types, but do not provide unambiguous information. Imaging of sand dunes is rigorously constrained by specific angular relations between the illumination vector and the orientation and angle of repose of the dune faces, but is independent of radar wavelength. With a single look angle, conditions that enable shallow subsurface imaging to occur do not provide the information necessary to determine whether the radar has recorded surface or subsurface features. The topographic linearity of many tectonic landforms is enhanced on images at regional and local scales, but the detection of structural detail is a strong function of illumination direction. Nontopographic tectonic lineaments may appear in response to contrasts in small-surface roughness or dielectric constant. The breakpoint for rough surfaces will vary by about 25 percent through the Magellan viewing geometries from low to high Venusian latitudes. Examples of anomalies and system artifacts that can affect image interpretation are described.

Ford, J. P.↗

Capacity Assessment and Cost Analysis of Geologic Storage of Hydrogen: A Case Study in Intermountain-West Region USA

Hydrogen is an integral component of the current energy transition roadmap to decarbonize the economy and create an environmentally-sustainable future. However, surface storage options (e.g., tanks) do not provide the required capacity or durability to deploy a regional or nationwide hydrogen economy. In this study, we have analyzed the techno-economic feasibility of the geologic storage of hydrogen in depleted gas reservoirs, salt caverns, and saline aquifers in the Intermountain-West (I-WEST) region. We have identified the most favorable candidate sites for hydrogen storage and estimated the volumetric storage capacity. Our results show that the geologic storage of hydrogen can provide at least 72% of total energy consumption of the I-WEST region in 2020. We also calculated the capital and levelized costs of each storage option. We found that a depleted gas reservoir is the most cost-effective candidate among the three geologic storage options. Interestingly, the cushion gas type plays a significant role in the storage cost when we consider hydrogen storage in saline aquifers. The levelized costs of hydrogen storage in depleted gas reservoirs, salt caverns, and saline aquifers with large-scale storage capacity are approximately $\$$1.15, $\$$2.50, and $\$$3.27 per kg of H 2 , respectively. Here, this work provides essential guidance for the geologic hydrogen storage in the I-WEST region.

08 HYDROGEN↗

Presentations by participants (edited and condensed)

The utility of Geomagnetic Automonous Shuttle-Launched Probe (GASP) for studying the earth's crust can be characterized in terms of lithospheric contributions by past satellite programs. In contrast to the POGO and MAGSAT satellites, GASP will orbit at a lower elevation to provide better resolved lithospheric magnetic anomalies for more detailed and improved geologic analysis. In the geological representation of satellite magnetic anomaly data, two current approaches can serve the analysis of GASP observations. When global scale coverage is available, spherical harmonic expansions of the observations may be utilized. When satellite elevation data is used, a useful and efficient approach is to determine the physical properties of an array of point equivalent sources by least squares matrix inversion of the observations, which will closely duplicate the observed field. An important preliminary step in the representation of satellite magnetic observations by either approach, is to register the data at constant elevation over uniform intervals of latitude and longitude. Further applications of GASP are discussed.

Vonfrese, R. R. B.↗

Analysis of geologic terrain models for determination of optimum SAR sensor configuration and optimum information extraction for exploration of global non-renewable resources. Pilot study: Arkansas Remote Sensing Laboratory, part 1, part 2, and part 3

Computer-generated radar simulations and mathematical geologic terrain models were used to establish the optimum radar sensor operating parameters for geologic research. An initial set of mathematical geologic terrain models was created for three basic landforms and families of simulated radar images were prepared from these models for numerous interacting sensor, platform, and terrain variables. The tradeoffs between the various sensor parameters and the quantity and quality of the extractable geologic data were investigated as well as the development of automated techniques of digital SAR image analysis. Initial work on a texture analysis of SEASAT SAR imagery is reported. Computer-generated radar simulations are shown for combinations of two geologic models and three SAR angles of incidence.

Kaupp, V. H.↗

Geologic and mineral and water resources investigations in western Colorado using ERTS-1 data

The author has identified the following significant results. Topography was found to be the most important factor defining folds on ERTS-1 imagery of northwestern Colorado; tonal variations caused by rock reflectance and vegetation type and density are the next most important factors. Photo-linears mapped on ERTS-1 imagery of central Colorado correlate well with ground-measured joint and fracture trends. In addition, photo-linears have been successfully used to determine the location and distribution of metallic mineral deposits in the Colorado Mineral Belt. True color composites are best for general geologic analysis and false color composites prepared with positive/negative masks are useful for enhancing local geologic phenomena. During geologic analysis of any given area, ERTS-1 imagery from several different dates should be studied.

Knepper, D. H., Jr.↗

Mechanisms of Waterflood Inefficiency: Analysis of Geological, Petrophysical and Reservoir History, a Field Case Study of FWU (East Section)

The petroleum reservoir represents a complex heterogeneous system that requires thorough characterization prior to the implementation of any incremental recovery technique. One of the most commonly utilized and successful secondary recovery techniques is waterflooding. However, a lack of sufficient investigation into the inherent behavior and characteristics of the reservoir formation in situ can result in failure or suboptimal performance of waterflood operations. Therefore, a comprehensive understanding of the geological history, static and dynamic reservoir characteristics, and petrophysical data is essential for analyzing the mechanisms and causes of waterflood inefficiency and failure. In this study, waterflood inefficiency was observed in the Morrow B reservoir located in the Farnsworth Unit, situated in the northwestern shelf of the Anadarko Basin, Texas. To assess the potential mechanisms behind the inefficiency of waterflooding in the east half, geological, petrophysical, and reservoir engineering data, along with historical information, were integrated, reviewed, and analyzed. The integration and analysis of these datasets revealed that several factors contributed to the waterflood inefficiency. Firstly, the presence of abundant dispersed authigenic clays within the reservoir, worsened by low reservoir quality and high heterogeneity, led to unfavorable conditions for waterflood operations. The use of freshwater for flooding exacerbated the adverse effects of sensitive and migratory clays, further hampering the effectiveness of the waterflood. In addition to these factors, several reservoir engineering issues played a significant role in the inefficiency of waterflooding. These issues included inadequate perforation strategies due to the absence of detailed hydraulic flow units (HFUs) and rock typing, random placement of injectors, and uncontrolled injected fresh water. These external controlling parameters further contributed to the overall inefficiencies observed during waterflood operations in the east half of the reservoir. A detailed understanding of the mechanistic factors of inefficient waterflood operation will provide adequate insights into the development of the improved recovery technique for the field.

Morgan, Anthony (ORCID:0000000211519153)↗

First look analysis of geologic ground patterns on ERTS-1 imagery of Missouri

Examination of ERTS-1 data for selected areas of Missouri revealed not only many of the known geologic features but also a number of unknown linear, circular and arcuate ground patterns. The number of new geologic elements that have been brought to light as well as the sharp definition and probable extensions of several known geologic features point out the importance of multispectral imagery via satellite and the synoptic views which they provide. To date, analysis and interpretations have been a first-look visual examination of the unenhanced projected images.

Allen, W. H.↗

Geologic landform analysis in the central Piedmont of Virginia and North Carolina, 1

The author has identified the following significant results. ERTS-1 imagery in the central Piedmont of Va. and N.C. reveals some geologic structures in the Precambrian and Paleozoic metamorphic terrain as well as structure in the younger Triassic deposits. A major synform five miles wide and more than 20 miles long has been identified in the metamorphic rocks north of Danville, Va. Structures in the metavolcanic Carolina slate belt are also identifiable near the confluence of the Dan and Staunton Rivers. Cleared land and other cultural features tend to coincide with topographic reflection of geologic units, thus enhancing the ERTS-1 resolution of some geologic structures. In other cases pseudostructures may be identified when regular geometric configurations of culture bear little or no relation to underlying geologic units. Interpreting geologic structure in the nearly flat and deeply weather Piedmont is a severe test of ERTS-1 imagery resolution. Doubling the resolution and providing stereoscopic overlap would increase the geologic usefulness of these photographs many fold.

Glover, L., III↗

Thermal and Evolved Gas Analysis of Geologic Samples Containing Organic Materials: Implications for the 2007 Mars Phoenix Scout Mission

The Thermal and Evolved Gas Analyzer (TEGA) instrument scheduled to fly onboard the 2007 Mars Phoenix Scout Mission will perform differential scanning calorimetry (DSC) and evolved gas analysis (EGA) of soil samples and ice collected from the surface and subsurface at a northern landing site on Mars. We have been developing a sample characterization data library using a laboratory DSC integrated with a quadrupole mass spectrometer to support the interpretations of TEGA data returned during the mission. The laboratory TEGA test-bed instrument has been modified to operate under conditions similar to TEGA, i.e., reduced pressure (e.g., 100 torr) and reduced carrier gas flow rates. We have previously developed a TEGA data library for a variety of volatile-bearing mineral phases, including Fe-oxyhydroxides, phyllosilicates, carbonates, and sulfates. Here we examine the thermal and evolved gas properties of samples that contain organics. One of the primary objectives of the Phoenix Scout Mission is to search for habitable zones by assessing organic or biologically interesting materials in icy soil. Nitrogen is currently the carrier gas that will be used for TEGA. In this study, we examine two possible modes of detecting organics in geologic samples; i.e., pyrolysis using N2 as the carrier gas and combustion using O2 as the carrier gas.

Lauer, H. V., Jr.↗