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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,315 records · Page 73
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Subsea ice-bearing permafrost on the U.S. Beaufort Margin: 2. Borehole constraints: SUBSEA PERMAFROST IN U.S. BEAUFORT II

Borehole logging data from legacy wells directly constrain the contemporary distribution of subsea permafrost in the sedimentary section at discrete locations on the U.S. Beaufort Margin and complement recent regional analyses of exploration seismic data to delineate the permafrost's offshore extent. Most usable borehole data were acquired on a ~500 km stretch of the margin and within 30 km of the contemporary coastline from north of Lake Teshekpuk to nearly the U.S.-Canada border. Relying primarily on deep resistivity logs that should be largely unaffected by drilling fluids and hole conditions, the analysis reveals the persistence of several hundred vertical meters of ice-bonded permafrost in nearshore wells near Prudhoe Bay and Foggy Island Bay, with less permafrost detected to the east and west. Permafrost is inferred beneath many barrier islands and in some nearshore and lagoonal (back-barrier) wells. The analysis of borehole logs confirms the offshore pattern of ice-bearing subsea permafrost distribution determined based on regional seismic analyses and reveals that ice content generally diminishes with distance from the coastline. Lacking better well distribution, it is not possible to determine the absolute seaward extent of ice-bearing permafrost, nor the distribution of permafrost beneath the present-day continental shelf at the end of the Pleistocene. However, the recovery of gas hydrate from an outer shelf well (Belcher) and previous delineation of a log signature possibly indicating gas hydrate in an inner shelf well (Hammerhead 2) imply that permafrost may once have extended across much of the shelf offshore Camden Bay.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Geologic influence on induced seismicity: Constraints from potential field data in Oklahoma

Abstract Recent Oklahoma seismicity shows a regional correlation with increased wastewater injection activity, but local variations suggest that some areas are more likely to exhibit induced seismicity than others. We combine geophysical and drill hole data to map subsurface geologic features in the crystalline basement, where most earthquakes are occurring, and examine probable contributing factors. We find that most earthquakes are located where the crystalline basement is likely composed of fractured intrusive or metamorphic rock. Areas with extrusive rock or thick (>4 km) sedimentary cover exhibit little seismicity, even in high injection rate areas, similar to deep sedimentary basins in Michigan and western North Dakota. These differences in seismicity may be due to variations in permeability structure: within intrusive rocks, fluids can become narrowly focused in fractures and faults, causing an increase in local pore fluid pressure, whereas more distributed pore space in sedimentary and extrusive rocks may relax pore fluid pressure.

Shah, Anjana K.↗
DOE OSTI2017

Fracture hydromechanical response measured by fiber optic distributed acoustic sensing at milliHertz frequencies: Fracture Hydromechanics From DAS

A new method of measuring dynamic strain in boreholes was used to record fracture displacement in response to head oscillation. Fiber optic distributed acoustic sensing (DAS) was used to measure strain at mHz frequencies, rather than the Hz to kHz frequencies typical for seismic and acoustic monitoring. Fiber optic cable was mechanically coupled to the wall of a borehole drilled into fractured crystalline bedrock. Oscillating hydraulic signals were applied at a companion borehole 30 m away. The DAS instrument measured fracture displacement at frequencies of less than 1 mHz and amplitudes of less than 1 nm, in response to fluid pressure changes of less 20 Pa (2 mm H 2 O). Displacement was linearly related to the log of effective stress, a relationship typically explained by the effect of self-affine fracture roughness on fracture closure. These results imply that fracture roughness affects closure even when displacement is a million times smaller than the fracture aperture.

58 GEOSCIENCES↗
DOE OSTI2018

Glacial cycles influence marine methane hydrate formation

Methane hydrates in fine-grained continental slope sediments often occupy isolated depth intervals surrounded by hydrate-free sediments. As they are not connected to deep gas sources, these hydrate deposits have been interpreted as sourced by in situ microbial methane. We investigate here the hypothesis that these isolated hydrate accumulations form preferentially in sediments deposited during Pleistocene glacial lowstands that contain relatively large amounts of labile particulate organic carbon, leading to enhanced microbial methanogenesis. To test this hypothesis, we apply an advection-diffusion-reaction model with a time-dependent organic carbon deposition controlled by glacioeustatic sea level variations. In the model, hydrate forms in sediments with greater organic carbon content deposited during the penultimate glacial cycle (~120-240 ka). As a result, the model predictions match hydrate-bearing intervals detected in three sites drilled on the northern Gulf of Mexico continental slope, supporting the hypothesis of hydrate formation driven by enhanced organic carbon burial during glacial lowstands.

58 GEOSCIENCES↗
DOE OSTI2017

Characterizing the Potential for Injection-Induced Fault Reactivation Through Subsurface Structural Mapping and Stress Field Analysis, Wellington Field, Sumner County, Kansas: Injection-Induced Fault Slip, Kansas

Kansas, like other parts of the central U.S., has experienced a recent increase in seismicity. Correlation of these events with brine disposal operations suggests pore fluid pressure increases are reactivating preexisting faults, but rigorous evaluation at injection sites is lacking. Here we determine the suitability of CO 2 injection into the Cambrian-Ordovician Arbuckle Group for long-term storage and into a Mississippian reservoir for enhanced oil recovery in Wellington Field, Sumner County, Kansas. To determine the potential for injection-induced earthquakes, we map subsurface faults and estimate in situ stresses, perform slip and dilation tendency analyses to identify well-oriented faults relative to the estimated stress field, and determine the pressure changes required to induce slip at reservoir and basement depths. Three-dimensional seismic reflection data reveal 12 near-vertical faults, mostly striking NNE, consistent with nodal planes from moment tensor solutions from recent earthquakes in the region. Most of the faults cut both reservoirs and several clearly penetrate the Precambrian basement. Drilling-induced fractures (N = 40) identified from image logs and inversion of earthquake moment tensor solutions (N = 65) indicate that the maximum horizontal stress is approximately EW. Slip tendency analysis indicates that faults striking <020° are stable under current reservoir conditions, whereas faults striking 020°–049° may be prone to reactivation with increasing pore fluid pressure. Although the proposed injection volume (40,000 t) is unlikely to reactive faults at reservoir depths, high-rate injection operations could reach pressures beyond the critical threshold for slip within the basement, as demonstrated by the large number of injection-induced earthquakes west of the study area.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Monitoring and Modeling Caprock Integrity at the In Salah Carbon Dioxide Storage Site, Algeria

The In Salah gas development project, initiated in 2004, involves the long-term storage of waste carbon dioxide associated with natural gas production at several central Algerian fields. Rather then vent the extracted CO 2 into the atmosphere the operators, BP, Sonatrach, and Statoil chose to have the gas compressed, dehydrated, transported, and injected into a deep saline aquifer leg of the Krechba gas reservoir (Matheison et al. 2011). For this effort three horizontal state-of-the-art injection wells were drilled to a depth of 1500-1800m, using geo-steering technology to follow the roughly 20m thick reservoir. To maximize the injectivity, the wells were oriented perpendicular to the direction of maximum stress, the dominant fracture direction. Long-term plans were to store up to 17 million tonnes of carbon dioxide during the life of the program (Matheison et al. 2010). The project at In Salah was a pioneering effort in several respects and involved the investment of over 100 million dollars by the member companies. One feature that distinguishes In Salah from several other industrialscale CO 2 sequestration projects, such as Sleipner (Chadwick et al. 2012), Weyburn (White et al. 2011), Decatur (Kaven et al. 2014), and Aquastore (Worth et al. 2014) is the generally smaller storage volume in terms of overall reservoir thickness and lower average porosities of around 15%. With the exception of Weyburn, these other sites are characterized by generally thick sequences of high porosity sandstones. Therefore, one might expect that the pressure buildup near the wells could be larger at In Salah, with consequences for reservoir deformation and caprock strain. The role of fractures in providing storage and increasing reservoir permeability is one factor that would likely impact the pressure distribution around the well. However, the detailed effect of existing fractures on flow was not established prior to the injection at In Salah. The unique features of the In Salah storage site point to the importance of wellbore, geophysical, and geochemical monitoring to ensure that the integrity of the storage complex is maintained both during and after injection. In 2005 a Joint Industry Project (JIP) was set up, in an effort to use various geophysical, geochemical, and production techniques to monitor the fate of the injected carbon dioxide (Matheison et al. 2011). Here in this paper we describe the efforts made to monitoring the fate of the injected carbon dioxide, the state of the caprock, the estimated outcome of the storage effort, and some of the uncertainties that remain.

58 GEOSCIENCES↗
DOE OSTI2021

Superhard Materials: Advances in the Search and Synthesis of New Materials

Materials with superior hardness can be categorized as ultrahard (Vickers hardness, H v ≥ 80 GPa) and superhard (H v ≥ 40 GPa). These materials are commonly used as cutting tools and abrasives in the machining and manufacturing industries. With its extreme hardness, diamond is the best known and most used ultrahard material for industrial applications. However, it is ineffective at cutting and drilling ferrous alloys due to diamond's high reactivity with iron and poor thermal stability in air. Additionally, the synthesis of diamond requires both high pressure (HP) and high temperature, making it an expensive process. These limitations have driven the search for alternative superhard materials that are capable of cutting steels and other materials at lower costs. This article reviews the concept of hardness and summarizes advancements in the synthesis and mechanical properties of hard materials. It begins with a review of methods to measure hardness, adding HP diffraction methods to more conventional hardness measurements. It then considers new ultrahard materials that exist within the B–C–N ternary system, with hardness approaching diamond but improved chemical stability. Finally, it surveys superhard nitrides, oxides, and borides as potential alternative materials, focusing on transition metal boride systems where the synthesis can be readily achieved at ambient pressure and scaled for industrial applications. We hope that this article serves as an overview of hard materials and guide for the comparison of data reported in the literature.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Trends in Unconventional Well Development—Methane Emissions Associated with the Use of Dual Fuel and Dedicated Natural Gas Engines

Abstract The process of unconventional natural gas recovery is becoming increasingly popular as the world’s demand for alternative fuels continues to grow. Natural gas has the potential to be a widely used fuel in the near future due to its availability and potential to displace petroleum‐based liquid fuels. As energy companies extract natural gas, current fuels, such as diesel, are consumed in mass quantities for drilling and hydraulic fracturing operations. To save on costs, and in an attempt to reduce emissions, many companies are investing in dual fuel and dedicated natural gas engines to power these operations. This trend results in new sources of methane emissions, which can contribute significantly to global warming. We are aware of the potential impact of these emissions and are conducting research funded by the Department of Energy to assess methane emissions from dual fuel and dedicated natural gas technologies, as industry moves towards more extensive use of natural gas as a fuel for onsite power production.

Johnson, Derek↗
DOE OSTI2021

Hydro-mechanical measurements and x-ray imaging of sheared crystalline rock fractures from EGS Collab experiments 1 & 2

Measuring hydro-mechanical properties of natural fractures is a prerequisite for optimizing hydraulic stimulation design and well placement. We completed experiments to characterize shear on natural fractures in schist, amphibolite, and rhyolite specimens drilled from EGS Collab Project’s field sites at the Sanford Underground Research Facility (SURF) in South Dakota. A triaxial direct shear method and coupled x-ray imaging were used to perform hydroshearing and mechanical shearing at the site’s in-situ stress conditions. This produced simultaneous measurements of fracture and matrix strength, permeability, stress-dependent aperture, dilation, and friction strength. Our results identified that only a subset of the natural fractures was weak enough for hydroshearing. Generally, hydroshearing increases fracture permeability by a factor of 10 or more and the enhancement is retainable over time. However, the shear slip does not always result in permeability enhancement. High content of phyllosilicates was found to associate with exceptionally weak fractures that also exhibited poor or even negative enhancement after stimulation. Combining our measurements with site data, we can predict that most observable fractures at the two EGS Collab sites do not meet the criteria for hydroshearing before tensile opening. In some cases, the visible fractures are low permeability and as strong as the adjacent rock. To induce hydroshearing before tensile opening, injection must target known weak and favorably oriented fractures with confirmed pre-existing permeability.

58 GEOSCIENCES↗
DOE OSTI2014

In situ SEM and ToF-SIMS analysis of IgG conjugated gold nanoparticles at aqueous surfaces

In this study, we report new results of in situ study of 5 nm goat anti-mouse IgG gold nanoparticles in a novel portable vacuum compatible microfluidic device using scanning electron microscope (SEM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The unique feature of the liquid flow cell is that the detection window is open to the vacuum allowing direct probing of the liquid surface. The flow cell is composed of a silicon nitride (SiN) membrane and polydimethylsiloxane (PDMS), and it is fully compatible with vacuum operations for surface analysis. The aperture can be drilled through the 100 nm SiN membrane using a focused ion beam. Characteristic signals of the conjugated gold nanoparticles were successfully observed through the aperture by both energy-dispersive X-ray spectroscopy (EDX) in SEM and ToF-SIMS. Comparison was also made among wet samples, dry samples, and liquid sample in the flow cell using SEM/EDX. Stronger gold signal can be observed in our novel portable device by SEM/EDX compared with the wet or dry samples, respectively. Our results indicate that analyses of the nanoparticle components are better made in their native liquid environment. This is made possible using our unique microfluidic flow cell.

aqueous surface↗
DOE OSTI2020

Temperature response and brine availability to heated boreholes in bedded salt

Abstract There is a growing need for disposal of high‐level nuclear waste. To reduce uncertainty associated with brine availability to repository excavations in salt formations, a collaboration between Sandia, Los Alamos, and Lawrence Berkeley National Laboratories is performing a series of borehole‐scale coupled process tests. Here, we report on the first round of the Brine Availability Test in Salt (BATS) project, a “shakedown” experiment called Phase 1s. Experimental testing included placing a resistive heater, a 260‐W radiative heater, and a 750‐W radiative heater within previously drilled horizontal boreholes at the Waste Isolation Pilot Plant (WIPP) while monitoring temperature and water inflow. The experiments successfully achieved the targeted temperature of 120 °C when using the 750‐W radiative heater. Simulations using FEHM (Finite Element Heat and Mass transfer code) and TOUGH‐FLAC (Transport Of Unsaturated Groundwater and Heat–Fast Lagrangian Analysis of Continua) were able to accurately predict the coupled thermo–hydro–mechanical–chemical response of salt, matching the observed temperature and brine production. Due to the extremely low permeability of salt, these systems take many years to reach steady state when perturbed by mining activities. Long‐term numerical simulations are used to develop the initial pressure and saturation conditions. The inclusion of a damaged rock zone with higher permeability around the borehole also affects the saturation and pressure distributions and plays an important role in dissipating the potential for thermal pressurization. Knowledge gained from this round of experimentation and simulation will be used to conduct the next BATS project experiment in new boreholes at WIPP.

58 GEOSCIENCES↗
DOE OSTI2025

Control of machining-induced residual stress via tool geometry and process parameter modification

Distortion generated in machined, monolithic, thin-walled aerospace components due to residual stresses leads to significant material and economic waste in the manufacturing industry. Inherent residual stress (IRS) present in stock materials combines with machining-induced residual stress (MIRS) to influence the final machined part distortion. It is hypothesized that MIRS can be controlled, based on the part geometry, through deliberate cutting tool geometry and process parameter modifications to negate the effect of IRS on distortion, consequently resulting in distortion-free parts. A finite element (FE) orthogonal cutting model is developed to study how tool geometry and process parameters influence machining-induced residual stress (MIRS). Orthogonal cutting experiments are performed on Al 7075-T651 samples to measure cutting forces and MIRS. A cutting force dynamometer is used to measure forces during cutting and a novel digital image correlation (DIC) based hole drilling technique is employed to measure the near-surface residual stress (RS) in the cut samples. These data are subsequently utilized to validate the FE prediction model. Various cases of cutting simulations involving different depths of cut, tool tip radii, and rake angles are performed to study their effects on RS. Similar to prior literature, increasing the depth of cut, tool tip radius, or rake angle is found to promote the formation of near-surface tensile stresses. The competing effects of material plowing and temperature are shown to determine the type of RS at the end of the cut. Moreover, a window of variation of RS (up to ± 400 MPa) is estimated within the given range of conditions, allowing for the control of MIRS through tool and process modification.

Mathews, Ritin [ORNL] (ORCID:0000000301440828)↗
DOE OSTI2020

Groundwater characterization and monitoring at a complex industrial waste site using electrical resistivity imaging

A contaminated industrial waste site in Washington State (USA) containing buried, metallic-waste storage tanks, pipes, and wells, was evaluated to determine the feasibility of monitoring groundwater remediation activities associated with an underlying perched aquifer system using electrical resistivity tomography. The perched aquifer, located ~65 m below ground surface and ~10 m above the regional water table, contains high concentrations of nitrate, uranium, and other contaminants of concern from past tank leaks and intentional releases of wastes to surface disposal sites. The extent of the perched water aquifer is not well known, and the effectiveness of groundwater extraction for contaminant removal is uncertain, so supplemental characterization and monitoring technologies are being evaluated. Numerical simulations of subsurface flow and contaminant transport were performed with a highly resolved model of the hydrogeologic system and waste site infrastructure, and these simulations were used as the physical basis for electrical resistivity tomography modeling. The modeling explicitly accounted for metallic infrastructure at the site. The effectiveness of using surface electrodes versus surface and horizontal subsurface electrodes, for imaging groundwater extraction from the perched water aquifer, was investigated. Although directional drilling is a mature technology, its use for electrode emplacement in the deep subsurface under a complex industrial waste site via horizontal wells has not yet been demonstrated. Results from this study indicate that using horizontal subsurface electrode arrays could significantly improve the ability of electrical resistivity tomography to image deep subsurface features and monitor remediation activities under complex industrial waste sites.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

A modular approach for high-flux lactic acid production from methane in an industrial medium using engineered Methylomicrobium buryatense 5GB1

Abstract Convergence of market drivers such as abundant availability of inexpensive natural gas and increasing awareness of its global warming effects have created new opportunities for the development of small-scale gas-to-liquid (GTL) conversion technologies that can efficiently utilize methane, the primary component of natural gas. Leveraging the unique ability of methanotrophs that use methane as carbon and energy source, biological GTL platforms can be envisioned that are readily deployable at remote petroleum drilling sites where large chemical GTL infrastructure is uneconomical to set-up. Methylomicrobium buryatense, an obligate methanotroph, has gained traction as a potential industrial methanotrophic host because of availability of genetic tools and recent advances in its metabolic engineering. However, progress is impeded by low strain performance and lack of an industrial medium. In this study, we first established a small-scale cultivation platform using Hungate tubes for growth of M. buryatense at medium-to-high-throughput that also enabled 2X faster growth compared to that obtained in traditional glass serum bottles. Then, employing a synthetic biology approach we engineered M. buryatense with varying promoter (inducible and constitutive) and ribosome-binding site combinations, and obtained a strain capable of producing l-lactate from methane at a flux 14-fold higher than previously reported. Finally, we demonstrated l-lactate production in an industrial medium by replacing nitrate with less-expensive ammonium as the nitrogen source. Under these conditions, l-lactate was synthesized at a flux approximately 50-fold higher than that reported previously in a bioreactor system while achieving a titer of 0.6 g/L. These findings position M. buryatense closer to becoming an industrial host strain of choice, and pave new avenues for accelerating methane-to-chemical conversion using synthetic biology.

Garg, Shivani↗
DOE OSTI2022

Application of machine learning to characterize gas hydrate reservoirs in Mackenzie Delta (Canada) and on the Alaska north slope (USA)

Here, artificial neural network-trained models were used to predict gas hydrate saturation distributions in permafrost-associated deposits in the Eileen Gas Hydrate Trend on the Alaska North Slope (ANS), USA and at the Mallik research site in the Beaufort-Mackenzie Basin, Northwest Territories, Canada. The database of Logging-While-Drilling (LWD) and wireline logs collected at five wells (Mount Elbert, Ignik Sikumi, and Kuparuk 7–11–12 wells at ANS, plus 2L-38 and 5L-38 wells at the Mallik research site) includes more than 10,000 depth points, which were used for training, validation, and testing the machine learning (ML) models. Data used in training the ML models include the well logs of density, porosity, electrical resistivity, gamma radiation, and acoustic wave velocity measurements. Combinations of two or three out of these five well logs were found to reliably predict the gas hydrate saturation with accuracy varying between 80 and 90% when compared to the gas hydrate saturations derived from Nuclear Magnetic Resonance (NMR)-based technique. The ML models trained on data from three ANS wells achieved high fidelity predictions of gas hydrate saturation at the Mallik site. The results obtained in this study indicate that ML models trained on data from one geological basin can successfully predict key reservoir parameters for permafrost-associated gas hydrate accumulations within another basin. A generalized approach for selecting a well log combination that can improve model accuracy is discussed. Overall, the study outcome supports earlier work demonstrating that ML models trained on non-NMR well logs are a viable alternative to physics-driven methods for predicting gas hydrate saturations.

58 GEOSCIENCES↗