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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

A Thermoplasticity Model for Oil Shale

Several regions of the world have abundant oil shale resources, but accessing this energy supply poses a number of challenges. One particular difficulty is the thermomechanical behavior of the material. When heated to sufficient temperatures, thermal conversion of kerogen to oil, gas, and other products takes place. This alteration of microstructure leads to a complex geomechanical response. In this work, we develop a thermoplasticity model for oil shale. The model is based on critical state plasticity, a framework often used for modeling clays and soft rocks. The model described here allows for both hardening due to mechanical deformation and softening due to thermal processes. In particular, the preconsolidation pressure—defining the onset of plastic volumetric compaction—is controlled by a state variable representing the kerogen content of the material. As kerogen is converted to other phases, the material weakens and plastic compaction begins. We calibrate and compare the proposed model to a suite of high-temperature uniaxial and triaxial experiments on core samples from a pilot in situ processing operation in the Green River Formation. In conclusion, we also describe avenues for future work to improve understanding and prediction of the geomechanical behavior of oil shale operations.

04 OIL SHALES AND TAR SANDS↗
DOE OSTI2022

Integration of Large-Scale Electrical Imaging into Geological Framework Development and Refinement

Geologic framework models (GFMs) are critical to the construction of reliable simulation models of groundwater flow and contaminant transport. To support GFM development, direct information (e.g., core samples, fluid samples, hydraulic testing) tends to be sparse and separated by large distances relative to the spatial scales of aquifer heterogeneity. There are additional challenges associated with highly contaminated legacy waste sites, where drilling is particularly costly, and invasive sampling requires specialized handling and disposal of hazardous materials. At these sites in particular, non-invasive geophysical imaging can play an important role in filling spatial gaps between boreholes and reducing characterization costs by optimizing and minimizing the number of necessary boreholes. Here this paper presents a case study demonstrating the use of large-scale (> 30 km 2 ) electrical mapping to identify hydrostratigraphy and potential paleochannels at the Hanford Site, located in Washington State, USA. In two field campaigns, over 36 line-kilometers of electrical resistivity tomography (ERT) data were collected along 14 transects. ERT surveys were sited and performed to image critical aspects (e.g., paleochannels, stratigraphic contacts) of the subsurface, demonstrating a general workflow for integrating ERT with GFM development. Inconsistencies between the GFM and ERT were catalogued to provide a basis for future site characterization using complementary geophysical methods and (or) direct sampling.

58 GEOSCIENCES↗
DOE OSTI2022

In situ detection and characterization of alkali-silica reaction damage in concrete using contactless ultrasonic wavefield imaging

Here we present work to characterize cracking damage in concrete caused by alkali-silica reactivity distress. We apply contactless ultrasonic scan inspection, exploiting Rayleigh wave scattering from concrete inhomogeneities. The scanning system utilizes a multi-channel MEMS sensor array to collect ultrasonic wavefield data from concrete subjected to ASR-promoting environments. The location and extent of ASR damage are established by internal expansion measurements from embedded strain gauges, scanning electron microscope images of cored samples, and expansion measurements from companion samples. A wavefield data processing method extracts oscillatory fields from the ultrasonic wavefield data to detect distinct zones of ASR damage. A damage index is proposed to further characterize the extent of ASR damage. The results confirm the feasibility and accuracy of the approach to characterize ASR damage in concrete. The fully contactless ultrasonic scanning measurement system does not require separate material samples and enables in situ characterization of ASR damage within concrete structures.

36 MATERIALS SCIENCE↗
DOE OSTI2025

An experimental study on gas-liquid phase fluid migration in hydrate-bearing sediments during hydrate dissociation

Natural gas hydrate production tests face problems such as severe sand blockage, poor gas-liquid phase separation, and significant land subsidence. This is because of the insufficient understanding of the complex phase transition and gas-liquid multi-phase fluid migration during hydrate dissociation. In hydrate-bearing sediment systems, hydrate phase transition couples with gas-liquid fluid migration. The phase transition causes changes in pore structure, which in turn modifies porous infiltration parameters and fluid flow capacity. Meanwhile, alterations in phase interfaces affect key parameters like surface tension and wettability. Gas-liquid fluid migration influences heat and mass transfer, thus affecting phase equilibrium and dissociation rates. To bridge the gap in describing gas-liquid fluid migration during hydrate dissociation in experiments, this research innovatively integrated an unsteady-state gas displacement by water and a quantitative hydrate dissociation process, independently developed a multi-phase seepage experimental system suitable for hydrate dissociation and determined the relationship between seepage parameters and hydrate saturation under different porosity. The results are as follows: a) Core samples with higher initial porosity show a greater recovery rate of fluid flow capacity. b) The retarding effect of multi-phase fluid has a more significant impact on the migration of the wetting phase fluid (water) than that of the non-wetting phase fluid (methane). c) During hydrate dissociation, the evolution of absolute permeability shows an “S-shaped” pattern, and the evolution of relative permeability shows a “wiring-harness” pattern. In conclusion, the findings can provide a theoretical basis for preventing geological disasters and for geotechnical engineering design during hydrate production.

58 GEOSCIENCES↗
DOE OSTI2024

Integrated experimental studies of pore structure and fluid uptake in the Bossier Shale in eastern Texas, USA

Within the Haynesville-Bossier Shale complex, the Bossier Shale has not been extensively studied by either industry and academia, despite it being an unconventional gas reservoir and a potential caprock for carbon storage in the underlaying Haynesville Shale. The lack of knowledge of the complex pore structures and fluid-rock interactions hinders the effective extraction of gas and the characterization of fluid reservoirs and sealing capacity. Integrated experimental studies of pore structure and fluid-rock interactions were conducted in seven Bossier Shale core samples collected in eastern Texas. Petrographic, geochemical, and petrophysical properties such as mineral composition, organic richness, thermal maturity, porosity, pore/pore throat diameter distribution, water-accessible pores, liquid water imbibition, and water vapor adsorption were characterized using complementary approaches of thin-section petrography, scanning electron microscopy, X-ray diffraction, total organic matter, pyrolysis, mercury intrusion porosimetry, nuclear magnetic resonance, (Ultra-) small angle X-rays scattering as well as small angle neutron scattering with deuterated liquids and contrast variation. Further, the results show that the thermally mature Bossier Shales are composed of mixed argillaceous mudstone, mixed mudstone, and mixed carbonate mudstone. The shale contains both organic and inorganic pores, with porosities of 3.24-9.37 %, pore-to-throat ratios of 1.65 to 19.4, and water-accessible pores accounting for 28.7-72.6 % of total pores. Approaches of liquid water imbibition and water vapor adsorption, with and without direct contact of water with shale samples, indicate that liquid water first enters the nano-sized pores under high capillary pressures, and water vapor adsorption is mainly controlled by both clay minerals and pores with diameters less than 10 nm. These findings contribute to a better understanding of pore structures and water-shale interactions and their controlling factors in the Bossier Shale.

58 GEOSCIENCES↗
DOE OSTI2018

Assessing the carbon sequestration potential of basalt using X-ray micro-CT and rock mechanics

Mineral carbonation in basaltic rock provides a permanent storage solution for the mitigation of anthropogenic CO 2 emissions in the atmosphere. 3D X-ray micro-CT (XCT) image analysis is applied to a core sample from the main basaltic reservoir of the CarbFix site in Iceland, which obtained a connected porosity of 2.05–8.76%, a reactive surface area of 0.10–0.33 mm -1 and a larger vertical permeability (2.07 × 10 -10 m 2 ) compared to horizontal permeability (5.10 × 10 -11 m 2 ). The calculations suggest a CO 2 storage capacity of 0.33 Gigatonnes at the CarbFix pilot site. The XCT results were compared to those obtained from a hydromechanical test applied to the same sample, during which permeability, electrical resistivity and volumetric deformation were measured under realistic reservoir pressure conditions. It was found that permeability is highly stress sensitive, dropping by two orders of magnitude for a -0.02% volumetric deformation change, equivalent to a mean pore diameter reduction of 5 μm. This pore contraction was insufficient to explain such a permeability reduction according to the XCT analysis, unless combined with the effects of clay swelling and secondary mineral pore clogging. Here the findings provide important benchmark data for the future upscaling and optimisation of CO 2 storage in basalt formations.

58 GEOSCIENCES↗
DOE OSTI2018

Assignment and calibration of relative permeability by hydrostratigraphic units for multiphase flow analysis, case study: CO 2 -EOR operations at the Farnsworth Unit, Texas

Included in the most critical factors for geological CO 2 storage site screening, selection, and operation is effective simulations of multiphase flow and transport. Relative permeability is probably the greatest source of potential uncertainty in multiphase flow simulation, second only to intrinsic permeability heterogeneity. The specific relative permeability relationship assigned greatly impacts forecasts of CO 2 trapping mechanisms, phase behavior, and long-term plume movement. A primary goal of this study is to evaluate the impacts and implications of different methods of assigning relative permeability relationships for CO 2 -EOR model forecasts. Most simulation studies published in the literature base selection of relative permeability functions on the geologic formation or rock type alone. In this study, we initially implemented reservoir model grids with previously-identified hydrostratigraphic units based on porosity and permeability relationship of the Morrow ‘B’ Sandstone, then assigned relative permeability functions for those hydrostratigraphic units. Specific, constrained relative permeability relationships were created and assigned to each hydrostratigraphic unit using petrophysical data and Mercury Intrusion Capillary Pressure (MICP) measurements, from core samples of each hydrostratigraphic unit. Results of forward simulations with the newly-calibrated models will be compared to those of previous models as well as to simulation results for a range of different relative permeability relationships. The study site is the Farnsworth Unit (FWU) in the northeast Texas Panhandle, an active CO 2 -EOR operation. The target formation is the Morrow ‘B’ Sandstone, a clastic formation composed of medium to course sands.

58 GEOSCIENCES↗
DOE OSTI2015

Numerical modeling of injection, stress and permeability enhancement during shear stimulation at the Desert Peak Enhanced Geothermal System

Creation of an Enhanced Geothermal System relies on stimulation of fracture permeability through self-propping shear failure that creates a complex fracture network with high surface area for efficient heat transfer. In 2010, shear stimulation was carried out in well 27-15 at Desert Peak geothermal field, Nevada, by injecting cold water at pressure less than the minimum principal stress. An order-of-magnitude improvement in well injectivity was recorded. In this work, we describe a numerical model that accounts for injection-induced stress changes and permeability enhancement during this stimulation. We use the coupled thermo-hydrological–mechanical simulator FEHM to (i) construct a wellbore model for non-steady bottom-hole temperature and pressure conditions during the injection, and (ii) apply these pressures and temperatures as a source term in a numerical model of the stimulation. A Mohr–Coulomb failure criterion and empirical fracture permeability is developed to describe permeability evolution of the fractured rock. The numerical model is calibrated using laboratory measurements of material properties on representative core samples and wellhead records of injection pressure and mass flow during the shear stimulation. The model captures both the absence of stimulation at low wellhead pressure (WHP ≤1.7 and ≤2.4 MPa) as well as the timing and magnitude of injectivity rise at medium WHP (3.1 MPa). Results indicate that thermoelastic effects near the wellbore and the associated non-local stresses further from the well combine to propagate a failure front away from the injection well. Elevated WHP promotes failure, increases the injection rate, and cools the wellbore; however, as the overpressure drops off with distance, thermal and non-local stresses play an ongoing role in promoting shear failure at increasing distance from the well.

15 GEOTHERMAL ENERGY↗
DOE OSTI2018

Comparison of experimental methods for estimating matrix diffusion coefficients for contaminant transport modeling

Here, diffusion cell and diffusion wafer experiments were conducted to compare methods for estimating effective matrix diffusion coefficients in rock core samples from Pahute Mesa at the Nevada Nuclear Security Site (NNSS). A diffusion wafer method, in which a solute diffuses out of a rock matrix that is pre-saturated with water containing the solute, is presented as a simpler alternative to the traditional through-diffusion (diffusion cell) method. Both methods yielded estimates of effective matrix diffusion coefficients that were within the range of values previously reported for NNSS volcanic rocks. The difference between the estimates of the two methods ranged from 14 to 30%, and there was no systematic high or low bias of one method relative to the other. From a transport modeling perspective, these differences are relatively minor when one considers that other variables (e.g., fracture apertures, fracture spacings) influence matrix diffusion to a greater degree and tend to have greater uncertainty than effective matrix diffusion coefficients. For the same relative random errors in concentration measurements, the diffusion cell method yields effective matrix diffusion coefficient estimates that have less uncertainty than the wafer method. However, the wafer method is easier and less costly to implement and yields estimates more quickly, thus allowing a greater number of samples to be analyzed for the same cost and time. Given the relatively good agreement between the methods, and the lack of any apparent bias between the methods, the diffusion wafer method appears to offer advantages over the diffusion cell method if better statistical representation of a given set of rock samples is desired.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Geochemical solid characterization of drill cuttings, core and drilling mud from Marcellus Shale Energy development

Million tons of drill cuttings generated from shale gas development are currently disposed of in landfills, buried in-situ, or reused as road fill. Cuttings, core samples and operating drilling mud from the Marcellus Shale Energy and Environmental Laboratory in WV were studied to better characterize drill cuttings and to evaluate trace metal mobility in various disposal environments. Results showed that physical and chemical properties of drill cuttings are impacted by the host-rock formation, calcium sources and the residual drilling-mud. Barite in residual drilling mud forms a coating around rock cuttings and influences the mobility of Sr in drill cuttings. Trace metals in drill cuttings are primarily associated with pyrite and total organic carbon (TOC) phases in the shale. As a result, based on sequential extraction results, various trace metal mobilities are controlled by additional solid fractions in drill cuttings, such as pyrite, TOC, calcite, barite and exchangeable clays in the shale.

58 GEOSCIENCES↗
DOE OSTI2020

Comparison of permeability predictions on cemented sandstones with physics-based and machine learning approaches

Permeability prediction has been an important problem since the time of Darcy. Most approaches to solve this problem have used either idealized physical models or empirical relations. In recent years, machine learning (ML) has led to more accurate and robust, but less interpretable empirical models. Using 211 core samples collected from 12 wells in the Garn Sandstone from the North Sea, this study compared idealized physical models based on the Carman-Kozeny equation to interpretable ML models. We found that ML models trained on estimates of physical properties are more accurate than physical models. The results show evidence of a threshold of about 10% volume fraction, above which pore-filling cement strongly affects permeability.

03 NATURAL GAS↗
DOE OSTI2015

Permeability and porosity of hydrate-bearing sediments in the northern Gulf of Mexico

Hydrate-bearing sands are being actively explored because they contain the highest concentrations of hydrate and are the most economically recoverable hydrate resource. However, relatively little is known about the mechanisms or timescales of hydrate formation, which are related to methane supply, fluid flux, and host sediment properties such as permeability. We used logging-while-drilling data from locations in the northern Gulf of Mexico to develop an effective medium theory-based model for predicting permeability based on clay-sized sediment fraction. The model considers permeability varying between sand and clay endpoint permeabilities that are defined from laboratory data. We verified the model using permeability measurements on core samples from three boreholes, and then used the model to predict permeability in two wells drilled in Walker Ridge Block 313 during the Gulf of Mexico Gas Hydrate Joint Industry Project Leg II expedition in 2009. We found that the cleanest sands (clay-sized fraction <0.05) had intrinsic (hydrate-free) permeability contrasts of 5-6 orders of magnitude with the surrounding clays, which is sufficient to provide focused hydrate formation due to advection of methane from a deep source or diffusion of microbial methane from nearby clay layers. In sands where the clay-sized fraction exceeds 0.05, the permeability reduces significantly and focused flow is less pronounced. In these cases, diffusion of dissolved microbial methane is most likely the preferred mode of methane supply for hydrate formation. In conclusion, our results provide important constraints on methane supply mechanisms in the Walker Ridge area and have global implications for evaluating rates of methane migration and hydrate formation in hydrate-bearing sands.

58 GEOSCIENCES↗
DOE OSTI2018

Assessing the geomechanical stability of interbedded hydrate-bearing sediments under gas production by depressurization at NGHP-02 Site 16

Establishing the geomechanical stability of marine sediments in the vicinity of a production well is one of the key design considerations in planning offshore gas production from marine hydrate reservoirs. This work presents an assessment of the sediment stability at India's National Gas Hydrate Program, Expedition 2 (NGHP-02) Site 16 Area B offshore eastern India, for which gas production is to be carried out by depressurization. One important feature of the study is that extensive calibration of constitutive model parameters has been conducted based on laboratory test data from pressured core samples. From analysis perspective, the site is challenging because the hydrate reservoir consists of thin layers of hydrate-bearing sands interbedded with mud. Moreover, depressurization at the depth of a reservoir more than 2750 m below sea surface will lead to a pore pressure drop, and accordingly an effective confining stress increase as high as 25 MPa. In dealing with thin interbedded hydrate-bearing strata, meshing requirements for flow and geomechanical analysis are quite different from those for reservoirs with thicker massive layers, An axisymmetric model and one-way coupling simulations were thus adopted for this study, in which the geomechanical study utilizes pore pressure and hydrate saturation output from the flow study, but the flow study does not takes the porosity changes from the geomechanical analysis. Instead, the reduction of porosity due to sediment deformation in the flow study is based on a pressure-dependent pore compressibility relationship derived from geomechanical modeling. The rationality is validated through back computing the pore compressibility from the geomechanical deformation results. Finally, the study shows that large compression in the reservoir will result in movement of the sediments from above and below, as well as laterally in smaller magnitudes; and the sediment is deemed stable during the gas production period.

58 GEOSCIENCES↗
DOE OSTI2020

Quantification of CO 2 Mineralization at the Wallula Basalt Pilot Project

In 2013, the Pacific Northwest National Laboratory led a geologic carbon sequestration field demonstration where ~1000 tonnes of CO 2 was injected into several deep Columbia River Basalt zones near Wallula, Washington. Rock core samples extracted from the injection zone two years after CO 2 injection revealed nascent carbonate mineralization that was qualitatively consistent with expectations from laboratory experiments and reactive transport modeling. In this study, we report on a new detailed analysis of the 2012 pre-injection and 2015 post-injection hydrologic tests that capitalizes on the difference in fluid properties between scCO 2 and water to assess changes in near-field, wellbore, and reservoir conditions that are apparent approximately two years following the end of injection. This comparative hydrologic test analysis method provides a new way to quantify the amount of injected CO 2 that was mineralized in the field test. Modeling results indicate that approximately 60% of the injected CO 2 was sequestered via mineralization within two years, with the resulting carbonates occupying ~4% of the available reservoir pore space. The method presented here provides a new monitoring tool to assess the fate of CO 2 injected into chemically reactive basalt formations but could also be adapted for long-term monitoring and verification within more traditional subsurface carbon storage reservoirs.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Bioadsorption of rare earth elements through cell surface display of lanthanide binding tags

In this study, with the increasing demand for rare earth elements (REEs) in many emerging clean energy technologies, there is an urgent need for the development of new approaches for efficient REE extraction and recovery. As a step toward this goal, we genetically engineered the aerobic bacterium Caulobacter crescentus for REE adsorption through high-density cell surface display of lanthanide binding tags (LBTs) on its S-layer. The LBT-displayed strains exhibited enhanced adsorption of REEs compared to cells lacking LBT, high specificity for REEs, and an adsorption preference for REEs with small atomic radii. Adsorbed Tb 3+ could be effectively recovered using citrate, consistent with thermodynamic speciation calculations that predicted strong complexation of Tb 3+ by citrate. No reduction in Tb 3+ adsorption capacity was observed following citrate elution, enabling consecutive adsorption/desorption cycles. The LBT-displayed strain was effective for extracting REEs from the acid leachate of core samples collected at a prospective rare earth mine. Our collective results demonstrate a rapid, efficient, and reversible process for REE adsorption with potential industrial application for REE enrichment and separation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Numerical Simulation of Permeability Change in Wellbore Cement Fractures after Geomechanical Stress and Geochemical Reactions Using X-ray Computed Tomography Imaging

X-ray microtomography (XMT) imaging combined with a three-dimensional (3D) computational fluid dynamics (CFD) modeling technique was used to study the effect of geochemical and geomechanical processes on fracture properties in composite Portland cement–basalt caprock core samples. The effect of fluid properties and flow conditions on fracture permeability was numerically studied by using fluids with varying physical properties and simulating different pressure conditions. CFD revealed that the application of geomechanical stress led to increased fluid flow, which resulted in increased fracture permeability. After CO2-reaction, XMT images displayed preferential precipitation of calcium carbonate within the fractures in the cement matrix and less precipitation in fractures located at the cement–basalt interface. CFD predicted changes in flow characteristics and differences in absolute values of flow properties due to different pressure gradients. CFD was able to highlight the profound effect of fluid properties on flow characteristics and hydraulic properties of fractures. This study demonstrates the applicability of XMT imaging and CFD as powerful tools for characterizing the hydraulic properties of fractures in a number of applications like geologic carbon sequestration and storage, hydraulic fracturing for shale gas production, and enhanced geothermal systems.

CO2 storage↗
DOE OSTI2019

Hydrate-filled Fracture Formation at Keathley Canyon 151, Gulf of Mexico, and Implications for Non-vent Sites

Near-vertical hydrate-filled fractures are found in subseafloor marine muds, at both advective methane vent sites and at sites without obvious methane and fluid advection (non-vent sites). At non-vent sites, the mechanisms that transport methane to the fractures and control how hydrate-filled fractures form are not well understood. However, these mechanisms are important to establish, as most of Earth's natural gas hydrate is likely bound in marine mud systems. In this work, we focus on understanding the origin of hydrate and how fracture form at non-vent sites by examining previously hydrate-bearing fractures in conventional cores taken from Keathley Canyon 151, U.S. northern Gulf of Mexico, drilled by the Gas Hydrate Joint Industry Project in 2005. We combine information from well logs, sediment cores, and science party results and add new X-ray computed tomography of archival sections and scanning electron microcopy of core samples to develop a conceptual model. We propose that locally generated microbial methane is transported via diffusion from small pores in marine mud into biomineralized burrows with larger pore size in a process called short-range migration. Hydrate forms in burrows once the methane diffuses into them and the dissolved methane concentration exceeds the solubility threshold. When hydrate fills a burrow, heave from additional hydrate growth places stress on the burrow edges, expands the fracture, and creates additional void space in which methane can diffuse and continue forming hydrate. Fractures slowly propagate in the direction of maximum principal stress.

58 GEOSCIENCES↗