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At least 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Experimental Study of Porosity Changes in Shale Caprocks Exposed to CO 2 -Saturated Brines I: Evolution of Mineralogy, Pore Connectivity, Pore Size Distribution, and Surface Area

Carbon capture, utilization, and storage, one proposed method of reducing anthropogenic emissions of CO 2 , relies on low permeability formations, such as shales, above injection formations to prevent upward migration of the injected CO 2 . Porosity in caprocks evaluated for sealing capacity before injection can be altered by geochemical reactions induced by dissolution of injected CO 2 into pore fluids, impacting long-term sealing capacity. Therefore, long-term performance of CO 2 sequestration sites may be dependent on both initial distribution and connectivity of pores in caprocks, and on changes induced by geochemical reaction after injection of CO 2 , which are currently poorly understood. This paper presents results from an experimental study of changes to caprock porosity and pore network geometry in two caprock formations under conditions relevant to CO 2 sequestration. Pore connectivity and total porosity increased in the Gothic Shale; while total porosity increased but pore connectivity decreased in the Marine Tuscaloosa. Gothic Shale is a carbonate mudstone that contains volumetrically more carbonate minerals than Marine Tuscaloosa. Carbonate minerals dissolved to a greater extent than silicate minerals in Gothic Shale under high CO 2 conditions, leading to increased porosity at length scales <~200 nm that contributed to increased pore connectivity. In contrast, silicate minerals dissolved to a greater extent than carbonate minerals in Marine Tuscaloosa leading to increased porosity at all length scales, and specifically an increase in the number of pores >~1 μm. Mineral reactions also contributed to a decrease in pore connectivity, possibly as a result of precipitation in pore throats or hydration of the high percentage of clays. Finally, this study highlights the role that mineralogy of the caprock can play in geochemical response to CO 2 injection and resulting changes in sealing capacity in long-term CO 2 storage projects.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1979

Bubble behavior during solidification in low gravity

The trapping and behavior of gas bubbles were studied during low-gravity solidification of carbon tetrabromide, a transparent metal-model material. The experiment was performed during a NASA-sponsored sounding rocket flight and involved gradient freeze solidification of a gas-saturated melt. Gas bubbles were evolved at the solid-liquid interface during the low-gravity interval. No large-scale thermal migration of bubbles, bubble pushing by the solid-liquid interface, or bubble detachment from the interface were observed during the low-gravity experiment. A unique bubble motion-fluid flow event occurred in one specimen: a large bubble moved downward and caused some circulation of the melt. The gas bubbles that were trapped by the solid in commercial-purity material formed voids that had a cylindrical shape, in contrast to the spherical shape that had been observed in a prior low-gravity experiment. These shapes were not influenced by the gravity level (0.0001 g-0 vs g-0), but were dependent upon the initial temperature gradient. In higher purity material, however, the shape of the voids changed from cylindrical in 1g to spherical in low gravity.

Papazian, J. M.↗
NASA NTRS1985

Thermal regimes in the detachment fault environment as deduced from fluid inclusions

Extensional tectonism, which dominates middle- and late-Tertiary geology in western Arizona, southeastern California, and southern Nevada, is characterized by normal regionally extensive, low-angle detachment faults. The decollement movement of Fupper plate rocks relative to lower plate assemblages created extensive zones of dilatency, including synthetic and antithetic listric normal faults, tear faults, tectonic crush breccias, shatter breccias, and gash veins in lithologic units above and below the detachment. The tectonically enhanced permeability above and below the detachment fault permitted mass migration of large volumes of hydrothermal solutions along the fault zone during and following upper plate movement. Major quantities of MgO, CaO, K2O, FeO/Fe2O3, SiO2 and CO2 were added to rocks in and near the detachment and related structures. Also introduced were varying amounts of trace elements including Mn, Cu, S, Mo, Ba, Au, Pb, Zn, U and/or Ag. Minerals containing fluid incusions were collected from all of these loci at locations in detachment faulted terranes in western Arizona and southeastern California.

Beane, R. E.↗
DOE OSTI2025

Unsteady- and Steady-State Relative Permeability Study with X-ray and Acoustic Monitoring for CO 2 Storage in Deep Saline Aquifers

In this study, we link the multiphase flow measurements with controls of sedimentary structures (e.g., heterogeneity and anisotropy) on relative permeability to variations in ultrasonic velocities for two deep saline aquifer formations (Entrada and Bluff Sandstones) in the San Juan Basin of the Southwestern USA. The rock specimens were extracted from outcrop sites near Durango, CO, USA. They have distinct differences in grain size, cementation composition, and individual chemical amounts, despite both formations being eolian sandstones. We performed a series of unsteady- and steady-state CO 2 -brine relative permeability experiments under capillary-controlled displacement rates. Unsteady-state experiments were conducted at 71 °C and 9.65 MPa; steady-state experiments were conducted at 85 °C and 22.8 MPa and 89 °C and 24.1 MPa for the Bluff and Entrada Sandstones, respectively. During the unsteady experiments, X-ray computed tomography was used to visualize multiphase flow in porous media and quantify saturations during brine drainage under various flow rates. Scan images and saturation profiles indicate that the CO 2 distribution in the pore volume was strongly impacted by the presence of high-angle cross-laminations, heterogeneous rock structure, and direction of bedding orientation. Those factors contribute to dramatic and quick initial breakthroughs and affect the overall saturation dynamics. Steady-state relative permeability tests were conducted at net flow rates of 1 mL/min for both brine drainage and imbibition. During the experimental steps, the CO 2 fractional flow was increased and decreased for both drainage and imbibition scenarios to mimic the front when CO 2 contacts brine and behind the front when brine enters space previously occupied by CO 2 . It was found that compressional velocity decreased, while shear waves slightly increased as brine saturation decreased. The hysteresis effects for the relative permeability and acoustic velocities were distinct. Furthermore, the CO 2 /brine front stability is quantified by applying a mobility ratio approach to spot saturations at which the boundary line between fluids becomes uneven. The results presented in this work can potentially boost the quality and precision of forecasts for the CO 2 storage projects in which the vertical and horizontal core-scale heterogeneity and anisotropy impact the plume migration within host reservoirs.

carbon dioxide (CO2)↗
DOE OSTI2018

Fluid-enhanced surface diffusion controls intraparticle phase transformations

Phase transformations driven by compositional change require mass flux across a phase boundary. In some anisotropic solids, however, the phase boundary moves along a non-conductive crystallographic direction. One such material is Li X FePO 4 , an electrode for lithium-ion batteries. With poor bulk ionic transport along the direction of phase separation, it is unclear how lithium migrates during phase transformations. Here, we show that lithium migrates along the solid/liquid interface without leaving the particle, whereby charge carriers do not cross the double layer. X-ray diffraction and microscopy experiments as well as ab initio molecular dynamics simulations show that organic solvent and water molecules promote this surface ion diffusion, effectively rendering Li X FePO 4 a three-dimensional lithium-ion conductor. Phase-field simulations capture the effects of surface diffusion on phase transformation. Lowering surface diffusivity is crucial towards supressing phase separation. In conclusion, this work establishes fluid-enhanced surface diffusion as a key dial for tuning phase transformation in anisotropic solids.

36 MATERIALS SCIENCE↗
DOE OSTI2018

The spatial footprint of injection wells in a global compilation of induced earthquake sequences

Fluid injection can cause extensive earthquake activity, sometimes at unexpectedly large distances. Appropriately mitigating associated seismic hazards requires a better understanding of the zone of influence of injection. We analyze spatial seismicity decay in a global dataset of 18 induced cases with clear association between isolated wells and earthquakes. We distinguish two populations. The first is characterized by near-well seismicity density plateaus and abrupt decay, dominated by square-root space-time migration and pressure diffusion. Injection at these sites occurs within the crystalline basement. The second population exhibits larger spatial footprints and magnitudes, as well as a power law–like, steady spatial decay over more than 10 kilometers, potentially caused by poroelastic effects. Far-reaching spatial effects during injection may increase event magnitudes and seismic hazard beyond expectations based on purely pressure-driven seismicity.

Science & Technology - Other Topics↗
NASA NTRS2004

Thermocapillary migration of a drop: an exact solution with Newtonian interfacial rheology and stretching/shrinkage of interfacial area elements for small Marangoni numbers

In this paper we analyze the effects of the following phenomena associated with the thermocapillary migration of a drop. The first is the influence of Newtonian surface rheology of the interface and the second is that of the energy changes associated with stretching and shrinkage of the interfacial area elements, when the drop is in motion. The former occurs because of dissipative processes in the interfacial region, such as when surfactant molecules are adsorbed at the interface in sufficient concentration. The interface is typically modeled in this instance by ascribing to it a surface viscosity. This is a different effect from that of interfacial tension gradients arising from surfactant concentration gradients. The stretching and shrinkage of interfacial area elements leads to changes in the internal energy of these elements that affects the transport of energy in the fluids adjoining the interface. When an element on the interface is stretched, its internal energy increases because of the increase in its area. This energy is supplied by the neighboring fluids that are cooled as a consequence. Conversely, when an element on the interface shrinks, the adjoining fluids are warmed. In the case of a moving drop, elements of interfacial area are stretched in the forward half of the drop, and are shrunk in the rear half. Consequently, the temperature variation on the surface of the drop and its migration speed are modified. The analysis of the motion of a drop including these effects was first performed by LeVan in 1981, in the limit when convective transport of momentum and energy are negligible. We extend the analysis of LeVan to include the convective transport of momentum by demonstrating that an exact solution of the momentum equation is obtained for an arbitrary value of the Reynolds number. This solution is then used to calculate the slightly deformed shape of the drop from a sphere.

Rheology/methods↗
DOE OSTI2010

THREE-DIMENSIONAL DISK-PLANET TORQUES IN A LOCALLY ISOTHERMAL DISK

We determine an expression for the Type I planet migration torque involving a locally isothermal disk, with moderate turbulent viscosity (5 x 10{sup -4} {approx}< {alpha} {approx}< 0.05), based on three-dimensional nonlinear hydrodynamical simulations. The radial gradients (in a dimensionless logarithmic form) of density and temperature are assumed to be constant near the planet. We find that the torque is roughly equally sensitive to the surface density and temperature radial gradients. Both gradients contribute to inward migration when they are negative. Our results indicate that two-dimensional calculations with a smoothed planet potential, used to account for the effects of the third dimension, do not accurately determine the effects of density and temperature gradients on the three-dimensional torque. The results suggest that substantially slowing or stopping planet migration by means of changes in disk opacity or shadowing is difficult and appears unlikely for a disk that is locally isothermal. The scalings of the torque and torque density with planet mass and gas sound speed follow the expectations of linear theory. We also determine an improved formula for the torque density distribution that can be used in one-dimensional long-term evolution studies of planets embedded in locally isothermal disks. This formula can be also applied in the presence of mildly varying radial gradients and of planets that open gaps. We illustrate its use in the case of migrating super-Earths and determine some conditions sufficient for survival.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

Wastewater disposal and earthquake swarm activity at the southern end of the Central Valley, California

Fracture and fault zones can channel fluid flow and transmit injection-induced pore pressure changes over large distances (>km), at which seismicity is rarely suspected to be human induced. We use seismicity analysis and hydrogeological models to examine the role of seismically active faults in inducing earthquakes. We analyze a potentially injection-induced earthquake swarm with three events above M4 near the White Wolf fault (WWF). The swarm deviates from classic main aftershock behavior, exhibiting uncharacteristically low Gutenberg-Richter b of 0.6, and systematic migration patterns. Some smaller events occurred southeast of the WWF in an area of several disposal wells, one of which became active just 5 months before the main swarm activity. Hydrogeological modeling revealed that wastewater disposal likely contributed to seismicity via localized pressure increase along a seismically active fault. Furthermore, our results suggest that induced seismicity may remain undetected in California without detailed analysis of local geologic setting, seismicity, and fluid diffusion.

58 GEOSCIENCES↗
DOE OSTI2017

The influence of interfacial slip on two-phase flow in rough pores

The migration and trapping of supercritical CO 2 (scCO 2 ) in geologic carbon storage is strongly dependent on the geometry and wettability of the pore network in the reservoir rock. During displacement, resident fluids may become trapped in the pits of a rough pore surface forming an immiscible two-phase fluid interface with the invading fluid, allowing apparent slip flow at this interface. We present a two-phase fluid dynamics model, including interfacial tension, to characterize the impact of mineral surface roughness on this slip flow. We show that the slip flow can be cast in more familiar terms as a contact-angle (wettability)-dependent effective permeability to the invading fluid, a nondimensional measurement which relates the interfacial slip to the pore geometry. The analysis shows the surface roughness-induced slip flow can effectively increase or decrease this effective permeability, depending on the wettability and roughness of the mineral surfaces. Configurations of the pore geometry where interfacial slip has a tangible influence on permeability have been identified. The results suggest that for large roughness features, permeability to CO 2 may be enhanced by approximately 30% during drainage, while the permeability to brine during reimbibition may be enhanced or diminished by 60%, depending on the contact angle with the mineral surfaces and degrees of roughness. For smaller roughness features, the changes in permeability through interfacial slip are small. As a result, a much larger range of effective permeabilities are suggested for general fluid pairs and contact angles, including occlusion of the pore by the trapped phase.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2011

Bifunctionally Graded Electrode Supported SOFC Modeling and Computational Thermal Fluid Analysis for Experimental Design

A comprehensive 3D computational fluid dynamics (CFD) model is developed for a bi-electrode supported cell (BSC) solid oxide fuel cell (SOFC). The model includes complicated transport phenomena of mass/heat transfer, charge (electron and ion) migration, and electrochemical reactions. The uniqueness of the modeling study is that functionally graded porous electrode property is taken into account, including not only linear but also nonlinear porosity distributions. The model is validated using experimental data from open literature. Numerical results indicate that BSC performance is strongly dependent on both operating conditions and porous microstructure distributions of electrodes. Using the proposed fuel/gas feeding design, the uniform hydrogen distribution within the porous anode is achieved; the oxygen distribution within the cathode is dependent on porous microstructure distributions as well as pressure loss conditions. Simulation results also show that fairly uniform temperature distribution can be obtained with the proposed fuel/gas feeding design. This modeling work can provide a pre-experimental analysis and guide experimental designs for BSC test.

carbon sequestration↗
DOE OSTI2016

Real-time Microseismic Processing for Induced Seismicity Hazard Detection

Induced seismicity is inherently associated with underground fluid injections. If fluids are injected in proximity to a pre-existing fault or fracture system, the resulting elevated pressures can trigger dynamic earthquake slip, which could both damage surface structures and create new migration pathways. The goal of this research is to develop a fundamentally better approach to geological site characterization and early hazard detection. We combine innovative techniques for analyzing microseismic data with a physics-based inversion model to forecast microseismic cloud evolution. The key challenge is that faults at risk of slipping are often too small to detect during the site characterization phase. Our objective is to devise fast-running methodologies that will allow field operators to respond quickly to changing subsurface conditions.

15 GEOTHERMAL ENERGY↗
NASA NTRS1994

Computations of drop collision and coalescence

Computations of drops collision and coalescence are presented. The computations are made possible by a recently developed finite difference/front tracking technique that allows direct solutions of the Navier-Stokes equations for a multi-fluid system with complex, unsteady internal boundaries. This method has been used to examine the boundaries between the various collision modes for drops of equal size and two examples, one of a 'reflective' collision and another of a 'grazing' collision is shown. From drops of unequal size, coalescence can result in considerable mixing between the fluid from the small and the large drop. This problem is discussed and one example showed. In many cases it is necessary to account also for heat transfer along with the fluid mechanics. We show two preliminary results where we are using extensions of the method to simulate such a problem. One example shows pattern formation among many drops moving due to thermal migration, the other shows unstable evolution of a solidification front.

Tryggvason, Gretar↗
DOE OSTI2018

Time Lapse Charged Wellbore Casing Controlled Source Electromagnetic Surveys for Monitoring Injected Carbon Dioxide

Carbon dioxide (CO2) injection for enhanced oil recovery (EOR) and long-term carbon storage extends the life of an oil field while keeping CO2 out of the atmosphere. Monitoring CO2 migration during EOR operations is critical to maximizing production and detecting unexpected CO2 migration quickly. In this project, we monitor CO2 migration using time-lapse charged well casing controlled source electromagnetics (CSEM) at an active EOR site undergoing CO2 injection. Since the electrical conductivity of the reservoir changes as CO2 displaces other fluids, this novel survey technique aims to monitor CO2 injection effectively and unobtrusively from the surface via electromagnetic field measurements. Of four time-lapse field campaigns spaced over two years, we have completed two. Each campaign consists of a CSEM survey supplemented by magnetotelluric and time-domain electromagnetic surveys. In the CSEM survey, a transmitter delivers alternating current to the subsurface at frequencies from 0.125 Hz to 16 Hz using steel well casings as electrodes. Charged well casing surveys detect deeper conductivity contrasts than surveys that use only surface electrodes, allowing CO2 movement at the depth of the reservoir to be imaged more clearly. We transmit on two well pairs. One pair is oriented in the east-west direction, and the other is oriented in the northeast-southwest direction. Receiver stations measure orthogonal components of the electric and magnetic fields. The measurements are repeated at the same locations in each field campaign. Data differences between campaigns provide information about changes in the electrical conductivity of the subsurface. We present the latest results from this ongoing project, including modeling, survey design, data processing techniques, and preliminary results from the field campaigns.

Magnetic and electrical methods, Geomagnetic induc↗
NASA NTRS1990

Particle migration in suspensions by thermocapillary or electrophoretic motion

Two problems of similar mathematical structure are presented: the thermocapillary motion of bubbles and the electrophoresis of colloidal particles. For both problems, it is shown that in a cloud of n particles surrounded by an infinite expanse of fluid, the velocity of each sphere under creeping flow conditions is equal to the velocity of an isolated particle, unchanged by interactions between the particles. However, when the cloud fills a container, conservation of mass shows that this result cannot continue to hold, and the average translational velocity must be calculated subject to a constraint on the mass flux. It is concluded that the average thermocapillary or electrophoretic translational velocity of a particle in the cloud is related to the effective conductivity of the cloud over the whole range of particle volume fractions, provided that the particles are identical, non-conducting and, for the thermocapillary problem, inviscid.

Acrivos, A.↗
DOE OSTI2018

Transport and Fate of Natural Gas and Brine Escaping from a Hydrocarbon Reservoir Through a Failed Deepwater Well in the Oceanic Subsurface of the Gulf of Mexico

The possibility of broaching, or the release of fluids at the seafloor due to a damaged or faulty well, is a hazard that must be assessed in the well permitting process. Here, this paper describes a numerical simulation study of a real-life scenario where a complex, permeable sandy formation, connected to the seafloor via known chimneys/seeps, is intersected by a damaged production well that drains another deeper, gas-bearing formation. The objective of the study is to determine the transport and fate of hydrocarbon reservoir fluids (gas and brines) escaping into the sandy formation through the casing shoe of the failed well, and to determine the time it takes for these contaminants to reach the ocean floor. We conducted a detailed simulation study to represent the conditions, properties, and behavior of the system under such failure conditions, and we investigated the migration of gas and brine for a range of reservoir and chimney properties. A key conclusion is that, for such complex systems, modeling the three-dimensional geometry of the system in detail is the key to describing transport and assessing the time and magnitude of potential releases. For the system studied here, transport times range from under 2 years (highest permeabilities) to many decades, ensuring significant time to respond to potential broaching hazards. Lastly, under the conditions investigated in this study, we also determine that gas-dominated releases associated with low rates of water flow into the sandy formation are likely to cause hydrate formation that can reduce permeabilities in the colder, upper regions of the chimneys and possibly mitigate releases.

58 GEOSCIENCES↗
NASA NTRS1979

Bubble behavior during solidification in low-gravity

The trapping and behavior of gas bubbles were studied during low gravity solidification of carbon tetrabromide. The flight experiments were performed during two sounding rocket flights (SPAR 1 and SPAR 3) and involved gradient freeze solidification of gas saturated melts. Gas bubbles were evolved at the solid-liquid interfaces during the low gravity intervals. No large-scale thermal migration of bubbles, bubble pushing by the solid-liquid interface, or bubble detachment from the interface were observed during the low gravity experiments. During the SPAR 3 experiment, a unique bubble motion-fluid flow event occurred in one specimen: a large bubble moved downward and caused some circulation of the melt. The gas bubbles that were trapped by the solid in commercial purity material formed voids that had a cyclindrical shape in SPAR 3, in contrast to the spherical shape that had been observed in SPAR 1. These shapes were not influenced by the gravity level, but were dependent upon the initial temperature gradient. In higher purity material the shape of the voids changed from cylindrical in one-g to spherical in low-g.

Papazian, J. M.↗