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All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Robust Carbon Dioxide Plume Imaging Using Joint Tomographic Inversion of Seismic Onset Time and Distributed Pressure and Temperature Measurements (Final Report)

We develop and demonstrate rapid and cost-effective methodologies for spatiotemporal tracking of CO2 plumes during geologic sequestration using joint inversion of seismic data and distributed pressure and temperature measurements. Key elements of our methodology are: (a) a computationally efficient approach to pressure and temperature propagation, (b) analysis of time lapse seismic data using a novel ‘seismic onset time’ approach to detect fluid front propagation, and (c) data assimilation and uncertainty assessment via joint inversion of pressure, temperature and time lapse seismic data, and (d) validating the numerical tomographic inversion using a CO2 injection demonstration projects, specifically data collected from the from the Petra Nova Parish Holdings CCUS project in the West Ranch Field, Texas and the Chester-16 reef CO2 injection site in Northern Michigan which is part of the DOE Midwestern Carbon Sequestration Project. The research team is led by Texas A&M University and includes Battelle as a subcontractor with support from Shell, Anadarko, Chevron and JX Nippon. A carbon dioxide (CO2) water-alternating-gas (WAG) pilot was conducted to gain insights into tertiary oil recovery potential via CO2 flood in the West Ranch Field as part of the Petra Nova project, the world’s largest post-combustion CO2 capture and utilization initiative. With a fluvial formation geology and large contrasts in permeability, this is a challenging and novel application of CO2 enhanced oil recovery (EOR). We build a predictive dynamic model of the subsurface that incorporates the multiphase and compositional data acquired during the pilot operation. The calibrated model is used for the carbon dioxide plume imaging. The study began with an initialization of the pilot sector model extracted from a calibrated full-field model. The pilot model calibration follows a two-step hierarchical workflow. First, we performed a large-scale update of the permeability distribution by integrating available bottomhole pressure and multiphase production data. In the second step, local permeability field is fine-tuned using a streamline-based method to match CO2 breakthrough times at the producers. The predictive capability of the calibrated model was verified through two blind validation tests: (1) the model showed good agreement with saturation logs acquired at two observation wells; and (2) the model reproduced the CO2 recovery as a fraction of the injected CO2. The use of seismic onset times has shown great promise for integrating near-continuous seismic surveys for updating geologic models. In this study, we analyze the impact of seismic survey frequency on the onset time approach aiming to extend the application of onset time to infrequent seismic surveys. In addition, we quantitatively examine the nonlinearity of the onset time method and compare it to the commonly used amplitude inversion method. We carry out a sensitivity analysis of seismic survey frequency based on the complete seismic survey data (over 175 surveys) of steam injection in a heavy oil reservoir (Peace River Unit) in Canada. Our results show that an adequate onset time map can be obtained from the infrequent seismic surveys by interpolation between seismic surveys as long as there is no change in the dominant underlying physics between the successive surveys. The study also shows that nonlinearity of the onset time method can be -smaller than that of the amplitude inversion method by several orders of magnitude. Application to the Brugge benchmark case shows that the onset time method obtains comparable permeability update as the traditional seismic amplitude inversion method with faster computation and improved convergence characteristics. We extend the streamline-based data integration approach to incorporate distributed temperature sensor (DTS) data using the concept of thermal tracer travel time. Then, a hierarchical workflow composed of evolutionary and streamline methods is employed to jointly history match the DTS and pressure data. Finally, CO2 saturation and streamline maps are used to visualize the CO2 plume movement during the sequestration process. The hierarchical workflow is applied to a carbon sequestration project in a carbonate reef reservoir within the Northern Niagaran Pinnacle Reef Trend in Michigan, USA. The monitoring data set consists of distributed temperature sensing (DTS) data acquired at the injection well and a monitoring well, flowing bottom-hole pressure data at the injection well, and time-lapse pressure measurements at several locations along the monitoring well. The history matching results indicate that the CO2 movement is mostly restricted to the intended zones of injection which is consistent with an independent warm-back analysis of the temperature data. In addition to employing simulation models and inverse methods for CO2 plume imaging, we also initialized a data-driven technology for detecting inter-well connectivity based on production and pressure data. Our machine-learning framework is built on the statistical recurrent unit (SRU) model and interprets well-based injection/production data into inter-well connectivity without relying on a geologic model. We test it on synthetic and field-scale CO2 EOR projects utilizing the water-alternating-gas (WAG) process. The validation of the proposed data-driven inter-well connectivity assessment is performed using synthetic data from simulation models where inter-well connectivity can be easily measured using the streamline-based flux allocation. The SRU model is shown to offer excellent prediction performance on the synthetic case. Despite significant measurement noise and frequent well shut-ins imposed in the field-scale case, the SRU model offers good prediction accuracy, the overall relative error of the phase production rates at most producers ranges from 10% to 30%. It is shown that the dominant connections identified by the data-driven method and streamline method are in close agreement. Texas A&M University, the lead organization in the project, was primarily responsible for the development of tomographic approaches for CO2 plume mapping in conjunction with distributed pressure, temperature and seismic onset time data. Battelle, as a subcontractor, was primarily responsible for the development of analytical and empirical methods for analyzing transient injection rate and pressure data from point/line sources such as injection and monitoring wells. An additional area of emphasis for Battelle was the use of machine learning for such tasks as inferring reservoir connectivity information from injection-production data, and identifying variable importance for machine learning-based proxy models developed from full-physics simulations. The two organizations also collaborated on the application of the tomographic inversion methodology for a field data set.

02 PETROLEUM↗
DOE OSTI2020

Experimental and Computational Studies on Superhard Material Rhenium Diboride under Ultrahigh Pressures

An emerging class of superhard materials for extreme environment applications are compounds formed by heavy transition metals with light elements. In this work, ultrahigh pressure experiments on transition metal rhenium diboride (ReB 2 ) were carried out in a diamond anvil cell under isothermal and non-hydrostatic compression. Two independent high-pressure experiments were carried out on ReB 2 for the first time up to a pressure of 241 GPa (volume compression V/V 0 = 0.731 ± 0.004), with platinum as an internal pressure standard in X-ray diffraction studies. The hexagonal phase of ReB 2 was stable under highest pressure, and the anisotropy between the a-axis and c-axis compression increases with pressure to 241 GPa. The measured equation of state (EOS) above the yield stress of ReB 2 is well represented by the bulk modulus K 0 = 364 GPa and its first pressure derivative K 0 ´ = 3.53. Corresponding density-functional-theory (DFT) simulations of the EOS and elastic constants agreed well with the experimental data. DFT results indicated that ReB 2 becomes more ductile with enhanced tendency towards metallic bonding under compression. The DFT results also showed strong crystal anisotropy up to the maximum pressure under study. The pressure-enhanced electron density distribution along the Re and B bond direction renders the material highly incompressible along the c-axis. Our study helps to establish the fundamental basis for anisotropic compression of ReB 2 under ultrahigh pressures

36 MATERIALS SCIENCE↗
NASA NTRS1962

Pressure Distribution Induced on a Flat Plate at a Free-Stream Mach Number of 1.39 by Rockets Exhausting Upstream and Downstream

An experimental investigation was made of the pressures induced on a flat plate at a free-stream Mach number of 1.39 by a supersonic rocket jet exhausting upstream and downstream. Measurements of the pressure distribution on a flat plate were made at zero angle of attack for 11 different locations of the jet exhaust nozzle beneath the wing. Measurements were made at ratios of rocket-exit total pressure to freestream static pressure from 6 to 60 and at a Reynolds number per foot of approximately 10 x 10 6 . The rocket when exhausted upstream produced a strong shock that moved further upstream with increasing rocket-exit total-pressure ratio. Positive incremental normal-force coefficients were obtained at all test positions. Data at 11 test positions are tabulated for rocket-on and rocket-off pressure coefficients as well as for incremental pressure coefficients for the 48 orifices of the flat plate for the range of ratio of rocket-exit total pressure to free-stream static pressure of the investigation. Changing the location of the model with respect to the plate had a negligible effect when the rocket was varied in the chordwise direction, but the pressure coefficients were reduced as the rocket was lowered away from the flat-plate wing.

Supersonic jet↗
NASA NTRS2003

Mechanical counter pressure on the arm counteracts adverse effects of hypobaric exposures

INTRODUCTION: Current space suits have limited movement due to gas pressurization during exposure to the vacuum of space. Alternatively, if pressure is applied by an elastic garment vs. pneumatic garment to produce mechanical counter pressure (MCP), several advantages are possible. In this study, we investigate local microcirculatory and other effects produced with and without a prototype MCP glove and sleeve during exposure to varying levels of vacuum. METHODS: The entire arms of eight male volunteers were studied at normal ambient pressure and during 5 min exposures to -50, -100, and -150 mm Hg with and without the MCP glove and sleeve. Pressure distribution, skin microvascular flow, and temperature were measured. RESULTS: The MCP glove and sleeve generated over 200 mm Hg on the middle finger, dorsum of the hand, and the wrist. However, pressure was significantly lower on the forearm and the upper arm. Without the glove and sleeve, only two of eight subjects tolerated -100 mm Hg. Also, no subject tolerated -150 mm Hg. However, subjects tolerated all vacuum pressures wearing the glove and sleeve. Skin microvascular flow and temperature remained within control values with the glove and sleeve at a chamber pressure of -150 mm Hg. DISCUSSION: The MCP glove and sleeve counteracts adverse effects of vacuum exposures due to lower pressure differentials. Pressure levels over the hand and wrist are similar to those of the current U.S. space suit glove and sleeve, but additional development is required to increase MCP over the forearm and upper arm.

NASA Discipline Cardiopulmonary↗
NASA NTRS2014

Investigation of the Effects of Facility Background Pressure on the Performance and Voltage-Current Characteristics of the High Voltage Hall Accelerator

The National Aeronautics and Space Administration (NASA) Science Mission Directorate In-Space Propulsion Technology office is sponsoring NASA Glenn Research Center to develop a 4 kW-class Hall thruster propulsion system for implementation in NASA science missions. A study was conducted to assess the impact of varying the facility background pressure on the High Voltage Hall Accelerator (HiVHAc) thruster performance and voltage-current characteristics. This present study evaluated the HiVHAc thruster performance in the lowest attainable background pressure condition at NASA GRC Vacuum Facility 5 to best simulate space-like conditions. Additional tests were performed at selected thruster operating conditions to investigate and elucidate the underlying physics that change during thruster operation at elevated facility background pressure. Tests were performed at background pressure conditions that are three and ten times higher than the lowest realized background pressure. Results indicated that the thruster discharge specific impulse and efficiency increased with elevated facility background pressure. The voltage-current profiles indicated a narrower stable operating region with increased background pressure. Experimental observations of the thruster operation indicated that increasing the facility background pressure shifted the ionization and acceleration zones upstream towards the thrusters anode. Future tests of the HiVHAc thruster are planned at background pressure conditions that are expected to be two to three times lower than what was achieved during this test campaign. These tests will not only assess the impact of reduced facility background pressure on thruster performance, voltage-current characteristics, and plume properties; but will also attempt to quantify the magnitude of the ionization.

Pressure Effects↗
NASA NTRS2022

Unsteady Pressure Acquisition on the 1.75% Scale SLS Block 1B Cargo Liftoff Configuration

Time-varying pressure on the core of the Space Launch System (SLS) Block 1B Cargo vehicle was acquired using instrumentation typically used for steady, time averaged pressure. Resono Pressure Systems, Inc. in partnership with the University of Wyoming have developed a unique hardware and software system for measuring unsteady pressure, which was implemented in a large-scale wind tunnel test through a nonreimbursable Space Act Agreement with NASA. The technique was applied to 12 pressure ports on the 1.75% scale SLS wind tunnel model. Tubing lengths of approximately 14 inches separated the pressure transducer module from the pressure taps on the model surface, and surface-mount validation sensors (Kulites) were installed in close proximity to 5 of the 12 pressure ports. Up to about 500 Hz, the frequency response of pressure fluctuations agreed to within 1 dB of amplitude and 10° of phase difference compared to the simultaneously-acquired surface-mount transducers. Sample results using the reconstructed pressure from the full azimuthal ring of taps are presented.

unsteady pressure↗
NASA NTRS1992

Blood pressure responses to LBNP in nontrained and trained hypertensive rats

To study the influences of 16 wk of endurance training on the reflex regulation of resting blood pressure, nontrained (NT) and trained (T) female hypertensive rats (SHR) were subjected to conditions of lower body negative pressure (LBNP). Measurements of muscle cytochrome oxidase activity and run time to exhaustion indicated that the animals were endurance trained. The rats (NT = 6, T = 7) were tranquilized with 300-600 micrograms.kg-1 diazepam (IV) before heart rates and blood pressures were measured over a range of 2.5-10.0 mm Hg of negative pressure. When subjected to conditions of LBNP, the reflex tachycardia of the T group was greater than the NT at the lower (-2.5 and -5.0 mm Hg) negative pressures. Although arterial pressure declines were similar in both groups, the T group experienced significantly less of a decline in central venous pressure than the NT animals. When chlorisondamine was used as a ganglionic blocker (2.5 mg.kg-1, IV), the fall in CVP at 10 mm Hg negative pressure was greater for the NT group while the fall in the initial systemic arterial pressure was more for the T group. From these results we concluded that training had altered the interaction between cardiopulmonary and arterial baroreflexes in these hypertensive rats and a nonneural component had been altered such as cardiac function.

Non-NASA Center↗
DOE OSTI2020

Use of a Pressurized Water Treatment to Prevent Cracking of Internal Gelation Sol-Gel Microspheres

Pressurized water treatments were investigated as a means to prevent cracking of internal gelation sol-gel microspheres upon drying and heating. A batch of gelled cerium oxide microspheres was prepared, split into two samples that were processed with and without a pressurized water treatment, and dried in air at room temperature. Thermal gravimetric analysis was used to compare the mass loss profiles between the two samples and to understand volatile emissions from cerium oxide microspheres during heat treatments up to 600 °C. Microspheres that were processed without a pressurized water treatment lost approximately 4.6 times more mass upon heating than microspheres that were subjected to a pressurized water treatment. Comparison of the cracking behavior of microspheres prepared with and without a pressurized water treatment indicated that microspheres subjected to a pressurized water treatment were virtually crack-free after heat treatments. Conversely, microspheres processed without a pressurized water treatment, which is typical of traditional washing processes, exhibited extensive cracking. Analysis of residues dried from pressurized water treatment effluents indicated that hexamethylenetetramine and urea, which are excess reactants from the internal gelation process, were removed from gelled microspheres during the pressurized water treatment step. Traditional processing methods for preparing internal gelation microspheres use specific feed solution and gelation parameters to reduce subsequent cracking upon drying and heating. Results from this study indicate that more aggressive gel-forming conditions may be used to produce crack-free microspheres, if a pressurized water treatment step is included after washing and before air-drying.

cerium oxide, internal gelation, microsphere, TRIS↗
DOE OSTI2023

Response of vibrational properties and thermal conductivity of perovskites to pressure

We study the response of SrTiO 3 and KTaO 3 's vibrational properties and thermal conductivity to pressurization. Our goal is to improve the understanding of the relationship between crystal structure, vibrational dynamics, and thermal conductivity in perovskites. We measure the thermal conductivity of SrTiO 3 and KTaO 3 up to 28 GPa by time-domain thermoreflectance. We also perform Raman scattering and stimulated Brillouin scattering measurements of SrTiO 3 and KTaO 3 to characterize changes in vibrational dynamics with pressure. The thermal conductivity of SrTiO 3 increases under pressure with a slope comparable to that of other perovskites whose thermal conductivity has been measured versus pressure. Alternatively, the thermal conductivity of KTaO 3 has a stronger pressure dependence than that of other materials with similar crystal structure. We correlate pressure-induced changes in Raman and Brillouin spectra with pressure-induced changes in thermal conductivity. We show that pressure-induced changes in phonon lifetimes dominate the pressure dependence of thermal conductivity. This study provides benchmark knowledge of why depends on pressure and improves understanding of structure/thermal-property relationships.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Thermal Pressure in the Laser‐Heated Diamond Anvil Cell: A Quantitative Study and Implications for the Density Versus Mineralogy Correlation of the Mantle

Abstract Thermal pressure is an inevitable thermodynamic consequence of heating a volumetrically constrained sample in the diamond anvil cell. Its possible influences on experimentally determined density‐mineralogy correlations are widely appreciated, yet the effect itself has never been experimentally measured. We present here the first quantitative measurements of the spatial distribution of thermal pressure in a laser‐heated diamond anvil cell (LHDAC) in both olivine and AgI. The observed thermal pressure is strongly localized and closely follows the distribution of the laser hotspot. The magnitude of the thermal pressure is of the order of the thermodynamic thermal pressure ( αK T Δ T ) with gradients between 0.5 and 1.0 GPa/10 μm. Remarkably, we measure a steep gradient in thermal pressure even in a sample that is heated close to its melting line. This generates consequences for pressure determinations in pressure‐volume‐temperature (PVT) equation of state measurements when using an LHDAC. We show that an incomplete account of thermal pressure in PVT experiments can lead to biases in the coveted depth versus mineralogy correlation. However, the ability to spatially resolve thermal pressure in an LHDAC opens avenues to measure difficult‐to‐constrain thermodynamic derivative properties, which are important for comprehensive thermodynamic descriptions of the interior of planets.

Yen, Connor Ethan↗
DOE OSTI2022

Preservation of high-pressure volatiles in nanostructured diamond capsules

High pressure induces dramatic changes and novel phenomena in condensed volatiles(1,2) that are usually not preserved after recovery from pressure vessels. In this study we report a process that pressurizes volatiles into nanopores of type 1 glassy carbon precursors, converts glassy carbon into nanocrystalline diamond by heating and synthesizes free-standing nanostructured diamond capsules (NDCs) capable of permanently preserving volatiles at high pressures, even after release back to ambient conditions for various vacuum-based diagnostic probes including electron microscopy. As a demonstration, we perform a comprehensive study of a high-pressure argon sample preserved in NDCs. Synchrotron X-ray diffraction and high-resolution transmission electron microscopy show nanometre-sized argon crystals at around 22.0 gigapascals embedded in nanocrystalline diamond, energy-dispersive X-ray spectroscopy provides quantitative compositional analysis and electron energy-loss spectroscopy details the chemical bonding nature of high-pressure argon. The preserved pressure of the argon sample inside NDCs can be tuned by controlling NDC synthesis pressure. To test the general applicability of the NDC process, we show that high-pressure neon can also be trapped in NDCs and that type 2 glassy carbon can be used as the precursor container material. Additional experiments on other volatiles and carbon allotropes open the possibility of bringing high-pressure explorations on a par with mainstream condensed-matter investigations and applications.

36 MATERIALS SCIENCE↗
DOE OSTI2021

A15 Nb 3 Si: a ‘high’ T c superconductor synthesized at a pressure of one megabar and metastable at ambient conditions

A15 Nb 3 Si is, until now, the only 'high' temperature superconductor produced at high pressure (~110 GPa) that has been successfully brought back to room pressure conditions in a metastable condition. Based on the current great interest in trying to create metastable-at-room-pressure high temperature superconductors produced at high pressure, we have restudied explosively compressed A15 Nb 3 Si and its production from tetragonal Nb 3 Si. First, diamond anvil cell pressure measurements up to 88 GPa were performed on explosively compressed A15 Nb 3 Si material to trace T c as a function of pressure. T c is suppressed to ~5.2 K at 88 GPa. Then, using these T c (P) data for A15 Nb 3 Si, pressures up to 92 GPa were applied at room temperature (which increased to 120 GPa at 5 K) on tetragonal Nb 3 Si. Measurements of the resistivity gave no indication of any A15 structure production, i.e. no indications of the superconductivity characteristic of A15 Nb 3 Si. This is in contrast to the explosive compression (up to P ~ 110 GPa) of tetragonal Nb 3 Si, which produced 50%–70% A15 material, T c = 18 K at ambient pressure, in a 1981 Los Alamos National Laboratory experiment. This implies that the accompanying high temperature (1000 °C) caused by explosive compression is necessary to successfully drive the reaction kinetics of the tetragonal → A15 Nb 3 Si structural transformation. Our theoretical calculations show that A15 Nb 3 Si has an enthalpy vs the tetragonal structure that is 70 meV atom –1 smaller at 100 GPa, while at ambient pressure the tetragonal phase enthalpy is lower than that of the A15 phase by 90 meV atom –1 . Furthermore, the fact that 'annealing' the A15 explosively compressed material at room temperature for 39 years has no effect shows that slow kinetics can stabilize high pressure metastable phases at ambient conditions over long times even for large driving forces of 90 meV atom –1 .

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Analysis of Completion Design Impact on Cluster Efficiency and Pressure-Based Well Communication in HFTS-2 Delaware Basin

The Hydraulic Fracturing Test Site 2 (HFTS-2) is a joint industry project in the Delaware basin to advance hydraulic fracturing understanding and improve productivity in shale reservoirs. The project integrates multi-disciplinary approaches to evaluate different completion designs, well spacing, inter-well communication, and stimulated rock volume, among other factors. This paper focused on two major areas related to hydraulic fracture performance. First, an analysis of different completion designs on cluster efficiency based on near well Distributed Acoustic Sensing (DAS). Second, an evaluation of well and completion designs on inter-well fracture driven interactions (FDIs) based on downhole pressure monitoring. Fluid/sand distribution and cluster efficiency analyses were based on near wellbore DAS data collected from two adjacent horizontal wells completed in two different landing zones in the Wolfcamp formation. These wells had different completion designs aiming to evaluate the effect of normal vs. extended stage lengths, perforation hole tapering and limited entry. Standard deviation from ideal fluid/sand distribution and waterfall plots were used to evaluate cluster efficiency for each design and stage. Inter-well FDIs analysis was conducted among the horizontal wells and a vertical monitor well. One horizontal well served as the monitor well while the other horizontal well was being treated. The vertical well was instrumented with downhole pressure and temperature gauges to aid monitoring fracture height growth. The pressure response during and after fracturing was characterized based on maximum pressure increase value and slope. Pressure response vs. FDIs trigger factors such distance, cluster efficiency and stage fluid volume were also analyzed. Based on the different completion and perforation designs tested, DAS analysis suggests that limited entry design worked best. Extreme limited entry showed the potential of high perforation erosion and reduced cluster efficiency. Here, the limited entry and tapered perforation design demonstrated potential to improve the cluster efficiency for extended stage lengths. Pressure monitoring across formation units proved to be critical to understand fracture interactions and fracture vertical growth. Pressure communication across different formation units during hydraulic fracturing operation indicate fractures grew upwards during Wolfcamp wells fracturing. However, this pressure communication dissipated over time. High intensity FDIs were recorded when the frac stages Downloaded from http://onepetro.org/URTECONF/proceedings-pdf/21URTC/1-21URTC/D011S018R001/2477607/urtec-2021-5289-ms.pdf/1 by Carol Worster on 28 February 2022 URTeC 5289 were closer to the pressure gauge location in the monitor wells. Some of these stages that produced high intensity FDIs also had high fluid volume per cluster and low cluster efficiency. The multi-disciplinary and high-quality data collected from HFTS-2 helped to further understand why completion approaches such as limited entry and tapered perforation design are successful in improving cluster efficiency. The DAS data combined with downhole high-resolution pressure measurements also helped to quantify the effect of lower cluster efficiency data on the incidence and intensity of FDIs.

58 GEOSCIENCES↗
DOE OSTI2020

Fast and Accurate Core Analysis by the Full-Immersion Pressure-Pulse Decay: Part 1—Theory

Summary Core-scale measurements are considered the ground truth that oil and gas or electric utility companies use to predict the migration of fluids such as oil, natural gas, carbon dioxide, or brine deep underground during their extraction or injection operations. To provide a greater understanding of petrophysical properties of low-permeability geologic formations such as shales and tight gas sandstones, this study introduces a novel core-analysis procedure. The technique follows conventional pressure-pulse-decay permeametry, where the pressure in an inlet chamber adjacent to a cylindrical core plug undergoes a rapid pressurization, the system is shut in, and the pressure reaches a new equilibrium. However, unlike a standard unidirectional pressure-pulse decay, the full-immersion pressure-pulse decay (Hannon 2019) applies a pressure disturbance to the entire outer surface area of the sample. This article covers the numerical simulator designed to model flow through an anisotropic porous sample in this scenario. The model assumes distinct but uniform permeabilities along the radial and axial directions of the cylindrical plug sample. When extracting a plug vertically (or perpendicular to bedding), the permeability along the radial direction associates with the horizontal permeability (i.e., parallel to bedding), whereas in the axial direction, flow occurs perpendicular to bedding (a vertical permeability). Investigations of these model outputs demonstrate an approximately 20-fold decrease in time to complete a full-immersion experiment compared with conventional pressure-pulse decay. Furthermore, the pressure-decay curves resulting from the full-immersion method have slightly different shapes than those resulting from other unidimensional transient methods. These differences begin to demonstrate that, under achievable experimental conditions, the analysis of pressure data from one full-immersion test could enable the simultaneous estimation of the apparent permeabilities parallel and perpendicular to bedding of a cylindrical sample in addition to its porosity. A follow-up article finalizes the proof of this capability with a parameter-estimation procedure and presents experimental verification through a proof-of-concept study. Described in greater detail in that article, the parameter estimator requires multiple forward simulations to analyze the data, which behooves minimizing the compute time for each simulation. By using an alternating direction implicit time-marching scheme and a structured but variably spaced grid, the numerical simulator built for this purpose provides a forward model output with suitable accuracy in approximately 0.5 seconds.

Energy & Fuels↗
DOE OSTI2024

Impact of Pressure-Dependent Interfacial Tension and Contact Angle on Capillary Heterogeneity Trapping of CO2 in Storage Aquifers

Summary Carbon dioxide (CO2) capillary trapping increases the total amount of CO2 that can be effectively immobilized in storage aquifers. This trapping, manifesting itself as accumulated CO2 columns at a continuum scale, is because of capillary threshold effects that occur below low-permeability barriers. Considering that capillary pressure is dictated by heterogeneous pore throat size, the trapped CO2 column height and associated CO2 saturation will vary spatially within a storage aquifer. This variation will be influenced by two pressure-dependent interfacial parameters—CO2/brine interfacial tension (IFT) and CO2/brine/rock contact angle. Our objective is to understand how the pressure dependence of these two parameters affects the heterogeneity of capillary trapped CO2 at a continuum scale. Our conceptual model is a 1D two-zone system with the upper zone being a flow barrier (low permeability) and the lower zone being a flow path (high permeability). The inputs to this model include microfacies-dependent capillary pressure vs. saturation curves and permeability values. The input capillary pressure curves were collected in the literature that represents carbonate microfacies (e.g., dolograinstone) in a prevalent formation in the Permian Basin. We then used the Leverett j-function to scale the capillary pressure curve for the two zones that are assigned with the same or different microfacies. During scaling, we considered the influence of pressure on both the IFT and contact angle of CO2/brine/dolomite systems. We varied the zone permeability contrast ratio from 2 to 50. We then assumed capillary gravity equilibriums and calculated the CO2 saturation buildup corresponding to various trapped CO2 column heights. The CO2 saturation buildup is defined as the CO2 saturation in the lower layer minus that in the upper one. We found that the saturation buildup can be doubled when varying pressure in a storage aquifer, after considering pressure-dependent IFT and contact angles. Thus, assuming these two parameters to be constant across such aquifers would cause large errors in the quantification of capillary trapping of CO2. The whole study demonstrates the importance of considering pressure-dependent interfacial properties in predicting the vertical distribution of capillary trapped CO2. It has important implications in developing a better understanding of leakage risks and consequent storage safety.

Engineering↗
DOE OSTI2023

Experimental study on particle formation in a pressurized oxy-fuel combustor using a novel in-situ optical instrument

Particle formation in pressurized oxy-fuel combustion can be fundamentally different from oxy-fuel combustion at atmospheric pressure. Under high pressures, the rate of char gasification with CO2 and H2O increases significantly and dominates the char reactions particularly at high temperatures. Also, the extent of fragmentation varies. This could result in a very different particle size distribution from that of air-fired combustion. To accurately obtain the particle size distribution in a pressurized oxy-fuel combustor without sampling bias, the particle measurement should be made at the system pressure. Very few published studies have accomplished this, and never under the conditions reported herein. In this work, we fire PRB coal in a 100 kWth staged pressurized oxy-fuel combustor (SPOC) under two pressures, 15 and 2 bara. A sampling probe (oil-cooled) is installed at the combustor outlet and the aerosol flow are sampled isokinetically. We utilize a state-of-the-art optical analyzer (Malvern Insitec) with a novel high-pressure and high-temperature flow cell to measure the particle size distribution and concentration in-situ in a sampled flow, which contains moist/corrosive flue gas under the process pressure and a controlled temperature that is kept above the dew point. The results show that the pressure can significantly influence the particle size distribution and concentration from the oxy-fuel combustor.

Cheng, Mao↗
DOE OSTI2023

Development of a High-Pressure Fuel Injection System for Use with Propane-DME

Paper details the design approach and performance of a high-pressure common rail fuel injection system used with Propane-DME mixtures targeting high injection pressures on a light duty 2.2L inline-4 compression ignition engine. The study estimates the bulk modulus of elasticity based on the hardware geometry and operating pressures to assess the compressibility of Propane and DME across a range of pressures typical of the LD engine application. The compressibility factor ranges from 500 to 3000 bar, significantly lower than the theoretical values for the conditions tested. The high-pressure pump performance is optimized via the implementation of an inlet metering valve operated on a crank-angle open/close sequence to control pressure at the common rail. The application of a model-based controller and the use of high-speed sampling of rail pressure indicate that pressure at the rail can be attained with the pump metering valve, and without use of the pressure relieve valve present in the rail. Results show a significant reduction on pumping work parasitics and of fuel heating, on the order of 40°C, at typical working conditions with the proposed approach. Injector rates of injection with Propane-DME are very similar to those of Diesel. Paper compares bench data of rates of injection versus simulation predictions across operating pressures of 200 to 1000bar and from injection commands spanning 0.20 to 2.0ms. Furthermore, the accuracy of the model predictions are attributed in part by to the updated fuel compressibility modulus descriptions attained during the testing.

42 ENGINEERING↗
NASA NTRS1974

Flight-measured inlet pressure transients accompanying engine compressor surges on the F-111A airplane

Two-F-111A airplanes were subjected to conditions that caused engine compressor surges and accompanying duct hammershock pressure transients. Flight speed ranged from Mach 0.71 to Mach 2.23, and altitude varied from approximately 3200 meters to 14,500 meters. A wide range of compressor pressure ratios was covered. Stabilized free-stream, engine, and duct conditions were established before each compressor surge. Dynamic pressure instrumentation at the compressor face and in the duct recorded the pressure transients associated with the surges. Hammershock pressures were analyzed with respect to the stabilized conditions preceding the compressor surges. The hammershock transients caused large pressure rises at the compressor face and in the duct. Hammershock pressure ratios at the compressor face were not affected by free-stream Mach number or altitude but were functions of engine variables, such as compressor pressure ratio. The maximum hammershock pressure ratio of approximately 1.83 occurred at a compressor pressure ratio of approximately 21.7.

Nugent, J.↗