Quantitative Pore-Scale Analysis of CO2 Foam for CCUS

Postponed access: the file will be accessible after 2021-01-03This experimental thesis is a part of ongoing projects lead by the Reservoir Physics group at the Department of Physics and Technology, University of Bergen. The main objectives of this thesis were to develop image analysis software to quantitatively describe CO2 foam for CCUS at the pore scale, investigate the separate and combined use of surfactants and nanoparticles as foaming agents for CO2 foam in the absence of oil at pore space, and to study calcite precipitation and dissolution in a micromodel to shed light on pore scale mechanisms during CO2 storage in carbonate reservoirs. The high pressure silicon wafer micromodels used enabled direct pore-scale visualization at relevant pore pressures of fluid dynamics, foam texture, foam stability, and foam performance. Micromodel porosity and permeability were found to be 0.607 ± 0.001 and 2.97 ± 0.07 D, respectively. Qualitative image analysis of fluid displacements occurring in the micromodel is useful to shed light on potential new displacement mechanisms, but provide limited information in a restricted field of view and it is time consuming. A major contribution in this thesis is the development of new image analysis tools that allow quantitative analysis on fluid displacement mechanisms and CO2 foam behavior. Access to dynamic, quantitative data from image analysis enables calculation of bubble generation and coalescence rates during CO2 injections, and direct comparison when parameters are varied in a controlled manner. The software development and experiments reported has been conducted in collaboration with PhD candidate Tore L. Føyen. The CO2 was injected in an unsteady-state approach, where the pores were initially fully saturated with fluid (brine and surfactants and/or nanoparticles) before the CO2 was injected at constant rate (1 μl/min or 4 μl/min). The microscope continuously captured images of the pore scale displacement during injection, and the images were analyzed by the developed software. The number of bubbles was obtained from each image and plotted as a function of the pore volumes CO2 injected. In addition density plots were used to illustrate the location of the bubbles and visualize the channels and foam generation path. Results from the CO2 foam experiments show that surfactant and nanoparticles generated a strong foam compared to baseline: bubbles numbers recorded when using foaming agents (surfactants and nanoparticles) increased significantly relative to the baseline (no foaming agent present, only brine), indicating a high CO2 mobility reduction. The number of bubbles increase with increasing surfactant concentration (0.05 wt% to 0.5 wt%), and the foam was found “shear thickening” for increasing rate. The comparison made between surfactant- and nanoparticle-stabilized foams at pore-scale indicates that surfactants have a higher ability to generate foams, whereas nanoparticles display a more significant potential to stabilize foams. The synergy between nanoparticles and surfactant demonstrated that foam generation and stability are independent of nanoparticles concentration in the absence of oil for the concentrations used in this thesis. The reported laboratory pore scale observations of calcite precipitation and dissolution were conducted in collaboration with PhD candidates Malin Haugen and Tore L. Føyen. A procedure for using of Sporosarcina pasteurii bacteria was developed as part of this thesis, and the calcite successfully precipitated in the pore space and calcite dissolution was studied at room temperature using 2 wt% hydrochloric acid. The procedure must be further developed to achieve a uniform distribution of calcite in the pore space to allow for controlled experiments related to the dissolution of calcite during CO2 storage in carbonate.Masteroppgave i petroleumsteknologiPTEK399MAMN-PET

Discharge flow of a granular media from a silo: effect of the packing fraction and of the hopper angle

International audienceSilos are widely used in the industry. While empirical predictions of the flow rate, based on scaling laws, have existed for more than a century (Hagen 1852, translated in [1]-Beverloo et al. [2]), recent advances have be made on the understanding of the control parameters of the flow. In particular, using continuous modeling together with a mu(I) granular rheology seem to be successful in predicting the flow rate for large numbers of beads at the aperture (Staron et al.[3], [4]). Moreover Janda et al.[5] have shown that the packing fraction at the outlet plays an important role when the number of beads at the apeture decreases. Based on these considerations, we have studied experimentally the discharge flow of a granular media from a rectangular silo. We have varied two main parameters: the angle of the hopper, and the bulk packing fraction of the granular material by using bidisperse mixtures. We propose a simple physical model to describe the effect of these parameters, considering a continuous granular media with a dilatancy law at the outlet. This model predicts well the dependance of the flow rate on the hopper angle as well as the dependance of the flow rate on the fine mass fraction of a bidisperse mixture

Exploring Mesoscale Structures using Chord Occultations of Saturn\u27s Rings

The Cassini spacecraft orbited Saturn for over 13 years and collected stellar occultations using an Ultraviolet Imaging Spectrograph (UVIS). Chord occultations were analyzed using autocorrelations at minimum ring plane radius to visualize the structure and correlation in the azimuthal direction. These particle tracking occultations cut a chord across the rings in the path of the star. By taking the autocorrelation of these chord occultations, 8 out of the 66 showed clumping within the first 3.0 km in azimuth, representing signs of a structure. Six of those occultations could be moonlets or propellers as their minimum ring plane radii are in the Propeller Belt region. The Fast Fourier Transform Power Spectrum of the autocorrelation was also taken, and 6 of the 8 had high peak power outputs at certain wavelengths. It is also observed that five of the occultations may contain self-gravity wakes

Pore-level Ostwald ripening of CO2 foams at reservoir pressure

The success of foam to reduce CO2 mobility in CO2 enhanced oil recovery and CO2 storage operations depends on foam stability in the reservoir. Foams are thermodynamically unstable, and factors such as surfactant adsorption, the presence of oil, and harsh reservoir conditions can cause the foam to destabilize. Pore-level foam coarsening and anti-coarsening mechanisms are not, however, fully understood and characterized at reservoir pressure. Using lab-on-a-chip technology, we probe dense (liquid) phase CO2 foam stability and the impact of Ostwald ripening at 100 bars using dynamic pore-scale observations. Three types of pore-level coarsening were observed: (1) large bubbles growing at the expense of small bubbles, at high aqueous phase saturations, unrestricted by the grains; (2) large bubbles growing at the expense of small bubbles, at low aqueous phase saturation, restricted by the grains; and (3) equilibration of plateau borders. Type 3 coarsening led to stable CO2 foam states eight times faster than type 2 and ten times faster than type 1. Anti-coarsening where CO2 diffused from a large bubble to a small bubble was also observed. The experimental results also compared stabilities of CO2 foam generated with hybrid nanoparticle–surfactant solution to CO2 foam stabilized by only surfactant or nanoparticles. Doubling the surfactant concentration from 2500 to 5000 ppm and adding 1500 ppm of nanoparticles to the 2500 ppm surfactant-based solution resulted in stronger foam, which resisted Ostwald ripening. Dynamic pore-scale observations of dense phase CO2 foam revealed gas diffusion from small, high-curvature bubbles to large, low-curvature bubbles and that the overall curvature of the bubbles decreased with time. Overall, this study provides in situ quantification of CO2 foam strength and stability dynamics at high-pressure conditions.publishedVersio

Regulating cars' safety standards in controlling fatal accidents: a comparative study / Ahmad Benyamine Noor Rahimin, Ahmad Mukmin Aimi Azmi and Mohd Shahril Madisa.

Technological advances have revolutionized the safety standards of cars in this modern era. It has become the integral part of the car itself and plays a major role in saving thousands if not millions of lives each year. This has brought about the creation of institutions such the Malaysian Institute of Road Safety Research (MIROS) and the introduction of the Malaysian Vehicle Assessment Programme (MyVAP). However, there is still a lack of rules and enforcement of safety standards in Malaysia. This paper was done to critically analyse the current situation in Malaysia regarding the issue of inadequate Acts, rules and regulations governing safety standard of passenger cars. This research represents the initial effort to provide comparisons and perhaps justifications towards an improvement of overall safety standards of cars in Malaysia by improving the already available safety standards or by enacting a new legislation in the future. The important comparative subjects in this research are the Third Australian Design Rule (ADR) governed under the Motor Vehicles Standards Act 1989 in Australia and also the Federal Motor Vehicle Safety Standards (FMVSS) and Regulations which is legislated by the National Highway Traffic Safety Administration in the United States of America (USA)

DarSIA: An Open-Source Python Toolbox for Two-Scale Image Processing of Dynamics in Porous Media

Understanding porous media flow is inherently a multi-scale challenge, where at the core lies the aggregation of pore-level processes to a continuum, or Darcy-scale, description. This challenge is directly mirrored in image processing, where pore-scale grains and interfaces may be clearly visible in the image, yet continuous Darcy-scale parameters may be what are desirable to quantify. Classical image processing is poorly adapted to this setting, as most techniques do not explicitly utilize the fact that the image contains explicit physical processes. Here, we extend classical image processing concepts to what we define as “physical images” of porous materials and processes within them. This is realized through the development of a new open-source image analysis toolbox specifically adapted to time-series of images of porous materials.publishedVersio

The effect of caffeine ingestion in prevention of post-operative ileus after caesarean section: a randomized controlled trial

Background: Caesarian section (CS) has become more prevalent than the vaginal delivery in Egypt. Many complications could occur after an abdominal surgery. One of the commonest but yet serious complications is the postoperative ileus that can possibly be prevented by caffeine ingestion. The aim of the study is to assess the value of caffeine ingestion in promoting intestinal motility and prevention of postoperative ileus after CS.Methods: This is a randomized controlled trial that was conducted on 560 cases who were recruited from emergency unit and inpatient wards in Ain Shams University maternity hospital. The patients were divided into two groups where the intervention group received caffeinated coffee while the other group received decaffeinated coffee.Results: There was statistically significant difference between the two groups regarding the bowel function after CS (p <0.05). The intervention group had improved intestinal functions after the CS. Patients from the intervention group had audible intestinal sound sooner than the control group. In addition, they passed flatus and were able to tolerate food in less time.Conclusions: Consuming caffeinated coffee after CS contributes significantly to faster restoration of intestinal function. Coffee is a popular drink and can be used to decrease the incidence of postoperative ileus-related complications

Laparoscopic diagnostic peritoneal lavage (L-DPL): A method for evaluation of penetrating abdominal stab wounds

BACKGROUND: The management of penetrating abdominal stab wounds has been the subject of continued reappraisal and controversy. In the present study a novel method which combines the use of diagnostic laparoscopy and DPL, termed laparoscopic diagnostic peritoneal lavage (L-DPL) is described METHOD: Five trauma patients with penetrating injuries to the lower chest or abdomen were included. Standard videoscopic equipment is utilized for the laparoscopic trauma evaluation of the injured patient. When no significant injury is detected, the videoscope is withdrawn and 1000 mL of normal saline is infused through the abdominal trochar into the peritoneal cavity, and the effluent fluid studied for RBCs, WBC, amylase debry, bile as it is uced in regular diagnostic peritoneal lavage RESULTS: Laparoscopic peritoneal lavage (L-DPL) was then performed and proved to be negative in all 5 patients. RBC lavage counts above 100,000/mcrl were not considered as a positive lavage result, because the bleeding source was directly observed and controlled laparoscopically. All patients recovered uneventfully and were released within 3 days. This procedure combines the visual advantages of laparoscopy together with the sensitivity and specificty of DPL for the diagnosis of significant penetrating intra-abdominal injury, when the diagnostic strategy of selective consevatism for abdominal stab wounds is adopted. CONCLUSION: A method of laparoscopic diagnostic peritoneal lavage (L-DPL) in hemodynamically stable patients with penetrating lower thoracic or abdominal stab wounds is described. The method is especially applicable for trauma surgeons with only basic experience in laparoscopic technique. This procedure is used to obtain conclusive evidence of significant intra-abdominal injury, confirm peritoneal penetration, control intra-abdominal bleeding, and repair lacerations to the diaphragm and abdominal wall. The combination of laparoscopy and DPL afforded by the L-DPL method adds to the sensitivity and specificity of DPL, and avoids under or over sesitivty, that have limited the use of DPL in the hemodynamically stable trauma patients with suspicious or proven peritoneal penetration

Engineering meter-scale porous media flow experiments for quantitative studies of geological carbon sequestration

This technical note describes the FluidFlower concept, a new laboratory infrastructure for geological carbon storage research. The highly controlled and adjustable system produces a strikingly visual physical ground truth of studied processes for model validation, comparison, and forecasting, including detailed physical studies of the behavior and storage mechanisms of carbon dioxide and its derivative forms in relevant geological settings for subsurface carbon storage. The design, instrumentation, structural aspects and methodology are described. Furthermore, we share engineering insights on construction, operation, fluid considerations, and fluid resetting in the porous media. The new infrastructure enables researchers to study variability between repeated CO2 injections, making the FluidFlower concept a suitable tool for sensitivity studies on a range of determining carbon storage parameters in varying geological formations

New Insights Into the Regulation of γδ T Cells by BTN3A and Other BTN/BTNL in Tumor Immunity

Recent findings in the immunology field have pointed out the emergent role of butyrophilins/butyrophilin-like molecules (BTN/BTNL in human, Btn/Btnl in mouse) in the modulation of γδ T cells. As long as the field develops exponentially, new relationships between certain γδ T cell subsets, on one hand, and their BTN/BTNL counterparts mainly present on epithelial and tumor cells, on the other, are described in the scientific literature. Btnl1/Btnl6 in mice and BTNL3/BTNL8 in humans regulate the homing and maturation of Vγ7+ and Vγ4+ T cells to the gut epithelium. Similarly, Skint-1 has shown to shape the dendritic epidermal T cells repertoire and their activation levels in mice. We and others have identified BTN3A proteins are the key mediators of phosphoantigen sensing by human Vγ9Vδ2 T cells. Here, we first synthesize the modulation of specific γδ T cell subsets by related BTN/BTNL molecules, in human and mice. Then, we focus on the role of BTN3A in the activation of Vγ9Vδ2 T cells, and we highlight the recent advances in the understanding of the expression, regulation, and function of BTN3A in tumor immunity. Hence, recent studies demonstrated that several signals induced by cancer cells or their microenvironment can regulate the expression of BTN3A. Moreover, antibodies targeting BTN3A have shown in vitro and in vivo efficacy in human tumors such as acute myeloid leukemia or pancreatic cancer. We thus finally discuss how these findings could help develop novel γδ T cell-based immunotherapeutical approaches