A nuclear magnetic resonance investigation of brine inclusions in Antarctic and artificial sea ice : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Physics at Massey University

Additional images with the print copy held in the library.The aim of this thesis is to use Nuclear Magnetic Resonance (NMR) techniques to examine the brine pockets in sea ice. Both the movement of the brine pockets within the ice, and the movement of the brine within the brine pockets is examined. The experiments are carried out using Earth's field NMR on sea ice in situ in Antarctica, and high field NMR equipment on artificially grown sea ice in New Zealand. The field work involved probe design, construction, and use. Investigations were carried out on brine content, and brine diffusion rates. The laboratory work involved growing realistic artificial sea ice, designing and constructing a temperature control system for the high field NMR machine, and carrying out experiments on the artificial sea ice samples. The brine pockets' morphology and distribution was examined. The brine and brine pocket movements over time, with a controlled temperature gradient, were also investigated. The results from the field work clearly showed multiple diffusion rates in sea ice, both faster and slower than that of water. The lab work showed that realistic sea ice had been grown, and that there was a migration of brine pockets in the direction of the temperature gradient

Compositional controls on melting and dissolving a salt into a ternary melt

We explore theoretically the controls on dissolution of salt A, in an undersaturated brine of salts A and B. We show that, as the concentration of B increases, the dissolution rate of A decreases, for brine of given temperature. We also show that there is a sharper decrease in dissolution rate with increasing concentration, for concentrations of B above a critical value, where B limits the equilibrium concentration. We explore the implications of the predictions for dissolution of KCl or NaCl, by a mixed brine of NaCl and KCl, a common reaction that may arise in dissolution of evaporites. We predict that, with mixed-composition brine, KCl crystals dissolve more rapidly than NaCl crystals, unless the (far-field) brine is nearly saturated in KCl. We also predict that the dissolution rate of these salts is largely independent of fluid temperature and is controlled by compositional diffusion

Selenium Biotransformations in an Engineered Aquatic Ecosystem for Bioremediation of Agricultural Wastewater via Brine Shrimp Production

An engineered aquatic ecosystem was specifically designed to bioremediate selenium (Se), occurring as oxidized inorganic selenate from hypersalinized agricultural drainage water while producing brine shrimp enriched in organic Se and omega-3 and omega-6 fatty acids for use in value added nutraceutical food supplements. Selenate was successfully bioremediated by microalgal metabolism into organic Se (seleno-amino acids) and partially removed via gaseous volatile Se formation. Furthermore, filterfeeding brine shrimp that accumulated this organic Se were removed by net harvest. Thriving in this engineered pond system, brine shrimp (Artemia franciscana Kellogg) and brine fly (Ephydridae sp.) have major ecological relevance as important food sources for large populations of waterfowl, breeding, and migratory shore birds. This aquatic ecosystem was an ideal model for study because it mimics trophic interactions in a Se polluted wetland. Inorganic selenate in drainage water was metabolized differently in microalgae, bacteria, and diatoms where it was accumulated and reduced into various inorganic forms (selenite, selenide, or elemental Se) or partially incorporated into organic Se mainly as selenomethionine. Brine shrimp and brine fly larva then bioaccumulated Se from ingesting aquatic microorganisms and further metabolized Se predominately into organic Se forms. Importantly, adult brine flies, which hatched from aquatic larva, bioaccumulated the highest Se concentrations of all organisms tested

Collaborative development of EFL in Vietnam through open source software

The University of Aizu, in collaboration with the University of Waikato, has been investigating the use of open source, server-based software for the enhancement of English language instruction in Vietnam. In this paper, we describe recent educational, technical, and English language reforms in Vietnam which have facilitated a new approach to the teaching and learning not only of English, but also Computer Science concepts. The paper concludes with a brief discussion of the efficacy of using open source tools and highly structured instructional approaches for English language teaching in developing nations

Fate and impact of organics in an immersed membrane bioreactor applied to brine denitrification and ion exchange regeneration

The application of membrane bioreactors (MBRs) to brine denitrification for ion exchange regeneration has been studied. The developed culture was capable of complete brine denitrification at 50 gNaCl.l−1. Denitrification reduced to c.60% and c.70% when salinity was respectively increased to 75 and 100 g.l−1, presumed to be due to reduced growth rate and the low imposed solids retention time (10 days). Polysaccharide secretion was not induced by stressed cells following salt shocking, implying that cell lysis did not occur. Fouling propensity, monitored by critical flux, was steady at 12–15 l.m−2.h−1 during salinity shocking and after brine recirculation, indicating that the system was stable following perturbation. Low molecular weight polysaccharide physically adsorbed onto the nitrate selective anion exchange resin during regeneration reducing exchange capacity by c.6.5% when operating up to complete exhaustion. However, based on a breakthrough threshold of 10 mgNO3−-N.l−1 the exchange capacity was comparative to that determined when using freshly produced brine for regeneration. It was concluded that a denitrification MBR was an appropriate technology for IEX spent brine reco

Long-time evolution of sequestered CO2_2 in porous media

CO$_2$ sequestration in subsurface reservoirs is important for limiting atmospheric CO$_2$ concentrations. However, a complete physical picture able to predict the structure developing within the porous medium is lacking. We investigate theoretically reactive transport in the long-time evolution of carbon in the brine-rock environment. As CO$_2$ is injected into a brine-rock environment, a carbonate-rich region is created amid brine. Within the carbonate-rich region minerals dissolve and migrate from regions of high concentration to low concentration, along with other dissolved carbonate species. This causes mineral precipitation at the interface between the two regions. We argue that precipitation in a small layer reduces diffusivity, and eventually causes mechanical trapping of the CO$_2$. Consequently, only a small fraction of the CO$_2$ is converted to solid mineral; the remainder either dissolves in water or is trapped in its original form. We also study the case of a pure CO$_2$ bubble surrounded by brine and suggest a mechanism that may lead to a carbonate-encrusted bubble due to structural diffusion

MOBILITY REDUCTION OF CO2 USING CO2 SOLUBLE SURFACTANTS

Addition of slightly CO2-soluble, brine-soluble, surfactants to high pressure CO2 for EOR may facilitate in-situ generation of CO2-in-brine foams for mobility control. These non-ionic surfactants have been demonstrated to dissolve in CO2 to concentrations of 0.1wt% at reservoir conditions and stabilize CO2-in-brine foams in a high pressure windowed cell. One such surfactant is Huntsman SURFONIC® N, a branched nonylphenol ethoxylates with averages of 12 (N-120) or 15(N-150) ethylene oxide repeat units in the hydrophile. SURFONIC® N-120 was selected for mobility reduction studies involving flow of CO2 into brine-saturated porous media. Transient mobility measurements were conducted using a water-wet Berea core (104mD), water-wet Bentheimer sandstone core (~1500mD), and several SACROC carbonate cores (3.6 and 8.9mD). The CO2 was injected into brine-saturated cores at superficial velocity of 10 ft/day, and surfactant was either not used (control), dissolved only in brine at 0.07wt%, dissolved only in CO2 at ~0.07wt%, or dissolved in brine and CO2 at 0.07wt%. In general, in-situ foam generation in relatively high permeability sandstone was evidenced during the first few pore volumes of CO2 injected by pressure drops that were 2-3 times greater than control tests regardless of what phase CO2 was in. Mobility reduction was more modest (20–50% increases in pressure drop) in lower permeability SACROC cores (3.6 and 8.9mD) when surfactant was dissolved in CO2. With surfactant dissolved in brine, pressure drops increased by a factor of 2–3 when CO2 was injected into an 8.9mD core. High pressure CT imaging of in-situ foam generation was conducted by injecting high pressure CO2 into 5wt% KI-brine-saturated Berea sandstone (3-8mD). Tests with no surfactant (control), or with surfactant dissolved either brine or CO2 at ~0.07wt%. At lower superficial velocities (0.47ft/day), in-siti foam generation was obvious only when surfactant was dissolved in brine. Higher flow rates (4.7ft/day) preferential flow of CO2 through high permeability layers and viscous fingering within layers that occurred during control tests was suppressed by addition of surfactant to either CO2 or brine. The most distinct CO2 foam front occurred with surfactant dissolved in brine

Comparing carbon sequestration in an oil reservoir to sequestration in a brine formation-field study

Geologic sequestration of CO2 in an oil reservoir is generally considered a different class than sequestration in formations which contain only brine. In this paper, the significance and validity of this conceptualization is examined by comparing the performance of CO2 injected into a depleted oil reservoir with the performance of similar injection into non-oil bearing sandstones using a field test at Cranfield Field, Mississippi as a case study. The differences considered are: (1)Residual oil in the reservoir slightly reduces the CO2 breakthrough time and rate of pressure build up as compared to a reservoir containing only brine, because under miscible conditions, more CO2 dissolves into oil than in to brine. (2)Dense wells provide improved assessment of the oil reservoir quality leading to improved prediction as well as verification of CO2 movement in this reservoir as compared to the sparsely characterized brine leg. The value of this information exceeds the risk of leakage. Assessment of the difference made by the presence of residual oil requires a good understanding reservoir properties to predict oil and gas distribution. Stratal slicing, attribute analysis and petrographic analyses are used to define the reservoir architecture. Real-time pressure response at a dedicated observation well and episodic pressure mapping has been conducted in the reservoir under flood since mid-2008; comparison measurements are planned for 2009 in down-dip environments lacking hydrocarbons. Model results using GEM compositional simulator compare well in general to measured reservoir response under CO2 flood; imperfections in model match of flood history document uncertainties Time laps RST logging is underway to validate fluid composition and migration models. Monitoring assessing the performance of the wells during the injection of CO2 suggests that the value of wells to provide field data for characterization exceeds the risk of leakage.Bureau of Economic Geolog