Acidic Brine Research Articles

Salinity mapping model and brine chemistry of Mishrif reservoir in Basrah oilfields, Southern Iraq

Cation and anion concentrations and boron isotopic ratio of brines in the Mishrif Formation (U. Campanian-Tuoronian) from North Rumaila, South Rumaila, Majnoon, Zubair, and West Qurna oilfields southern Iraq were investigated. The aims of this study are to define the type, origin of the oilfield waters, and its flow model in the subsurface oil traps. Mishrif brines are characterized by having higher concentrations of sodium (50,500–84,200 ppm), chlorine (102,100–161,500 ppm), and boron (21.9–31.1 ppm) with lower sulfate contents (187–1350 ppm) relative to the modern seawater. Samples have slightly depleted in δ 11B (35.4‰) relative to seawater fall near the seawater intrusion of the diagram Cl/Br Vs δ 11B and occupied the field of evaporated seawater on the diagrams of Cl vs B and 1/Br vs δ 11B. The brine of Na-chloride type is characteristics of the Mishrif reservoir in all oilfields except WQ which defined by facies of Na-Ca-chloride type. A weak acidic brine of a salinity six-time greater than seawater plays a role in generating the formation pressure and controlling the fluid flow. The reservoir rock-fluid interactions were interpreted using boron isotopes which eventually reveal an ongoing dilution process by the present seawater intrusion and injection water used for the secondary production under conditions of high-temperature digenetic reactions. The 11B in the oilfield water is resulted from uptake of the tetrahedral borate after precipitation of calcium carbonate, while 10B is sourced from the thermal maturation of organic matters.

A thiotrophic microbial community in an acidic brine lake in Northern Chile.

The endorheic basins of the Northern Chilean Altiplano contain saline lakes and salt flats. Two of the salt flats, Gorbea and Ignorado, have high acidic brines. The causes of the local acidity have been attributed to the occurrence of volcanic native sulfur, the release of sulfuric acid by oxidation, and the low buffering capacity of the rocks in the area. Understanding the microbial community composition and available energy in this pristine ecosystem is relevant in determining the origin of the acidity and in supporting the rationale of conservation policies. Besides, a comparison between similar systems in Australia highlights key microbial components and specific ones associated with geological settings and environmental conditions. Sediment and water samples from the Salar de Gorbea were collected, physicochemical parameters measured and geochemical and molecular biological analyses performed. A low diversity microbial community was observed in brines and sediments dominated by Actinobacteria, Algae, Firmicutes and Proteobacteria. Most of the constituent genera have been reported to be either sulfur oxidizing microorganisms or ones having the potential for sulfur oxidation given available genomic data and information drawn from the literature on cultured relatives. In addition, a link between sulfur oxidation and carbon fixation was observed. In contrast, to acid mine drainage communities, Gorbea microbial diversity is mainly supported by chemolithoheterotrophic, facultative chemolithoautotrophic and oligotrophic sulfur oxidizing populations indicating that microbial activity should also be considered as a causative agent of local acidity.

Uranium transport in acidic brines under reducing conditions

The behavior of uranium in environments, ranging from those of natural systems responsible for the formation of uranium deposits to those of nuclear reactors providing 11% of the world’s electricity, is governed by processes involving high-temperature aqueous solutions. It has been well documented that uranium is mobile in aqueous solutions in its oxidized, U6+ state, whereas in its reduced, U4+ state, uranium has been assumed to be immobile. Here, we present experimental evidence from high temperature (>100 °C) acidic brines that invalidates this assumption. Our experiments have identified a new uranium chloride species (UCl4°) that is more stable under reducing than oxidized conditions. These results indicate that uranium is mobile under reducing conditions and necessitate a re-evaluation of the mobility of uranium, particularly in ore deposit models involving this metal. Regardless of the scenario considered, reducing conditions can no longer be considered a guarantee of uranium immobility.

CO2 charged brines changed rock strength and stiffness at Crystal Geyser, Utah: Implications for leaking subsurface CO2 storage reservoirs

CO2 geological storage in saline aquifers results in acidification of resident brine. Chemical reactions between acidified brine and rock minerals lead to dissolution and precipitation of minerals at various time scales. Mineral dissolution and precipitation are often neglected in assessing the mechanical integrity of target storage formations, yet, changes in rock strength and deformational behavior can impact trapping mechanisms. This study shows the impact of exposure to CO2-charged brine on shear strength and stiffness of various outcrop rocks evaluated through triaxial testing. The tested rocks were exposed to CO2-charged brine over geological time at a naturally occurring near-surface seepage along the Little Grand Wash Fault and Salt Wash Grabens, which include the Crystal Geyser site near the town of Green River, Utah. Prior work suggests that this site provides a near-surface structural analog for possible fault-controlled CO2 leakage over time scales that exceed expected injection time scales (10–100 years). Results show mechanical alteration in various aspects: (1) CO2-charged brine alteration at near-surface conditions results in mineral dissolution/precipitation and reduction of shear strength and brittleness of Entrada sandstone and Summerville siltstone samples, and (2) carbonate precipitation in fractured Mancos shale leads to matrix stiffening and fracture mineralization resulting in overall stiffer and likely tighter shale. Additional discrete element simulations coupled with a bonded-particle-model confirm the role of cement bond size alteration as one of the main controls for rock chemo-mechanical alteration in sandstones. The chemo-mechanical alteration path that mimics cement dissolution (under stressed subsurface conditions) results in vertical compaction and lateral stress relaxation. Overall, results show that rock exposure to CO2-charged brine can impart distinct petrophysical and geomechanical changes according to rock lithology and location with respect to major CO2 conduits. While mineral dissolution in the storage rock may result in undesired reservoir strains and changes of stresses, mineral precipitation downstream from a leakage path can help seal potentially induced fractures.

Microbial communities and their predicted metabolic functions in a desiccating acid salt lake.

The waters of Lake Magic in Western Australia are among the most geochemically extreme on Earth. This ephemeral saline lake is characterized by pH as low as 1.6 salinity as high as 32% total dissolved solids, and unusually complex geochemistry, including extremely high concentrations of aluminum, silica, and iron. We examined the microbial composition and putative function in this extreme acid brine environment by analyzing lake water, groundwater, and sediment samples collected during the austral summer near peak evapoconcentration. Our results reveal that the lake water metagenome, surprisingly, was comprised of mostly eukaryote sequences, particularly fungi and to a lesser extent, green algae. Groundwater and sediment samples were dominated by acidophilic Firmicutes, with eukaryotic community members only detected at low abundances. The lake water bacterial community was less diverse than that in groundwater and sediment, and was overwhelmingly represented by a single OTU affiliated with Salinisphaera. Pathways associated with halotolerance were found in the metagenomes, as were genes associated with biosynthesis of protective carotenoids. During periods of complete desiccation of the lake, we hypothesize that dormancy and entrapment in fluid inclusions in halite crystals may increase long-term survival, leading to the resilience of complex eukaryotes in this extreme environment.

Experimental evaporation of hyperacid brines: Effects on chemical composition and chlorine isotope fractionation

Hyperacid brines from active volcanic lakes are some of the chemically most complex aqueous solutions on Earth. Their compositions provide valuable insights into processes of elemental transfer from a magma body to the surface and interactions with solid rocks and the atmosphere. This paper describes changes in chemical and δ37Cl signatures observed in a 1750 h isothermal evaporation experiment on hyperacid (pH 0.1) sulphate-chloride brine water from the active lake of Kawah Ijen volcano (Indonesia). Although gypsum was the only evaporite mineral identified in the evolving brine, decreasing Si concentrations may ultimately result in amorphous silica precipitation. Geochemical simulations predict the additional formation of elemental sulphur at lower water activities (aH2O ≤ 0.65) that were not reached in the experiment. Absence of other sulphates and halides despite the high load of dissolved elements (initial TDS ca. 100 g/kg) can be attributed to increased solubility of metals, promoted by extensive formation of complexes between the variety of cations and the major anions (HSO4−, Cl−, F−) present. Chlorine deviations from a conservative behaviour point to losses of gaseous hydrogen chloride (HCl(g)) and consequently an increase in Br/Cl ratios.Chlorine isotope fractionation that accompanied the escape of HCl(g) showed a marked change in sign and magnitude in the course of progressive evaporation of the brine. The calculated factor of fractionation between HCl(g) and dissolved Cl for the initial interval (before 500 h) is positive (1000lnαHCl(g)-Cldiss.=+1.55±0.49‰to+3.37±1.11‰), indicating that, at first, the escaping HCl(g) was isotopically heavier than the dissolved Cl remaining in the brine. Conversely, fractionation shifted to the opposite direction in the subsequent interval (1000lnαHCl(g)-Cldiss.=5.67±0.17‰to-5.64±0.08‰), in agreement with values reported in literature. It is proposed that Cl isotopic fractionation in highly acidic brines is controlled by the distribution of dissolved chlorine species, which changes from Cl− to HClo dominance with the progressive pH decline.The Kawah Ijen lake acquired its extreme composition through influx of sulphur and halogen-rich magmatic gas components and extensive rock dissolution. If hyperacid brines with comparable chemical composition existed on Mars, evaporation processes up to the extent reported here (aH2O=0.85), were likely accompanied by losses of gaseous HCl. The resulting changes in Cl isotope compositions, Br/Cl, S/Cl and other ratios in the residual brine might be potentially recorded in assemblages of halogen-bearing secondary evaporation minerals. Also, volcanic-hydrothermal brines as these would extend the stability of liquid water on the Martian surface down to a temperature of −90 °C.

Elevated olivine weathering rates and sulfate formation at cryogenic temperatures on Mars

Large Hesperian-aged (~3.7 Ga) layered deposits of sulfate-rich sediments in the equatorial regions of Mars have been suggested to be evidence for ephemeral playa environments. But early Mars may not have been warm enough to support conditions similar to what occurs in arid environments on Earth. Instead cold, icy environments may have been widespread. Under cryogenic conditions sulfate formation might be blocked, since kinetics of silicate weathering are typically strongly retarded at temperatures well below 0 °C. But cryo-concentration of acidic solutions may counteract the slow kinetics. Here we show that cryo-concentrated acidic brines rapidly chemically weather olivine minerals and form sulfate minerals at temperatures as low as −60 °C. These experimental results demonstrate the viability of sulfate formation under current Martian conditions, even in the polar regions. An ice-hosted sedimentation and weathering model may provide a compelling description of the origin of large Hesperian-aged layered sulfate deposits on Mars.

Carbon geosequestration in limestone: Pore-scale dissolution and geomechanical weakening

Carbon dioxide geosequestration in deep saline aquifers or oil and gas reservoirs is a key technology to mitigate anthropogenic greenhouse gas emissions. Porous carbonate rock is a potential host rock for CO2 storage; however, carbonate rock chemically reacts when exposed to the acidic brine (which is created by the addition of CO2, CO2-saturated brine). These reactive transport processes are only poorly understood, particularly at the micrometre scale, and importantly how this affects the geomechanical rock properties. We thus imaged a heterogeneous oolitic limestone (Savonnières limestone) core before and after flooding with brine and CO2-saturated brine at representative reservoir conditions (323K temperature, 10MPa pore pressure, 5MPa effective stress) in-situ at high resolutions (3.43μm and 1.25μm voxel size) in 3D with an x-ray micro-computed tomograph; and measured the changes in nano-scale mechanical properties induced by acid exposure. Indeed the carbonate rock matrix partially dissolved, and absolute and effective porosity and permeability significantly increased. This dissolution was confined to the original flow channels and inlet points. Importantly, the rock matrix weakened significantly (- 47% in indentation modulus) due to the acid exposure.

Microbubbles Loaded with Nickel Nanoparticles: A Perspective for Carbon Sequestration.

This work reports a microfluidic study investigating the feasibility of accelerating gaseous carbon dioxide (CO2) dissolution into a continuous aqueous phase with the use of metallic nickel (Ni) nanoparticles (NPs) under conditions specific to carbon sequestration in saline aquifers. The dissolution of CO2 bubbles at different pH levels and salinities was studied to understand the effects that the intrinsic characteristics of brine in real reservoir conditions would have on CO2 solubility. Results showed that an increased shrinkage of CO2 bubbles occurred with higher basicity, while an increased expansion of CO2 bubbles was observed with a proportional increase in salinity. To achieve acceleration of CO2 dissolution in acidic brine containing high salinity content, the catalytic effect of Ni NPs was investigated by monitoring change in CO2 bubble size at various Ni NPs concentrations. The optimal concentration for the Ni NPs suspension was determined to be 30 mg L-1; increasing the concentration up to 30 mg L-1 showed a significant increase in the dissolution of CO2 bubbles, but increasing from 30 to 50 mg L-1 displayed a decrease in catalytic potential, due to the decreased translational diffusion coefficient that occurs at higher concentrations. The optimal additive concentration of Ni NPs was tested with variations of solution at acidic and basic conditions and different levels of salinity to reveal how effectively the Ni NPs behave under real reservoir conditions. At the acidic level, Ni NPs proved to be more effective in catalyzing CO2 dissolution and can sufficiently alleviate the negative impact of salinity in brine.

Incorporating Nanoscale Effects into a Continuum-Scale Reactive Transport Model for CO2-Deteriorated Cement.

Wellbore cement deterioration is critical for wellbore integrity and the safety of CO2 storage in geologic formations. Our previous experimental work highlighted the importance of the portlandite (CH)-depleted zone and the surface dissolution zone in the CO2-attacked cement. In this study, we simulated numerically the evolution of the CH-depleted zone and the dissolution of the cement surfaces utilizing a reduced-dimension (1D) reactive transport model. The approach shows that three nanoscale effects are important and had to be incorporated in a continuum-scale model to capture experimental observations: First, it was necessary to account for the fact that secondary CaCO3 precipitation does not fill the pore space completely, with the result that acidic brine continues to diffuse through the carbonated zone to form a CH-depleted zone. Second, secondary precipitation in brine begins via nucleation kinetics, and this could not be described with previous models using growth kinetics alone. Third, our results suggest that the CaCO3 precipitates in the confined pore space are more soluble than those formed in brine. This study provides a new platform for a reduced dimension model for CO2 attack on cement that captures the important nanoscale mechanisms influencing macroscale phenomena in subsurface environments.

Hydrological evolution and chemical structure of a hyper-acidic spring-lake system on Whakaari/White Island, NZ

White Island has a long and varied history of acid spring discharge and shallow ephemeral lake formation on its main crater floor. In the 12months prior to the onset of the 1976–2000 eruptive episode, mass discharge from the spring system increased ca. 10-fold, pointing to a strong coupling of the hydrothermal environment to the evolving magmatic system. Between 1976 and 1978, the formation of numerous eruption vents to 200m depth in the Western Sub-crater abruptly changed the hydraulic gradients in the volcano, resulting in the reversal of groundwater flow in the massif towards the newly-formed crater(s). This affected not only the style of volcanic activity (leading to phreatic-phreatomagmatic-magmatic eruption cycles), but also led to the demise of the spring system, with discharge from the main crater declining by a factor>100 by 1979. Eruptive activity ended shortly after a moderate Strombolian eruption in mid-2000, after which ephemeral lakes started to form in the eruption crater complex.Between 2003 and 2015 there were three complete lake filling and evaporative cycles, reflecting varying heat flow through the conduit system beneath the lake. Over these cycles, lake water concentrations of Cl and SO4 varied between ca. 35–150 and 5–45g/L respectively, with pH values temporally ranging from +1.5 to −1. Springs appeared on the Main Crater floor in 2004, and their discharges varied with lake level, pointing to the lake level being a primary control over the piezometric surface in the crater area. Springs closest to the crater complex show direct evidence of crater lake water infiltration into the crater floor aquifer, whereas distal spring discharges show compositional variations reflecting vertical displacement of the interface between shallow, dilute condensate and underlying acidic brine fluids.Source components for the spring fluids include magmatic vapour, dissolved andesitic host rocks, seawater and meteoric water. Lake waters, on the other hand, consist predominantly of magmatic vapour, meteoric water and solutes derived from host andesites and their altered derivatives. δ2H and δ18O signatures of the enclosing acid brine fluids, indicate they are predominantly seawater which have been affected by both vapour loss, but also mixing with arc-type vapour.An interesting finding of this study is that crater floor deformation correlates directly to both lake level and volatile emissions, in an apparent poroelastic response to the establishment of a hydrostatic water column in the eruption crater complex, and a net decrease in permeability owing to hydrothermal mineralization in the conduit (predominantly elemental sulfur and sulfate minerals). The hydrostatic pressurization of the vent environment also leads to increased gas pressures and flows through fumarolic channels, and consequent expansion of fumarolic areas on the main crater floor.A period of unrest, which commenced in August 2012 and lasted until October 2013, included the extrusion of a small dome into the eruption crater complex. This activity, and related high heat flow, led once again to evaporation of the lake, and ongoing phreatic eruption activity which has provided interesting insights into the role which elemental sulfur, associated hydrothermal alteration minerals and of course water play in regulating pressures in the magmatic-hydrothermal environment.

A comprehensive assessment of the performance of corrosion resistant alloys in hot acidic brines for application in oil and gas production

ABSTRACTFour stainless steels and alloys (17-4 PH, X4CrNiMo 16-5-1, F6NM and UNS N09935) were evaluated in relation to their application in the oil and gas industry. These materials were tested in solutions exhibiting a range of chloride concentrations, pH values and temperatures of interest for the oil and gas producing environments. The pitting sensitivity was investigated by means of potentiodynamic polarisation measurements, based on the ASTM G61 standard, in conjunction with a morphological study performed by scanning electron and optical microscopy. The resistance to stress corrosion cracking (SCC) was evaluated in compliance with the ASTM G123 standard. Erosion–corrosion was assessed by exposing the materials under electrochemical control to a flux of erodent glass microspheres in a rotating disc electrode device. A ranking of the materials resistance was derived, based on appropriate parameters, devised to effectively and synthetically represent the complex sets of environments of interest for the relevant application. Our results showed, as expected, that UNS N09935 displays the best performance with respect to pitting resistance and susceptibility to SCC as well as a very good resistance to erosion–corrosion. Among the other investigated materials, 17-4 PH showed higher resistance to pitting, X4CrNiMo 16-5-1 and F6NM longer time to SCC failure while 17-4 PH and X4CrNiMo 16-5-1 exhibited superior ability to withstand erosion–corrosion damaging.

Enhancing the Corrosion Inhibition Behaviour of Epoxidized Natural Rubber-Polyaniline Dodecylbenzenesulfonate Blend via the Incorporation of WO3

Electrically-conductive (in the region of 10−3 S.cm−1) epoxidized natural rubber-polyaniline dodecylbenzenesulfonate [ENR-PAni.DBSA] blend was prepared, and the effect of incorporation of WO3 on its corrosion inhibition behaviour for carbon steel was assessed for the first time. It was found that the electrical conductivity of this blend could be enhanced by up to an order of magnitude for WO3 loadings of 20.0–22.5 wt.%. From both total immersion and electrochemical corrosion tests, ENR-PAni.DBSA blends with 20.0–22.5 wt.% of WO3 were found to be the best corrosion inhibitors for carbon steel, in both acid and artificial brine environments. However, a blend containing a higher WO3 content (i.e. 25.0 wt.%) showed a significant poorer corrosion inhibition behaviour for carbon steel due to its more severe phase separation and porosity between the ENR host matrix and WO3.

Laboratory Insights into Water-rock-CO2 Interactions Controlling the Isotopic Composition of CO2 Leaking from Storage Sites

A series of batch laboratory experiments were conducted involving synthetic saline waters, crushed core and CO2 to study the effect of these reactions on potentially leaking CO2. The purpose of these experiments was to study the evolution of carbon isotope values of dissolved inorganic carbon (DIC) after CO2 injection under simulated reservoir conditions. Observed increases in bicarbonate alkalinity can be attributed to the dissolution of calcite in carbonic acid brine. Furthermore, the isotopic analysis results suggest that the equilibrium carbon isotope values of DIC are controlled largely by added CO2 and system temperature, and not by calcite dissolution. The measured isotopic value of the CO2 in the headspace of each reaction cylinder remained unchanged. Hence, leakage detection with carbon isotope tracer methods appears feasible as long as the injected CO2 is isotopically distinct from baseline carbon compounds (preferably > 10 ‰ difference in δ13C).

An experimental study of the solubility and speciation of tantalum in fluoride-bearing aqueous solutions at elevated temperature

The solubility of Ta2O5 (solid) and the speciation of tantalum in HF-bearing aqueous solutions have been determined at temperatures of 100–250°C and vapour-saturated water pressure. Tantalum is transported as the species Ta(OH)50 at low HF concentration and pH ∼1–3. At higher HF concentration, tantalum mobility is controlled by the species TaF3(OH)3− and TaF50; the presence of TaF50 is only evident at ⩽150°C. Equilibrium constants range from −17.4±0.45 to −16.4±0.12 for the formation of Ta(OH)50 from crystalline Ta2O5 and from −8.24±0.64 to −8.55±0.68 for the formation of TaF3(OH)3− at 100 and 250°C, respectively. For TaF50, they were determined to be 0.13 at 100°C and −0.35 at 150°C.In many respects, the behaviour of tantalum in acidic fluoride-bearing solutions is similar to that of niobium. The solubility of Ta2O5 (solid) is not dependent on HF concentration in fluoride-poor fluids, but rises rapidly at higher HF concentration. However, at the conditions of our experiments, namely a pH of ∼2, temperature up to 250°C, and a wide range of HF concentrations, Ta2O5 (solid) solubility is almost invariably lower than that of Nb2O5 (solid). Modelling of Nb and Ta leaching confirmed the preferential mobility of niobium under most conditions expected in natural fluoride-rich hydrothermal systems. This modelling also demonstrated that both niobium and tantalum are rapidly deposited upon removal of fluoride from an acidic brine. As a result of hydrothermal alteration, the Nb/Ta ratios of secondary minerals may increase relative to those of the primary mineral, or remain largely unaffected, depending on the pH of the fluid.

Accessible reactive surface area and abiotic redox reactivity of iron oxyhydroxides in acidic brines

The reactivity of iron oxyhydroxide nanoparticles in low pH and high ionic strength solutions was quantified to assess abiotic contributions to oxidation–reduction chemistry in acidic brine environments, such as mine groundwater seepage, lakes in Western Australia, and acid mine drainage settings, which are of global interest for their environmental impacts and unique geomicrobiology. Factors expected to influence accessible and reactive surface area, including Fe(II) adsorption and aggregate size, were measured as a function of pH and CaCl2 concentration and related to the kinetics of redox reactions in aqueous suspensions of synthetic goethite (α-FeOOH), akaganeite (β-FeOOH), and ferrihydrite (Fe10O14(OH)2) nanoparticles. Aqueous conditions and iron oxyhydroxides were chosen based on characterization of natural iron-rich mine microbial mats located in Soudan Underground Mine State Park, Minnesota, USA. Quinone species were used as redox sensors because they are well-defined probes and are present in natural organic matter. Fe(II) adsorption to the iron oxyhydroxide mineral surfaces from aqueous solution was measurable only at pH values above 4 and either decreased or was not affected by CaCl2 concentration. Concentrations at or above 0.020M CaCl2 in acetate buffer (pH 4.5) induced particle aggregation. Assessment of Fe(II) adsorption and particle aggregation in acidic brine suggested that accessible reactive surface area may be limited in acidic brines. This was supported by observations of decreasing benzoquinone reduction rate by adsorbed Fe(II) at high CaCl2 concentration. In contrast, the hydroquinone oxidation rate increased at high CaCl2 concentrations, which may be due to suppressed adsorption of Fe(II) generated by the reaction. Results suggest that iron geochemical cycling in acidic brine environments will be substantially different than for iron oxyhydroxides in low-saline waters with circumneutral pH. These findings have implications for acidic brine lakes and acid mine drainage locations that contain precipitated iron oxyhydroxides.

An engineering solution for CO2 injection in saline aquifers

In this proposed CO2 injection system, brine is extracted from the target storage aquifer by means of a lateral horizontal completion located near the top of the formation. It should be noted that the brine is not lifted to the surface. An Electrical Submersible Pump (ESP) is used to extract the brine and boost its pressure, before it is mixed with CO2 that is injected down the vertical section of the well. The mixing takes place in the vertical section of the well below the upper lateral. The CO2–brine mix is then injected into the same formation through a lower lateral. A down-hole tool would be used to maximise agitation and contact area between CO2 and brine in the vertical mixing section of the well, which may be tens to hundreds of metres long, depending on the thickness of the formation.The advantages of this method are that there is little overall pressure increase, because CO2 is mixed with brine extracted from the formation, and also the extracted brine is already at high pressure when it is mixed with the CO2, greatly increasing the solubility of CO2 and reducing the volume of brine required. Energy is not expended lifting the brine to surface nor is there any concern about handling large volumes of acidic brine in the surface equipment. In this study, in addition to the concept of the down-hole mixing (DHM) method which is presented, the application of the DHM method in a hypothetical storage site (Lincolnshire—Smith et al., 2012) is also examined. The calculations are performed to identify the optimum rates of water extraction and injection of dissolved CO2 in brine.

Effect of Traditional Canning in Acetic Brine on the Antioxidants and Vitamins inBoletus edulisandSuillus luteusMushrooms

The effect of canning in traditional acetic brine on antioxidants and vitamins in Boletus edulis and Suillus luteus mushrooms was determined. Fresh mushrooms were canned in mild and strong acetic brine (containing 0.7 and 1.5% acetic acid in the final product respectively). Analysis was carried out on fresh and canned (over 12 months of storage) mushrooms; 100 g of fresh mushrooms contained 78.0–203.8 mg of total polyphenols, 18.0–33.7 mg of total flavonoids, 2.9–17.0 mg of l-ascorbic acid, 57.06–61.84 µg of total tocopherols, 139.9–238.9 µg of B1 vitamin, 171.1–418.6 µg of B2 vitamin, 2601–2648 µg of B3 vitamin, and 47.61–75.14 µg of B6 vitamin. Antioxidant activity was 36.9–132.3 mmol TE determined with ABTS, 25.6–27.2 mmol TE with DPPH and 64.4–246.4 mmol Fe2+ by FRAP assay. Canning and subsequent storage resulted in changes in all the parameters analysed: antioxidants −13 to −64%; B-group vitamins −84 to + 38%; antioxidant activity −68 to + 107%. Practical Application Wild edible mushrooms are very popular foodstuffs due to their exceptional taste and texture. Fresh mushrooms are highly perishable and processing techniques that can maintain their nutrition value as well as quality parameters are necessary. In Central Europe canning mushrooms with spices and vegetables with addition of acetic acid brine has traditionally been used for preserving mushrooms. The practical application of this research is to evaluate effect of preserving two wild mushroom species by canning in traditional acetic brine on the quality parameters of those mushrooms. The results can be used to determine whether this method of mushroom processing can be used on a larger scale by the industry to substitute currently used methods providing better quality and nutritional value.

LABORATORY STUDY ON CARBONATE ROCKS CHARACTERIZATION AND POROSITY CHANGES DUE TO CO2 INJECTION

Enhanced oil recovery methods must be improved continuously to provide higher recovery factors for the new fields under development in a globally competing market. CO2 injection processes in carbonate rocks involve reactions between acid brine and the rock. These interactions promote petrophysical changes in the rock structure due to calcite dissolution or precipitation. Lab experiments in saturated coquina samples were carried out to better understand the effects on porosity by CO2 injection. X-ray Photoelectron Spectrometer (XPS) was used to analyze the surface chemistry of the rock sample for elemental composition measurement. X-Ray Micro-CT and Mercury Injection Capillary Pressure (MICP) were carried out to calculate mean porosity in the rock sample. X-Ray scans were run for each pore volume injected. The results show that dissolution should be considered when supercritical CO2 is injected in the reservoir. This process has relevance for project design, risk analysis, economic evaluation and reservoir behavior forecast.

Impacts of Mineral Reaction Kinetics and Regional Groundwater Flow on Long-Term CO2 Fate at Sleipner

We conducted coupled reactive mass transport modeling of CO2 storage in a sandy aquifer resembling the uppermost layer in the Utsira Sand, Sleipner, North Sea, in order to investigate the general effects of rate laws and regional groundwater flow on long-term CO2 fate in saline aquifers. The temporal and spatial evolution of CO2 plume and the fate of injected CO2 were simulated with a series of scenarios with different rate law formulations for dissolution and precipitation reactions and different flow regimes. The results indicated the following: (1) Changing the dissolution rate laws of the main soluble silicate minerals can influence the silicate reactions and mineral trapping by impacting the sensitivity of the relevant coupled reaction’s rate to the acidification of brine. The steeper the slope of rate−ΔGr (Gibbs free energy of reaction) relationships, the more sensitive the coupled reaction rate and the mineral trapping are to the acidification of brine. The predicted fraction of CO2 mineral trappin...