Injection Of Waters Research Articles

Process-Based and Probabilistic Quantification of Co and Ni Mobilization Risks Induced by Managed Aquifer Recharge.

Managed aquifer recharge (MAR) is an increasingly used water management technique that enhances water availability while commonly generating water quality benefits. However, MAR activities may also trigger adverse geochemical reactions, especially during the injection of oxidant-enriched waters into reducing aquifers. Where this occurs, the environmental risks and the viability of mitigating them must be well understood. Here, we develop a rigorous approach for assessing and managing the risks from MAR-induced metal mobilization. First, we develop a process-based reactive transport model to identify and quantify the main hydrogeochemical drivers that control the release of metals and their mobility. We then apply a probabilistic framework to interrogate the inherent uncertainty associated with adjustable model parameters and consider this uncertainty (i) in long-term predictions of groundwater quality changes and (ii) in scenarios that investigate the effectiveness of modifications in the water treatment process to mitigate metal release and mobility. The results suggested that Co, Ni, Zn, and Mn were comobilized during pyrite oxidation and that metal mobility was controlled (i) by the sediment pH buffering capacity and (ii) by the sorption capacity of the native aquifer sediments. Both tested mitigation strategies were shown to be effective at reducing the risk of elevated metal concentrations.

KEY ROLE OF FOSSIL SEAWATER IN NEOGENE SEDIMENTARY ROCKS FOR LANDSLIDE OCCURRENCES IN THE NORTHERN PART OF CENTRAL JAPAN

The south-western area of Niigata Prefecture has the highest landslide densities in Japan. Saline groundwater emerges from several landslides in this area and is an influential factor in the occurrence of these landslides. The geochemical approaches to groundwaters and application of the electromagnetic surveys for landslide slopes revealed the hydrogeological structure of the large-scale landslides which was located on the outlet of saline waters from deep reservoirs and landslide-prone area where wide zonal distributions of saline water at depths of more than 50–100 m and fresh water at depths of shallower than 50–100 m. It is most likely that the saline groundwater behavior emerging in large-scale landslides is controlled by injections of the geo-pressured saline waters from deep reservoirs. The injection of the geo-pressured waters into the landslide mass likely results in excess pore pressure, which is a possible cause of landslide occurrence. On the other hand, the shallow fresh groundwater is inferred to be meteoric water of origin that replaced the saline groundwater, which likely weakened the shear strength of bedrocks, resulting in landslides. Thus, pore saline water plays an important key role in the occurrence of landslides, both large-scale landslides with low frequency and common landslides.

Injection of High Chlorophyll-a Waters by a Branch of Kuroshio Current into the Nutrient-Poor North Pacific Subtropical Gyre

An unusual eastward flow was observed branching out from the Kuroshio Current near the island of Taiwan in the western North Pacific in during the period June–July 2010. The branch meandered eastward approximately 21°N, carrying high chlorophyll-a (Chla) waters for over 1000 km from 125°E into the nutrient-poor North Pacific subtropical gyre (NPSG). The branch was warmer and fresher than the surrounding waters, with temperature–salinity properties resembling those of Kuroshio Current. Thus, we called it the eastward cross-shore Kuroshio branch (ECKB). Injecting fresher waters far into the central NPSG, the ECKB flowed at a mean surface speed of 0.5 m per second, as shown in satellite altimeters, a Lagrangian drifter, and the Japan-Meteorological-Agency (JMA) 137°E-meridian cruise transect. The mechanism of the ECKB was linked to a surface cyclonic wind anomaly to the north at approximately 22–24°N. The cyclonic wind anomaly cooled the ocean surface beneath it via Ekman suction and then enhanced the subtropical front to its south at approximately 21°N near the Kuroshio Current. The strengthened subtropical front subsequently induced an eastward flow that bifurcated from the main stream of the northward-flowing Kuroshio Current.

The possibility of application of computer simulation to predict the direction of the reaction during injection of reservoir waters

Currently, practically the entire volume of water extracted in the process of hydrocarbon exploitation is utilized by injection into deposits. Changes in the physico-chemical parameters (pH, red-ox potential, temperature, etc.) of the water during extraction and the contact of the injected water with the native water and deposit rock may result in the precipitation of sediment particles and suspensions. It causes clogging of the near-wellbore zone and limits the amount of water that can be injected with the injection well. Due to the high complexity of the system: the injected water–reservoir rock, and a wide range of interactions between individual components, the analytical data does not always allow for the correct interpretation of the course of the processes and determination of their impact on the permeability of the near-well zone. Using the results of physico-chemical analyses of the composition of separator water samples with different properties – two samples with low mineralization S1K (575 mg/dm3) and S4K (551 mg/dm3), a sample with high S2K (306 428 mg/dm3) and medium mineralization S3K (79 858 mg/dm3) – calculations were performed using the PHREEQC program for the three databases: phreeqc.dat, wateq4f.dat and pitzer.dat. It was found that in the case of low mineralization waters, the results obtained in each of the databases are similar for the minerals present in all the databases. However, in the case of solutions with high mineralization, there are significant differences in the obtained results. The calculated solubility indices allowed to determine the direction of the precipitation/dissolution reaction of individual minerals in the deposit and to indicate the risks, mainly with the formation of iron compounds deposits, for the operation of the injection well. Laboratory tests of water mixing were also carried out. The formation of iron oxide deposits that could damage the near-well zone was observed, which confirmed the results obtained during computer simulations.

Spreading and Vertical Structure of the Persian Gulf and Red Sea Outflows in the Northwestern Indian Ocean

AbstractIn the Indian Ocean, salty water masses from the Persian Gulf and Red Sea are important sources of salt, heat, and nutrients. Across the Arabian Sea, these outflows impact human and biological activities, their thermohaline characteristics and shapes exhibiting important spatial and seasonal variability. The knowledge of the water masses properties is important to validate realistic simulations of the Indian Ocean. A classical approach to study these water masses is to track them on specific isopycnal levels. Nevertheless, their peaking thermohaline characteristics are not always found at a specific density but rather spread over a range. Here, we develop a detection algorithm able to capture the full vertical structure of the outflows, that we applied to a data set of about 126,000 vertical profiles. We are thus able to quantify the changes in their thermohaline signatures and in their vertical structures, characterized here by the intensity of the salinity peaks of the water masses and lateral injection of fresh and salty waters, and describe their spatial variability. Across the northwestern Indian Ocean, the salty outflows undergo several changes, diminishing their thermohaline signatures and peaks and layering. In their early stages in the narrow Gulf of Oman and Aden, the outflows present configurations indicative of diapycnal mixing. In the same regions and along the western edge of the Arabian Sea, these water masses are subject to lateral mixing. All over the Arabian Sea, salt fingering conditions are met for lower layers of the outflows.

Impact of the Agulhas Return Current on the oceanography of the Kerguelen Plateau region, Southern Ocean, over the last 40 kyrs

The oceanography of the western Indian sector of the Southern Ocean is extremely complex due to the presence of several subantartic islands and plateaus that alter the zonal flow of the Antarctic Circumpolar Current. The circulation is even more complex around the Kerguelen Islands (KI) as the hydrological fronts merge with the Agulhas Return Current, the latter transporting warm surface waters from the low latitudes to the Subantarctic Zone (SAZ) east of KI. Here we present new sea-surface and sub-surface temperatures, based on diatom and radiolarian census counts respectively, in two cores covering the last 40,000 years (40 kyrs) to infer past oceanographic changes in the KI region. In core MD11-3353, located in the Polar Front Zone (PFZ) west of KI, both sea-surface and sub-surface temperatures follow the expected glacial-interglacial pattern, with a constant difference of ∼3 °C, suggesting that the structure of the top 500 m of the water column did not change drastically over this period. In core MD12-3396CQ, located in the SAZ east of KI, the sub-surface temperature record again follows the expected glacial-interglacial pattern while the diatom-based reconstruction shows a strong warming during the 40-24 kyrs period, with a mean difference between the two of ∼9 °C. The temperature difference subsequently reverts to ∼3 °C during the glacial termination and Holocene. We suggest that the large difference between surface and sub-surface temperatures during the 40-24 kyrs period resulted from the injection of warm surface waters from the Indian low latitudes. This signal was transported to the core site by a strengthened Agulhas Return Current during the glacial, when the Agulhas leakage to the Atlantic was reduced. Our study thus proposes that the surface conditions in the SAZ of the KI region are shaped by the interplay between the migration of the Southern Ocean hydrological fronts and the Agulhas (Return) Current, both being climatically modulated.

Investigation of Reasons for Damage to a Steel Pipeline Used For the Injection of Formation Waters

The article presents results of the research on the causes of failure of the DN 80 steel pipeline used for injection of formation waters. Based on the research results, it was found that the cause of perforation and subsequent material losses in the DN 80 pipeline wall made of L360NB steel was under deposit corrosion.

A New Genetic Type of Leaching Zone in Salts of the Verkhnyaya Kama Potassium Salt Deposit: Hydrochemical, Mineralogical, and Structural Indicators

The brine-saturated leaching zone discovered in the Verkhnyaya Kama salt deposit is scrutinized. It comprises a cavernous core (40 × 70 m) composed of aposylvinite syngenite (halite rock with gypsum and kalistrontite) and a recrystallization aureole (60–80 m wide) without secondary sulfates. The leaching zone is overlain by a linear zone of the weathering and decarbonatizaton of marls in the suprasalt sequence. This zone is controlled by a nearly latitudinal anticlinal ridge extending parallel to the Durinsky trough related to synsedimentary normal faulting. Injection of suprasalt waters into the salt body is attributed to deformations of the salt sequence as a result of its articulated bending during the formation of the Durinsky trough in the Early Permian. Brines in the studied leaching zone are linked with the infiltrational suprasalt calcium sulfate waters. Their position in the general genetic typification of natural brines and waters circulating in the salt body of the Verkhnyaya Kama deposit is defined.

An experimental study toward possible benefits of water in oil emulsification in heavy oil reservoirs: comparing role of ions and nanoparticles

The current study presents a comparison between tertiary injection of smart water (MgCl2 and NaCl brines) and nanofluid (Fe3O4 and Fe3O4/Chitosan) with a focus on the effect of water in heavy oil emulsification on the oil production. For this purpose, seawater (as a secondary injection fluid) and various concentrations of nanofluids and brines (as tertiary injection fluids) were injected into a carbonate sand pack. The produced fluid (oil + water) was separated by centrifugal force and the oil/water ratio was determined, which was then used in preparing different water in oil emulsions. The emulsions were then analyzed. The ultimate oil recoveries were monitored during tertiary injection of certain nanofluids and smart waters and were discussed from the perspective of emulsion resistance to the phase separation. The effect of salt type and concentration of salt and Fe3O4/Chitosan nanocomposites was investigated on the formation and stabilization of emulsions. Finally, the performance of smart water and nanofluid injection at the optimum concentrations were compared. According to the results obtained, 10000 ppm MgCl2 presented the best performance in the formation and stabilization of the emulsions as compared to the other concentrations. The synthesized nanocomposite also showed the best result at 0.05 wt%. Comparing the emulsification in smart water and nanofluid revealed that the emulsions developed during nanofluid injection were more stable and therefore led to a higher oil recovery factor.

Effects of Salinity and Individual Ions on Crude-Oil/Water Interface Physicochemical Interactions at Elevated Temperature

Summary Advanced waterflooding processes through injection of optimized-chemistry waters have recently become popular for enhanced oil recovery (EOR) in carbonate reservoirs. In this study, we describe the results from a series of experiments (including interfacial tension (IFT), interfacial shear rheology, and droplet-coalescence times) at elevated temperature to determine the effects of both salinity and individual water ions on different physicochemical interactions occurring at the crude-oil/water interface. In addition, the results from microscopy imaging of the interface and ζ-potential/average oil-droplet size in crude-oil/water/brine emulsions are reported at ambient temperature. Reservoir crude oil was used for these measurements, and ionic strengths of different brines were varied from high-salinity seawater (56,000 ppm total dissolved solids) to pure deionized (DI) water (zero salinity). The dynamic and equilibrium IFTs of crude-oil/brine interfaces were found to be lower than those of the crude-oil/DI-water interface. Both the 10-times-reduced-salinity seawater and 10-times-reduced-salinity seawater enriched with sulfates showed relatively higher IFT compared with high-salinity multivalent-ion brines, whereas the initial rate of IFT change with time was observed to be the lowest with sulfate-rich brine. The interfacial-rheology results showed that the transition times for the interface to become elastic-dominant from a viscous-dominant regime were found to be the lowest for low-salinity sulfate-rich brine and the greatest with high-salinity multivalent-ion brines. The coalescence times determined for crude-oil droplets in different brines showed delayed coalescence with sulfate-rich brine and DI water, whereas the fastest coalescence was observed with the high-salinity multivalent-ion brine containing magnesium (Mg2+) and calcium (Ca2+) ions. All these results on IFT, interfacial shear rheology, and crude-oil-droplet-coalescence times obtained at elevated temperature agreed well with previously reported ambient-temperature data to indicate similar trends for different water ion interactions occurring at the crude-oil/water interface. However, faster kinetics of interfacially active molecules together with reduced viscosities of fluid phases resulted in lower IFTs, shorter interfacial-film-transition times, and rapid coalescence times with DI water and different brines at elevated temperature. Microscopy-imaging results at ambient temperature showed formation of aggregates with DI water and two low-ionic-strength brines to demonstrate the better activity of interfacially active molecules to result in stable interfaces. The highest negative ζ-potentials were observed in DI water and sulfate-rich brine at ambient temperature. The oil-droplet diameters measured in crude-oil/brine emulsions showed the smallest droplet sizes with DI water and sulfate-rich brine. These measured data from different experimental techniques at both elevated and ambient temperatures therefore showed good consistency with each other, demonstrating the importance of having certain salinity levels and key ions, such as Mg2+ and Ca2+, in the injection water to enhance the coalescence between released oil droplets. Considering the importance of snap-off and oil-droplet coalescence on improving oil-phase connectivity, injection-water salinities and ionic compositions should be designed for optimal interactions at the crude-oil/water interface to capitalize on both of these effects in advanced waterflooding.

Investigation of Barium Sulfate Precipitation and Prevention Using Different Scale Inhibitors under Reservoir Conditions

In this work, scaling tendency and amount of precipitation of barium sulfate (BaSO4) were determined; the process is depending on temperature, pressure and mixing ratio of injection and formation of waters. Results showed that BaSO4 precipitation is largely dependent on mixing ratio. Temperature and pressure had no influence on BaSO4 precipitation. Different scale inhibitors, including a new inhibitor package, were used for preventing BaSO4 precipitation. The new scale inhibitor consists of three different acids such as phosphonate acid, hydrochloric acid solution, isopropyl alcohol, ammonium chloride and water. In addition, the lowest interfacial tensionon the boundary of oil and new inhibitor occurred at 10% of hydrochloric acid. Furthermore, effect of temperature, mixing ratio of waters and barium concentration on the inhibition efficiency of BaSO4 formation was studied. Results showed that the new inhibitor has the highest efficiency for preventing BaSO4 precipitation at any temperature, mixing ratio and barium concentration. Moreover, formation damage due to BaSO4 formation with and without scale inhibitors was determined by core flood tests. In the presence of new inhibitor, the damaged rock permeability ratio was improved from 0.59 to 0.924.

Shale-fluid interactions during forced lmbibition and flow-back

One way to minimize the need for disposal of flow-back waters produced during the hydraulic fracturing of unconventional reservoirs is, potentially, to recycle these fluids by recovering and re-injecting them during hydraulic fracturing of nearby new wells. These flow-back waters contain, however, large concentrations of dissolved salts. During hydraulic fracturing of unconventional reservoirs, a well may undergo extended shut-in periods, following the initial hydraulic-fracture stimulation. The concern here, therefore, is that the salts dissolved in the re-injected flow-back waters may precipitate in the subsurface, thus promoting scale formation; or alternately, because of their high salinity, these same fluids may cause the dissolution of various minerals present in the subsurface. Large divalent cations (e.g., Ca2+, Ba2+ and Sr2+) and anions (e.g., CO32− and SO42) may chemically interact with and cause the swelling of clay fractions, thus blocking pores in certain pore size ranges. All these phenomena (i.e., scale formation, clay swelling, minerals dissolution) can influence the petrophysical properties of the formation, including its permeability, porosity, contact angle, etc. One way to potentially overcome some of these technical challenges, is to pre-treat these flow-back waters, prior to re-injection (e.g., via chemical precipitation, followed by membrane filtration) in order to remove unwanted salts. However, such pre-treatment is costly, and the degree of salt removal needed to prevent formation damage is important in determining the economic viability of flow-back water recycle via re-injection. A key focus of this work, therefore, is to study the impact that the injection of flow-back waters, that have undergone varying degrees of pre-treatment and clean-up, will have on the flow-through characteristics of a tight-gas reservoir, particularly of the Marcellus Shale formation. To do so, we have carried-out forced-imbibition experiments with shale samples from various depths in the Marcellus formation, whose properties span high to low ranges of TOC, clay content and matrix permeabilities. We have studied the forced-imbibition characteristics, at an injection pressure of 24,233 kPa (3500 psig), of various flow-back fluids into shale cores saturated with methane at a pore pressure of 17,338 kPa (2500 psig) and a confining stress of 27,680 kPa (4000 psig). Following the forced imbibition experiments, we analyzed the cores for potential changes in permeability and porosity. Quantification of the ion content of the injected and recovered fluids was also performed using Ion Chromatography (IC). The IC analysis of the recovered fluids indicates substantial interactions and geochemical reactions between the invading fluids and the shale cores. The injection of flow-back fluids shows significant impact on the flow-through characteristics, with untreated flow-back fluids, which have the highest cation and anion content, also exhibiting the highest observable reductions in permeability (>90%).

Paleoceanographic and climatic implications of a new Mediterranean Outflow branch in the southern Gulf of Cadiz

The presence of contourite drifts in the southern Gulf of Cadiz (GoC) along the Moroccan margin raises questions about the (re)circulation of Mediterranean Outflow Water (MOW) in the GoC and the origin of the currents depositing them. Here, we compare two cores representative of Iberian and Moroccan contourite drifts, covering the last 22 kyr. Although the whole sequence is contouritic in character, it reflects the interaction of distinctive silty-contourite facies (high flow velocity periods) imbedded in muddy-contourite facies (low flow velocity periods). Evidence from benthic foraminifera δ13C, sortable silt grain-size, oceanographic CTD profiles and numerical simulations, indicate the Mediterranean water mass as the source of the southern contourite deposits. Our data, therefore, suggests an additional branch of upper-MOW veering southwards off the Straits of Gibraltar along the Moroccan margin. During MIS-(Marine Isotope Stage) 2, upper-MOW was a sluggish current while in the Holocene upper-MOW dominated as a fast, semi-steady flow. Throughout the deglaciation, silty contourites associated with higher flow speeds were deposited in the northern and southern GoC during cold events such as Heinrich Stadial 1 (HS1) and the Younger Dryas, forced by global millennial-scale climate variability. Millennial variability also appears to drive the deposition of silty-contourites in the Holocene. We estimated an average duration of 1 ka for the process of depositing a fast contourite unit. The case of silty-contourite I6 (within HS1) allows us to illustrate with extremely high resolution a “rapid” sequential change in circulation, with gradual slow-down of dense Mediterranean water while surface was freshening (HS1), provoking injection of high-salinity intermediate waters (via contour-currents) into the GoC, and hence the North Atlantic. The subsequent brief collapse of dense water formation in the Mediterranean Sea triggered a major increase in sea surface temperatures (10 °C/ka) in the GoC, developing into the next interstadial (Bølling/Allerød). The impact of Mediterranean intermediate waters is manifested here by triggering a substantial rearrangement of intermediate and deep circulation in the North Atlantic, which would have further impacted the Atlantic Meridional Overturning Circulation (AMOC).

Hydrogeochemical Aspects Associated with the Mixing of Formation Waters Injected Into the Hydrocarbon Reservoir

Abstract Formation waters extracted with crude oil and natural gas, due to their amount and chemical composition can be a problem for petroleum companies operating hydrocarbon deposits. On average, the world generates 2 to 3 times more water than oil. On average, the world generates 2 to 3 times more water than crude oil. T he amount of extracted water increases with the time of exploitation of the deposit, in the case of deposits at the final stage of depletion, the amount of extracted water is 5 to 8 times bigger than petroleum. Formation waters from hydrocarbons deposits are usually the highly mineralized brines. Large quantities of highly mineralized waters extracted with crude oil and gas are disposed of in various ways or neutralized. T he most common way of disposing of these waters is by injecting them into rock mass. As a result of injection of reservoir waters into hydrocarbon deposits, the waters interact with the storage formations. In these formations, there may be numerous reactions of mineral water with the rock environment. T he injection of reservoir waters will also cause mixing of waters that can disturb the state of thermodynamic equilibrium and will alter the chemistry of these waters. It was analyzed by the geochemical modeling of the interaction of the reservoir waters of Przemyśl natural gas field. Using the PHREEQC program, the chemical reactions related to the mixing of reservoir waters of different chemical types have been studied. It has been found that is possible to precipitation appropriated minerals as a result of mixing water with different chemical composition.

Macrophyte response to the protection and restoration measures of four water bodies

Macrophytes are a good long-term indicator of quality of aquatic ecosystems and are essential for the proper functioning of the entire lake ecosystem. Submerged vegetation is considered to be indicative of an improvement of the ecological status of these lakes. Here, we analyzed the distribution, structure, and diversity of vegetation communities in four eutrophic water bodies (postglacial lakes: Slawskie and Uzarzewskie and man-made lakes: Maltanski Reservoir and Turawa Średnia Reservoir) after the application of restauration and protections measures. The restoration measures included biomanipulation, phosphorus inactivation, hypolimnion aeration, or injection of nitrate-rich waters to the hypolimnion. All of them were sustainable and did not cause drastic changes in the ecosystem. Between 9 and 17 macrophyte communities were found in the examined water bodies. The largest effects were observed after the simultaneous use of three lake restoration techniques which led to the appearance of 17% charophytes. Pronounced effects leading to the higher contribution of elodeids to the macrophyte community were achieved in the lake in which two methods were applied. Least effective was the method focused on hypolimnion restoration in a small lake, which did not cause the reappearance of submerged vegetation. Spontaneous recovery achieving good status is also possible in a large lake in case of applying the thorough conservation measures. An intensive growth and diversity of macrophytes was a result of the improvement in the water quality as a consequence of undertaken protective activities and/or restoration measures. However, the re-colonization of submerged macrophytes during restoration process is not obvious and the feed-back mechanisms may delay a response of the ecosystem. The vegetation of the studied lakes was unstable, showing high variability in individual years of research, which indicates that these ecosystems are still under reconstruction and not reach equilibrium state yet.

Experimental recharge by small-diameter wells: the Pirna, Saxony, case study

Managed aquifer recharge has been used for various regions worldwide to improve water quantity and quality. Furthermore, contaminated site treatment often requires injection of water together with specific additives to support natural attenuation processes. Handel et al. (in J Hydrol 517:54–63, 2014. doi:10.1016/j.jhydrol.2014.05.003) introduced a new recharge approach, applying cost-efficient small-diameter wells. Numerical studies were applied, among others, to investigate the effect of subsurface structures on injection process. Besides this, a comparison with an infiltration basin was made. To close the gap between the theoretical work and the practical use of this technique for medium-term injection of clean waters and to provide an experimental validation of the small-diameter well recharge, two injection tests using a small-diameter well (1″ inner diameter) were performed at the test site Pirna, Saxony, Germany. In a first short-term test, stepwise increasing injection rates were applied and showed only a slight increase in well water levels. In a second test (using the same well), groundwater was injected continuously for 14 days. The constant injection rate of 0.75 l/s resulted in a recharged water volume of 900 m3, showing the high-performance potential of such wells for clean water infiltration.

Role of tides on the formation of the Antarctic Slope Front at the Weddell‐Scotia Confluence

AbstractThe structure of the Antarctic Slope Front (ASF) and the associated Antarctic Slope Current (ASC) on the Scotia Sea side of the Weddell‐Scotia Confluence (WSC) is described using data from a hydrographic survey and three 1 year long moorings across the continental slope. The ASC in this region flows westward along isobaths with an annual mean speed of ∼0.2 m s−1, with time variability dominated by the K1 and O1 tidal diurnal constituents, a narrowband oscillation with ∼2‐week period attributable to the spring/neap tidal cycle, and seasonal variability. Realistic and idealized high‐resolution numerical simulations are used to determine the contribution of tides to the structure of the ASF and the speed of the ASC. Two simulations forced by realistic atmospheric forcing and boundary conditions integrated with and without tidal forcing show that tidal forcing is essential to reproduce the measured ASF/ASC cross‐slope structure, the time variability at our moorings, and the reduced stratification within the WSC. Two idealized simulations run with tide‐only forcing, one with a homogeneous ocean and the other with initial vertical stratification that is laterally homogeneous, show that tides can generate the ASC and ASF through volume flux convergence along the slope initiated by effects including the Lagrangian component of tidal rectification and mixing at the seabed and in the stratified ocean interior. Climate models that exclude the effects of tides will not correctly represent the ASF and ASC or their influence on the injection of intermediate and dense waters from the WSC to the deep ocean.

Corrosion and durability of offshore steel water injection pipelines

Carbon steel pipelines are widely used for injection of sea and other waters into oil and gas wells so as to increase the rate of recovery, particularly from mature fields. Internal corrosion usually is mild. However, cases of very aggressive channelling corrosion along the bottom of the pipeline have been observed. Practical experience and anecdotal observations have attributed this to microbiologically influenced corrosion even though extensive use is made of preventative measures including biocides, oxygen scavengers, corrosion and scale inhibitors, and pipeline pigging. Interpretation of data and observations for five water injection pipelines, made available by industry, indicate that microbiologically influenced corrosion may play a part in causing channelling corrosion but that the most likely cause is under-deposit corrosion under pipe debris that settles during periods of pipeline shut-downs and low water velocity.

An analysis of hydrogeological behavior in the Geyser Valley, Kronotskii nature reserve, Kamchatka after the disaster of June 3, 2007

This paper describes the results from observations of the hydrogeological behavior in the Geyser Valley in 2007–2013 at the main monitored geysers and springs and in Lake Podprudnoe after the disastrous landslide of June 3, 2007. According to observations at Bolshoy Geyser, its mean eruption period is almost two times shorter compared to that before the landslide; it is 63 min now. Its activity is controlled by the level of Lake Podprudnoe. Velikan Geyser was found to have a significantly shorter period of eruption, decreasing from the mean annual value of 379 min (in 2007) to 335 min during the first 3 years after the disastrous landslide, with the mean annual eruption period subsequently stabilizing. It was found that Velikan Geyser showed an increasing period of eruption within its hydrogeologic cycle during winter (by about 50 min on average). The mean annual value of the deeper discharge component in the hydrothermal system (as determined by the chloride technique) is estimated as 215 kg/s; it was observed to decrease (by 30%) during the spring-summer flooding. The injection of meteoric waters from Lake Podprudnoe did not produce any significant hydrochemical changes in the Velikan and Pervenets geysers, but the main component of the deeper heat carrier was found to be diluted in Bolshoy Geyser. On the whole, the gas composition of the pipes in the geysers and boiling springs is dominated by the atmospheric component, while the feeder reservoir of Velikan Geyser is dominated by CO2 and N2 with considerable concentrations of methane and hydrogen. TOUGH2 modeling showed that the decrease in the eruption period was related to the hydrodynamic effects of Lake Podprudnoe. We examined the influence of seismicity on the eruption behavior of Velikan Geyser.

Biogeochemical patterns in the Atlantic Inflow through the Strait of Gibraltar

The effects of tidal forcing on the biogeochemical patterns of surface water masses flowing through the Strait of Gibraltar are studied by monitoring the Atlantic Inflow (AI) during both spring and neap tides. Three main phenomena are defined depending on the strength of the outflowing phase predicted over the Camarinal Sill: non-wave events (a very frequent phenomenon during the whole year); type I Internal wave events (a very energetic event, occurring during spring tides); and type II Internal wave events (less intense, occurring during neap tides).During neap tides, a non-wave event comprising oligotrophic open-ocean water from the Gulf of Cádiz is the most frequent and clearly dominant flow through the Strait. In this tidal condition, the inflow of North Atlantic Central Water (NACW) provides the main nutrient input to the surface layer of the Alboran Sea, supplying almost 70% of total annual nitrate transport to the Mediterranean basin. A low percentage of active and large phytoplankton cells and low average concentrations of chlorophyll (0.3–0.4mgm−3) are found in this tidal phase. Around 50% of total annual phytoplankton biomass transport into the Mediterranean Sea through the Strait presents these oligotrophic characteristics.In contrast, during spring tides, patches of water with high chlorophyll levels (0.7–1mgm−3) arrive intermittently, and these are recorded concurrently with the passage of internal waves coming from the Camarinal Sill (type I internal wave events). When large internal waves are arrested over the Camarinal Sill this implies strong interfacial mixing and the probable concurrent injection of coastal waters into the main channel of the Strait. These processes result in a mixed water column in the AI and can account for around 30% of total annual nitrate transport into the Mediterranean basin. Associated with type I internal wave events there is a regular inflow of large and active phytoplankton cells, transported in waters with relatively high nutrient concentrations, which constitutes a significant supply of planktonic resources to the pelagic ecosystem of the Alboran Sea (almost 30% of total annual phytoplankton biomass transport).