Deep Offshore Research Articles

Surface Currents and Relative-Wind Stress in Coupled Ocean–Atmosphere Simulations of the Northern California Current System

Abstract The dependence of surface-current damping on the definition of surface current for the relative wind is examined in coupled ocean–atmosphere numerical simulations of the northern California Current System (nCCS) during March–October 2009. The model response is analyzed for wind stress computed from relative wind for six different choices of effective model surface velocity. Simulations without surface-current coupling are also considered. As a function of the geographically varying uppermost grid-level depth, the model uppermost grid-level velocity is found to have a wind-drift component with a log-layer structure. Mean geostrophic wind work is concentrated in the shelf and slope regions during March–May (MAM) and in the deep offshore region in June–September (JJAS). The surface-current damping effect on ocean kinetic energy depends more strongly on the parameterization of atmospheric planetary boundary layer (PBL) turbulence than on the surface-current coupling formulation: weaker PBL mixing gives stronger surface-current damping. The damping effect is stronger in the less energetic offshore region than in the more energetic region closer to the coast. During MAM, the changes in kinetic energy and geostrophic wind work in the shelf and slope regions are spatially correlated, while during JJAS, the changes in geostrophic wind work are strongly modulated by SST–stress coupling. The wind-drift-corrected surface-current formulations result in large changes in the effective wind work based on the product of stress and relative-wind surface current but result in only small changes in the kinetic energy of the circulation. Significance Statement Ocean currents and atmospheric winds are coupled by the exchange of momentum across the air–sea interface, the strength of which depends on the relative wind, the difference between the surface wind and surface current. The purpose of this work was to examine the dependence of a coupled ocean–atmosphere model of the northern California Current System (nCCS) on the representations of the relative-wind surface current and turbulent mixing in the lower atmosphere. The model surface current was found to have a shallow wind-drift response. The model ocean circulation was driven primarily by near-coast winds during the spring and by offshore winds during the summer. The ocean response depended more strongly on the atmospheric turbulent mixing than on the surface current representation.

Behavioral response of megafauna to boat collision measured via animal-borne camera and IMU

Overlap between marine megafauna and maritime activities is a topic of global concern. Basking sharks (Cetorhinus maximus; CM) are listed as Globally Endangered under the IUCN, though reported sightings appear to be increasing in Ireland. While such trends in the region are welcome, increasing spatiotemporal overlap between CM and numerous water users poses an increased risk of boat strikes to the animals. To demonstrate the risk and impact of boat strikes on marine megafauna, we present camera-enabled animal-borne inertial measurement unit (IMU) data from a non-lethal boat strike on a CM within a proposed National Marine Park in Ireland. We tagged a ~7-m female CM in County Kerry, Ireland, which was struck by a boat ~6 h after tag deployment. Comparison of pre-strike data with 4 h of video and ~7.5 h of IMU data following the boat strike provides critical insight into the animal’s response. While the CM reacted momentarily with an increase in activity and swam to the seafloor, it quickly reduced its overall activity (i.e., overall dynamic body acceleration, tailbeat cycles, tailbeat amplitude, and vertical velocity) for the remainder of the deployment. Notably, the animal also ceased feeding for the duration of the video and headed towards deep offshore waters, which is in stark contrast to the pre-strike period where the animal was consistently observed feeding along the surface in shallow coastal water. This work provides insight into a CM’s response to acute injury and highlights the need for appropriate protections to mitigate risks for marine megafauna.

Seismic net-to-gross estimation for a geologic model update: A case study from a turbidite lobe reservoir in the deepwater of the Niger Delta

Geologic model updates are routinely performed in mature fields to obtain improved descriptions of facies distributions and reservoir properties such as volume of shale, net to gross (NTG), and porosity, for better understanding of the static and dynamic behaviors of reservoirs for effective well placement, improved production, and monitoring. A simple but integrated seismic NTG estimation approach, using detuned seismic amplitudes is used in guiding NTG modeling during the geologic model update of a thin turbidite lobe reservoir in a mature oil field in the deep offshore Niger Delta. The objective is to address NTG overestimation and gross rock volume (GRV) uncertainty in a previous model arising from seismic amplitude tuning effects. A seismic NTG approach is chosen relative to sophisticated deterministic or stochastic inversion techniques to avoid tuning effects, which usually bias NTG estimates in thin turbidite reservoirs. The primary data set is a 2019 reprocessed prestack depth-migrated (PSDM) seismic data vintage, which had better resolution, higher signal-to-noise ratio, and more appropriate angle-stack apertures for amplitude variation with angle fidelity, than the older 2011 PSDM seismic data that are used in the previous geologic model. The methodology involved rock-physics analysis, seismic data quality checks (QCs), tuned area determination, detuning of composite seismic amplitudes of the top and base reservoir, and their direct calibration to NTG at wells. Good correlations are obtained between the detuned composite seismic amplitudes and NTG at wells. The seismic NTG map shows good calibrations at wells and provides a robust trend for net sand modeling in the oil pool and aquifer. Static model QCs and dynamic simulations prove that the seismic NTG attribute addressed the GRV uncertainty in the earlier model, thus giving confidence for using the updated model for the planning and geosteering of infill wells, sand completions, reservoir monitoring, and production.

On the kite-platform interactions in offshore Airborne Wind Energy Systems: Frequency analysis and control approach

This study investigates deep offshore, pumping Airborne Wind Energy systems, focusing on the kite-platform interaction. The considered system includes a 360 m2 soft-wing kite, connected by a tether to a winch installed on a 10-meter-deep spar with four mooring lines. Wind power is converted into electricity with a feedback controlled periodic trajectory of the kite and corresponding reeling motion of the tether. An analysis of the mutual influence between the platform and the kite dynamics, with different wave regimes, reveals a rather small sensitivity of the flight pattern to the platform oscillations; on the other hand, the frequency of tether force oscillations can be close to the platform resonance peaks, resulting in possible increased fatigue loads and damage of the floating and submerged components. A control design procedure is then proposed to avoid this problem, acting on the kite path planner. Simulation results confirm the effectiveness of the approach.

Data analysis of the TetraSpar demonstrator measurements

Floating offshore wind turbines can extract energy from deep offshore locations, typically unfit for fixed bottom designs. The complex interaction between the structural behavior of the floating offshore wind turbine and the stochastic site conditions, however, is an active area of research. Characterizing the relationship between the environmental conditions and loads may help design reduced-order models, surrogate models, and physics-based engineering models for floating wind turbines. This study uses data from the TetraSpar prototype equipped with a 3.6 MW Siemens Gamesa wind turbine. One-to-one simulations performed using an aero-servo-hydro-elastic software are included for comparison. Various tools, including linear correlation, mutual information, feature ordering using conditional independence, and sensitivity analysis using a data-driven variogram fit, are used for the assessment. This study is also helpful in validating the engineering model for future global sensitivity analysis using elementary effects or Sobol indices that require a rigid sampling of features and can, therefore, only be calculated with simulation tools. We find a good agreement between the experiments and simulations. The 10-min. damage equivalent loads on the tower show a correlation, particularly with the wind speed statistics and the significant wave height.

Cuvier's beaked whale (Ziphius cavirostris) detection through surface-sourced eDNA: A promising approach for monitoring deep-diving cetaceans

Among cetaceans, the Cuvier’s beaked whale is considered an extreme diver, thus not one of the easiest cetacean species to be studied due to its elusive behaviour and a preference for deep offshore waters. Although dedicated cetacean surveys have increased our knowledge on the distribution of Cuvier’s beaked whales in the Mediterranean Sea, knowledge gaps still remain where the study effort is non-existent. In this context, the use of new molecular methodologies capable of intercepting small traces of DNA left in the environment (eDNA) by marine organisms represents a valid approach to infer species’ occurrence. Moreover, the collection of water from the superficial layer is suitable for targeting marine mammals, as the constraints imposed by their nature implies periodic and frequent surfacing in order to breathe, releasing exhalants rich in their epithelial cells. Therefore, we designed and tested a taxon-specific primer set to infer Cuvier’s beaked whale presence, with the aims of 1) examining the effectiveness of the eDNA technique to detect the presence of a deep-diving cetacean in open waters, using the Cuvier’s beaked whale as case study; 2) providing data on the occurrence of this species within the Canyon of Caprera over a six-months study period and 3) assessing the species presence in adjacent waters in the central northern Mediterranean Sea based on the analysis of samples collected in a Citizen Science campaign. Results from this study demonstrated that superficial waters may retain biological traces of this cetacean despite the fact that it mostly inhabits deep waters. Specifically, this study provides evidence of the regular presence of Cuvier’s beaked whale in the Canyon of Caprera, with a preference for bathymetry in the range of 700–1000 m. Molecular traces’ distribution suggests a potential inshore movement of this species during Fall, which might be related to migration of its cephalopod prey or a shift in prey preferences, although this aspect requires further investigation. Overall, this study showed that the stronger positive signals were recorded in sampling stations located on surfaces above submarine canyon systems, demonstrating the importance of these areas as elective habitats for the Cuvier’s beaked whale, thus the pivotal priority to their conservation.

A review of Eunicoidea (Annelida) from Falkland Islands waters including a new species of Hyalinoecia

Abstract Historic species records of the families Onuphidae and Eunicidae, from the Falkland Islands region, are reviewed and updated, new records added from intertidal and nearshore localities on and around the Falkland Islands, and a new species of Hyalinoecia described. Eight genera are reported from around the region including eight taxa of Onuphidae and two of Eunicidae, although most are only known from deep offshore waters. Kinbergonuphis dorsalis is re-described from type material, Kinbergonuphis sp. from the Falkland Islands is described and discrepancies between the two descriptions are examined. Hyalinoecia falklandica sp. nov. is described and the history of the genus and its misidentification in the region is discussed. The new species is distinguished from all other species in the genus through a combination of simple, unidentate falcigers on chaetigers 1 and 2, ventral cirri present to chaetigers 3 or 4, and branchiae present from chaetigers 26 or 27 to the end of the body. The historic record of Marphysa aenea from the Falkland Islands is also shown to be a misidentification and the actual, as-yet-undetermined species present is described. Problems surrounding a correct identification of Marphysa species, other species that do not quite fit current descriptions, and additional Eunicoidea taxa that might be expected to occur in the region are also discussed.

Investigation of flow and viscosity characteristics of hydrate slurries within a visual-loop system

With the gradual advancement of oil and gas exploration into deep offshore, the hydrate blockage has emerged as a critical concern for the flow assurance. We conducted constant-velocity hydrate formation and variable-velocity rheology experiments with a novel visual-loop to analyze slurry flow and viscosity change in pipelines. Results showed staged pressure variations during hydrate formation-aggregation-deposition process, and it could be analyzed judiciously with a developed viscosity model. Initially, hydrates dispersed as small flocculent particles with minor aggregation, gradually raising differential pressure, and the critical viscosity model parameter, hydrate aggregation rate (m) was <1. Subsequently, particle aggregation and wall adhesion dominated, resulting in reduced hydrate flow volume and possible blockage of special pipelines (e.g., dead-leg), with m-values >1. Finally, as hydrate growth continued, substantial adhesion to the pipeline reduced flow diameter, significantly increasing blockage risk. However, the addition of sufficient surface-active ingredients improved hydrate dispersibility and enabled the slurry to maintain the first stage, exhibiting long-term stability with an m-value <1. Additionally, the apparent viscosity of the hydrate slurry within the pipeline was accurately determined utilizing a novel approach, accounting for its yield-pseudoplastic behavior. The calculated viscosities closely matched post-sampling rheometer measurements, and were effectively predicted by the developed viscosity model.

Formation damage challenges and solutions in cased hole gravel pack completions in deep offshore unconsolidated laminated sandstone formations in the Sakarya Field

A comprehensive experimental formation damage study for the Sakarya Field was conducted to identify production impairment mechanisms induced by operational fluids. The study reveals that the retention of operational fluids leads to irreversible reductions in gas permeability to a certain degree. This fluid retention is associated with the amount of loss and retention time of operational fluids into the reservoir, as well as the types of clays present in the gas bearing zone. Fluid retention damage is more severe for samples with lower permeability and higher silt content. While sandy plugs typically experience a reduction in permeability of less than 10%, low-permeability silty samples can exhibit reductions as high as 35%. The most effective approach to minimize this damage includes maintaining the lowest possible overbalance pressure, applying completion methodologies with minimal fluid invasion, and ensuring timely and effective cleanup. Another source of damage appears to result from acidic dissolution of native carbonate minerals and destabilization of delicate clays (e.g., chlorite). This leads to slight compaction and associated immediate reduction in permeability, reaching as high as 50% when combined with other operational fluid damage in some cases. In such environments, it is recommended to use a milder alternative acid solution that specifically targets the filter cake and debris around perforations, minimizing the dissolution of native carbonate minerals and interaction with clays. Due to the low uniaxial compressive strength (UCS) of the formation, evidence of sanding and proppant embedment was observed. To mitigate this issue, an optimum gravel pack design and execution during well completion is vital. Additionally, avoiding abrupt bean-up and bean-down during well tests and production will help limit sanding and proppant embedment. The novel experimental methodology and field implications derived from this study may serve as a guideline to solve formation damage challenges in similar fields facing similar issues. Initiating such detailed studies in the early stages of field development is critical to ensure maximum recovery from the least damaged and disturbed reservoirs.

Common Ground: The Unique Synergy Between the Oil Field and Aerospace

Though disparate locations, outer space and the oil field have much more in common than one might think. Both can be taxing on operations and often redefine the idea of an isolated and, at times, hostile work environment. Harsh atmospheric conditions and wide-ranging pressure regimes call for unique technological applications and operations to achieve the best performance and results, whether it’s the gravitational and meteorological challenges of another planet or the crushing pressures and changing meta-ocean conditions of the deep offshore. Despite the obvious differences, operating in both the terran oil field and the blackness of space offer hurdles that can be cleared by similar means. Shared technologies between the two industries have been around for decades and center around disciplines like automation, robotics, and remote sensing. The National Aeronautics and Space Administration (NASA) itself has dabbled in oilfield studies, especially when it comes to greenhouse gas emissions and their impact on the atmosphere. In 2021, the agency’s Jet Propulsion Laboratory, along with the University of Arizona and Arizona State University, completed a study to identify methane super-emitters in the Permian Basin. The month-long, airborne study concluded that fixing the worst leaks identified in the area’s infrastructure could cut methane emissions by 55 tons an hour, equivalent to 5.5% of the US Environmental Protection Agency’s estimates of all methane emissions from hydrocarbon production across the entire US. The study pointed to malfunctioning equipment as the likely culprit for the 123 sources found. Conversely, NASA has also tapped into oilfield technology for some of its planned drilling operations on the moon. It will be the first such operation on any planetary body outside of the Earth. One of the earliest directives of NASA’s Artemis program is to try and find water near the lunar South Pole. Polar Resources Ice Mining Experiment-1 (PRIME-1) will be the first in-situ resource utilization demonstration on the moon. For the first time, NASA will robotically sample and analyze for ice from below the surface. PRIME-1 will use TRIDENT (The Regolith and Ice Drill for Exploring New Terrain) to drill in a single location at a site with a high likelihood of having water, whether in liquid or ice form. TRIDENT was developed and supplied by Honeybee Robotics, which also supplies geotechnical tools and sensors, among other tech, to the oil patch. The system, to be integrated into VIPER, NASA’s first robotic moon rover, will drill about a meter below the surface, each time bringing up samples that NASA will analyze with a mass spectrometer. The launch of the NOVA-C, which carries the PRIME-1, was previously delayed. At press time, the payload was due to blast off on board Space X’s Falcon 9 rocket in early 2024. NASA said in October the VIPER will reach its destination at Mons Mouton near the lunar South Pole in November 2024.

Heat treatment effects on collapse of JCO-E steel pipes under external pressure: Experiments and numerical predictions

The paper examines the collapse resistance of thick-walled steel pipes, candidates for deep offshore applications, fabricated with the JCO-E process. It describes primarily a combined experimental, numerical and analytical work on the collapse of two JCO-E pipes, a 30-inch-diameter X60 pipe and a 24-inch-diameter X65 pipe, both with D/t ratio approximately equal to 20 and focuses on the effects of heat treatment. The JCO-E pipes are subjected to full-scale external pressure testing, which determines their collapse (ultimate) and propagation pressure. Prior to testing, both pipes have been subjected to a thermal heating, similar to the typical heating conditions for the application of a 3-layer coating system (i.e. 3-layer polypropylene system). Initial ovality and thickness measurements along the pipes have also been obtained. Furthermore, strip specimens, extracted from the ”as fabricated” and ”heat treated” pipes, have been subjected to uniaxial testing, so that the corresponding material properties are measured. In addition to experimental work, numerical calculations are performed using nonlinear finite element models that simulate the collapse testing procedure and employ the measured material properties. The experimental and numerical results on collapse and propagation pressure of the pipes are compared with the corresponding predictions of the DNV-ST-F101 standard, and the value of fabrication factor αfab is discussed. Finally, a numerical study is conducted to investigate the effect of yield strength recovery, due to heat treatment, on collapse of pipes with different values of D/t.

Biosurfactant from a thermo-halophilic strain of Bacillus alveayuensis isolated from a Brazilian oil reservoir: Production, chemical characterization, antimicrobial activity, and efficiency in wettability reversal and oil removal from oil-soaked sand.

Biosurfactants (BS) are amphiphilic molecules from microbial secondary metabolism capable of reducing surface and interfacial tension between non-miscible phases, thus having a wide range of industrial and environmental applications. In this context, the present work aimed to study the biosurfactant produced by the bacterial strain Ar70C7-2, isolated from rocky samples of a deep offshore Brazilian oil reservoir, to evaluate its application in the oil industry. Its optimized production conditions, chemical structure, stability in extreme conditions, surface-active properties in porous media, and antibacterial action were evaluated. Strain Ar70C7-2 showed 100% similarity to Bacillus alveayuensis and was able to produce 0.27 g/L of crude BS in the Mineral Medium with glycerin and NH4NO3 at a ratio of 2, under fixed conditions of 70 g/L NaCl, incubation at 55 °C, and no stirring. The semi-purified BS presented emulsification index (E24) above 55%, surface tension of 31.8 mN/m, interfacial tension (against n-hexadecane) of 17.6 mN/m and CMC of 65 mg/L. The BS belongs to the class of lipopeptides, with a protein composition of 7% and fatty acid chain ranging from C14 to C18, with homologue C16 as the most abundant. Mass spectra of BS indicate the presence of surfactin, iturin, and fengycin families. Semi-purified BS was able to remove approximately 30% of the motor oil (10W40) present in oil-soaked sand, as tested by the contaminated sand washing method; it also promoted the alteration of carbonate wettability, as demonstrated in the flotation test and by the Washburn method. BS inhibited growth of the sulfate-reducing bacteria (SRB) Desulfovibrio marinus BRS-1 at concentrations of 2250 μg/mL and showed bactericidal action at concentrations of 2500 μg/mL. These results demonstrate that the biosurfactant produced by strain Ar70C7-2 has the potential for application in MEOR, bioremediation, and controlling SRB growth, encouraging further studies to validate its prospect in laboratory and field conditions.

Intelligent Production Prediction of Deep Offshore Hydrocarbon Reservoir: A Case Study of Niger-Delta Region of Nigeria

Current methods for predicting output, such as material balancing and numerical simulation, need years of production history, and the model parameters employed determine how accurate they are. The use of artificial neural network (ANN) technology in the production forecasting of a deep offshore field under water injection/water flooding in Nigeria’s Niger-Delta region is investigated in this study. Oil, water, and gas production rates were predicted using well models and engineering features. Real-world field data from producer and water injection wells in deep offshore is used to test the models’ performance. Ninety percent (90%) of the historical data were utilised for training and validating the model framework before being put to the test with the remaining information. The predictive model takes little data and computation and is capable of estimating fluid production rate with a coefficient of prediction of more than 90%, with simulated results that match real-world data. The discoveries of this work could assist oil and gas businesses in forecasting production rates, determining a well’s estimated ultimate recovery (EUR), and making informed financial and operational decisions.

An Examination of Drill Rig NOx Emission

This article creates awareness of greenhouse gases (GHG). The greenhouse gases play a significant role in climate change. The GHG includes NOx which is N2O, NO, and NO2. NOx can be produced from several human activities, including agricultural practices and drill rigs engine activities. However, drill rig emissions have received limited attention in Nigeria compared to agricultural emissions. This article addresses this research gap by examining the production of NOx emissions from drill rigs in Nigeria and its contributing effects. It also discusses the effects of climate change, which include increases in temperature, rainfall, rising sea levels, and the incidence of flooding. Storm aberrations, shortages of usable land, and potable water accompany this. The study adopts a methodology based on the correlation established by Russell (2006) to derive formation emission factors for onshore, offshore, and deep offshore Nigerian wells. The formation emission factors are based on the number of wells drilled in these locations from 2002 to 2004 and the average depth of wells in these locations. The analysis reveals that while NOx levels in Nigeria are currently low, they exhibit a constant upward trend. This observation is significant for a country heavily reliant on the petroleum industry for foreign exchange earnings and economic stability. Furthermore, considering Nigeria's vulnerability to the impacts of climate change and associated hazards, understanding the effect of drill rig NOx emissions and its production becomes crucial. By shedding light on this overlooked aspect, this research contributes to a more comprehensive understanding of the environmental implications and sustainable practices in Nigeria's petroleum sector.

Spatial and seasonal distribution of particulate phosphorous and nitrogen in the Persian Gulf: Nitrogen enrichment ties to diazotroph bloom in stratified warm waters

Understanding the particulate organic and inorganic forms of nutrients and their elemental stoichiometry in suspended particulate matter of marginal seas has important implications in several areas. Here, we present the findings from two consecutive research expeditions conducted in September 2021 and January 2022 aboard the Persian Gulf Explorer research vessel, focused on the particulate P and N in the Persian Gulf and the Strait of Hormuz. The prominent features of spatial and seasonal distribution characteristics were nearshore-offshore decreasing gradients in particulate nutrients, the summer-to-winter declining trend in particulate nutrients more notably for particulate organic nitrogen, and higher biomass N:P ratio in summer than in winter with high spatial inhomogeneity. The trends were mainly governed by shallow remineralization of organic matter, resuspension of fine sediments, summer stratification/winter mixing of the water column, and inflow of the Indian Ocean Surface Waters from the Gulf of Oman. The contribution of inorganic N in the particulate pool of N (1.8% in summer and 1.3% in winter) was much less than the contribution of inorganic P in the particulate pool of P (23.0% in summer and 32.4% in winter), and hence the biomass N:P was higher than the corresponding bulk N:P by a factor of ∼1.5. Seasonal pattern in biomass N:P was similar to those observed at many sites being higher in the summer and lower in the winter. The formation of summer thermocline, characterized by high surface temperature (∼33 °C) and limited upward flux of remineralized inorganic nutrients, coincided with the proliferation of nitrogen-fixing cyanobacteria. Samples collected from the deep offshore region in summer showed significantly higher biomass N:P ratio, reaching up to 47, which is far beyond the classical Redfield ratio of 16. The central Persian Gulf experienced less seasonal variations than the deep region in the western Persian Gulf, the northwestern Arvand estuary, and the northwestern Gulf of Oman.

An Overview of Downhole Electrical Machines and their Benefits

– New technology to the deeper offshore areas and to the exploitation of deep offshore reservesand deep offshore reserves must offer safe, economically viable and ecologically acceptable solutions toincrease oil and gas recoveries. The use of electricity in downhole applications has shown to be beneficial.This article discusses the advantages of electrical machines in downhole applications that are alreadyavailable or developing. For downhole applications, permanent magnet devices are mostly used.

Fossil Benthic Foraminifera in the Nakdong River Delta (Southeast Korea) and off Fukuoka (Southwestern Japan) during the Early Holocene –Responses of the Neritic Faunas Under the Holocene Rapid Sea-Level Rise–

We studied fossil benthic foraminifera in three and seven sediment cores from the Nakdong River delta and of off Fukuoka, respectively, to assess sedimentation along the coasts of the strait between Korea and Japan during the early Holocene. Fossil benthic foraminifera in coarse-grained deposits/sandy sediments from ∼9.4–9.3 ka in cores ND-01 and KND-3 of the Nakdong River delta are characterized by a mixture of shallow-water and offshore species. These data suggest the development of transgressive deposits at ∼9.4–9.3 ka, likely associated with sea-level rise driven by the rapid retreat of glaciers at high latitudes (e.g. Laurentide Ice Sheet). Off Fukuoka, two clusters represent high-energy conditions characterized by common occurrences of attached benthic foraminifera; these clusters became dominant in the upper parts of our study intervals. Such attached species occurred commonly earlier, at around 10 ka, at deep offshore sites (> 60 m water depth) relative to shallow sites (< 60 m water depth). These findings are consistent with the development of current-dominated deposits at deep offshore sites at around 10 ka. Transgressive deposits in the Nakdong River delta and abundant attached species off Fukuoka at around 9 ka likely resulted from sea-level rise along the coasts of the strait between Korea and Japan driven by intermittent enhancement of the Tsushima Warm Current.

Application of nano-silica in offshore oil wells cementation

The oil and gas market is worth billions of dollars annually. Costs increase throughout the drilling process, from initial exploration through improved oil recovery and production (EOR). Exploration, drilling, cementation, production, enhanced oil recovery (EOR), and other areas of the oil and gas industry stand to benefit greatly from nanotechnology. Nanotechnology may help alleviate some issues with cement slurry. Nano-silica is an excellent alternative to commonly used additives like calcium. Since the quantity of nano-silica needed varies from that of Calcium, chloride and silica are employed instead. Both chloride and silica have very little differences. Nano-silica can be used for a variety of purposes. Cement slurry with nano-silica added has a shorter thickening time, higher compressive strength, lower porosity and permeability, and less fluid loss. Maximum cementation and well integrity can be achieved with nano-silica. Nano-silica shortens the WOC time, which in turn lowers the total capital expenditures. For extremely deep offshore wells, nano-silica is a must-have. Many people have been thinking about using nanotechnology in the oil industry recently. Strength, microstructure, and durability are just some of the cement properties that have been shown to improve when nanoparticles are included into the matrix. To achieve the goals of this study, we review the literature on the application of nanotechnology in the petroleum industry, focusing on the use of nano-silica in cementing oil wells. The effects of silica nanoparticles on the properties of both uncured and cured cement are investigated and reported. The use of nano-silica into cement improved its performance, the study found, by ensuring proper zonal isolation and lengthening well life.

The early evolution of the Neotethys in the eastern Mediterranean area: implication of new evidence from the Levant basin and margin

Analysis and re-evaluation of recently obtained data from seismic reflection surveys and deep offshore and onland boreholes from the continental margin of Israel and the adjacent Levant basin, combined with pre-existing data, provide significant new insight into their early, Triassic to Middle Jurassic, development. Thick Middle Jurassic and older sediments in the Levant basin next to Israel cover a substantial relief of a pre-existing thin crust that was shaped in the Middle Triassic or earlier times. In the Levant margin near the present-day coastal area and further onshore the early development of the basin was accompanied by two major deformation phases, in the Triassic and in the Middle Jurassic, separated by a period (much of the Late Triassic and Early Jurassic) in which deformation and subsidence slowed down considerably or ceased. In contrast, in the Mt Carmel area conspicuous faulting and magmatism took place in the Late Triassic (older history unknown); that is, during the period of tectonic quiescence farther south, implying significantly different evolution of this and the more southern parts of the margin. Few Triassic igneous rocks are known onshore Israel, but widespread Late Triassic submarine volcanic rocks, associated with deep-marine sediments, were documented in the remnants of the northern extension of the Levant basin in the present-day area of Turkey and Cyprus, which probably represent the same regional tectonic phase. Renewed subsidence of the Levant margin and adjacent lands since the late part of the Early Jurassic was associated with renewed faulting along the Levant margin and in the adjacent lands, involving significant changes in the deformation pattern. A Middle Jurassic continental slope, &gt;1 km high from top to base, developed along the Levant margin and deep-water conditions in the adjacent basin were established. This configuration is expected to have existed also in earlier times, in association with the formation of the basin's thin crust next to the much thicker crust beneath the bordering continental area, but evidence for the earlier depositional history is limited by the lack of deep seismic and well data. In view of the extensive evidence presented here, a Cretaceous age for the formation of the Levant basin and margin that was recently suggested appears to be unlikely.

First Report of Sphenothallus Hall (Cnidaria, Medusozoa) from the Mesozoic Erathem (Upper Triassic, Slovenia)

Sphenothallus Hall, 1847, one of the most widely distributed and longest ranging genera in the fossil record, has been documented from all systems of the Paleozoic Erathem except the Permian (Table 1), although it has been stated (e.g., Choi, 1990; Bolton, 1994; Fatka et al., 2012) that the genus also occurs in that system. At present the first appearance of this epibenthic, polypoid medusozoan cnidarian lies in Cambrian Stage 3, while the previously known youngest occurrences are in the Pennsylvanian System. Sphenothallus has been found in numerous formations on all continents except Australia and Antarctica. It occurs in a variety of marine facies ranging from shallow nearshore to deep offshore and has even been found in strata of coastal lacustrine origin, probably as an allochthonous element (Lerner and Lucas, 2011). Many of the rock units known to contain Sphenothallus also contain conulariids (Table 1), an extinct group of marine scyphozoans that may have been closely related to Sphenothallus (Van Iten et al., 1992, 1996). Van Iten et al. (1992) interpreted Sphenothallus as a medusozoan cnidarian of uncertain class-level affinities, but later Dzik et al. (2017) documented internal peridermal structures that may be homologous to similar features in the periderm of coronate scyphozoans (see for example illustrations in Van Iten, 1992, and Van Iten et al., 1996).