Search Results (188)

Τhe Greek Seas are one of the most favorable locations for offshore wind energy development in the Mediterranean basin. In 2023, the Hellenic Hydrocarbons & Energy Resources Management Company SA published the draft National Offshore Wind Farm Development Programme (NDP-OWF), including the main pillars for the design, development, siting, installation, and exploitation of offshore wind farms, along with the Strategic Environmental Impact Assessment. The NDP-OWF is under assessment by the relevant authorities and is expected to be finally approved through a Joint Ministerial Decision. In this work, the preliminary offshore wind energy assessment of the Greek Seas is performed using the CERRA wind reanalysis data and in situ measurements from six offshore locations of the Greek Seas. The in situ measurements are used in order to assess the performance of the reanalysis datasets. The results reveal that CERRA is a reliable source for preliminary offshore wind energy assessment studies. Taking into consideration the potential offshore wind farm organized development areas (OWFODA) according to the NDP-OWF, the study of the local wind characteristics is performed. The local wind speed and wind power density are assessed, and the wind energy produced from each OWFODA is estimated based on three different capacity density settings. According to the balanced setting (capacity density of 5.0 MW/km²), the annual energy production will be 17.5 TWh, which is equivalent to 1509.1 ktoe. An analysis of the wind energy correlation, synergy, and complementarity between the OWFODA is also performed, and a high degree of wind energy synergy is identified, with a very low degree of complementarity. Full article

The Copernicus European Regional Reanalysis (CERRA) was released in August 2022, providing a continental atmospheric reanalysis, and, in addition, the New European Wind Atlas (NEWA) is a recently released hindcast product that can be used to create a high temporal and spatial resolution wind resource atlas of Europe. In order to demonstrate the suitability of the NEWA and CERRA wind datasets for offshore wind energy applications, the accuracy of these datasets was assessed for the Mediterranean Sea, a basin with a high potential for the development of offshore wind projects. Long-term in situ measurements from 13 offshore locations along the basin were used in order to assess the performance of the CERRA and NEWA wind speed datasets in the hourly and seasonal time scales by using a variety of different evaluation tools. The results revealed that the CERRA dataset outperforms NEWA and is a reliable source for offshore wind energy assessment studies in the examined areas, although special attention should be paid to extreme value analysis of the wind speed. Full article

Accurate short-term wave forecasting is critical for the safe and efficient operation of marine structures that rely on real-time, phase-resolved ocean wave information for control and monitoring purposes (e.g., digital twins). These systems often depend on environmental sensors (e.g., waverider buoys, wave-sensing LIDAR). Challenges arise when upstream sensor data are missing, sparse, or phase-shifted due to drift. This study investigates the performance of two machine learning models, time-series dense encoder (TiDE) and long short-term memory (LSTM), for forecasting phase-resolved ocean surface elevations under varying degrees of data degradation. We introduce the $\tau$-trimming algorithm, which adapts the prediction horizon based on uncertainty thresholds derived from historical forecasts. Numerical wave tank (NWT) and wave basin experiments are used to benchmark model performance under short- and long-term data masking, spatially coarse sensor grids, and upstream phase shifts. Results show under a 50% probability of upstream data loss, the $\tau$-trimmed TiDE model achieves a 46% reduction in error at the most upstream target, compared to 22% for LSTM. Furthermore, phase misalignment in upstream data introduces a near-linear increase in forecast error. Under moderate model settings, a ±3 s misalignment increases the mean absolute error by approximately 0.5 m, while the same error is accumulated at ±4 s using the more conservative approach. These findings inform the design of resilient, uncertainty-aware wave forecasting systems suited for realistic offshore sensing environments. Full article

CO₂ geo-storage is a promising approach in reducing greenhouse gas emissions and controlling global temperature rise. Although numerous studies have reported that offshore saline aquifers have greater storage potential and safety, current suitability evaluation models for CO₂ geo-storage primarily focus on onshore saline aquifers, and site-level evaluations for offshore CO₂ geo-storage remain unreported. In this study, we propose a framework to evaluate the site-level offshore CO₂ geo-storage suitability with a multi-tiered indicator system, which considers three types of factors: engineering geology, storage potential, and socio-economy. Compared to the onshore CO₂ geo-storage suitability evaluation models, the proposed indicator system considers the unique conditions of offshore CO₂ geo-storage, including water depth, offshore distance, and distance from drilling platforms. The Analytic Hierarchy Process (AHP) and Fuzzy Comprehensive Evaluation (FCE) methods were integrated and applied to the analysis of the Ying–Qiong Basin, South China Sea. The results indicated that the average suitability score in the Yinggehai Basin (0.762) was higher than that in the Qiongdongnan Basin (0.691). This difference was attributed to more extensive fault development in the Qiongdongnan Basin, suggesting that the Yinggehai Basin is more suitable for CO₂ geo-storage. In addition, the DF-I reservoir in the Yinggehai Basin and the BD-A reservoir in the Qiongdongnan Basin were selected as the optimal CO₂ geo-storage targets for the two sub-basins, with storage potentials of 1.09 × 10⁸ t and 2.40 × 10⁷ t, respectively. This study advances the methodology for assessing site-level potential of CO₂ geo-storage in offshore saline aquifers and provides valuable insights for engineering applications and decision-making in future CO₂ geo-storage projects in the Ying–Qiong Basin. Full article

The Davie Fracture Zone (Davie FZ)—among the longest offshore transform systems in East Africa—mediated Madagascar’s southward displacement following Gondwana’s Early Jurassic breakup. This giant structure has a distinct topography and gravity field signals. However, it is buried by thick sediments in its northern segment offshore Tanzania, hindering understanding of the internal structures and their origin. In this study, we applied 2-D multichannel seismic to analyze the structural characteristics and evolution of the Davie FZ. The Davie FZ is located in the oceanic domain, which is bordered by the landwards-dipping overthrust fault at the continent–ocean boundary. Volcano sediments atop the basement with undulating Moho reflection below depict a typical oceanic domain. Distinct compressive deformation characterized by the crustal undulation of around 40 km wavelength forms folded oceanic crust, and Late Jurassic sediments onlap onto the crest of the folded basement. The Davie FZ is localized in a corridor with the thickened oceanic crust and is presented by positive flower structures with faulted uplifted basement and deepened Moho. The Davie FZ evolved from a proto-transform fault located in Gondwana before the spreading of the West Somali Basin. During the Late Jurassic, a kinematic change shifted the spreading direction from NW–SE to N–S, resulting in a strike-slip of the Davie FZ and contemporaneous transpressional deformation offshore Tanzania. The Davie FZ is an excellent case to understand the tectonic-magmatic process forming this transform margin. Full article

In recent years, significant exploration successes and research progress in volcanic hydrocarbon reservoirs across China’s offshore basins have highlighted their importance as key targets for deep hydrocarbon exploration. In the Shimentan Formation of the Xihu Sag, East China Sea Shelf Basin (ECSSB), low-yield gas flows have been encountered through exploratory drilling; however, no major reservoir breakthroughs have yet been achieved. Assessing the large-scale reservoir potential of volcanic sequences in the Shimentan Formation is thus critical for guiding future exploration strategies. Based on previous exploration studies of volcanic reservoirs in other Chinese basins, this study systematically evaluates the hydrocarbon potential of these volcanic units by microscopic thin section identification, major element analysis, integrates drilling data with seismic interpretation techniques—such as coherence cube slicing for identifying volcanic conduits, dip angle analysis for classifying volcanic edifices, and waveform classification for delineating volcanic lithofacies. The main findings are as follows: (1) The Shimentan Formation is primarily composed of intermediate to acidic pyroclastic rocks and lava flows. Volcanic facies are divided into three facies, four subfacies, and six microfacies. Volcanic edifices are categorized into four types: stratified, pseudostratified, pseudostratified-massive, and massive. (2) Extensive pseudostratified volcanic edifices are developed in the Hangzhou Slope Zone, where simple and compound lava flows of effusive facies are widely distributed. (3) Comparative analysis with prolific volcanic reservoirs in the Songliao and Bohai Bay basins indicates that productive reservoirs are typically associated with simple or compound lava flows within pseudostratified edifices. Furthermore, widespread Late Cretaceous rhyolites in adjacent areas of the study region suggest promising potential for rhyolitic reservoir development in the Hangzhou Slope Zone. These results provide a robust geological foundation for Mesozoic volcanic reservoir exploration in the Xihu Sag and offer a methodological framework for evaluating reservoir potential in underexplored volcanic regions. Full article

The aim of the present work is to assess the wind and hydrogen production capacity of the Black Sea basin from a spatial point of view, by using reanalysis data that covers a 10-year interval (2015–2024). Based on the ERA5 data it was possible to highlight the general distribution of the wind resources at 100 m height, with more consistent resources being noticed in the region of the Azov Sea or in the north-western sector of the Black Sea, where average values of 8.3 m/s are expected. Taking into account that at this moment in the Black Sea area there are no operational offshore wind farms, several generators ranging from 3 to 15 MW were considered for assessment. In this case, from a single turbine, we can expect values in the range of 11.04 GWh (3 MW system) and 89 GWh (15 MW system), respectively. As a next step, the electricity generated from each wind turbine was used to highlight the hydrogen production of several electrolysers systems (or PEMs). The equivalent number of PEMs was identified, and in some cases it was noticed that some devices will not reach their full capacity, while for smaller PEMs a single 10 MW wind turbine could support the operation of almost four modules. Regarding hydrogen output, a maximum of 1560 tons/year can be expected from the PEMs connected to a 15 MW wind turbine. Full article

Giant clams are ecologically important coral reef animals, with many species facing imminent local extinction. While many regions have undertaken recent assessments of their biodiversity assets, persistent gaps remain even in otherwise well-surveyed areas. This study sought to understand the geographic distribution of smaller-bodied and morphologically similar giant clams, specifically Tridacna maxima and T. noae, in the eastern Indian Ocean. Due to the difficulties in reliably identifying these species using morphological characters, we confirmed species identity and investigated intraspecific variation using sequence data from the mitochondrial cytochrome C oxidase subunit I gene (COI). Seventy whole animal vouchers were newly sampled from a 1500 km span of remote northwestern Australian coastline over a decade, as part of an ongoing coral reef survey expedition of the Western Australian Museum and partners. Tridacna maxima had a limited distribution and was only genotyped from offshore oceanic reefs in the Rowley Shoals and Cocos Keeling Islands. In contrast, T. noae was well established beyond Ningaloo Reef, and was abundant at inshore sites throughout the Pilbara and Kimberley, and even offshore to Ashmore Reef. Phylogeographically, T. maxima did not group with conspecifics from the Western Pacific Ocean, including the east coast of Australia, but instead clustered with individuals from Malaysia, China, Taiwan, and Indonesia; T. noae exhibited a similar pattern. The affinity of Western Australian individuals with representatives from the Indo-Malay region and not eastern Australia will be an important consideration for these commercially important species. Novel haplotypes in both tested species occur in Western Australia. Continued sampling of eastern and central Indian Ocean giant clams, especially to continue to document the range of T. noae, is encouraged to understand connectivity in this basin. Together, these findings contribute to an improved baseline for conservation initiatives of these iconic coral reef animals in Western Australia. Full article

In recent years, the twin-barge float-over method has been widely used in offshore installations. This paper conducts numerical simulation and experimental research on the twin-barge float-over installation of offshore wind turbines (TBFOI-OWTs), focusing primarily on seakeeping performance, and also explores the influence of the gap distance on the hydrodynamic behavior of TBFOI-OWTs. Model tests are conducted in the ocean basin at Tsinghua Shenzhen International Graduate School. A physical model with a scale ratio of 1:50 is designed and fabricated, comprising two barges, a truss carriage frame, two small wind turbines, and a spread catenary mooring system. A series of model tests, including free decay tests, regular wave tests, and random wave tests, are carried out to investigate the hydrodynamics of TBFOI-OWTs. The experimental results and the numerical results are in good agreement, thereby validating the accuracy of the numerical simulation method. The motion RAOs of TBFOI-OWTs are small, demonstrating their good seakeeping performance. Compared with the regular wave situation, the surge and sway motions in random waves have greater ranges and amplitudes. This reveals that the mooring analysis cannot depend on regular waves only, and more importantly, that the random nature of realistic waves is less favorable for float-over installations. The responses in random waves are primarily controlled by motions’ natural frequencies and incident wave frequency. It is also revealed that the distance between two barges has a significant influence on the motion RAOs in beam seas. Within a certain range of incident wave periods (10.00 s < T < 15.00 s), increasing the gap distance reduces the sway RAO and roll RAO due to the energy dissipated by the damping pool of the barge gap. For installation safety within an operating window, it is meaningful but challenging to have accurate predictions of the forthcoming motions. For this, this study employs the Whale Optimization Algorithm (WOA) to optimize the Long Short-Term Memory (LSTM) neural network. Both the stepwise iterative model and the direct multi-step model of LSTM achieve a high accuracy of predicted heave motions. This study, to some extent, affirms the feasibility of float-over installation in the offshore wind power industry and provides a useful scheme for short-term predictions of motions. Full article

This study examined a sediment plume from Australia’s largest river, The River Murray, which was produced during a major flood event in 2022–2023. This flood resulted from successive La Niña events, causing high rainfall across the Murray–Darling Basin and ultimately leading to a significant riverine flow through South Australia. The flood was characterised by a significant increase in riverine discharge rates, reaching a peak of 1305 m³/s through the Lower Lakes barrage system from November 2022 to February 2023. The water quality anomaly within the coastal region (<~150 km offshore) was effectively quantified and mapped utilising the diffuse attenuation coefficient at 490 nm (Kd490) from products derived from MODIS Aqua Ocean Color satellite imagery. The sediment plume expanded and intensified alongside the increased riverine discharge rates, which reached a maximum spatial extent of 13,681 km². The plume typically pooled near the river’s mouth within the northern corner of Long Bay, before migrating persistently westward around the Fleurieu Peninsula through Backstairs Passage into Gulf St Vincent, occasionally exhibiting brief eastward migration periods. The plume gradually subsided by late March 2023, several weeks after riverine discharge rates returned to pre-flood levels, indicating a lag in attenuation. The assessment of the relationship and accuracy between the Kd490 product and the surface-most in situ turbidity, measured using conductivity, temperature, and depth (CTD) casts, revealed a robust positive linear correlation (R² = 0.85) during a period of high riverine discharge, despite temporal and spatial discrepancies between the two datasets. The riverine discharge emerged as an important factor controlling the spatial extent and intensities of the surface sediment plume, while surface winds also exerted an influence, particularly during higher wind velocity events, as part of a broader interplay with other drivers. Full article

The Guangdong Province is rich in waterways, including those of the Pearl River. The entire watershed of the Pearl River system spans the territory of six provinces. Considering the overarching objective of building a ‘beautiful Bay Area’ under the guidance of Outline Development Plan for the Guangdong-Hong Kong-Macao Greater Bay Area as well as the ecological problems that span over river basins and regions in Guandong Province, public interest litigation is a useful tool in protecting the environment. Analyzing 95 first-instance (trial) judgements handed down in Guangdong Province between 2018 and 2021, we sought to evaluate public interest litigation as a means of safeguarding aquatic ecology in the Greater Bay Area (GBA), China. Cases were categorized for: firstly, their approach to determining the extent of ecological damage; secondly, the procedure used for receiving and auditing restorative compensation; thirdly, the collaboration between the court and government departments in the management and use of restorative compensation; and fourthly, the collaborative ‘public–private’ supervision utilized to monitor the implementation of restorative compensation and actual restoration. Our insights are intended to provide guidance for cooperative opportunities in the large transregional water systems and offshore areas of mainland China. Full article

Installing offshore wind jackets faces increasing risks from dynamic marine conditions and is challenged by trajectory deviations due to coupled hydrodynamic and environmental factors. To address the limitations of software, such as long simulation times and tedious parameter adjustments, this study develops a rapid prediction model combining Radial Basis Function (RBF) and Backpropagation (BP) neural networks. The model is enhanced by incorporating both numerical simulation data and real-world measurement data from the launching operation. The real-world data, including the barge attitude before launching, jacket weight distribution, and actual environmental conditions, are used to refine the model and guide the development of a fully parameterized adaptive controller. This controller adjusts in real time, with its performance validated against simulation results. A case study from the Pearl River Mouth Basin was conducted, where datasets—capturing termination time, six-degrees-of-freedom motion data for the barge and jacket, and actual environmental conditions—were collected and integrated into the RBF and BP models. Numerical models also revealed that wind and wave conditions significantly affected lateral displacement and rollover risks, with certain directions leading to heightened operational challenges. On the other hand, operations under more stable environmental conditions were found to be safer, although precautions were still necessary under strong environmental loads to prevent collisions between the jacket and the barge. This approach successfully reduces weather-dependent operational delays and structural load peaks. Hydrodynamic analysis highlights the importance of directional strategies in minimizing environmental impacts. The model’s efficiency, requiring a fraction of the time compared to traditional methods, makes it suitable for real-time applications. Overall, this method provides a scalable solution to enhance the resilience of marine operations in renewable energy projects, offering both computational efficiency and high predictive accuracy. Full article

Routine core permeability and porosity are crucial in assessing flow units within a reservoir because they define a reservoir’s storage and flow capacities. A limited amount of work has been conducted on the lower cretaceous (Barremian to Valanginian) sandstones in the Bredasdorp Basin, offshore South Africa, focusing on the flow zones and the possible effect of diagenetic minerals on the individual flow zones, limiting understanding of reservoir quality and fluid flow behavior across the field. Nine hundred routine core analysis datasets were used to determine the flow units within the reservoir from three wells (F-A10, F-A13, and F-O2) from independent methods, namely: the Pore Throat Radius, Flow Zone Indicator, Stratigraphic Modified Lorenz Plot, and Improved Stratigraphic Modified Lorenz Plot. The results showed six flow units: fracture, super-conductive, conductor, semi-conductor, baffle, and semi-barrier. The super-conductive flow units contributed the most flow, whereas the semi-barrier and baffle units contributed the least flow. Petrography analyses revealed that the diagenetic minerals present were smectite, illite, glauconite, siderite, micrite calcite, and chlorite. The pore-filling minerals reduced the pore spaces and affected pore connectivity, significantly affecting the flow contribution of the baffle and semi-barrier units. Micrite calcite and siderite cementation in FU5 of F-A13 and FU9 of F-O2 significantly reduced the intergranular porosity by filling up the pore spaces, resulting in tight flow units with impervious reservoir quality. It was noted that where the flow unit was classified as super-conductive, authigenic clays did not significantly affect porosity and permeability as they only occurred locally. However, calcite and silica cementation significantly affected pore connectivity, where the flow unit was classified as a very low, tight, semi-barrier, or barrier. Full article

As of 2019, 119 oil and gas fields were involved in the Paleogene of the Bohai exploration area, accounting for more than 85% of the total number of oil and gas fields in the Bohai Bay Basin. Previous studies have confirmed that there are significant differences in the degree of oil and gas enrichment in the Paleogene of the Bohai exploration area. However, how these differences affect the hydrocarbon generation potential, and oil and gas resource distribution in each region has not been thoroughly studied; the controlling factors contributing to these differences have also not been fully elucidated. In view of this, based on the research results of projects on oil and gas exploration in the Bohai Bay Basin over the past decade, this paper statistically analyzed a large amount of data on source rocks, sedimentation rates, etc., and explored the differential enrichment of oil and gas in the Bohai exploration area and its genetic mechanisms. The research shows that from the offshore to the center of the marine area, the Paleogene oil and gas enrichment horizons have the characteristics of changing from old to new; the Paleogene source rocks in the offshore and marine areas have significant differences in thickness, total organic carbon content, organic matter type and maturity, and these differences determine the hydrocarbon generation potential and oil and gas resource distribution in each area; the sedimentary filling process in the Bohai exploration area is mainly controlled by tectonic uplift and subsidence and changes in lake level, and it has experienced stages such as rifting and lake transgression, thus showing obvious differences in provenance and sedimentary reservoirs; three sets of source–reservoir–caprock combinations are developed in the Bohai exploration area, and oil and gas are mainly enriched in the source rock strata and adjacent reservoirs. The middle and upper source–reservoir–caprock combinations have the best configurations, and from the offshore to the marine area, oil and gas show a trend from enrichment in Es3 to enrichment in Es1–Ed. Due to the differences in sag types, there is differential enrichment of oil and gas in the Bohai exploration area. According to the sedimentation rate, the sag types in the study area can be divided into early-developed type, inherited-developed type and late-developed type. The sag types in the Bohai exploration area show the characteristics of gradually changing from the offshore to the late type in the marine area, and there is a good corresponding relationship between the sag types and the vertical enrichment strata of oil and gas. The research results can provide a reference for discussing the oil and gas accumulation laws and future exploration and development of the Bohai exploration area. Full article

The Pearl River Mouth Basin (PRMB) had two potential provenances (intrabasinal and extrabasinal) during the Paleogene Enping Formation period. However, the understanding of their differences in source supply and evolution over time and space is limited due to the regional restriction in borehole coverage. This study aims to address the knowledge gap by utilizing detrital zircon U-Pb dating data, seismic data, and borehole data. Specifically, this study focuses on examining the characteristics of provenance evolution and sedimentary infilling within the Enping Formation in various sags of the northern PRMB. The results indicate temporal and spatial variability in provenance from the lower Ep⁴ and Ep³ to the upper Ep² and Ep¹ Members. The influence of extrabasinal provenance from the South China Block (SCB) was prominent in the northern region of the Zhu I Depression during the deposition of Ep⁴ and Ep³ Members, while intrabasinal provenance from local uplifts remained a significant source for most sags. During this period, sediment transportation occurred over short distances, leading to the widespread development of smaller fan deltas and braided river deltas. In contrast, extrabasinal provenance became dominant during the deposition of Ep² and Ep¹ Members throughout the entire Zhu I Depression. This shift promoted the development of large-scale, shallow, braided river deltas with sediment transported over long distances. The analysis reveals a close correspondence between the shifting provenance and the evolution of sedimentary infilling patterns in the PRMB. As a result, the sags transitioned from being under-filled or balanced-filled to being balanced-filled or over-filled. This study holds immense significance for oil and gas exploration as well as the prediction of favorable sedimentary sand bodies in offshore petroliferous basins. Full article