Marine Gas Hydrate Deposits Study: Temperature Inversion Advantages

<p>The Arctic MArine Geoscience Expedition (AMAGE) program led by the Korea Polar Research Institute (KOPRI) is a multidisciplinary undertaking to investigate the geological environment and methane release phenomena in the Arctic seas. The icebreaking research vessel (IBRV) Araon has carried out three expeditions in the Chukchi Plateau (CP) and the East Siberian Seas in 2016, 2018 and 2019. In the first 2016 expedition, a chain of topographic mounds (with the height of several tens meters and the width of hundreds meters) was identified by subbottom profiler and multibeam bathymetric survey in the western continental slope of the CP. Gas hydrate samples were first retrieved in the Araon Mound-6 among the mound structures in the CP and ESS areas during the expedition. The detailed morphology and subsurface structures of the mounds were mapped from the subsequent expeditions in 2018 and 2019. More gas hydrate samples were obtained in the Araon Mound-3 and Araon Mound-6 in these expeditions. To examine gas hydrate occurrence conditions, we conducted geophysical surveys including seismic (sparker in 2018 and multi-channel in 2019) and heat flow methods during these expeditions. The seismic profiles obtained using two seismic methods show very well-developed bottom simulating reflectors (BSRs) which are widespread on the western slope of the study area. The BSR depths detected on the seismic profiles are well coincided with the depths of the lower boundary of the gas hydrate stability zone calculated from the geothermal gradient of heat flow measurement.</p><p>Arctic gas hydrates are considered to be vulnerable to the ongoing rapid Arctic warming. The AMAGE program will provide comprehensive understanding on poorly-known gas hydrate in the Arctic in the various research fields of geology, geophysics, geochemistry, biogeoscience, and oceanography.</p>

The Double C Block (DCB) is an innovative composite Concrete Masonry Unit (CMU) developed to offer enhanced thermal performance over standard hollow core blocks (HCBs). The DCB features an original design consisting of a polyurethane (PUR) foam inserted between two concrete c-shaped layers, thus acting as the insulating layer and the binding agent of the two concrete elements simultaneously. The purpose of this research is to describe the results obtained when assessing the thermal transmittance (UDCB and UHCB) of these blocks using three different methodologies: theoretical steady-state U-value calculations, numerical simulation using a Finite Element Method (FEM), and in situ monitoring of the U-value by means of the Heat Flow method (HFM). The results obtained show that the three methodologies corroborated each other within their inherent limitations. The DCB showed a performance gap of 52.1% between the predicted FEM simulation (UDCB was 0.71 W/(m2K)) and the values measured via HFM, which converged at 1.47 W/(m2K). Similarly, a gap of 19.9% was observed when assessing the HCB. The theoretical value via FEM of UHCB was 1.93 W/(m2K) and the measured one converged at 2.41 W/(m2K). Notwithstanding this, the DCB showed superior thermal performance over the traditional block thanks to a lower U-value, and it complies with the Maltese building energy code. Further improvements are envisaged.

Sustainable construction materials for low-cost housing: Thermal insulation potential of expanded SBR composites with leather waste

This work outlines the theretical and field activities conducted under the Bulgarian Science Fund Project GEOHydrate: Geothermal evolution of marine gas hydrate deposits - Danube paleodelta, Black Sea. The purpose of this research is to enhance our understanding and perspectives of the study the connection between marine gas hydrate deposits formation and the measured in situ heat flow in seafloor sediments. The aim of the GEOHydrate project is to prove the hypothesis about the existence on the seafloor of measurable temperature and heat flow (T&HF) anomalies above gas hydrates deposits (GHDs) and the possibility to restore the 4D-process of GHDs growth from these anomalies. GEOHydrate data include 2D and 3D seismic and CSEM; in situ heat flow; hydro- and geo-physicochemical measurements; scientific drilling and logging. They are results from the projects BLASON, ASSEMBLAGE, GHASS and specially developed tools and methods for GHDs research from the German projects SUGAR I-III. The applied methods include seismic data interpretation; basin analysis; forward and inverse geothermal problems. The new heat flow approach continues to develop in the EU project DOORS with new cruise data and interpretation. Expected practical results are contribution to direct methods for GHDs search, resource estimation with a high signal-to-noise ratio, and a reduction in the future production costs from proper planning and reducing the number of production wells. Results contribute to mitigating the effects of 3 modern global threats - climate change, clean air, and the cost of energy. European GHDs production is the most prospect and important for Bulgaria and Romania. Acknowledgments: This work was supported by: Bulgarian Science Fund project KP-06-OPR04/7 GEOHydrate “Geothermal evolution of marine gas hydrate deposits - Danube paleodelta, Black Sea” (2018-2023); European Union project 101000518 DOORS: Developing Optimal and Open Research Support for the Black Sea (2021-2025).

Numerical simulations for short-term depressurization production test of two gas hydrate sections in the Black Sea

Temperature changes affect pavement performance such as strength reduction at elevated temperature or crack initiation and development at low thermal conditions. Thermal diffusivity of paving materials is one of parameters helps to determine exactly temperature distribution in pavement structures. Currently, the thermal diffusivity can be determined through thermal conductivity, mass density of material, and specific heat capacity. Nevertheless, the specific heat capacity is quite complicated to obtain for composite materials. Literature reported different experimental methods used for determining the thermal conductivity of building materials such as heat flow method (ASTM C 518), guarded-hot-plate approach (ASTM C 177), hot wire technique (ASTM C 1113), and transient plane heat source solution (ISO 22007-2:2015). However, these methods were found not suitable for pavements due to large granular sizes and heterogeneous properties of pavement materials. This study developed a device to determine the thermal diffusivity of pavement materials in the laboratory without the needs of heat capacity and thermal conductivity of the composites. The temperature distributed in the hot mixed asphalt concrete type 19 having air void content of 9.7%, bitumen content of 4%, and density of 2.14 (T/m3) was first measured by this device. The thermal diffusivity was then determined based on the heat transfer theory, and the result was 4.556 × 10−7(m2/s), consistent with the one from previous studies.

We find all optimisers for the Brascamp-Lieb inequality, thus completing the problem which was settled in special cases by Barthe; Carlen, Lieb and Loss; and Bennett, Carbery, Christ and Tao. Our approach to the solution is based on the heat flow methods introduced by the second and third sets of authors above. We present the heat flow method in the form which is most appropriate for our study and also expand the structural theory for the Brascamp-Lieb inequality as necessary for the description of the optimisers.

The gas hydrate system of the western Black Sea Basin

In-situ borehole temperature measurements confirm dynamics of the gas hydrate stability zone at the upper Danube deep sea fan, Black Sea

Experimental set-up design for gas production from the Black Sea gas hydrate reservoirs

The Black Sea experiences widespread methane-rich gas emissions and elevated hydrogen sulfide concentrations, extending from coastal to deep basin areas. The toxicity of hydrogen sulfide and the powerfull greenhouse gas methane, can lead to local acidification, posing threats to ecosystems. Monitoring these compounds is essential for economic growth tied to Black Sea ecosystem services. Also, the rise in seawater temperatures due to climate change increases the risk of the Black Sea releasing methane stored under gas hydrates form into the atmosphere, potentially becoming a important carbon source.The significant release of methane from the seafloor accentuates environmental apprehensions, playing a role in the creation of the Earth's largest anoxic water body (Kosarev, 2007; Riboulot et al., 2017). This underscores the necessity of investigating the dynamics of these gases and closely monitoring their concentrations to gain a comprehensive understanding of their environmental repercussions.This presentation outlines the fieldwork conducted under the European Project H2020 - DOORS, comprising two field campaigns, METZE and METZE2 (Methane dynamics at Varna lakes and the Zelenska coastal Seeps), which investigated methane dynamics in distinct Black Sea environments, namely Varna Lake and Zelenka gas-seeps. They took place in September 2022 and March 2023. The purpose of this research is to enhance our understanding of the environmental challenges associated with methane concentrations in this unique marine setting. The work initiated a study focused on comprehending methane emissions off the coast of Varna by mapping gas emission sites and measuring their flow rates, taking into account environmental factors such as seasonality and extreme events affecting methane flow rate variability. So, in situ methane sensor deployed for several months at Varna lake indicaticates that the coastal methane fluxes exhibit a noteworthy variability, with daily processes exerting discernible influences on fluxes levels. Also, preliminary findings suggest discernible seasonal fluctuations in both the molecular and isotopic compositions in the water column and sediment pore waters, alongside variations in emission flow rates. AcknowledgementsThe authors thank the different projects and programs for their financial supports: DOORS by the EU Project number 101000518, ORAGGE by Interdisciplinary graduate School for the Blue planet (ANR-17-EURE-0015 and "Investissements d'Avenir"), SEAMLESS by INSU LEFE Programme 2022.ReferencesKosarev, A. N., 2007, The Black Sea Environment, Springer.Riboulot, V., Cattaneo, A., Scalabrin, C., Gaillot, A., Jouet, G., Ballas, G., Marsset, T., Garziglia, S., and Ker, S., 2017, Control of the geomorphology and gas hydrate extent on widespread gas emissions offshore Romania: Bulletin De La Societe Geologique De France, v. 188, no. 4.

Geological control and magnitude of methane ebullition from a high-flux seep area in the Black Sea—the Kerch seep area

The Black Sea hydrogen sulfide inventory is about 4 600×1012 g, which makes this sea the largest anoxic basin on earth. Anoxic conditions in the basin have been established 7 500 years ago. This review presents the contemporary inventory of dissolved sulfide and sulfur intermediates and discusses mechanisms of physical mixing in the anoxic interior. Special emphasis is given to concentrations of dissolved sulfide and other chemical species in the bottom convective layer located at depths below 1 700–1 750 m. The width and concentrations of dissolved sulfide in the bottom layer are directly proportional to the heat flow from the bottom. The mechanism of double diffusion driven by geothermal heat flux is the main mixing process in bottom waters. Hydrogen sulfide production in the water column by sulfate-reducing bacteria is the main source of dissolved sulfide, and sulfate reduction is the dominant process of organic matter mineralization in the Black Sea anoxic zone. Sulfur budget calculations suggest that Bosporus flux cannot be considered to be the major sulfur sink and factor for deep basin ventilation. Mesoscale physical dynamics along the periphery of the basin as well as pycnocline erosion during exceptionally severe winters are probably major ventilation mechanisms for the anoxic zone. The sulfur isotopic studies of the water column also support the importance of ventilation processes below the oxic/anoxic interface. Physical mixing processes and global climate change impact on the thermohaline structure of the Black Sea water column control the magnitude and direction of the processes within the sulfur cycle.

Clumped methane isotopologue-based temperature estimates for sources of methane in marine gas hydrates and associated vent gases

Effect of Sb and In additives on thermal and electrical properties of Sn–9Zn–4Bi alternative lead-free solder alloy