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  • PANGAEA  (51)
  • MDPI  (3)
  • 2020-2024  (54)
Document type
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Year
  • 1
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    An All-At-Once Newton Strategy for Marine Methane Hydrate Reservoir Models (2020)
    MDPI
    Details
    Publication Date: 2023-02-08
    Description: The migration of methane through the gas hydrate stability zone (GHSZ) in the marine subsurface is characterized by highly dynamic reactive transport processes coupled to thermodynamic phase transitions between solid gas hydrates, free methane gas, and dissolved methane in the aqueous phase. The marine subsurface is essentially a water-saturated porous medium where the thermodynamic instability of the hydrate phase can cause free gas pockets to appear and disappear locally, causing the model to degenerate. This poses serious convergence issues for the general-purpose nonlinear solvers (e.g., standard Newton), and often leads to extremely small time-step sizes. The convergence problem is particularly severe when the rate of hydrate phase change is much lower than the rate of gas dissolution. In order to overcome this numerical challenge, we have developed an all-at-once Newton scheme tailored to our gas hydrate model, which can handle rate-based hydrate phase change coupled with equilibrium gas dissolution in a mathematically consistent and robust manner.
    Type: Article , PeerReviewed
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Microscale Processes and Dynamics during CH4–CO2 Guest Molecule Exchange in Gas Hydrates (2021)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: The exchange of CH4 by CO2 in gas hydrates is of interest for the production of natural gas from methane hydrate with net zero climate gas balance, and for managing risks that are related to sediment destabilization and mobilization after gas-hydrate dissociation. Several experimental studies on the dynamics and efficiency of the process exist, but the results seem to be partly inconsistent. We used confocal Raman spectroscopy to map an area of several tens to hundreds µm of a CH4 hydrate sample during its exposure to liquid and gaseous CO2. On this scale, we could identify and follow different processes in the sample that occur in parallel. Next to guest-molecule exchange, gas-hydrate dissociation also contributes to the release of CH4. During our examination period, about 50% of the CO2 was bound by exchange for CH4 molecules, while the other half was bound by new formation of CO2 hydrates. We evaluated single gas-hydrate grains with confirmed gas exchange and applied a diffusion equation to quantify the process. Obtained diffusion coefficients are in the range of 10−13–10−18 m2/s. We propose to use this analytical diffusion equation for a simple and robust modeling of CH4 production by guest-molecule exchange and to combine it with an additional term for gas-hydrate dissociation.
    Type: Article , PeerReviewed
    Format: text
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    Heat Flow Measurements at the Danube Deep-Sea Fan, Western Black Sea (2021)
    MDPI
    Details
    Publication Date: 2024-02-07
    Description: Seafloor heat flow measurements are utilized to determine the geothermal regime of the Danube deep-sea fan in the western Black Sea and are presented in the larger context of regional gas hydrate occurrences. Heat flow data were collected across paleo-channels in water depths of 550–1460 m. Heat flow across levees ranges from 25 to 30 mW m−2 but is up to 65 mW m−2 on channel floors. Gravity coring reveals sediment layers typical of the western Black Sea, consisting of three late Pleistocene to Holocene units, notably red clay within the lowermost unit cored. Heat flow derived from the bottom-simulating reflector (BSR), assumed to represent the base of the gas hydrate stability zone (GHSZ), deviates from seafloor measurements. These discrepancies are linked either to fast sedimentation or slumping and associated variations in sediment physical properties. Topographic effects account of up to 50% of heat flow deviations from average values. Combined with climate-induced variations in seafloor temperature and sea-level since the last glacial maximum large uncertainties in the prediction of the base of the GHSZ remain. A regional representative heat flow value is ~30 mW m−2 for the study region but deviations from this value may be up to 100%.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: text
    Location Call Number Limitation Availability
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Stable oxygen and hydrogen isotopic composition of pore water (δ18O-H2O; δ2H-H2O) prepared from MeBo core GeoB22603-1 recovered from the Danube Deep-Sea Fan (2020)
    PANGAEA
    Details
    Publication Date: 2023-04-27
    Keywords: Black Sea; Center for Marine Environmental Sciences; Danube deep sea fan; DEPTH, sediment/rock; Device type; gas hydrate; GeoB22603-1; light hydrocarbons; M142; M142_03-1; MARUM; MeBo200; Meteor (1986); Methane; Method/Device of event; Optional event label; pore water; RV Meteor; Sample type; Submarine Gas Hydrate Resources; SUGAR; SUGAR project; δ18O, water; δ Deuterium, water
    Type: Dataset
    Format: text/tab-separated-values, 68 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 5
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    Stable oxygen and hydrogen isotopic composition of pore water (δ18O-H2O; δ2H-H2O) prepared from MeBo core GeoB22620-1 recovered from the Danube Deep-Sea Fan (2020)
    PANGAEA
    Details
    Publication Date: 2023-04-27
    Keywords: Black Sea; Center for Marine Environmental Sciences; Danube deep sea fan; DEPTH, sediment/rock; Device type; gas hydrate; GeoB22620-1; light hydrocarbons; M142; M142_21-1; MARUM; MeBo200; Meteor (1986); Methane; Method/Device of event; Optional event label; pore water; RV Meteor; Sample type; Submarine Gas Hydrate Resources; SUGAR; SUGAR project; δ18O, water; δ Deuterium, water
    Type: Dataset
    Format: text/tab-separated-values, 12 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 6
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    Stable oxygen and hydrogen isotopic composition of pore water (δ18O-H2O; δ2H-H2O) prepared from MeBo core GeoB22605-1 recovered from the Danube Deep-Sea Fan (2020)
    PANGAEA
    Details
    Publication Date: 2023-04-27
    Keywords: Black Sea; Center for Marine Environmental Sciences; Danube deep sea fan; DEPTH, sediment/rock; Device type; gas hydrate; GeoB22605-1; light hydrocarbons; M142; M142_06-1; MARUM; MeBo200; Meteor (1986); Methane; Method/Device of event; Optional event label; pore water; RV Meteor; Sample type; Submarine Gas Hydrate Resources; SUGAR; SUGAR project; δ18O, water; δ Deuterium, water
    Type: Dataset
    Format: text/tab-separated-values, 52 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 7
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    Heat flow data during Maria S. Merian cruise MSM34/2 (2020)
    PANGAEA
    Details
    Publication Date: 2023-04-27
    Description: Data for estimating heat flow in the western Black Sea are provided, based on measurements made during Expedition MSM34 (R/V Maria S. Merian). Data are located in the Bulgarian and Romanian Sector of the Black Sea in water depths ranging from 420 to 1500 m. Data were always collected with the GEOMAR-owned 6 m long heat-probe tool, consisting of 22 Thermistors (at 26 cm spacing) along a sensor-string, a reference pressure gauge and calibration thermometer (T100 sensor). Raw data are required to be calibrated relative to the T100 sensor. Calibration data for both expeditions are provided in form of temperature offsets for each thermistor. Data provided include per station all original (raw) data for each deployment (temperature as function of time, pressure/Depth) for each thermistor, as well as initial results after separating each individual measurement sequence into penetration files (pen-files) where the temperature calibration has been applied. Results report an average thermal Gradient, heat-flux and thermal conductivity over the total penetraiton Depth of 6m. Detailed information (temperature and thermal conductivity as function of depth at each location) is given in graphical form as well as ascii data per individual penetration.
    Keywords: Black Sea; Comment; Conductivity, thermal; Depth, bathymetric; Event label; File content; File format; File name; File size; heat flow; Heat flow; Heat-Flow probe; HF; LATITUDE; LONGITUDE; Maria S. Merian; MSM34/2; MSM34/2_003-1; MSM34/2_028-1; MSM34/2_029-1; MSM34/2_030-1; MSM34/2_031-1; MSM34/2_032-1; MSM34/2_033-1; MSM34/2_034-1; MSM34/2_035-1; MSM34/2_036-1; MSM34/2_037-1; MSM34/2_038-1; MSM34/2_044-1; MSM34/2_045-1; MSM34/2_046-1; MSM34/2_047-1; MSM34/2_048-1; MSM34/2_049-1; MSM34/2_050-1; MSM34/2_067-1; MSM34/2_068-1; MSM34/2_069-1; MSM34/2_070-1; MSM34/2_071-1; MSM34/2_072-1; MSM34/2_072-2; MSM34/2_073-1; MSM34/2_076-1; MSM34/2_077-1; MSM34/2_078-1; MSM34/2_079-1; MSM34/2_080-1; MSM34/2_081-1; MSM34/2_082-1; MSM34/2_083-1; MSM34/2_084-1; MSM34/2_085-1; MSM34/2_086-1; MSM34/2_087-1; MSM34/2_088-1; Sample code/label; Station label; Temperature gradient; Uniform resource locator/link to file
    Type: Dataset
    Format: text/tab-separated-values, 442 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 8
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    Chemical composition of pyrosome carcasses collected during SONNE cruise SO242/2 (2022)
    PANGAEA
    Details
    Publication Date: 2023-07-04
    Description: During RV SONNE cruise SO242/2 (September 2015) to the DISCOL site in the Peru Basin (SE Pacific), pyrosome carcasses were collected at the seafloor. Aboard, these carcasses were stored frozen and in the lab on land, they were freeze-dried and ground to fine powder. Their carbon and nitrogen content, δ13C and δ15N were measured on an elemental analyzer coupled with a isotope ratio mass spectrometer (EA-c-IRMS).
    Keywords: C/N content; Carbon; Carbon/Nitrogen ratio; COLBOX; Collector Box; CTD/Rosette; CTD-RO; Date/Time of event; DISCOL; Elementar Analyzer coupled to an Isotope Ratio Mass Spectrometer (EA-IRMS); Elevation of event; Event label; JPI-OCEANS; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Latitude of event; Longitude of event; Nitrogen; Peru Basin; pyrosome; Sample code/label; SO242/2; SO242/2_176_COLBOX-salp; SO242/2_179_COLBOX-salp; SO242/2_204-1; Sonne_2; South Pacific Ocean; South Pacific Ocean, Peru Basin; δ13C; δ15N
    Type: Dataset
    Format: text/tab-separated-values, 18 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 9
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    Total fatty acids from pyrosome carcasses collected during SONNE cruise SO242/2 (2022)
    PANGAEA
    Details
    Publication Date: 2023-07-04
    Description: During RV SONNE cruise SO242/2 (September 2015) to the DISCOL site in the Peru Basin (SE Pacific), pyrosome carcasses were collected at the seafloor. Aboard, these carcasses were stored frozen and in the lab on land, they were freeze-dried and ground to fine powder. Total fatty acid in pyrosome tissue were extracted following the Bligh and Dyer method and their isotopic compositions and concentrations were measured on a gas chromatograph coupled with an isotopic ratio mass spectrometer (EA-c-IRMS).
    Keywords: COLBOX; Collector Box; CTD/Rosette; CTD-RO; Date/Time of event; DISCOL; Elevation of event; Event label; Fatty acids, total; Fatty acids, δ13C; JPI-OCEANS; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Latitude of event; Longitude of event; Peru Basin; pyrosome; Sample code/label; SO242/2; SO242/2_176_COLBOX-salp; SO242/2_179_COLBOX-salp; SO242/2_204-1; Sonne_2; South Pacific Ocean; South Pacific Ocean, Peru Basin; total fatty acid
    Type: Dataset
    Format: text/tab-separated-values, 375 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
  • 10
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    Phospholipid fatty acids of sediment push cores during SONNE cruise SO242/2 (2022)
    PANGAEA
    Details
    Publication Date: 2023-07-04
    Description: During RV SONNE cruise SO242/2 (September 2015) to the DISCOL site in the Peru Basin (SE Pacific) push cores of sediment were taken in the abyssal plains with ROV Kiel 6000 (GEOMAR). The sediment cores were sliced in 0-2 and 2-5 cm intervals and stored frozen until further processing ashore. In the lab on land, sediment samples were freeze-dried, ground to fine powder, phospholipid-derived fatty acids (PLFAs) in the sediment were extracted following the Bligh and Dyer method and they were measured on a gas chromatograph coupled with an isotopic ratio mass spectrometer (EA-c-IRMS).
    Keywords: Date/Time of event; Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; DISCOL; Elevation of event; Event label; JPI-OCEANS; JPI Oceans - Ecological Aspects of Deep-Sea Mining; JPIO-MiningImpact; Laboratory code/label; Latitude of event; Longitude of event; Peru Basin; Phospholipid fatty acids; Phospholipid fatty acids, δ13C; PLFA; PUC; Push corer; Sample code/label; SO242/2; SO242/2_166_PUC-74-24-10; SO242/2_183_PUC-81-69-33; SO242/2_202_PUC-46-61-79; Sonne_2; South Pacific Ocean; Station label
    Type: Dataset
    Format: text/tab-separated-values, 774 data points
    Location Call Number Limitation Availability
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    DATA PANGAEA
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