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  • 1
    Publication Date: 2021-02-08
    Description: Seafloor elongated depressions are indicators of gas seepage or slope instability. Here we report a sequence of slope-parallel elongated depressions that link to headwalls of sediment slides on upper slope. The depressions of about 250 m in width and several kilometers in length are areas of focused gas discharge indicated by bubble-release into the water column and methane enriched pore waters. Sparker seismic profiles running perpendicular and parallel to the coast, show gas migration pathways and trapped gas underneath these depressions with bright spots and seismic blanking. The data indicate that upward gas migration is the initial reason for fracturing sedimentary layers. In the top sediment where two young stages of landslides can be detected, the slope-parallel sediment weakening lengthens and deepens the surficial fractures, creating the elongated depressions in the seafloor supported by sediment erosion due to slope-parallel water currents.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 2
    Publication Date: 2019-09-23
    Description: This study presents 2D seismic reflection data, seismic velocity analysis, as well as geochemical and isotopic porewater compositions from Opouawe Bank on New Zealand’s Hikurangi subduction margin, providing evidence for essentially pure methane gas seepage. The combination of geochemical information and seismic reflection images is an effective way to investigate the nature of gas migration beneath the seafloor, and to distinguish between water advection and gas ascent. The maximum source depth of the methane that migrates to the seep sites on Opouawe Bank is 1,500–2,100 m below seafloor, generated by low-temperature degradation of organic matter via microbial CO2 reduction. Seismic velocity analysis enabled identifying a zone of gas accumulation underneath the base of gas hydrate stability (BGHS) below the bank. Besides structurally controlled gas migration along conduits, gas migration also takes place along dipping strata across the BGHS. Gas migration on Opouawe Bank is influenced by anticlinal focusing and by several focusing levels within the gas hydrate stability zone.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
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  • 3
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    HWU
    In:  [Poster] In: 7. International Conference on Gas Hydrates (ICGH 2011), 17.-21.07.2011, Edinburgh, Scotland, United Kingdom . Proceedings of the 7th International Conference on Gas Hydrates (ICGH2011) ; 591/1-9 .
    Publication Date: 2012-03-16
    Description: The production of natural gas via injection of fossil-fuel derived CO2 into submarine gas hydrate reservoirs can be an example of tapping a hydrocarbon energy source in a CO2-neutral manner. However, the industrial application of this method is technically challenging. Thus, prior to feasibility testing in the field, multi-scale laboratory experiments and adapted reaction-modeling are needed. To this end, high-pressure flow-through reactors of 15 and 2000 mL sample volume were constructed and tested. Process parameters (P, T, Q, fluid composition) are defined by a fluid supply and conditioning unit to enable simulation of natural fluid-flow scenarios for a broad range of sedimentary settings. Additional Raman- and NMR-spectroscopy aid in identifying the most efficient pathway for CH4 extraction from hydrates via CO2 injection on both microscopic and macroscopic level. In this study we present experimental set-up and design of the highpressure flow-through reactors as well as CH4 yields from H4-hydrate decomposition experiments using CO2-rich brines and pure liquefied CO2.
    Type: Conference or Workshop Item , NonPeerReviewed
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  • 4
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    ECO2 Project Office
    In:  ECO2 Deliverable, D12.2 . ECO2 Project Office, 6 pp.
    Publication Date: 2019-03-11
    Description: In order to proceed with speculative modelling of the impacts of potential leakage of geologically stored carbon, it is necessary to develop plausible scenarios. Here a range of such scenarios are developed based on a consensus of the possible geological mechanisms of leakage, namely abandoned wells, geological faults and operational blowouts. Whilst the resulting scenarios remain highly speculative, they do enable short term progress in modelling and provide a basis for further debate and refinement.
    Type: Report , NonPeerReviewed , info:eu-repo/semantics/book
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  • 5
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    ECO2 Project Office
    In:  ECO2 Deliverable, D12.1 . ECO2 Project Office, 14 pp.
    Publication Date: 2019-03-11
    Type: Report , NonPeerReviewed , info:eu-repo/semantics/book
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  • 6
    Publication Date: 2019-03-11
    Type: Report , NonPeerReviewed , info:eu-repo/semantics/book
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  • 7
    Publication Date: 2019-03-11
    Type: Report , NonPeerReviewed , info:eu-repo/semantics/book
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  • 8
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    HWU
    In:  In: Proceedings of the 7th International Conference on Gas Hydrates (ICGH2011). HWU, Edinburgh, 279/1-6.
    Publication Date: 2012-07-06
    Description: Within the German gas hydrate initiative SUGAR, we have developed a new tool for predicting the formation of sub-seafloor gas hydrate deposits. For this purpose, a new 2D/3D module simulating the biogenic generation of methane from organic material and the formation of gas hydrates has been added to the petroleum systems modeling software package PetroMod®. T ypically, PetroMod® simulates the thermogenic generation of multiple hydrocarbon components including oil and gas, their migration through geological strata, and finally predicts the oil and gas accumulation in suitable reservoir formations. We have extended PetroMod® to simulate gas hydrate accumulations in marine and permafrost environments by the implementation of algorithms describing (1) the physical, thermodynamic, and kinetic properties of gas hydrates; and (2) a kinetic continuum model for the microbially mediated, low temperature degradation of particulate organic carbon in sediments. Additionally, the temporal and spatial resolutions of PetroMod® were increased in order to simulate processes on time scales of hundreds of years and within decimeters of spatial extension. As a first test case for validating and improving the abilities of the new hydrate module, the petroleum systems model of the Alaska North Slope developed by IES (currently Shlumberger) and the USGS has been chosen. In this area, gas hydrates have been drilled in several wells, and a field test for hydrate production is planned for 2011/2012. The results of the simulation runs in PetroMod® predicting the thickness of the gas hydrate stability field, the generation and migration of biogenic and thermogenic methane gas, and its accumulation as gas hydrates will be shown during the conference. The predicted distribution of gas hydrates will be discussed in comparison to recent gas hydrate findings in the Alaska North Slope region.
    Type: Book chapter , NonPeerReviewed
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  • 9
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    HWU
    In:  In: Proceedings of the 7th International Conference on Gas Hydrates (ICGH2011). HWU, Edinburgh, UK, 129/1-13.
    Publication Date: 2019-09-23
    Description: The accumulation of methane hydrate in marine sediments is basically controlled by the accumulation of particulate organic carbon at the seafloor, the kinetics of microbial organic matter degradation and methane generation in marine sediments, the thickness of the gas hydrate stability zone (GHSZ), the solubility of methane in pore fluids within the GHSZ and the ascent of deepseated pore fluids and methane gas into the GHSZ. Our present knowledge on these controlling factors is discussed and new estimates of global sediment and methane fluxes are presented. A new transport-reaction model is applied at a global grid defined by these up- dated parameter values. The model yields an improved and better constrained estimate of the global inventory of methane gas hydrates in marine sediments (3000 ± 2000 Gt of methane carbon).
    Type: Book chapter , NonPeerReviewed , info:eu-repo/semantics/bookPart
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  • 10
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    HWU
    In:  In: Proceedings of the 7th International Conference on Gas Hydrates (ICGH2011). HWU, Edinburgh, UK, 591/1-9.
    Publication Date: 2012-07-06
    Description: The production of natural gas via injection of fossil-fuel derived CO2 into submarine gas hydrate reservoirs can be an example of tapping a hydrocarbon energy source in a CO2-neutral manner. However, the industrial application of this method is technically challenging. Thus, prior to feasibility testing in the field, multi-scale laboratory experiments and adapted reaction-modeling are needed. To this end, high-pressure flow-through reactors of 15 and 2000 mL sample volume were constructed and tested. Process parameters (P, T, Q, fluid composition) are defined by a fluid supply and conditioning unit to enable simulation of natural fluid-flow scenarios for a broad range of sedimentary settings. Additional Raman- and NMR-spectroscopy aid in identifying the most efficient pathway for CH4 extraction from hydrates via CO2 injection on both microscopic and macroscopic level. In this study we present experimental set-up and design of the highpressure flow-through reactors as well as CH4 yields from H4-hydrate decomposition experiments using CO2-rich brines and pure liquefied CO2.
    Type: Book chapter , NonPeerReviewed
    Format: text
    Location Call Number Limitation Availability
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