TY - JOUR
A1 - Heeschen, Katja U.
A1 - Janocha, Julian
A1 - Spangenberg, Erik
A1 - Schicks, Judith Maria
A1 - Giese, Ronny
T1 - The impact of ice on the tensile strength of unconsolidated sand
BT - a model for gas hydrate-bearing sands?
JF - Marine and petroleum geology
N2 - Tensile strength is an important parameter when it comes to predictions of potential fracturing of sediments by natural processes such as the emplacement of ice or gas hydrate lenses, as well as anthropogenic fracturing or else the stability of engineering constructions such as boreholes. Yet, tensile strength (sigma(tau)) measurements of unconsolidated ice-bearing or gas hydrate-bearing sands are scarce and affected by a large variability.
In the course of the SUGAR project we successfully used ice as a model for pore-filling and "load-bearing" gas hydrate in sand to determine compressional wave velocity. We were thus able to verify comparable formation characteristics and morphologies of ice and gas hydrate within the pore space. As these are important values for the tensile strength of ice/hydrate-bearing sands, ice was also used as a model for hydrate-bearing sands, despite differences in the mechanical behavior and strength of pure ice and gas hydrate. Water-saturated sand cores with ice saturations (S-ice) between 0 and 100% were tested at -6.8 degrees C. The varying S-ice were a result of the freezing point depression caused by saline solutions of different concentrations. The sigma(tau) was directly determined using a sleeve-fracturing test with an internal pressure that was created within the frozen samples. The setup was also adapted to fit a pressure vessel for tests using confining pressure.
The correlation of S-ice - sigma(tau) shows an exponential increase of sigma(tau) with S-ice. Whereas at S-ice < 60% the increase is small, it is large at S-ice > 80%. In conjunction with the change in strength, the viscoelastic behavior changes. A clear peak strength occurs at S-ice > 80%. We conclude that given 60% < S-ice < 80% the pore-filling morphology of the ice converts into a frame-building habitus and at S-ice > 80% the frame gains strength while the amount of residual water decreases. Tensile failure and cracking now exceed grain boundary sliding as the prevailing failure mode. The ice morphology in the sand is non-cementing and comparable to a gas hydrate-sand mixture.
KW - tensile strength
KW - ice-grain mixture
KW - gas hydrate
KW - saline permafrost
KW - ice
KW - frozen soil
Y1 - 2020
U6 - https://doi.org/10.1016/j.marpetgeo.2020.104607
SN - 0264-8172
SN - 1873-4073
VL - 122
PB - Elsevier
CY - Oxford
ER -
TY - JOUR
A1 - Schicks, Judith Maria
A1 - Erzinger, Jörg
A1 - Ziemann, Martin Andreas
T1 - Raman spectra of gas hydrates : differences and analogies to ice 1h and (gas saturated) water
N2 - It is generally accepted that Raman spectroscopic investigations of gas hydrates provide vital information regarding the structure of the hydrate, hydrate composition and cage occupancies, but most research is focused on the vibrational spectra of the guest molecules. We show that the shape and position of the Raman signals of the host molecules (H2O) also contain useful additional information. In this study, Raman spectra (200-4000cm(-1)) of (mixed) gas hydrates with variable compositions and different structures are presented. The bands in the O-H stretching region (3000- 3800cm(-1)), the O-H bending region (1600-1700cm(-1)) and the O-O hydrogen bonded stretching region (100-400cm(-1)) are compared with the corresponding bands in Raman spectra of ice Ih and liquid water. The interpretation of the differences and similarities with respect to the crystal structure and possible interactions between guest and host molecules are presented. (c) 2005 Elsevier B.V. All rights reserved
Y1 - 2005
UR - http://www.sciencedirect.com/science/journal/13861425
U6 - https://doi.org/10.1016/j.saa.2005.02.019
SN - 1386-1425
ER -
TY - THES
A1 - Schicks, Judith Maria
T1 - Der Einfluss molekularer Eigenschaften von Gasen auf die Hydratbildungsprozesse, die thermodynamischen Eigenschaften und die Reaktionen von einfachen und gemischten Gashydraten
Y1 - 2013
CY - Potsdam
ER -
TY - JOUR
A1 - Li, Zhen
A1 - Spangenberg, Erik
A1 - Schicks, Judith Maria
A1 - Kempka, Thomas
T1 - Numerical simulation of hydrate formation in the LArge-Scale Reservoir Simulator (LARS)
JF - Energies : open-access journal of related scientific research, technology development and studies in policy and management
N2 - The LArge-scale Reservoir Simulator (LARS) has been previously developed to study hydrate dissociation in hydrate-bearing systems under in-situ conditions. In the present study, a numerical framework of equations of state describing hydrate formation at equilibrium conditions has been elaborated and integrated with a numerical flow and transport simulator to investigate a multi-stage hydrate formation experiment undertaken in LARS. A verification of the implemented modeling framework has been carried out by benchmarking it against another established numerical code. Three-dimensional (3D) model calibration has been performed based on laboratory data available from temperature sensors, fluid sampling, and electrical resistivity tomography. The simulation results demonstrate that temperature profiles, spatial hydrate distribution, and bulk hydrate saturation are consistent with the observations. Furthermore, our numerical framework can be applied to calibrate geophysical measurements, optimize post-processing workflows for monitoring data, improve the design of hydrate formation experiments, and investigate the temporal evolution of sub-permafrost methane hydrate reservoirs.
KW - methane hydrate
KW - temperature sensor
KW - electrical resistivity tomography
KW - hydrate formation
KW - numerical simulation
Y1 - 2022
U6 - https://doi.org/10.3390/en15061974
SN - 1996-1073
VL - 15
IS - 6
PB - MDPI
CY - Basel
ER -
TY - JOUR
A1 - Li, Zhen
A1 - Spangenberg, Erik
A1 - Schicks, Judith Maria
A1 - Kempka, Thomas
T1 - Numerical Simulation of Coastal Sub-Permafrost Gas Hydrate Formation in the Mackenzie Delta, Canadian Arctic
JF - Energies
N2 - The Mackenzie Delta (MD) is a permafrost-bearing region along the coasts of the Canadian Arctic which exhibits high sub-permafrost gas hydrate (GH) reserves. The GH occurring at the Mallik site in the MD is dominated by thermogenic methane (CH4), which migrated from deep conventional hydrocarbon reservoirs, very likely through the present fault systems. Therefore, it is assumed that fluid flow transports dissolved CH4 upward and out of the deeper overpressurized reservoirs via the existing polygonal fault system and then forms the GH accumulations in the Kugmallit-Mackenzie Bay Sequences. We investigate the feasibility of this mechanism with a thermo-hydraulic-chemical numerical model, representing a cross section of the Mallik site. We present the first simulations that consider permafrost formation and thawing, as well as the formation of GH accumulations sourced from the upward migrating CH4-rich formation fluid. The simulation results show that temperature distribution, as well as the thickness and base of the ice-bearing permafrost are consistent with corresponding field observations. The primary driver for the spatial GH distribution is the permeability of the host sediments. Thus, the hypothesis on GH formation by dissolved CH4 originating from deeper geological reservoirs is successfully validated. Furthermore, our results demonstrate that the permafrost has been substantially heated to 0.8-1.3 degrees C, triggered by the global temperature increase of about 0.44 degrees C and further enhanced by the Arctic Amplification effect at the Mallik site from the early 1970s to the mid-2000s.
KW - gas hydrate
KW - permafrost
KW - methane
KW - faults
KW - climate change
KW - Mallik
KW - numerical simulations
Y1 - 2022
U6 - https://doi.org/10.3390/en15144986
SN - 1996-1073
VL - 15
IS - 14
PB - MDPI
CY - Basel
ER -