Modeling fluid flow in sedimentary basins with sill intrusions: Implications for hydrothermal venting and climate change

Large volumes of magma emplaced within sedimentary basins have been linked to multiple climate change events due to release of greenhouse gases such as CH4. Basin-scale estimates of thermogenic methane generation show that this process alone could generate enough greenhouse gases to trigger global incidents. However, the rates at which these gases are transported and released into the atmosphere are quantitatively unknown. We use a 2D, hybrid FEM/FVM model that solves for fully compressible fluid flow to quantify the thermogenic release and transport of methane and to evaluate flow patterns within these systems. Our results show that the methane generation potential in systems with fluid flow does not significantly differ from that estimated in diffusive systems. The values diverge when vigorous convection occurs with a maximum variation of about 50%. The fluid migration pattern around a cooling, impermeable sill alone generates hydrothermal plumes without the need for other processes such as boiling and/or explosive degassing. These fluid pathways are rooted at the edges of the outer sills consistent with seismic imaging. Methane venting at the surface occurs in three distinct stages and can last for hundreds of thousands of years. Our simulations suggest that although the quantity of methane potentially generated within the contact aureole can cause catastrophic climate change, the rate at which this methane is released into the atmosphere is too slow to trigger, by itself, some of the negative δ13C excursions observed in the fossil record over short time scales (< 10,000 years)

On the characterization of methane in rocket nozzle cooling channels

In recent years there has been a growing interest in methane as an alternative rocket fuel due to its favourable specific gravity, storage temperature and thermal stability, in addition to its ability to support In-Situ Resource Utilization. Due to these properties methane supports the ongoing design trend of strategic reduction in system complexity and increase of reusability. The current work presents a first step in addressing the lack of information in open literature on the characteristics of methane under conditions found in rocket nozzle cooling channels, i.e. elevated inflow temperature and a high single sided heat load. A new experimental facility has been established at KTH Royal Institute of Technology in cooperation with GKN Aerospace, and as part of ESA's Future Launcher Preparatory Programme. This facility is shown to enable direct measurement of the Heat Transfer Coefficient (HTC) of methane under a range of conditions, with a limited uncertainty and good repeatability. For inflow temperatures of around 400 K, mass flows up to 15 g/s and pressures up to 3 MPa, it has been observed that the effect of single sided heating results in a significant development of the flow field, which influences the heat transfer in second half of the test section. This development results in an increase of the HTC towards the end of the cooling channel. No significant effect of the pressure on the HTC has been observed under the current experimental conditions.</p