Evaluating influencing factors of methane interception in Bohai bay basin's aerobic zone based on experiment coupled with modeling

Marine sediments serve as reservoirs for methane, a potent greenhouse gas and a promising clean energy source. As methane migrates from deep to shallow layers, it undergoes oxidation-reduction reactions with various electron acceptors, such as sulfate, nitrate, and oxygen. Aerobic Oxidation of Methane (AeOM) plays a crucial role where dissolved oxygen is available, particularly in marginal seas with shallow water depths. For now, research on AeOM is not in-depth, especially quantitative works. In the Bohai Sea's petroleum and natural gas basins, methane leakage from sediments is common, and conditions for methane oxidation are present. The sediments play a significant role in oxidizing methane, presenting a highly worthwhile subject for research. Therefore, utilizing laboratory data on AeOM, we employed the TOUGH + HR simulation platform to reproduce the AeOM process by an experimental conceptual model. The calibration of microbial kinetic parameters was conducted using sampling and testing data to analyze the characteristics of methane oxidation. Moreover, relationships between kinetic parameters and temperature were established, facilitating parameter estimation. The maximum oxidation rate (q_m) shows an exponential relationship with temperature, whereas the microbial decay constant (b) displays a linear relationship. We quantitatively analyzed the characteristics of methane oxidation under different influencing factors, including temperature, pressure, and gas migration velocity. The results revealed that temperature is a key factor in determining methane consumption rates, with higher temperatures leading to significantly faster methane consumption due to its influence on microbial activity. The average oxidation rate was recorded as 0.35 μmol/day at 4 °C. This rate increased to 3.05 μmol/day at 10 °C and further rose to 3.96 μmol/day at 15 °C. Notably, there was a dramatic jump to 15.13 μmol/day when the temperature reached 28 °C. By enhancing methane supply (solubility), pressure can boost methane oxidation consumption. 1 MPa–5 MPa pressure increase raises average methane oxidation rates by 93 %. Methane migration velocity primarily affects the supply efficiency of methane and a 50 μL/min to 150 μL/min velocity increase raises rates by 10.3 %. Compared with the results across various temperatures, pressures, and methane migration velocities, we believe that temperature and pressure have a significant impact on methane oxidation consumption, while methane migration velocity has no significant impact. The temperature and pressure changes should be focused on to evaluate the effect of sediment on methane oxidation interception. This study enhances the understanding of the quantitative assessment of seabed methane leakage and the marine sediment carbon cycle.