Uncertainty Analysis of Biogas Generation and Gas Hydrate Accumulations in the Baiyun Sag, South China Sea.

In this study, we use petroleum systems modeling (PSM) to quantitatively simulate the uncertainty of biogenic gas generation modes and their impact on the spatial distribution and resource assessment of gas hydrates in the Baiyun Sag, South China Sea. The results are as follows: (1) Biogenic gas generation is significantly affected by thermal state and organic matter type. Low temperature is a primary reason for gas hydrate occurrence in shallower sediments when sufficient methane gas is present. This may be due to higher thermal conductivity of the overlying sediments, slower sediment burial rates, or other geological processes. (2) Natural gas hydrate resources are significantly controlled by biogenic gas generation. In addition to the thermal conditions of the source rock or sediment, the nature of the organic matter is another crucial factor. Generally, low-temperature methanogens produce more methane gas because they require less energy, whereas high-temperature methanogens require more energy and thus produce less methane gas. (3) The biogas generation thermal model is key to controlling the location and quantity of natural gas hydrate resources. The three possible gas-phase models, K0, K1, and K2 (representing different methanogens), produce varying amounts of methane gas over time, resulting in different amounts of natural gas hydrate resources. Additionally, the preservation of various methanogens in biogas source rocks can alter reservoir formation locations, influencing the scale and genetic model of natural gas hydrate resources.