Gas migration and gas hydrate formation in marine sediments

点击翻译按钮获取中文摘要

We propose to use data generated in the IODP/OPD program to constrain numerical models of gas hydrate formation in marine sediments. In particular, we aim to better understand the fate of methane gas that is released from hydrates upon burial below the hydrate stability zone. This gas may migrate upwards to generate hydrate at the base of the stability zone or it may be removed from the stability zone by sediment burial. Very high gas hydrate saturations can be reached if methane is recycled back into the stability zone while the hydrate saturation is usually limited to < 1% if the gas cannot penetrate the pore throats and flow through the sediment matrix. Methane recycling at the base of the stability zone has been neglected in previous model studies aiming to constrain the global inventory of methane hydrate in marine sediments. Hence, the size of the hydrate inventory may be much larger than previously thought if hydrate-bound methane is recycled back into the stability zone by wide-spread gas ascent. Our proposed work is important because it may yield improved estimates of hydrate abundances. Thereby it will help to better quantify the impact of hydrate dissociation on global climate change and to validate the potential of gas hydrates as future energy resource.