Mechanisms driving pathway-opening migration of gas in marine clayey sediments

Abstract

The occurrence of hydrocarbon gases in marine sediments is prevalent worldwide. Their leakage into the atmosphere is recognized as a significant contributor to global warming. However, the mechanism by which these gases invade overlying sediments and the conditions under which gas presence in the seabed becomes unsustainable remain poorly understood. Here we present an analysis procedure that for the first time captures the entire process of initial gas invasion, cavity/bubble growth and upward rise in low-permeability marine sediment. Attention has been paid to the effect of water depth, sediment thickness and strength profile on gas migration patterns, in an attempt to derive thresholds of gas pressure necessary to facilitate initial invasion and gas quantity adequate for upward migration. Discussions are made in regard to gas migration-induced formation of submarine geological structures and the potential of hydrocarbon gas leakage. These findings advance understanding of the mechanisms governing gas migration in marine environments and their broader implications for submarine geology.