Coupling processes between self-oscillation of formation pressure and periodic migration-accumulation of natural gases in Yinggehai Basin, South China Sea

摘要

The modeling of formation pressure in Yinggehai shows that DF1-1 diapir has oscilla- torily released thermal fluids twice since 5.0 Ma, which may be controlled by the multi-structural subsidences and their accompanying thermal events. Using thermal indicators of formation tem- perature by DST, l/s mixed clay minerals, homogeneous temperature of inorganic fluid inclusion and δ~13C of methane to trace the thermal fluid migrating order and path, we found that there are two orders of natural gas migration-accumulation in the upper site over the top of the overpres- sured compartment. Based on the oscillatory development of formation pressure, we postulate there would exist earlier (before 5.0 Ma) gas accumulation in their deeper site.