Abstract:

In combination with analysis of hydrocarbon generation and expulsion history, hydrocarbon fluid flow stages and oil migration history in Yanchang Formation of Longdong area in Ordos Basin are studied by analyzing fluid inclusions through microfluorometric and microscopic thermometry technology. The results reveal that the time of oil expulsion from source rocks is the early stage of Early Cretaceous. Two hydrocarbon fluid flow stages have occurred in Yanchang Formation. The first stage of hydrocarbon fluid flow happened in the Early Cretaceous (from 133 to 100 Ma) during hydrocarbon generation and expulsion of main source rocks, and the second stage of hydrocarbon fluid flow happened in the Late Cretaceous (from 100 to 70 Ma) during the tectonic uplift. Oil migration in the Early Cretaceous showed a continuous process with different oil migration strength, but it weakened gradually as a result of the cease of oil generation caused by the tectonic uplift during the Late Cretaceous and ultimately ended in the late stage of the Late Cretaceous.

Key words: fluid inclusion, fluid flow stage, migration history, Longdong area, Ordos Basin