Fault-fracture mesh petroleum plays in the Zhanhua Depression, Bohai Bay Basin: Part 2. Oil-source correlation and secondary migration mechanisms

The geochemical data provide strong support for two sharply contrasting hydrocarbon migration scenarios: (1) short distance lateral migration is dominant in the central sag areas; and (2) the fault-fracture mesh facilitated vertical migration, and coupled with the regional porous Guantao Formation sand sheets, makes the structural, stratigraphic and lithological features over basement high blocks the focal points for petroleum accumulation. Therefore, further exploration in this highly mature petroleum province should focus on heavy oils in the shallow Neogene strata and light oils in the tight sandstones of the deep sag areas.