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

摘要: Abstract The chemical compositions of crude oils from over 20 oilfields in the Zhanhua Depression, Bohai Bay Basin, were studied order to understand their genetic relationships, thermal maturity and biodegradation ranking. Molecular geochemical parameters indicate presence three possible oil families reservoirs ranging Paleozoic (basement) Neogene. A number biomarker features support deposition source rocks for these under a wide range depositional environments. majority discovered depression belong FL family, display characteristics consistent with dominantly freshwater (to slightly brackish water) lacustrine rock Es 3 member Shahejie Formation. somewhat geographically restricted SL family are apparently linked saline lacustrine, carbonate-evaporite distributed mostly upper 4 Formation Bonan-Gubei sag areas. thermally less mature BL occur within 1 , 2 or Dongying near central areas, show close affinities interbedded intercalating calcareous mudstones shales deposited water setting. generally mature, whereas most usually low maturity. Oil-source correlation demonstrates strong relationships between Eocene–Oligocene formation areas accumulated shallow Neogene petroleum plays. data provide two sharply contrasting hydrocarbon migration scenarios: (1) short distance lateral is dominant areas; (2) fault-fracture mesh facilitated vertical migration, coupled regional porous Guantao sand sheets, makes structural, stratigraphic lithological basement high blocks focal points accumulation. Therefore, further exploration this highly province should focus on heavy strata light tight sandstones deep