Hydrocarbon sources

distribution of the major source rocks and timing of hydrocarbon generation and expulsion are poorly understood in Puffin oilfield

constraining future exploration.Two-dimension hydrocarbon generation modeling and biomarker fingerprinting reveal that the Lower Vulcan marine shale is the most important source rocks in the study area and its peak hydrocarbon generation and expulsion occurred from Cretaceous to Miocene.In contrast

the Plover source rocks got over matured during the Late Jurassic

and contributed limited hydrocarbons due to its low capability of hydrocarbon generation.The events chart shows that the traps on the Puffin horst were mainly formed in the Jurassic-Cretaceous period.Before the Miocene

the hydrocarbon generated from the Vulcan source rocks mainly accumulated in the Jurassic traps in the graben as faults were undeveloped in strata above the Jurassic.At the end of Miocene

lots of vertical faults were created or reactivated by the regional tectonic compression

causing that hydrocarbons in the early pools vertically migrated to and accumulated in the shallow Cretaceous reservoirs.So oil in the discovered Cretaceous reservoirs is mostly secondary.