STUDY OF CHARGE HISTORY IN THE JURONG SAG, JIANGSU REGION

Regarding exploration of marine Palaeozoic and Mesozoic strata in South of China,the Jurong Sag in the Jiangsu region belongs to the area where was explored in the early stage.Oil and gas show were discovered in many levels in the Jurong Sag.Organic inclusions hosted in calcite vein in reservoir rock from Well Rong2 in the Jurong Sag were divided into different groups according to fluorescence color.Off-line crushing was used to analyze the hydrocarbon released by organic inclusions hosted in calcite vein from reservoir rock in Well Rong2 and Rong3.Through comparing organic inclusion oils with light oil in reservoir,source of hydrocarbon and charge history in the Jurong Sag were discussed combining burial history in Jurong Sag.The results show that multiple charging episodes took place in Well Rong2 and Rong3;Fluid inclusion oils represent the earlier charge while different n-alkanes distribution in different groups fluid inclusions in Well Rong2 shows that hydrocarbons charged in the earlier stage underwent biodegradation;Hydrocarbons charged in the earlier charging episode were derived from Permian source rock,however present light oils in Triassic reservoir rock charged in the later charging episode were derived from Permian and part Triassic source rocks due to its quick subsiding during the Late Cretaceous.