南黄海盆地北部坳陷海底沉积物酸解烃类气体地球化学异常与深部油气属性

南黄海盆地北部坳陷海底沉积物酸解烃甲烷和酸解烃乙烷异常分布显示相同的特征,在西部存在1个高异常区,东部存在1个低异常区。酸解烃类气体的C1/(C2+C3)—δ13C1相关图显示酸解烃类气体属于热成因类型。烃类气体的C1—C2交会图和C1/(C2+C3)—C2/(C3+C4)交会图指示异常区的深部油气属性属于"油气并存"区和"干气"区,其中西部异常区以"油气并存"为主,东部异常区以"干气"为主。

GEOCHEMICAL ANOMALIES AND OIL AND GAS ATTRIBUTION OF ACID HYDROCARBON GASES FROM SEABED SEDIMENTS IN THE NORTHERN DEPRESSION,SOUTH YELLOW SEA BASIN

The stable carbon isotopic composition of the hydrocarbon gases and methane of the seabed sediments from the Northern Depression, South Yellow Sea Basin is studied for hydrocarbon gases a- nomalies, origin types, and attribution of oil and gases. The Northern Depression is considered as a geologically prospective area for oil and gas accumulation, not only in the Mesozoic-Cenozoic, but also in the Mesozoic-Paleozoic. Surface geochemical prospecting, base on the seabed seepage of hydrocarbons from subsurface accumulations, could be advantageous in such areas. In light of this, 100 seabed sediment samples were collected from the Northern Depression, the South Yellow Sea Basin. The geochemical anomaly distribution of acid methane and acid ethane from seabed sediments show a high anomaly area in the west and a low anomaly area in the northern depression, South Yellow Sea. C1/（C2＋C3）—δ^13C1 diagram of acid hydrocarbon gases from seabed sediments may indicate their thermal genetic type. C1 — C2 diagram and C1 / （C2 ＋ C3 ） — C2 / （C3＋ C4 ） diagram show oil and gas attribution in the high anomaly area and dry gas attribution in the high anomaly area among low anomaly areas.