北黄海盆地中东部近表层沉积物顶空轻烃地球化学特征

通过北黄海盆地253个站位的顶空轻烃数据分析,对该盆地中东部地区的含油气特征进行了讨论。该区轻烃指标为非均匀-严重非均匀地化场,与其他含油气盆地相比,研究区属中等强度的地球化学场。高值主要分布在东部坳陷和中西部隆起区,经过数据预处理和趋势分析,东部坳陷区表现为CH4和C2H6以上重烃的高背景和高强度异常,中部坳陷为低背景和中等强度异常。综合油气地质条件分析认为东部坳陷含油气特征明显优于中部坳陷。轻烃CH4指标在研究区西南部受到沉积环境的一定影响,但其他区域异常反映了油气渗漏特征。趋势异常主要分布在构造边界断层位置,反映了烃类气体沿裂隙通道运移的特点。

Near-surface Headspace Gas Geochemical Characteristics in the Eastern and Middle Depression of North Yellow Sea Basin

The light hydrocarbon geochemical characteristics were discussed after the analysis of 253 marine sediment sites samples in the Eastern and Middle Depression of North Yellow Sea Basin.The geochemical field was non-uniformity with serious of heterogeneity,and the intensity was moderate compared to other petroliferous basins.The content of hydrocarbon in the eastern depression and middle-western uplift was high,nevertheless the background value and the intensity of abnormity in eastern depression is stronger than that in the middle depression.With the comprehensive analysis of petroleum geological conditions,it indicates that the hydrocarbon-bearing characteristics in the eastern depression are obviously better than that in the middle depression.The methane content in southwestern area has less relationship with depositional environment,but its regional abnormity in other area is a indicator of hydrocarbon seepage.The trend abnormity is mainly distributed at structural boundary and its faults,they are the paths of hydrocarbon gas migrating through the fractures.