渤海辽东湾海域JZ25油气藏成藏期次研究

Reservoir-forming Periods of JZ25 Hydrocarbon Reservoir in Liaodong Bay,Bohai Sea

渤海辽东湾海域JZ25油气藏油气主要来自于辽西凹陷古近系沙河街组三段烃源岩。通过对沙河街组三段砂岩储层中的有机包裹体研究认为，该地区经历了2期油气充注：第1期发生于石英次生加大作用之前，有机包裹体主要分布于石英碎屑颗粒的微裂缝之中，以液态烃相包裹体为主，但丰度低、成熟度低，对油气成藏贡献小；第2期发生于石英次生加大作用之后，有机包裹体主要分布于沿切割石英碎屑颗粒及其次生加大边的微裂缝面或长石颗粒的溶蚀孔隙中，丰度高，是JZ25油气藏的主要形成时期。根据均一温度测试结果，结合沉积埋藏史和地温史综合分析认为，JZ25油气藏的主要形成时期为古近纪末期和新近纪初期，距今约23～21Ma。

The oil-gas of JZ25 hydrocarbon reservoir is from the hydrocarbon sources of the third member of Shahejie formation, Liaoxi sag. We conclude that there are 2 stages of hydrocarbon charges after studying the organic inclusions in the sandstone of the third member of Shahejie formation. The first stage happened prior to a quartz overgrowth period, during which the organic inclusions were distributed in the micro-fractures of quartz elastic grains. Liquid hydrocarbon inclusions are the main inclusions, with low GOI and maturation, contributing little to the hydrocarbon accumulation. The second stage happened after quartz overgrowth and JZ25 reservoir was formed mainly in this stage. At this stage the organic inclusions were distributed in the micro-fractures along the cutting quartz clastic grains or the dissolution pores of feldspath grains, with low GOI and maturation. According to the homogenization temperature combined with burial and geotemperature history, JZ25 hydrocarbon reservoir is considered to be formed between 23-21Ma, which is the end of Palaeogene and the early stage of Neogene.