根据储层沥青和流体包裹体综合判识油气成藏期:以黄骅坳陷北大港古生界潜山为例

渤海湾盆地潜山油气资源较丰富，近期黄骅坳陷古生界潜山油气勘探取得重大进展，但油气藏的形成时期及期次尚不明确.以黄骅坳陷北大港古生界潜山为例，综合利用储层沥青、流体包裹体观察、测温、拉曼光谱及红外光谱分析等地球化学分析手段，结合烃源岩生烃史，对其油气成藏期进行了系统研究.结果表明:研究区古生界发育碳质、胶质-沥青质、油质3种沥青，经历了生物降解和氧化作用等多种次生改造过程，结合研究区的构造演化及生烃史，推测早侏罗世中期之前存在油气充注；古生界潜山发育两期烃类包裹体，第一期包裹体发黄褐色荧光，主要分布于石英颗粒表面及方解石脉内，均一温度峰值区间为75~80℃，第二期包裹体包括黄色、蓝绿色荧光两类，分布在石英颗粒内裂缝、穿石英颗粒裂缝及方解石脉内，均一温度峰值范围分别为85~90℃和95~100℃；综合古生界潜山储层沥青及包裹体特征，结合烃源岩生烃史，确定古生界存在两期油气充注，分别为中三叠世（235~223 Ma）和新近纪-第四纪（22~0 Ma），且以晚期成藏为主. 

Comprehensive Identification of Oil and Gas Accumulation Period by Fluid Inclusion Technique and Reservoir Bitumen Characteristics: A Case Study of the Paleozoic Buried Hill in Beidagang,Huanghua Depression

The oil and gas resources of the buried hills in the Bohai Bay Basin are abundant. The oil and gas exploration in the Paleozoic buried hills in the Huanghua Depression has made significant progress recently,but the accumulation period of the oil and gas reservoirs is still unclear.The systematic study on the hydrocarbon accumulation period of the Paleozoic oil and gas reservoirs in the Beidagang buried hill is carried out using comprehensive utilization of reservoir solid bitumen analysis method,fluid inclusion analysis method and microscopic temperature measurement technology,in combination with Raman spectroscopy and infrared spectrum analysis and other geochemical analysis methods. The results show that the study area has three kinds of reservoir bitumen,including carbonaceous bitumen,colloid-asphaltene bitumen and oily bitumen,which have undergone various secondary transformation processes such as biodegradation and oxidation. It is confirmed that there is oil and gas charge before the middle Early Jurassic according to structural evolution of the study area.Two hydrocarbon inclusions are developed in the study area. The first stage of the inclusions shows yellow-brown fluorescence,which is mainly distributed on the surface of quartz particles and calcite veins. The homogenization temperature peak range is 75-80 ℃. The second phase inclusions show yellow and blue-green fluorescence,which are distributed in the fractures within the quartz grains,fractures through quartz grains and the calcite veins. The homogenization temperature peak ranges of the two are 85-90 ℃ and 95-100 ℃ respectively.Combining with the hydrocarbon generation history of source rocks,there are two stages of hydrocarbon accumulation in Paleozoic reservoirs,which are Middle Triassic (235-223 Ma) and Neogene-Quaternary (22-0 Ma),and the second period is the major stage.