东营凹陷胜坨地区沙河街组沉积体系及其油气源特征

Depositional system and its hydrocarbon characteristics of Shahejie group of Shengtuo region in Dongying depression

古近系沙河街组是东营凹陷胜坨地区最重要的储集层段。利用岩心观察、扫描电镜、岩心分析化验资料和地震资料对胜坨地区古近系沙河街组沉积特征及其油气源特征进行了研究。结果表明,东营凹陷北部陡坡带发育不同成因类型的砂砾岩群体,在平面上沿胜坨北部陡坡带呈裙带状分布,优质储层主要发育在中扇辫状水道砂体中。胜坨地区各类砂砾岩扇体油藏受断裂活动和生烃系统的双重控制,形成了在平面上由下降盘、断裂带到上升盘依次分布岩性油气藏、构造油气藏、地层型油气藏。油源对比结果表明,深层沙四段岩性油气藏和部分沙三中上构造岩性油气藏中的原油来自于沙四段成熟烃源岩。胜北断层上升盘的地层油藏中,以低成熟稠油为主,生物标志物体现出沙三上烃源岩特征;在下降盘沙三段储层中的原油来自沙三下烃源岩,中—浅层(沙三中—沙二)有大量原油来自于沙三和沙四段烃源岩的成熟混源油。油气主要的运移通道是储集性砂体和断层。

The early Tertiary Shahejie group is the most important reservoir in Shengtuo region, Dongying depression. Its depositional characteristics were re.searched by means of core observation, scanning electron microscope （SEM）, core lab analysis data and seismic data, Glutenite suites of various genetic types developed in the northern abrupt slope, which take skirt-type distribution transversely along the northern Shengtuo region. High quality reservoir is mainly located in middlefan plaiting channel sand body, Both fracture activity and hydrocarbon generation system seriously affect the prevailing reservoirs in studied area. Accordingly, lithologic hydrocarbon reservoir, structural hydrocarbon reservoir and stratigraphic hydrocarbon reservoir embed in downthrown side, fracture zone and upthrown side separately. According to oil-source correlation, oil found in the deep Es4 and part in the upper layers is generated from Es4 mature hydrocarbon. The low-mature heavy oil dominates in the Shengbei stratigraphic reservoir and upthrown side. Biomarkers reflect its upper-Es4 origin. Oil in Es3 is generated from downthrown side, while mixed source oil from Es3 and Es4 is observed in middle-shallow group. Hydrocarbon mainly migrates through reserve sandstone and faults.