东营凹陷沙二段沉积特征再认识及油气精细勘探意义

Re-Understandings of Sedimentary Features and Hydrocarbon Implications of the Second Member (Es2) Interval of Shahejie Formation, Dongying Sag

东营凹陷沙二段是勘探程度较高的陆相盆地含油气层系,基于岩芯观察、测录井及地震资料系统分析,开展了沙二段沉积特征再认识研究。认为沙二段不仅发育建设期三角洲,同样发育改造期和破坏期三角洲沉积类型。其中沙二下亚段表现为早期建设性、中期快速湖侵期改造–破坏性和晚期建设性三角洲特征;沙二上亚段先后发育干旱气候–弱物源–改造性三角洲和湿润气候–建设/改造性三角洲。三角洲沉积特征及其演化主要由盆地抬升与剥蚀过程、古气候及物源输入、古地理及古风浪等因素控制。改造型(如河口坝、沿岸砂坝复合体)和破坏型(滩坝)三角洲砂体在东营凹陷富油气盆地中较为广泛发育,是寻找隐蔽圈闭及增储上产值得关注的重要领域。

The second member (Es2) of Shahejie Formation, Dongying Sag, is a high-maturity hydrocarbon interval in China. Based on core observations, well and seismic data, this study conducted a sedimentary investigation for Es2 of Shahejie Formation. The results showed that besides the development of constructive river-derived delta, both the reworked and destroyed delta formed in Dongying paleo-lake. The lake experienced early constructive, medium reworked to destroyed, late constructive delta in the lower phase of Es2, Shahejie Formation. The upper interval of Es2 experienced weak source input and reworked delta process under arid paleo-climate settings, followed by constructive and reworked delta process under humid paleo-climate environment. The sedimentary system is controlled by tectonic activities, deposits source inputting, paleo-climate and paleo-wind directions during Eocene to Oligocene time. The reworked sandbodies, such as mouth-bars, banks along shoreline, and sand shoals, see as important targets for oil exploration in mature hydrocarbon basins.