松辽盆地北部双城地区白垩系营城组—登娄库组石油勘探突破及地质意义

Petroleum exploration breakthrough and geological significance in Cretaceous Yingcheng and Denglouku formations of Shuangcheng area,northern Songliao Basin,NE China

基于钻井地质、地球化学、地球物理和生产测试资料,采用含油气系统研究方法,对松辽盆地北部双城地区白垩系营城组—登娄库组含油组合烃源岩、储集层、盖层特征以及烃类生成、圈闭演化和石油充注过程进行剖析。研究表明,研究区烃源岩分布在营城组,有机质主要来源于低等水生生物和藻类,丰度达到优质生油岩级别;原油具有轻质、高凝固点和高蜡的特征,与营城组烃源岩具有良好的亲缘关系。储集层包括登娄库组砂岩和营城组砂砾岩两套;直接盖层为登四段泥岩。石油于姚家组—嫩江组沉积期生成,分别于嫩江组沉积期和古近纪—新近纪聚集成藏。圈闭经历了营城组沉积末期、泉头组沉积末期和嫩江组沉积末期3期演化,形成构造和构造-岩性两类油藏。稳定的构造背景、良好的生储盖组合、近距离运移、晚期充注为油藏形成的有利因素。

Based on drilling geological, geochemical, geophysical and production test data, the characteristics of source rocks, reservoir rocks and caprocks, as well as the process of hydrocarbon generation, trap evolution and oil accumulation of the oil-bearing assemblage composed of the Cretaceous Yingcheng Formation(K1yc) and Denglouku Formation(K1d) in the Shuangcheng area, northern Songliao Basin, were analyzed by using the research methods for petroleum systems. The source rocks mainly exist in K1yc, with the organic matters mainly originated from lower aquatic organisms and algae, and reaching the grade of high-quality source rock in terms of organic abundance. The crude oil, which is characterized by low density, high freezing point and high wax content, is believed to have generated by the K1yc source rocks. The reservoir rocks include K1d sandstones and K1yc glutenites. The mudstone in the fourth member of K1d serves as the direct caprock of the oil reservoir. The oil was generated during the period between Yaojia Formation and Nenjiang Formation, and then accumulated during the periods of Nenjiang Formation and Paleogene–Neogene. The traps evolved in three stages:the late Yingcheng Formation, the late Quantou Formation and the late Nenjiang Formation, forming structural and structural-lithologic reservoirs. It is concluded that good source-reservoir-caprock assemblage, late hydrocarbon charging, short migration distance and stable tectonic setting are favorable factors for the formation of oil reservoirs.