陆相断陷湖盆缓坡带滩坝砂体与油气勘探

Oil-gas Exploration of Beach-bar on the Gentle Slope Belt in the Rift Lacustrine Basin

滩坝砂体已逐渐成为我国陆相断陷盆地油气勘探的重要领域之一。在国内外相关文献调研的基础上,论述了滩坝的类型与特征、控制因素、沉积模式、成藏规律及勘探技术。断陷湖盆滩、坝砂体主要见于缓坡滨浅湖地区,可分为砂质滩坝、砾质滩坝、生物碎屑和碳酸盐岩滩坝,其中砂质滩坝是断陷湖盆最常见的滩坝类型。滩坝的发育明显受到古地貌、水动力强度、湖平面变化以及物源条件的控制,具备多种类型的沉积模式,在有效烃源岩、较好储层和有利输导系统的配合下,形成以岩性、构造-岩性为主的油气藏。滩坝砂体的勘探包括地质和地球物理两个方面,地质方法能够从宏观上把握滩坝的类型和分布规律,而地球物理方法的优点在于对确定的滩坝砂体从形态和分布特征上进行精细描述,因此,综合地质和地球物理方法对滩坝砂体进行研究是实现滩坝砂体油气勘探取得突破行之有效的方法。

The beach-bar has been become an important exploration area of the rift lacustrine basin in China.Based on the document surveys,the types,characteristics,controlled factors,sedimentary model,accumulation and exploration technology of the beach-bar have been discussed.The beach-bar usually develops on the gentle slope belt in the shore-shallow lake,and include sandy beach-bar,gravelly beachbar,biodetritus and carbonatite baech-bar,thereinto the sandy beach-bar being the most common type.The development of the beach-bar is obviously controlled by paleogeomorphology,hydrodynamic force,lake level and provenances supply and it has various sedimentary models.In the cooperation of effective source rock,better reservoir and favorable conducting system,the beach-bar mainly form lithologic trap or structure-lithologic trap.The recognition and description methods of beach-bar include geological analysis and geophysical technologies.The advantages of geological analysis are macroscopical constraint to genetic types and distribution of beach-bar,whereas the advantages of geophysical technologies are subtle description and forecast for shape and location of beach-bar.Consequently,combining geological analysis and geophysical technologies to study beach-bar is a more helpful way for oil-gas exploration.