鄂尔多斯盆地环县地区长6沉积体系展布特征

Distribution Characteristics of the Chang 6 Sedimentary System(Triassic) in Huanxian Area,Ordos Basin

岩矿资料表明,鄂尔多斯盆地西部环县地区延长组长6三角洲沉积体系物源来自西部。进一步的地震相研究表明,该三角洲沉积体系在虎洞一带分为两支,一支沿环县—樊家川一线呈东西方向展布,另一支顺洪德方向呈北东向延展,并在耿湾—罗卜塬附近与东北物源体系的安边三角洲交汇。

Decrease of debris and nonresistance minerals and increase of stable minerals such as quartz and zircon from west to east in the Huanxian region show that sediments of the Chang 6 delta system in this area was from the western regions. Three kinds of seismic facies could be recognized in the Chang 6 beds：the middle or high amplitude value-subparallel-relatively continuous reflection, the foreset reflection and the middle or low amplitude value-parallel reflection, corresponding to the deltaic plain, the deltaic front and the prodelta clay（ or interdistributary clay）, respectively. Distribution characteristics of seismic facies suggest that the Huanxian Chang 6 delta system could be divided into two branches in the Hudong region：one extends easternwards from Huanxian to Fanjiachuan, another goes to Hongde in NE direction and meets with the Anbian delta in Gengwan-Luobuyuan region. The front parts of the eastern Huanxian delta of Well Huan 4-Huan 41 are the ideal places to explore the lens and pinchout reservoirs.