论文部分内容阅读
以鄂尔多斯盆地延长组长8段为例,运用高分辨率层序地层学的短期基准面旋回原理,详细分析了以水下分流河道和河口坝沉积为主体的辫状河三角洲前缘厚层储集砂体的成因。研究表明,各种成因砂体的发育受沉积基准面升降、可容纳空间(A)与沉积物补给通量(S)比值变化的控制。在基准面上升过程中,当A/S<1时,沉积以叠加式水下分流河道砂体为主,当A/S>1时,沉积则为完整式河道砂体;在基准面下降过程中,当A/S<1时,沉积以完整式河口坝砂体为主,当A/S>1时,沉积则以叠加式河口坝为主。在此基础上,在西峰地区长8段辫状河三角洲前缘砂体中识别出3种类型和6种亚类型的成因砂体,并且从湖岸线到湖泊中心方向,从该套砂体中可明显地区分出3个微相组合区:水下分流河道组合区、水下分流河道与河口坝混合区及河口坝组合区。
Taking the 8th block of Yanchang Formation in Ordos Basin as an example, the short-term base-level cycle principle of high-resolution sequence stratigraphy is used to analyze the characteristics of the braided river delta front thick deposit, which is mainly composed of submarine distributary channel and estuary dam. Set sand body causes. The results show that the development of all kinds of sand bodies is controlled by the change of sedimentary datum and the change of the ratio of space (A) to sediment flux (S). When A / S <1, the deposition is mainly composed of superimposed underwater distributary channel sand bodies. When A / S> 1, the sedimentary units are complete channel sand bodies. When the A / S <1, , When A / S <1, the sediments are dominated by intact estuarine bar sand bodies. When A / S> 1, the sedimentation is dominated by superimposed estuarine dam. On this basis, three types and six subtypes of genetic sandbodies are identified in the braided delta front sandbodies of the 8th member of the Xifeng area, and from the lakeshore line to the center of the lake, Three micro-facies assemblages can be clearly distinguished: submerged distributary channel combination area, underwater distributary channel and estuary dam mixing area and estuary dam combination area.