基于地震沉积学方法的沉积相研究——以涠西南凹陷涠洲组三段为例

The Research of Sedimentary Facies based on Seismic Sedimentology Method:A case study of the three-section of Weizhou Formation in Weixi'nan depression

探讨地震沉积学方法在陆相薄互层的沉积相研究思路。地震沉积学主要是利用三维高精度地震资料来研究沉积岩及其形成过程,提高分辨率处理和分频解释有利于建立高频层序地层格架,等时地层切片可以用来约束划分最小等时地层单元。90°相位转换使地震同相轴具有岩性意义,可以用来刻画薄层砂体的形态及分布特征。优选能反映砂体形态的属性与反射波形特征,并结合物源方向、沉积体系类型来编制精细的沉积相分布图。以涠西南凹陷古近系涠洲组三段地层为例,开展地震沉积学方法的沉积相研究。识别并确立了研究区内7砂组最小等时地层单元,利用东西方向物源特征及砂体形态、90度相位转换地震振幅属性、波形特征,准确的勾画出7砂组以东、西两侧向湖盆推进的辫状河三角洲为规律的沉积相图。

This paper discusses the research idea of sedimentary facies in continental thin and interbed sandbody based on seismic sedimentology method.Seismic sedimentology mainly applies high-precision 3D seismic data to study sedimentary rock and its forming process,and improve resolution processing and frequency-division interpretation help to establish high-frequency sequence stratigraphic framework,and isochronous stratigraphic sections can be applied to divide the minimum isochronous stratigraphic unit.The 90° phase shift technology make the seismic events have lithological significance,which is used for describing the form and distribution characteristics of thin sand body.Optimization reflects the properties of sand body and characteristics of the reflection waveform,and precise sedimentary facies distribution diagram is established by combining source directions and sedimentary system types.Take three-section of Weizhou Formation in Weixi'nan Depression as an example,and carry out sedimentary facies research based on seismic sedimentology method.Seven sand groups as the minimum isochronous stratigraphic unit are recognized and established in the study area.By using source direction of east and west,shape of sand body,amplitude property of 90°phase shift data,waveform characteristics to accurately lay out seven sand group sedimentary facies diagram reflecting the law of which is braided river delta from east and west sides filling the lacustrine area.