地震沉积学在三角洲沉积体系分析中的应用——以辽河东部凹陷牛居地区为例

Application of Seismic Sedimentology in Analysis of Deltaic Sedimentary System--A Case Study of Niuju Area of Eastern Liaohe Depression

辽河东部凹陷牛居地区沙三上亚段主要储层为辫状河三角洲砂体,由于储层横向变化大、岩性复杂多变,常规的地震—沉积分析方法应用效果不佳。为更准确地刻画有利沉积相带,引用地震沉积学的基本研究方法,借鉴陆相沉积盆地的研究实践,提出了适用于本工区的地震沉积学研究流程。结合井震标定建立等时地层格架,将沙三上亚段分为四个砂层组,在等时地层格架下,利用低频资料对主河道砂体的敏感性识别主河道发育位置,通过90°相位转换,赋予地震反射岩性意义,优选地震属性展开等时地层切片分析识别主要相带分布范围。实践表明,利用地震沉积学可实现三角洲沉积相带的精细刻画,对明确有利相带分布及沉积体系演化特征具有重要意义。

The main reservoir of upper Es3 in Niuju area of eastern sag of Shahejie Formation,is a braided river delta sand body.Due to the large lateral variation in the reservoir,the complexity in the lithology and the diversity in the seismic reflection characteristics,conventional seismic sedimentary analysis methods are not effective.In order to more accurately describe the favorable sedimentary facies belt,based on seismic sedimentology method,and the practice in continental sedimentary basins,this paper proposes an effective flow of seismic sedimentology.Combined with well seismic calibration,the upper Es3 in Niuju area of Shahejie Formation is first divided into four sand layers,the isochronous stratigraphic framework is then established,Under the isochronous stratigraphic framework,the sensitivity of low frequency data to the main channel sand body is used to identify the development position of the main channel.Through 90°phase conversion and the seismic reflection lithology,the seismic attribute is optimized to expand the isochronous stratigraphic slice analysis to identify the main phase zone distribution range.The exploration practice shows that the fine characterization of delta sedimentary facies can be realized by using seismic sedimentology,which is of great significance to clarify the distribution of favorable facies and the evolution characteristics of sedimentary system.Well Niu 94 deployed by this technology has become the first high-yielding well among the Niuju area,indicating that seismic sedimentology plays a key role in guiding the discovery of oil and gas in the deltaic sedimentary system of this area.