地震沉积学在辫状河三角洲水下分流河道演化分析中的应用——以春光探区新近系沙湾组一段为例

Application of seismic sedimentology on evolution analysis of underwater distributary channels in braided river delta--by taking the first member of Neogene Shawan formation in Chunguang oilfield of Junggar basin as an example

春光探区油气资源丰富,但其井网密度小,砂体叠置关系复杂,随着勘探开发的进一步深入,急需对其砂体展布规律及沉积期次进行研究,为岩性油藏的进一步开发提供技术支持。此次研究以地质资料为依据,综合利用地震沉积学90°相位转换、地层切片等关键技术对春光探区N1S1Ⅱ砂组辫状河三角洲前缘水下分流河道砂体平面分布和演化过程进行精细刻画。研究表明,N1S1Ⅱ^3小层的沉积演化过程为多条高弯度分流河道,从东南向西北迁移,发育三种类型的圈闭,而N1S1Ⅱ4小层经历了两条规模较大的分流河道发育、废弃的过程,发育两种类型的圈闭。并根据邻井资料实现了对未知井点砂体期次的精确预测,为稀井区利用地震沉积学进行砂体期次研究奠定了基础。

Chunguang oilfield has abundant hydrocarbon resources.However,its well density is sparse and sand body superposition is complex,with the further development of exploration and development,it is urgent to make a study on the sand body distribution and sedimentary stages to provide technical support for the further development of lithologic reservoirs.Based on the geological data,the plane distribution and evolution process of underwater distributary channel sand bodies in N1S1Ⅱformation of Chunguang oilfield are described by using 90°phase transformation of seismic sedimentology and stratigraphic slicing.The results show the sedimentary evolution of N1S1Ⅱ3layer is the process of several high-bend diversion rivers migrate from southeast to northwest,with three types of traps are formed.The sedimentary evolution of N1S1Ⅱ4 layer is the process of development and abandonment of two large-scale subaqueous distributary channels,during this time two types of traps are developed.According to the data of adjacent wells,the accurate prediction of sand body stages at unknown well points is realized,which lays a foundation for the study of sand body stages in sparse well areas by using seismic realized,which lays a foundation for the study of sand body stages in sparse well areas by using seismic sedimentology.