地震属性在马仙地区下干柴沟组下段沉积环境分析中的应用

在对20多口钻井的录井资料、岩心特征、粒度特征、测井资料及沉积层序分析的基础上，研究了柴达木盆地北缘西段马仙地区古近系下干柴沟组下段的沉积特征及演化规律。结果表明:研究区古近系下干柴沟组下段的沉积环境主要是以辫状河河流相的心滩、河漫滩、泛滥平原为主，在下干柴沟组下段沉积时期为一明显的水进过程。三维地震数据精细构造解释基础上的地震属性研究也很好地反映了研究区下干柴沟组下段沉积时期沉积环境的变化规律:早期以东北部的物源为主，正北方只有少量物源供给，砂体主要受东北部物源控制;之后东北部物源向西迁移，供给量逐渐减小，北部物源供给量逐渐增大;晚期2个物源逐渐靠近，河流相砂体呈连片分布。结合区域地质分析初步弄清了下干柴沟组下段沉积环境的演化过程，明确了3套砂体的分布规律，为柴北缘马仙地区下一步的油气勘探工作提供了可靠的地质依据。

Application of Seismic Attributes to Analysis of Depositional Environment:Taking Lower Member of Xiaganchaigou Formation of the Paleogene System of Maxian Region as an Example

Based on the analyses of sedimentary sequence,lithology,particle size,and logging data from more than 20 drilling wells in Maxian region on the northern margin of the Qaidam Basin,the sedimentary characteristics and its evolution of Paleogene Lower Xiaganchaigou Formation were studied.The results showed that braided fluvial facies were the main sediment types of this formation,including channel bar,point bar,and flood plain,and the environment with water withdrawal was the main depositional environment in this period.According to the fine structural interpretation of 3D seismic data,seismic attributes can also well illustrate the changes of depositional environment of the Lower Xiaganchaigou Formation:In the early period,the sediments were mainly from northeast of the Maxian region,and a little from the north,and sandbodies were mainly dominated by the northeastern provenance;Along with the basin development,the northeastern provenance gradually migrated westward,and its supplies also decreased,in contrast,the supplies from the northern provenance increased;In the later period,the above two provenances got closed,and then developed large and contiguous sandbodies.Preliminary conclusions about the environmental evolution of Lower Xiaganchaigou Formation in Maxian region and three sandbodies distribution can provide reliable geological data for the next oil and gas exploration.