利用地震正演模拟方法研究地层结构——以鄂尔多斯盆地合水地区延长组三段为例

Research on stratigraphic structure based on seismic forward modeling:A case study of the third member of the Yanchang Formation in Heshui area,Ordos Basin

地层结构研究是开展地层等时对比、储层精细表征的前提。为了明确鄂尔多斯盆地合水地区延长组三段的地层结构特征,采用了地震正演模拟方法。首先,基于前积地震反射结构,设计三种地层结构概念模型,即等厚尖灭式、底部地层减薄式和地层等比例减薄式;然后开展地震正演模拟,总结不同地层结构的波形响应差异;最后将正演模拟结果与实际地震剖面进行对比、分析。结果表明,前两种样式均呈现与实际地震剖面相似的前积地震反射结构,可作为研究区的潜在地层结构样式。结合测井响应特征,认为研究区地层结构为底部地层减薄式。该方法可为其他相似研究区提供借鉴。

It is necessary to fully understand stratigraphic structure before isochronal stratigraphic correlation and reservoir characterization.For the third member of the Yanchang Formation in Heshui,Ordos Basin,we use seismic forward modeling to investigate its configuration.In view of clinoform seismic reflections,we design three conceptual models to describe the stratigraphic structure.After forward modeling,we compare synthetic reflections with observed reflections and conclude that two models are feasible in this prospect.In accordance with log responses,one model is finally determined to best describe the stratigraphic structure in this prospect.This method may also apply to other prospects with similar geologic setting.