薄互层地震波形特征研究——以博兴洼陷沙四段滩坝砂为例

Research on the characteristics of thin-alternating-bed seismic waveform——A case study of the beach bar sandstones of Es_4 in Boxing Sag

陆相断陷湖盆中薄互层非常普遍,如滩坝砂岩,具有横向变化快、单层厚度薄等特点,加之受地震资料分辨率低等因素的影响,致使其地震预测难度极大。文中在分析博兴洼陷沙四段滩坝砂岩发育区各种岩性地球物理特征的基础上,从正演模型入手,结合实际验证,分析了不同岩性及其组合的地震反射特征,找出了研究区砂体组合反射在地震波形结构、极大值两侧面积比等地震属性上的表现形式,总结了薄互层及其组合模式与地震反射各属性的对应关系,以此进行地震属性预测,取得良好效果,在东营凹陷西部沙四段滩坝砂岩储层的勘探中较准确地预测出储层的发育带。

Thin-alternating-beds exist commonly in rifted terestrial lake basin, like beach bar sandstones; they have some common characteristics, like the fast changes in horizontal direction and thinness of a single bed; these features, in addition to the low seismic data resolution, make the seismic prediction difficult. In this study, we have analyzed all kinds of lithologic geophysical signatures in the area where the beach bar sandstones developed in Es4 in Boxing Sag, and analyzed the seismic reflection features of different lithologies and their combinations using an inversion model combined with actual well results. The study determined the seismic attributes, such as the seismic waveform structure and the ratio of the areas on both sides of the maximum of the seismic reflections from different sandstone combinations, and summed up the corresponding relationships of the thin-alternating-beds and their combination patterns with the attributes of each seismic reflection. Using these results, we have predicted exactly the development belt of reservoir in exploring the bank and dam body reservoir of Es4 in the west of Dongying Depression.