大民屯凹陷沙四段湖相页岩油地震预测关键技术与应用

大民屯凹陷沙四段湖相页岩油地层岩性复杂、有效厚度薄、储层变化快,利用常规的叠后地震方法预测“甜点”的精度较低,制约了页岩油资源的经济有效动用。针对研究区页岩油地质特征,以提高“甜点”预测精度为导向,探索形成了地震资料优化处理、叠前弹性参数联合反演、有效裂缝预测等多项关键技术。在地震资料处理方面,形成了以“全程Q补偿”为核心的宽频保幅处理技术思路,道集质量和频带宽度得到有效改善,提高了地震解决复杂地质问题的能力;在储层预测方面,综合应用叠前弹性参数联合反演技术和AVOZF反演技术,实现了岩性、脆性、TOC含量及有效裂缝等地质参数的高分辨率预测,明确了大民屯沙四段页岩油“甜点”分布的有利区,落实Ⅰ类、Ⅱ类“甜点”面积约为143 km²。现场实践结果表明,新钻的水平井地质评价结果与储层预测吻合程度高,储层的钻遇率达66.4%。研究结果为大民屯凹陷页岩油资源的勘探开发提供了有力技术支撑。

Key technologies and Applications of Seismic Prediction for Lacustrine Shale Oil in the Fourth Member of Shahejie Formation in Damintun Sag

The lacustrine shale oil formation in the fourth member of Shahejie Formation in Damintun Sag is complex in lithology, thin in effective thickness, and rapid in reservoir change. The “sweet spots” prediction using the conventional post-stack seismic method has a low accuracy, which restricts the economical and effective production of shale oil resources. In view of the geological characteristics of shale oil in the study area, a number of key technologies such as seismic data optimization processing, joint inversion of pre-stack elastic parameters, and effective fracture prediction have been explored and developed, with the aim of improving the prediction accuracy of “sweet spots”. In terms of seismic data processing, a broadband amplitude preservation processing technology idea with “full Q compensation” as the core has been developed, the gather quality and frequency bandwidth have been effectively improved, enhancing the ability to solve complex geological problems with seismic methods; in terms of reservoir prediction, the pre-stack elastic parameter joint inversion technology and AVOZF inversion technology have been comprehensively applied, so that the high-resolution prediction of geological parameters such as lithology, brittleness, TOC content and effective fractures has been achieved, the favorable areas for the distribution of shale oil “sweet spots” in the fourth member of Damin Tunsha have been identified, and the area of Class Ⅰ and Class Ⅱ “sweet spots” is 143 km². The field practice results show that the geological evaluation results of the newly drilled horizontal wells are highly consistent with the reservoir prediction, and the drilling catching rate of the reservoir is 66.4%. The research results provide strong technical support for the exploration and development of shale oil resources in Damintun Sag.