王变阳，高潮，杜彦军，等. 鄂尔多斯盆地延安组软沉积变形构造特征及古地震意义[J].河南理工大学学报(自然科学版)，doi:10.16186/j.cnki.1673-9787.2026030031.

WANG B Y，GAO C, DU Y J, et al. Soft-sediment deformation structures and their paleoseismic significance of the Yan'an Formation, Ordos Basin [J]. Journal of Henan Polytechnic University( Natural Science), doi: 10.16186/j.cnki.1673-9787.2026030031.

鄂尔多斯盆地延安组软沉积变形构造特征及古地震意义(网络首发)

王变阳1  高潮1  杜彦军2  杨泽光1  何斌1  郭睿1

1.陕西延长石油（集团）有限责任公司研究院，陕西 西安 710065；2.延长油田股份有限公司 靖边采油厂 陕西 榆林 718500

摘要：目的 为探究鄂尔多斯盆地陕北斜坡南部延安组软沉积变形的成因机制及其对古地震活动的指示意义，并分析其对油气储层分布的预测价值。方法 采用野外剖面实测与精细考察相结合的方法，以延安–安塞沿线“整套延安组”野外剖面为研究对象，通过对延6、延5和延4地层中发育的软沉积变形层位和小型层内断层进行系统观察与描述，分析其区域展布、沉积环境及变形构造特征，结合区域古构造背景、断层特征和前人成果，综合判断变形成因，进而分析其与湖盆深水砂体分布的关系，开展油气储层预测。结果 延6、延5和延4地层中识别出3套软沉积变形层位和2处小型层内断层；变形构造以液化底劈、液化卷曲变形、枕状构造和液化角砾为主，分布较为广泛。综合分析表明，上述变形与燕山运动Ⅱ幕引发的3期古地震活动密切相关，属原地成因。在此基础上，基于古地震活动对湖盆底形和深水砂体分布的控制机理，圈定了深水砂体有利区。经下寺湾油田钻探验证，在有利区内获得工业油流，证实了研究认识的可靠性。结论 延安组软沉积变形是燕山运动Ⅱ幕古地震活动的直接响应，其发育特征可为盆地古地震重建提供重要依据；同时，古地震活动对湖盆深水砂体分布具有显著控制作用，相关研究成果对陕北斜坡南部延安组后续油气勘探具有重要理论指导意义。

关键词：鄂尔多斯盆地；延安组；软沉积变形；古地震活动

doi: 10.16186/j.cnki.1673-9787.2026030031

基金项目：国家科技重大专项项目（2025ZD1400205）

收稿日期：2026-03-25

修回日期：2026-06-26

网络首发日期：2026-08-10

Soft-sediment deformation structures and their paleoseismic significance of the Yan'an Formation, Ordos Basin (Online)

Wang Bianyang1, Gao Chao1, Du Yanjun2 Yang Zeguang1, He Bin1, Guo Rui1

1.Research Institute of Shaanxi Yanchang Petroleum (Group) Co., Ltd., Xi’an, 710065, Shaanxi, China;2.Jingbian Oil Production Plant, Yanchang Oilfield Co., Ltd., Yulin 718500, Shaanxi, China

Abstract: Objectives  To investigate the genesis mechanism of soft-sediment deformation in the Yan'an Formation in the southern part of the northern Shaanxi Slope, Ordos Basin, and its indicative significance for paleoseismic activity, as well as to analyze its predictive value for hydrocarbon reservoir distribution. Methods By combining outcrop profile measurement and detailed investigation, this study takes the complete Yan'an Formation outcrop along the Yan'an–Ansai area as the research object. Through systematic observation and description of the soft-sediment deformation horizons and small intraformational faults developed in the Yan-6, Yan-5, and Yan-4 strata, we analyze their regional distribution, sedimentary environment, and deformation structural characteristics. Based on the regional paleotectonic setting, fault characteristics, and previous research results, the genesis of the deformation is comprehensively determined. Furthermore, its indication for the distribution of deep-water sand bodies in the lake basin is analyzed, and oil and gas reservoir prediction is carried out. Results Three sets of soft-sediment deformation layers and two small-scale intrastratal faults were identified in the Yan 6, Yan 5, and Yan 4 members. The deformation structures are mainly liquefaction-induced features such as liquefied diapirs, liquefied convolute deformation, pillow structures, and liquefied breccias, with relatively wide distribution. Comprehensive analysis indicates that these deformations are closely related to three episodes of paleoseismic activity associated with the Episode II of the Yanshan Movement and are of in-situ origin. On this basis, based on the control mechanism of paleoseismic activity on lake basin bottom morphology and deep-water sand body distribution, favorable areas for deep-water sand bodies were delineated. Drilling verification in the Xiasiwan Oilfield confirmed industrial oil flow within the favorable areas, validating the reliability of the research findings. Conclusions The soft-sediment deformation in the Yan'an Formation is a direct response to the paleoseismic activity of the Episode II of the Yanshan Movement, and its development characteristics can provide important evidence for reconstructing paleoseismic events in the basin. Meanwhile, paleoseismic activity plays a significant role in controlling the distribution of deep-water sand bodies in the lake basin. The relevant research results have important theoretical guiding significance for the subsequent oil and gas exploration of the Yan'an Formation in the southern part of the northern Shaanxi Slope.

Keywords: Ordos Basin;  Yan’an Formation; SSDs; Paleoseismic activity