东海陆架盆地西湖凹陷宁波构造带反转背斜分段差异变形及其油气地质意义

Segmented differential deformation of inverted anticlines and its significance on hydrocarbon accumulation in the Ningbo structural zone， Xihu Sag， East China Sea Shelf Basin

唐贤君 朱虹浩 李宁 余一欣 钟荣全 余浪

Xianjun TANG Honghao ZHU Ning LI Yixin YU Rongquan ZHONG Lang YU

西湖凹陷宁波构造带Y背斜是近些年东海陆架盆地油气勘探评价的热点区域，但该构造油气差异富集主控因素及有利勘探方向仍不十分明确。通过对宁波构造带Y背斜进行精细构造解析，研究了背斜分段差异变形特征及其主控因素，探讨了其油气地质意义。研究结果表明：根据构造形态差异，可将Y背斜划分为南、中、北3段，各段次级背斜受控于不同的反转断裂，中段挤压抬升幅度最大。控制Y背斜南、北分段差异变形的主要因素为区域挤压应力作用、先存控洼断裂差异以及刚性基底导致的局部应力集中等。相对于Y背斜南、北段，中段的强烈挤压收缩过程引发整体抬升，将原本独立发育的南、北段次级背斜卷入变形，进而形成南、北差异的大型复式背斜。南北差异变形及不同期次叠加变形导致Y背斜不同部位油气差异富集。据此提出了花港组和龙井组多个有利勘探领域，为该地区的天然气勘探提供了重要方向。

The Y-shaped anticline， situated in the Ningbo structural zone， Xihu Sag， has emerged as a focal point in hydrocarbon exploration and assessment in the East China Sea Shelf Basin in recent years. However， the dominant factors controlling the differential hydrocarbon accumulation and favorable exploration targets in this anticline are yet to be clarified. Through fine structural analysis， we investigate the segmented differential deformation of the Y-shaped anticline and controlling factors， as well as its significance on hydrocarbon accumulation. The results indicate that the Y-shaped anticline can be divided into southern， central， and northern segments based on the differences in structural morphology. The secondary anticlines in these segments are governed by various inverted faults， with the central segment exhibiting the most significant compressional uplift. The main factors controlling the differential deformation in the southern and northern segments include regional compressive stress， differences in pre-existing sub-sag-controlling faults， and localized stress concentration induced by rigid basement. In contrast， the central segment experienced uplift overall driven by intense compression and contraction. Consequently， the originally separated secondary anticlines in the southern and northern segments underwent deformation， eventually forming a large anticlinorium featuring disparities in the southern and northern parts. The differential deformation of the southern and northern segments， coupled with the multistage superimposed deformation， results in differential hydrocarbon accumulation in different parts of the Y-shaped anticline. It can be concluded from these findings that the Huagang and Longjing formations contain multiple favorable exploration targets， which will be of great help to gas exploration in the Xihu Sag.

10.11743/ogg20250112