渤海湾盆地石臼坨东428潜山构造成因解析:华北克拉通破坏的深度揭示

Structural Analysis of Shijiutuo East 428 Buried Hill in Bohai Bay Basin:Implications on Destruction of the North China Craton

渤海湾盆地是在中生代华北克拉通破坏基础上,经由新生代深埋形成的叠合盆地,遭受了多期不同性质构造叠加改造。渤海海域油气资源的勘探逐步走向深层,深部潜山油气藏成为重要的勘探目标。本文以石臼坨东428潜山构造(以下简称428构造)为例,探索渤海湾盆地潜山的形成和构造演化。基于前人对渤海湾盆地内构造和储层特征的研究成果,通过对地震剖面的精确解析,结合相干切片和其他地质资料,系统研究428构造各个阶段的变形特征,特别是对428构造的断裂特征进行了平面和剖面上的解析与断裂组合分析。结果发现:428构造东、西侧现今差异主要是由一条斜跨该构造的NEE向断裂导致的,对比邻区野外应变测量分析,识别出五期构造应力场,分别对应于印支期、燕山期和喜山期的各阶段应力场变化,并结合428构造及其周缘残留地层等方面的证据,进而认为428构造经历了中生代印支期-燕山早期逆冲、燕山中-晚期伸展、燕山末期挤压及新生代右行右阶的走滑-拉分构造叠加的多期复合构造模式。

The Bohai Bay basin is a superimposed basin formed by Cenozoic deep-burial following the Mesozoic destruction in North China Craton.The exploration of oil and gas resources in the Bohai Bay Basin is gradually shifting towards deep-layer targets,particularly the deeply-buried hill reservoirs.In this paper,we take the Shijiutuo East 428 buried hill as an example to explore the formation and tectonic evolution of the buried hills in the Bohai Bay Basin.Based on the previous results on the structure and reservoir characteristics in the Bohai Bay Basin,we interpreted the seismic profiles in the study area,and combining with coherent slices and other geological data,we systematically analyzed the deformation of the Shijiutuo East 428 buried hill.Moreover,we analyzed the fault pattern of the Shijiutuo East 428 Structure through profile interpretation.The results showed that the present-day structural difference between the east and west parts of the Shijiutuo East 428 buried hill is mainly caused by an oblique propagation of NEE-trending fault in the whole buried hill.We identified 5 tectonic stages by strain measure and analysis in the adjacent areas,combined with the evidence from the Shijiutuo East 428 buried hill and the surrounding residual strata,and discussed their stress fields in the Indosinian,Yanshanian and Himalayan periods,respectively.Then we concluded that the Shijiutuo East 428 buried hill experienced multi-stage structural activities including the Indosinian folding,the Early Yanshanian thrusting,the Middle-Late Yanshanian extension,the Late Yanshanian compression,and the Cenozoic right-stepping dextral strike-slip faulting.