印支——燕山运动对大港探区古潜山形成的控制作用

Control effect of Indosinian-Yanshan movement on the formation of buried hill in Dagang exploration area

基于三维地震勘探及钻井资料,系统研究了古生界、中生界残留地层分布及基岩断裂体系,重构了晚三叠世—早白垩世期间的古构造格架。根据古构造样式及演化的研究,明确大港探区基底构造经历了印支—早燕山阶段的逆冲褶皱和差异隆升、燕山运动中期拉分断陷两大演化阶段。探区内古潜山圈闭形成与分布受控于上述古构造演化,印支—燕山运动构造变形对古潜山发育的影响主要表现在3个方面:(1)印支—早燕山期古构造背景控制潜山类型的有序分布,形成古地貌残丘潜山、断块-地貌潜山以及构造变形潜山,并表现出与古近纪盆地结构反转分布的特点;(2)潜山内幕圈闭样式与裂缝型储层发育则受古构造变形体系控制,古隆起与古斜坡区古逆冲及走滑构造控圈闭特点明显;(3)印支—燕山构造运动控制古生界差异剥蚀,跷跷板反转的古斜坡区发育内幕隐蔽型潜山圈闭。中生代印支—燕山运动决定和影响了大港探区古潜山的油气类型和分布,综合考虑构造和石油地质因素,大港探区中、低位序古地貌残丘潜山和内幕隐蔽型潜山勘探潜力较大,而远离生烃灶的高位序断块潜山油气保存条件差、潜力最小。

Based on 3D seismic exploration and drilling data, the distribution of Paleozoic and Mesozoic residual strata and fault system of bed rock were systematically studied, and the palaeotectonic framework in the Late Triassic-Early Cretaceous period was reconstructed. According to the studies of palaeotectonic style and evolution, the basement of Dagang exploration area expe- rienced two evolution periods, i. e. , thrust fold and differential uplift during the Indosinian-early Yanshan period and pull-apart fault depression during the middle Yanshan Movement. The formation and distribution of buried hill traps in the exploration area is controlled by the above palaeotectonic evolution. The effect of tectonic deformation in Indosinian-Yanshan Movement on the development of buried hills is mainly manifested in three aspects： （ 1 ） the ordered distribution of all types of buried hills is con- trolled by the palaeotectonic setting during the Indosinian-early Yanshan period , thus forming paleogeomorphic residual buried hill, fault block-geomorphic buried hill and tectonized buried hill, and possessing the characteristics of inversion distribution a- gainst the Paleogene basin structure; （2） the buried hill inner trap style and development of fractured reservoir are controlled by the paleotectonic deformation system. Traps are obviously controlled by paleothrust and strike-slip structure in the paleohigh and palaeoslope area; （3） the Paleozoic differential erosion is controlled by the Indosinian-Yanshan Movement, and pragmatic buried hill inner traps are developed in the palaeoslope area with seesaw reversion. The Mesozoic Indosinian-Yanshan Movement deter- mines and exerts influences on the oil and gas type and distribution of buried hills in the Dagang exploration area. Comprehen- sively considering structural and petroleum geology factors, the middle- and low- order paleogeomorphic residual buried hill and pragmatic buried hill have great exploration potential, while the high-order fault block far away from source kitchens has the least exploration potential due to poor hydrocarbon preservation conditions.