平衡剖面技术对东海西湖凹陷正反转构造及其成藏控制的研究

Application of balanced section technique to the study of positive inversion structure and hydrocarbon accumulation control in Xihu Depression of East China Sea

利用平衡剖面技术,对东海西湖凹陷第三系的正反转构造发育的期次、强弱进行了研究。把西湖凹陷划分为早、中、晚3期反转。其中,始新世末的早期反转主要发生在盆地的西斜坡带,且研究区由南向北反转强度增大;渐新世末的中期反转主要发生在盆地的东缘断裂带,且研究区由南向北反转强度减弱;中中新世末的晚期反转主要发生在盆地的中央隆起带,且研究区由南向北反转强度增大;总体反转作用由早到晚依次增强。反转作用形成多种类型的构造圈闭,具有面积较大、圈闭完整的特征,对油气的运移聚集十分有利,同时对油气的保存及储层物性有改造作用。根据目前的勘探,西湖凹陷的3个构造反转带是寻找油气最有利的地区。

Balanced section technique has been applied to the study of the stage and strength of the Tertiary positive inversion structure in Xihu Depression of East China Sea. The Xihu Depression is recognized as a 3-stage inversion of early, medium and late inversion. The early inversion in late Eocene mainly occurred in the western slope of the basin, and the inversion strength increased from south to north in the study area. The medium reversion in late Oligocene mainly occurred in the eastern fault zone of the basin, and the inversion strength decreased from south to north in the study area. The late inversion in late middle-Miocene mainly occurred in the central uplift belt of the basin, and the inversion strength increased from south to north in the study area. The inversion action generally intensified along time. The inversion action had formed various structural traps which were large and intact, and very favorable to oil and gas migration and accumulation. Meanwhile, the inversion action also had a transformation effect on reservoir physical property. Present exploration shows that the three structural inversion belts are most favorable zones for oil and gas prospecting in Xihu Depression.