胶莱盆地莱阳期原型盆地的沉积格局及有利油气勘探区选择

胶莱盆地油气勘探目的层系莱阳组的沉积体现了湖盆由开始发育→萎缩消亡的全过程 ,不同构造位置其沉积相的组合特征存在差异。对古水流方向、大野头凸起等正向构造单元的形成时期的分析表明 :在莱阳组沉积时期 ,莱阳凹陷为一受五龙村断裂控制的相对独立的沉积单元 ,湖盆水体较深 ;高密—诸城凹陷为一受五荣断层和沂沭断裂带控制的东北高西北低的快速充填的盆地 ,以洪积相、河流相为主 ,仅在局部低洼地带发育湖相沉积 ;原型盆地的沉积格局和油藏的保存条件决定了本区油气勘探方向的选择 ,莱阳凹陷中西部莱阳组覆盖区为本区有利油气勘探区。

SEDIMENTARY PATTERN OF PROTOTYPE BASIN IN THE DEPOSITION PERIOD OF LAIYANG FORMATION AND THE ADVANTAGEOUS AREAS FOR OIL AND GAS EXPLORATION OF JIAOLAI BASIN

Laiyang formation of Jiaolai Basin is the target stratum for oil and gas exploration. By measuring several field sections, we find that Laiyang formation reveals the whole processes from development to death of the lake basin and its sedimentary facies differ in different structural locations. The analyses of sedimentary facies, paleocurrent orientations,combined with the researches of positive tectonic units such as Dayetou uplift and Chaigou horst, indicate that Laiyang sag is a relatively independent sedimentary unit with rather deep water of deep lake or semideep lake depths controlled by Wulongcun fault during the deposition period of Laiyang formation. Its sediments mainly originated from Jiaobei uplift area and Dayetou uplift. Gaomi-Zhucheng sag was a fast-filled basin controlled by Wurong fault and Yishu fault zone, high in the north-east and low in the north-west, characterized by the development of pluvial facies and fluvial facies in most areas, and the development of lake facies only in local low-lying regions. Selection for advantageous hydrocarbon reservoir exploration areas mainly relies on the sedimentary pattern of prototype basin and conservation conditions. The middle-west area of Laiyang sag overlaid with Laiyang formation is the most advantageous exploration area.