东巴伦支海盆地沉积充填特征及油气勘探潜力

Sedimentary filling characteristics of the East Barents Sea Basin and its hydrocarbon exploration potential

东巴伦支海盆地的形成演化与乌拉尔洋的闭合有关,由3种原型盆地叠加在一起所形成,具有多套生储盖组合、多期生排油气作用和多旋回油气成藏作用的中晚叠合型盆地特征。两次重要的地质事件I1(P2)和B(T-J,K1),将盆地划分为3套地层层序:与乌拉尔洋闭合有关的下部被动陆缘碳酸盐地层层序(LCSS),与乌拉尔运动有关的中部裂谷陆源碎屑地层层序(MRSS)和与新地岛运动有关的上部陆相坳陷地层层序(UDSS)。叠合盆地多功能要素组合控制着油气藏的形成和分布,后期盆地对前期盆地的破坏作用明显。晚二叠世—三叠纪裂谷期快速伸展和高速沉降(最大速度为150mm/a)决定了烃源岩的高成熟度,拗陷期储盖配置形成了两套有利的成藏组合,中新生代的两次构造反转决定了油气圈闭的主要类型和分布范围,不同油源和不同期次生成的油气与圈闭的相互配置,形成了强弱叠加的油气改造模式。盆地的油气成藏具有5种模式,有利勘探领域是与古近纪走滑断层有关的大型转换背斜、盆地边缘斜坡三角洲、与反转运动有关的凹陷中部继承性突起、盆内隆起和地堑地垒以及下部层序(LCSS)的礁体中。

The East Barents Sea Basin was superimposed together by three different prototype basins and chartered by middle-late superimposed basin with a multiple reservoir-cap combinations, multi-phase hydrocarbon generation and expulsion and multi-cycle hydrocarbon accumulation. Its formation and evolution were related to the closure of Ural Ocean- Three stratigraphic sequences of the basin are divided by two major geological events I1 （P2）and B （T-J, K1 ）. One is the lower carbonate sedimentary sequence （LCSS） in the passive continental margin, related to the closure of the Ural Ocean. Another is the middle rift sedimentary sequence （MRSS）, related to the Urals movement. The third is the upper depression sedimentary sequence （UDSS）, related to the Novaya Zemlya movement. Functional elements combination controls the formation and distribution of hydrocarbon reservoirs in the superimposed basin. Irate basin played an obvious destruction role in the development of the pre-basiru Late Permian- Triassic rapid rift stretch and high-speed subsidence （maximum speed of 150 mm/a） determine high maturity of the source rocks. Under reservoir-cap assemblages during depression period two sets of favorable plays formed. Mesozoic and Cenozoic tectonic inversions played an important role in the formation and transformation of traps, hydrocarbon migration and accumulation. Different hydrocarbon sources and generation in different stages match with traps each other and form oil and gas transformation models with strong or weak superimpositions. There are five hydrocarbon accumulation models in the basin. The favorable exploration area is mainly in the large-scale conversion anticlines, related to Tertiary strike-slip faults, the slope deltas on basin edge, the inherited protrusions in the depression center related to the I,ate Triassic inversion, the uplifts inside the basin, the horsts and the gardens, also the reefs in the LCSS.