柴达木盆地北缘西段油气成藏机理与有利勘探方向

通过对柴北缘西段典型油气藏的解剖认为,该区油气藏的形成取决于烃类生成、圈闭发育、储盖组合、油气运移和聚集诸要素在时间和空间上的有机配置;油气分布严格受生烃坳陷的控制,古圈闭、古隆起是油气长期运移的低势区,能优先捕获油气,具有发育深层原生油气藏的有利条件;浅层次生油气藏的形成与断裂活动密不可分,断裂的封闭性及其圈闭的保存条件是次生油气藏发育的决定因素;侏罗系自生自储式、第三系下生上储式储盖组合广泛发育,良好的储集性能与储盖组合是油气富集的重要保障;成藏静态要素与动态要素的有机配置,控制了该区油气最终是否成藏。通过综合评价认为冷湖-南八仙构造带、马海-大红沟隆起带勘探程度较高,下一步应作为战略展开勘探领域,赛什腾坳陷带应作为战略突破勘探领域。

PETROLEUM ACCUMULATION MECHANISM AND ADVANTAGE DIRECTION OF EXPLORATION IN THE WEST SEGMENT OF THE NORTHERN FRINGE OF QAIDAM BASIN

The thoughts was based on the dissection of the typical reservoir in the west segment ot the northern fringe of Qaidam basin. The formation of the reservoir in this area lies on the organic configuration in hydrocarbon birth, trap growth, reservoir-caprocks assemblage, oil remotion and accumulation and each main factors on the space on time. The distribution of oil is controlled by hydrocarbon depression strictly. The palaeo-trap and palaeo-uplift are the long-term low potential energy area that oil moves and fells on. It can catch the oil preferentially and has the advantage conditions of the growth of deep-seated primary reservoir. The formation of the low-seated secondary reservoir is inseparable with fault activity. The closing of the faults and the preservation of the traps are the decisive factors of the secondary reservoir growth. The reservoir-caprocks assemblages of Jurassic self-generating and self-reservoiring and tertiary lower-generating and upper-reservoiring grow diffusely. The favorable reservoiring capability and reservoir-caprocks assemblages are the important guarantee of the oil enrichment in great force. The organic configuration of static and dynamic factors of oil accumulation is linchpin. It controls whether the oil can be accumulated at last in this area. The synthetical opinion thinks that the palaeo-uplift which formatted at Yanshan terminal era and the tertiary palaeo-structure are the best practical and advantage next direction of exploration in the west segment of the northern fringe of Qaidam basin. At the same time, it is well worth exploring new stratum and realm too. For example, stratum unconformity of Mesozoic and Cenozoic, stratigraphic overlapped and basement buried hills etc.