关键词: 准噶尔盆地, 侏罗系, 层序地层学, 基准面旋回, 沉积相, 岩性油藏

Abstract: The prospecting degree is low,and the subtle reservoirs are very common in the central part of Junggar Basin.The principles and methods of high-resolution sequence stratigraphy were used to predict the distribution rules of the Jurassic reservoir.Based on drilling data and seismic calibration results,the Jurassic System was divided into four long-term base-level cycles bounded by unconformity and sedimentary transform surfaces.There are mainly three types of short-term base-level cycles,which control the formation of coastal-shallow lagoon sheet sand,mouch bar and subaqueous distributary channel sediments of braided stream delta front.According to stacking patterns of short-term cycles and calibration of logs restrained by key interfaces,a log interpretation model for the Jurassic medium-term base-level cycles was established,and 14 medium-term cycles were distinguished.Under the control of dynamic variation of the accommodation-sediment ratio,the favorable reservoirs were usually developed during the rising stage of the medium-term base levels.The sandstones deposited during descending stage are laterally interconnected,while the lithologic reservoirs can not be formed easily in this stage.The drilling data confirm that the mid-lower part of SQ3 sequence is the main interval for development of lithologic reservoirs.

Key words: Junggar Basin, Jurassic System, sequence stratigraphy, base-level cycle, sedimentary facies, lithologic reservoir