【摘要】 裂后充填阶段的碳酸盐岩缓坡沉积已逐渐成为深层油气勘探的重点领域之一。以塔里木盆地下寒武统肖尔布拉克组为例,基于最新拼接处理42条二维地震大测线、柯坪地区9个剖面点及12口完钻井测井及取芯等资料,系统开展了其沉积前古构造格局及岩相古地理响应特征、储层宏观分布与内部结构差异等研究。结果表明:1)沉积期盆内发育"三隆两洼"古构造格局,对肖尔布拉克期碳酸盐岩缓坡体系(组合)内部分异产生明显控制作用,高能颗粒滩及丘滩带分布在古隆起周缘,古洋流进一步复杂化了沉积物构成,划分出塔西南古隆起北缘颗粒滩为主的坡坪式缓坡、柯坪—温宿低隆起丘滩复合体均斜型缓坡、轮南—牙哈低隆起丘滩复合体孤岛型缓坡;2)古隆起周缘中缓坡高能相带构成了肖尔布拉克组储层发育的重要载体,早期云化作用有效保存了原始孔隙,埋藏期以先期孔隙为基础进一步调整改造,预测规模储层主要分布于三大古(低)隆区周缘高能丘滩带内,面积达9×104km2。不同类型缓坡体系的储层差异明显,其中坡坪式缓坡的颗粒滩储层以Ⅱ类储层为主、分布稳定为特点,最具规模性,可作为下一步油气勘探的重点关注区带。基于实例解剖认为,裂后沉降期碳酸盐岩缓坡体系分异具明显受构造控制特点,深化沉积前古构造格局认识是预测有利储集相带的关键,直接影响后续规模储层预测及品质评价。更多还原

【Abstract】 Carbonate ramps in the post-rift filling stage have gradually become recognized as areas having the greatest potential for deep hydrocarbon exploration. In the Lower Cambrian Xiaoerbulake Formation in the Tarim Basin,for example,the pre-depositional paleotectonic framework and the lithofacies response to the paleogeography,as well as the regional distribution of reservoirs and the differences in their internal architecture were systematically analyzed from 42 of the most recently processed 2 D seismic lines,nine outcrops in the Keping area and data from 12 wells,etc. The results show that(1)the paleotectonic pattern of three uplifts and two sags occurred during the early Cambrian,and exerted obvious control of the sedimentary differentiation in the Xiaoerbulake carbonate ramp system. Highenergy grain shoals and mound-shoal complexes developed around the paleo-highs. Paleocurrents complicated the sediment composition. Three sub-types of ramp are recognized in the Xiaoerbulake Formation:a slope-plateau ramp dominated by grain shoals at the northern margin of the paleo-high of the SW Tarim Basin;a homoclinal ramp dominated by a mound-shoal complex on Keping-Wsu lower high,and an isolated‘island’sub-type in the Lunnan-Yaha lower high.(2)A peripheral high-energy facies belt of the paleo-uplift constitutes an important carrier for the Xiaoerbulake Formation reservoir. Early dolomitization has effectively preserved the original pores throughout the subsequent burial period. The reservoirs are mainly located in the peripheral high-energy facies belts of the three paleo-highs,covering an area of about 9 × 104 km2. The reservoirs in the different ramp systems have obvious differences. The grain-shoal dominated type ramp in the SW Tarim uplift shows the greatest potential for future exploration for extra-large-scale Type II reservoirs. From the example anatomy,it is believed that the paleotectonic pattern was the primary control of carbonate ramp formation during the post-rift filling stage,and needs further work to fully understand its influence on the distribution of reservoir facies and internal architecture.更多还原