右江裂谷盆地下二叠统层序成因格架与储层分布

SEQUENCE GENETIC FRAMEWORK AND RESERVOIR DISTRIBUTION OF LOWER PERMIAN IN YOUJIANG RIFTING BASIN

右江裂谷盆地呈现孤台与台盆相间分布的沉积格局，下二叠统可划分出６个三级层序。沉积背景不同，则层序充填序列、内部构型和成因格架各异。其中孤台层序发育主要受海平面变化和碳酸盐自旋回的控制，以碳酸盐岩为主，层序界面特征明显，通常缺失ＬＳＴ，海平面曲线具有跳跃、间断、不对称特点；台盆层序发育则主要受同沉积断裂活动控制，主要由硅质灰岩、硅泥岩和硅质岩构成，层序发育完整，海平面曲线呈现渐变、连续、对称特征，能客观地反映沉积盆地的连续变化史。右江裂谷盆地层序格架中的有利储集体主要包括：①孤台中受层序界面控制的古岩溶储层；②与ＬＳＴ相关的残积体（孤台）和混屑浊积岩（台盆）；③与ＴＳＴ有关的海侵型丘礁滩灰岩（孤台）和钙屑碎屑流沉积（台盆）；④与ＨＳＴ有关的丘礁滩灰岩、白云岩（孤台）和钙屑重力流沉积（台盆）；⑤碳酸盐孤台。

The Youjiang Rifting Basin is of a sedimentary framework of isolated platforms alternating with platform basins and the Lower Permian in the basin may be divided into six 3rdorder sequences.The filling succession,internal configuration and genetic framework of the sequence are various in different sedimentary settings.The isolated platform sequence development is mainly controlled by the sealevel change and carbonate selfcycling,which is mainly composed of carbonate rocks,has obvious sequence interface property,usually lacks of lowstand system tracks (LST) and is possessed of a skipping,discontinuous and dissymmetric sealevel curve;however,the platform basin sequence development is mainly controlled by syndepositional fracture activity,which is chiefly composed of the siliceous limestone,silica mudstone and silicalite,has a complete sequence and is possessed of a gradual change,continuous and symmetric sealevel curve that can objectively reflect a continuous evolution history of the sedimentary basin.The hopeful reservoirs in the sequence genetic framework in Youjiang Rifting Basin mainly include:the palaeokastified reservoir controlled by sequence interface in the isolated platform;the eluvial complex (isolated platform) and mixclast tubidite (platform basin) related to LST;the transgressive knollreef beach limestone (isolated platform) and calcarenaceous flow sediment (platform basin) related to TST;knollreef beach limestone,dolomite (isolated platform) and calcarenaceous gravity flow sediment (platform basin) related to HST;and isolated carbonate platform.