鄂尔多斯盆地上古生界岩性圈闭类型探讨  

Discussion of Types of Upper Paleozoic Lithologic Trap in Ordos Basin

作　　者：张满郎[1] 李熙喆[1] 谷江锐[1] 谢武仁[1] 

机构地区：[1]中国石油勘探开发研究院廊坊分院,河北廊坊065007

出　　处：《天然气地球科学》2010年第2期243-250,共8页Natural Gas Geoscience

基　　金：国家重大科技专项(编号:2008ZX05013-003)资助

摘　　要：鄂尔多斯上古生界砂体主要发育于SQ8(山2段)和SQ11(盒8下油层组)的低位体系域,发育河口坝砂体圈闭、泥岩超覆圈闭、受沟谷地貌控制的河道充填砂体圈闭以及辫状河下切谷砂体圈闭。SQ8(山2段)下切谷和地形坡折带控制优质储层的发育和气藏的分布。下切谷河道砂体的两侧为分流间湾、沼泽泥岩所围限,上覆层为河漫泥岩,形成凸镜状岩性圈闭。河口坝—水下分流河道叠置砂体的发育受控于水下地形坡折带,发育由侧向封堵和湖侵泥岩超覆形成的复合圈闭。SQ8(山2段)气藏主要分布于盆地的中东部,河道的限制性较强,含气区带相对集中。SQ11(盒8下油层组)气藏分布明显受侧向遮挡带和岩性致密带控制,气藏主要分布在盆地的中西部,由于辫状河道的摆动性很强,含气砂体广布连片,高产富集区为下切的高能河道砂体。Sandbodies of upper Paleozoic of Ordos basin are mainly developed in lowstand system tracts of SQ8 （corresponding to the 2nd member of Shanxi Formation） and SQ11 （ corresponding to the lower part of 8th member of Shihezi Formation ）. Main lithologic traps are identified including mouth bar sandbody trap, mudstone over- lapped trap, filled channel trap controlled by ravine landform and the sandbody trap resulted from incised valley of Braided River. The development of high quality reservior and the distribution of gas reservoir of SQ8 are controlled by incised valley and topographic breaks. Both sides of the incised valley sandbodies are bounded and restricted by mudstone of distributary bay or distributary swamp, the top of incised valley sandbodies are overlied by floodplain mudstone and thus forming lentoid lithologic trap. The development of underwater distributary channel-mouth bar sandbody assemblages is controlled by underwater topographic breaks where complex traps are formed by lateral sealing of distributary bay mudstone and overlapping of lake transgressive mudstone. Gas reservoirs of SQ8 are mainly distributed in relatively concentrated gas zone in the mid east of Ordos basin as the channels of SQ8 are strongly restricted. Gas reserviors of SQ11 are mainly distributed in the mid-west of the basin, which are obviously controlled by lateral sealing belt in the east side and compacted sandstone belt in the north margin. Gas-bearing sandbodies of SQ11 are widely distributed and continuously superimposed because of the strong oscillation of braided channel and the gas enriching region with high yielding is high-energy incised channel sandbody.

关 键 词：鄂尔多斯盆地 上古生界 岩性圈闭 下切谷 地形坡折带 气藏分布 

分 类 号：TE122.3[石油与天然气工程—油气勘探]