依据岩性、岩石结构、沉积构造、剖面结构、古生物组合等标志分析认为,塔河油田六区奥陶系主要为碳酸盐岩台地相沉积环境,发育连续性较好的灰岩.溶蚀作用沿节理裂隙进行,形成的规模较大的岩溶管道是有利的储集空间.储层中均发育斑状白云石砂屑灰岩,白云石砂屑团块普遍含油.储层中白云石化作用是由所处的台地边缘的潮坪澙湖环境所决定,白云石化作用优化了碳酸盐岩储集性能,在方解石转化为白云石的过程中体积减小,形成大量的次生孔隙.储层中的裂缝和缝合线主要发育在均质泥微晶灰岩中,这种泥微晶灰岩主要形成在碳酸盐开阔台地低洼处的低能环境.均质泥微晶灰岩厚度大且裂缝发育,有利于发生岩溶作用.高角度的断层及裂缝的发育使得塔河油田奥陶系发育大量竖直溶洞,低角度裂缝及潜水面的变化使厚层泥微晶灰岩发生顺层溶蚀.发育的多套顺层大型溶洞成为塔河油田最重要的储集空间.

Based on the analysis of lithology, rock structure, sedimentary structure, profile texture, and paleontological combination data from Block-6 of Tahe Oil Field, it is concluded that the Ordovician reservoirs consist of continuously developing limestone that deposited in the environment of carbonate platform facies. The large scale of karst pipelines that formed by dissolution along the joints or fissures are the favorable reservoir space. Porphyritic dolomitic calcarenite develops in reservoirs and generally contains oil. The dolomization in the reservoirs is determined by the specific tidal flat-lagoon environment in the platform margin in this located area. The dolomization improves the reservoir property and produces large amounts of secondary pores due to decreasing rock volume during the transformation from calcite to dolomite. Fractures and stylolites mainly develop in homogeneous micritic and microcrystalline limestones which are generally formed in the low-energetic low-laying lands of carbonate open platform. Thick-bedded homogeneous micritic and microcrystalline limestones with fractures is favorable to karstification. Existence of high angular faults and fractures promoted developing a lot of vertical karst caves while existence of low angular fractures and changing phreatic surfaces affected the migration of underground rivers which made these limestones corrode along the beds and shapes several sets of large-scaled bedding caves. These bedding caves became the most important reservoir space in Tahe Oil Field.