伊通盆地莫里青断陷双二段岩性油气藏成藏特征

岩性油气藏是伊通盆地莫里青断陷的主要油气藏类型,其中双阳组是莫里青油田勘探主要目的层。通过分析岩芯、录井、测井及试油测试资料,双二段由上至下可以分为5个砂组,各个砂组均主要发育水下扇和扇三角洲沉积砂体,且主要集中分布在西北缘同生断裂控制下的靠山凹陷附近。同时,莫里青断陷发育较厚的暗色泥岩,较高的有机质丰度,达到了好烃源岩的标准。双二段各个砂组砂体属于低孔低渗储层,在剖面上主要呈"泥包砂"特征,其近烃源岩分布的特征有利于形成小而肥的透镜状砂体油气藏。试油结果表明,产油量大于1 t/d的井80%分布在双二段的四砂组,是双二段主要油气产层。该岩性油气藏在平面上主要分布在靠山凹陷的伊22和伊39两个井区附近的水下扇砂体中。

Characteristics of lithologic hydrocarbon reservoir in the second member of Shuangyang Formation in Moliqing fault depression of Yitong Basin

Lithologic hydrocarbon reservoirs are the main reservoir type in Moliqing fault depression of Yitong Basin，in which Shuangyang Formation is the exploration and development target strata in Moliqing oil field． Through analyzing drill core，logging and oil testing data，the second member of the Shuangyang Formation can be divided into five sand groups in descent order，which are mainly from subaqueous fan and fan delta sedimentary sand body，and are mainly distributed in Kaoshan depression controlled by contemporaneous faults in the northwest margin． Meanwhile，thick dark mudstone is well developed in the Moliqing fault depression， with high organic mat- ter abundance，and has reached the standard of good hydrocarbon source rocks． All the sand groups are low in po- rosity and low in permeability reservoirs，characterized mainly by “sand wrapped by mud”in the cross section． Those sand groups are adjacent to hydrocarbon source rocks，which made it easy for the formation of small and rich oil and gas reservoirs with shape of lentoid． The results indicate that wells with oil production greater than 1 t/d of 80 percent are distributed in the fourth sand group，which is the major hydrocarbon reservoir in the second member of Shuangyang Formation and mainly distributed in the subaqueous sand body near the well areas of Yi ～22 and Yi ～19 in Kaoshan depression in the plane．