渤海湾盆地东营凹陷古近系沙河街组三段沉积相类型及平面分布特征

SEDIMENTARY FACIES TYPES OF THE THIRD MEMBER OF THE SHAHEJIE FORMATION IN THE PALEOGENE OF THE DONGYING DEPRESSION, THE BOHAIWAN BASIN AND THEIR DISTRIBUTION CHARACTERS ON PLANE

综合运用地质、测井、地震等资料对渤海湾盆地东营凹陷古近系沙河街组三段的沉积相类型及其平面分布特征进行了全面系统的研究。结果表明,研究区古近系沙三段发育三角洲、扇三角洲、近岸水下扇、湖底扇、滨浅湖、半深湖和深湖等 7 种沉积相类型。从沉积相平面分布来看,沙三早、中期东营凹陷北部陡坡带发育扇三角洲和近岸水下扇相,南部缓坡带发育三角洲和扇三角洲相,东西轴向发育东营三角洲和高青三角洲沉积,盆地内部半深湖—深湖环境内发育湖底扇相。沙三晚期湖盆萎缩,深湖、半深湖范围缩小,各类骨架砂体自盆缘向盆内形成有利的油气储集体。

Based on the synthetical analysis of geological, logging and seismic data, the sedimentary facies types of the third member of the Shahejie Formation in the Paleogene of the Dongying Depression, the Bohaiwan Basin and their distribution characters on plane were studied roundly and systematically. The results showed that seven types of sedimentary facies were developed in this area, that is, fan delta, delta, inshore subaqueous fan, sublacustrine fan, shore shallow lake, half-deep lake and deep lake facies. During the Early and Middle Sha-3 periods, fan delta facies and inshore subaqueous fan facies were developed on the northern steep slope zone of the Dongying Depression, delta facies and fan delta facies on the southern gentle slope zone, the Dongying and the Gaoqing delta deposits along the east-west axis, and sublacustrine fan facies in half-deep lake and deep lake environments within the basin. During the Late Sha-3 period, the lake basin shrinked. With various skeleton sandbodies expanding from basin margins to interior of the basin, the range of half-deep lakes and deep lakes reduced gradually to form favorable hydrocarbon reservoirs.