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

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.