| Dongying Depression, located in the south of Jiyang Depression in Bohaiwan Basin, is one of the petroliferous depressions in Bohaiwan Basin. There developed a set of strata mainly consisting of red clastic sediments during the period of the lower the fourth member of Shahejie Formation and the first member of Kongdian Formation in Dongying Depression. In recent years, industrial oil and gas flow has been successively found in many parts of this set of strata, indicating that this set of strata is an alternative one in oil-gas exploration in Dongying Depression. However, due to the limitations of the exploration data, previous researches on this set of strata are far from being enough, especially in the knowledge of some basic problems concerning the origin of sediments, which greatly influences the comprehensive understanding and analysis of sedimentary structures of the basin. Under such circumstances, it is very necessary to carry a basic research on the origin types of sediments.This thesis focuses on studying clastic rocks in Dongying Depression. By employing a large number of data of cores, logging and paleontology, etc., and adopting many testing and analytic techniques, the thesis carries a thorough and detailed research on the origin types of sediments in this depression and then explores the reservoir properties of the sediments of different origin types.The thesis classifies clasitc sediments into two types: aqueous sediments and aeolian sediments by the types of geological agents. Starting from the analysis of the rock properties, sedimentary structures, grain size distribution, logging characteristics and other aspects of clastic rocks, the thesis establishes the identification signs of origin types for aqueous sediments in Dongying Depression, thus providing the basis for the extensive research of aqueous sediments. The research result shows that the aqueous sediments formed in Dongying Depression during the period of the lower the fourth member of Shahejie Formation and the first member of Kongdian Formation, mainly consists of proluvial sediments, lacustrine sediments and sediments of mixed origin types. And proluvial sediments can be further divided into debris-flow sediments, temporary river sediments and sheet flow sediments. These sediments exist not in isolation, but in combination according to a certain assemblage. The combination types mainly include the combination of proluvial sediments, the combination of proluvial sediments and lacustrine sediments, and the combination of lacustrine sediments.Through the analysis of sedimentary structures, grain size, mineral components, main elements, rare earth elements, surface textures of quartz grains and other aspects of clastic sediments, this thesis identifies the existence of aeolian sediments which is the first time to be found in the eastern parts of China of the Eocene. Moreover, this thesis further identifies that aeolian sediments can be divided into two types: aeolian sandstones and aeolian dust sediments.This thesis further analyzes the reservoir properties of the sediments of different origin types and their combinations, and holds that the reservoir properties of temporary river sediments formed in the combination of proluvial sediments or in the transition section of the combination of proluvial sediments and lacustrine sediments are the best. During the comparison of sealing capacity of mudstones, the thesis finds that the reservoir properties of the secondary mudstones reworked by water currents are better than those of aeolian mudstones. Further analysis shows that the grain size distribution of these two types of mudstones is quite different and also shows that the sealing capacity is closely related to the contents of clay grains and silt grains. In order to solve the problem concerning the grain size tests of red mudstones, this thesis presents a new method for analyzing the grain size of red mudstones.
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