Sequence Stratigraphy And Subtle Reservoir Prediction Of Middle Oil-Bearing Series, Honggang To Sifangtuozi In South Songliao Basin

Based on the theory of high resolution sequence stratigraphy and predecessors’research, though analysis of geological and geophysical data, this paper mainly discuss midium-term cycles(the 4th order sequence) division and sedimentary analysis of Middle Oil-bearing series in the area Honggang to Sifangzuozi, South Songliao Basin, also choose the key research area for the 5th sequence division and reservoir forecasting. Based on the summary of pool forming character, the paper forecast the favorable play of subtle-trap.Due to geological background of the research area and the the sequential deposition of research horizon, the paper generalized the method of high resolution sequence division which is suit for the research area. Five long-term base level cycles (the 3rd order sequence) and eight midium-term cycles (the 4th order sequence) can be recognized from the Qingshankou Formation to Yaojia Formation. Moreover, the version of base-level cycles’division and high-resolution sequence framework are constructed and characters of sequences are analyzed in the sequence framework.The main types of sedimentary facies developing in the research area are confirmed. By using the geological and geophysical technologies, distribution paper of depositional systems during rising and falling periods of medium-term base level are described. In addition, regular pattern of distribution of reservoir sandbodies and sedimentary models in high-resolution sequence are constructed, which set up the foundation for subtle-trap forecast.According to the short-term cycles’division (the 5th order sequence) of key area of the Saertu oil-bearing layer in Sifantuozi, the type and character of sedimentary micro-facies in every short-term cycle are analysed and identified. The distribution of sedimentary micro-facies and reservoir sandbodies in high-resolution sequence framework are also determined, which is directed the next exploration of subtle-trap in the key area.Based on the research of regional of distribution reservoir sandbodies, and combined with other pool forming conditions, main types of subtle-traps developing in the research area and its controlling elements are defined. The model of subtle-traps developing is determined and different ideas for exploration of subtle-traps have been developed. The favorable types of subtle-trap and the exploration areas are forecasted as to to different sequences, and based on which, some targets and favorable targets for subtle-traps exploration have been proposed.