Research On Favorable Area Prediction And Deposition System Definition Of Yanan Series In Jurassic System In South Jiyuan Slope Area

Odors basin is the second large oil-gas bearing basin in China, whose main reservoirs are Yanchang serious in Tertiary system and Yanan serious in Jurassic system. During several years of exploration and development, South Jiyuan slope area is proved to be a huge accumulation. The reservoir is controlled not only by the characteristics of sedimentary facies and sand distribution, but also palaeogeomorphology. As a result, it is critical to depict the character of the area’s palaeogeomorphology.Both of the previous study and rock observation show that the main source of reservoir comes from west and northwest area. Study in this dissertation indicates all of the layers belong to a fluvial facies named Gan-shan River. Because of the humid climate in Yan10series, the river got expanded. But the adjacent source makes the sedimentary facies to be braided rive. With the expanding of the river, braided river in Yan9series gradually changed into anastomosed stream in Yan7series, so the middle8series develops both of the sedimentary character. Series Yan6and Yan4+5also yield anastomosed stream with subfacies like swamp and bet lands.Several kinds of pictures were depicted in this dissertation for field description such as bed thickness, sand thickness, sedimentary facies and top formation structure. Study shows the palaeogeomorphology of the accumulation can be divided into former river valley, palaeo-slope, alluvial flat and river valley.Furthermore, this dissertation defined the hydrocarbon accumulation regulation of South Jiyuan slope area combining palaeogeomorphology, type of reservoir, accumulation model and reservoir property. At last, based on the study result and test material, the favorable area was picked out.