The Study On The Sedimentary Microfacies And Favorable Reservoir Prediction Of Paleogene In Zhao Zhouqiao Oilfield, Jinxian Depression

The article has studied the sedimentary microfacies and favorable reservoir prediction in time of ES3-ES4 of Zhao Zhouqiao Oilfield which lies in the central south of Jinxian depression, by analyzing the relevant information such as drilling core description, well-log and seismic data with the direction of sedimentological theory.Based on the analysis of lithologic character, well-log and seismic data, combining with the correlations of single well facies and profile facies, the systemic studies of sedimentary characterization, spacial spreads of sandbodies and controlling factors of ES3-ES4 of Zhao Zhouqiao Oilfield are done. The study indicates that inherited developing characteristic of the sandbodies are obviously, and the main sedimentary facies in the area are delta and beach-bar. There are two kinds of genetic types of the beach-bar: the one is nearshore-bar, which comes from lakeshore sandbodies reformed by strom wave; the other comes from belta which reformed by normal wave and sedimented beside the belta front. The palaeotectonic setting, effects of the wind-storm, the direction of the wave action, abundant provenance, palaeoclimate and palaeowind direction were the main factors which controll the forming and distribution of the bar. Three models can be builded on the base of that.There are great quantities of interbedded deposits of greyblack mudstone and gypsum rock in Es4 in the middle and southern of Zhao Zhouqiao Oilfield. The origion is evaporating of episodic deepwater salt lake, studied by sedimentary feature, palaeotectonics, palaeoclimate and palaeosalinity. The aisles connecting Jinxian Depression with the salts in the deep of the earth's crust are the intense fracturing discordogenic faults and a series of growth normal faults in both the inner and the eastern edge of the sag.On the basis of the drill core observation and the study of regional tectonic setting, soft sediment deformation structures related to earthquake of the paleogene period are recognized in Zhao Zhouqiao Oilfield, which include step faults inner the lay, liquefied curling deformation structures, load structures, and so on. The seismites were mainly developed in Es₄, but not occurred in Es₃. The fact reveals that the tectonic movement has been actived during Es4.The period of the seismites develped just fits the period of the central anticlinal zone. A great amount of micro-fractures formed and connected with original pore when the earthquake was active. The permeability and physical property of reservoirs can be improved obviously. Seismites are potential reservoirs and will become new exploration aims in the near future.There are both acidic and alkali diagenetic environments in Zhao Zhouqiao Oilfield. Alkali diagenism environment is the main type in Middle-Southern part of the oilfield. The pores of quartz grain and the overgrowth are the main types of the storage.In the Northern part of the research field, the aqueous medium condition is acidic by the incursion of the acidic mass which was from the process of the organic material changed into hydrocarbon in the clastic reservoir above 1750m. During this period, the corrosion of the carbonate rock highly improved the capacity of the storage.Three zones of secondary pore are developed in Zhaozhouqiao oilfield, including III oil layer in Member 3, II and IV oil layer in Member 4 of Shahejie Formation. Delta front mouth bar, distributary channel under water and offmeare bar have good capacity as the reservoir through analysing the distribution of the microface in the plane. These microfaces can be treated as the point of the exploratory development in the future.