Application of high frequency lake level change in the prediction of tight sandstone thin reservoir by sedimentary simulation

Abstract

The reservoir distribution of block X in Ordos Basin is mainly controlled by the lake level change. The frequent rise and fall of lake level results in the thin interbedded reservoir. Because the seismic data is not sensitive to tight sandstone and it is difficult to predict thin reservoir, this paper uses the Sedimentary Simulation Technology Based on the principle of sequence stratigraphy to predict thin reservoir in the study area. In the process of sediment simulation, the key to this study is to obtain the accurately high-frequency lake level change curve (The frequency of curve is consistent with that of logging, which depends on the number of vertical grids in the process of sedimentary simulation) and reflect it in the model. Because there is only one well in the study area and the data is relatively scarce, the conventional analysis and test data are difficult to provide the characteristics of lake level change. Therefore, this paper uses the INPEFA (Integrated Prediction Error Filter Analysis) technology to analyze the high frequency lake level change. Through the INPEFA processing of GR curve, the obtained lake level change has a clear trend of change, which can directly see the macro change of lake level and the secondary change of lake level in the stratum. On the premise of obtaining the high frequency lake level change curve, in order to ensure that the simulation results can reflect the characteristics of thin layer, combined with the formation thickness and the high frequency lake level change curve, the vertical step size is refined (refined to 60), and the sedimentary simulation is carried out. The simulation results show the characteristics of high resolution, the thin layer is in good agreement with the logging results, and the change of sandstone caused by the secondary rise and fall of lake level is also well reflected in the model. According to the characteristics of tight sandstone reservoir, the high-quality reservoir prediction is carried out by using the simulation results, which provides a new idea for tight sandstone exploration in this area.