关键词: ^薄互层, 疏松砂岩, 时移地震, AVO, 各向异性

Abstract: According to the characters of thin interbeded layer unconsolidated reservoirs, a new method based on the anisotropic medium theory is presented for timelapse seismic AVO analysis. By means of welllog data and rock physical data measured in laboratory, the proper porous unconsolidated rock physical model for objective oilfield has been determined, and with a moving average procedure the Backus parameters are calculated, then the rock elastic parameters are calculated and the variation of Thomsen parameters are analyzed. Finally with log data, the angle gathers are synthesized to analyze timelapse seismic AVO responses versus the variation of oil saturation and pressure of the oil reservoir. The simulation data show that the timelapse AVO response of the thin interbeded layer unconsolidated sandstone is sensitive to the effective pressure change of reservoir, and when oil saturation and pressure change, the timelapse AVO response rules of PP wave and PS wave are different. The study in this paper shows that seismic simulation is an effective method and an important tool in studying timelapse seismic feasibility and in distinguishing the variation of effective pressure and oil saturation of reservoir.

Key words: thin interbeded layer, unconsolidated sandstone, time lapse seismic, AVO, anisotropic.