薄互层疏松砂岩储层时移地震AVO研究

针对薄互层疏松砂岩油藏特征,提出了基于各向异性介质理论的时移地震AVO响应分析方法.利用测井数据和实验室岩石物理测量数据,确定了适合目标油田储层的高孔低胶结岩石物理模型,利用移动平均法计算薄互层油藏Backus参数,从而计算岩石弹性参数变化和分析Thomsen参数变化,计算各向异性介质界面反射和透射系数,利用测井资料合成角道集,分析了油藏含油饱和度和压力变化时的时移地震AVO效应.模拟数据分析表明,疏松砂岩对油藏有效压力变化十分敏感,含油饱和度与压力变化时,P-P波和P-SV转换波的时移地震AVO响应是不同的.研究表明,地震模拟是进行时移地震可行性分析和有效区分油藏压力与含油饱和度变化的重要工具,对于充分挖掘我国油田潜力具有重要意义.

Study on Time-Lapse Seismic AVO of Thin Interbeded Layer Unconsolidated Sandstone Eservoir

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.