论文详情
针对含油气砂岩储层大多为双相介质薄储层的特点,利用薄层反射透射系数矩阵方程并结合Gassmann方程获得薄砂体储层的弹性参数、PP波及PS波地震响应,用以对比分析入射波频率、孔隙度、流体类型及流体饱和度对地震反射的影响。模拟分析结果表明:在薄层极性固定的情况下,薄砂层反射振幅随着频率的增大、孔隙度的减小而增大;中、低孔隙度下流体类型及饱和度的不同在地震响应上差异较小,高孔隙度下反射PP波振幅会显示出含气异常;相同孔隙度下,含气储层的泊松比较不含气储层的泊松比低,而在含油与含水情况下的泊松比相近。说明对于薄砂岩储层,利用反演泊松比的方法判别储层是否含气是可靠的,而区分油水层则缺乏足够的地震异常。
Based on the fact that hydrocarbon-bearing sand reservoirs are mostly thin beds in two-phase media,the elastic parameters,PP-wave and PS-wave seismic responses from a thin sand model are simulated using thin-bed reflection/transmission coefficient matrix equations and the Gassmann equation.The influences of incident-wave frequency,porosity,fluid type,and saturation on seismic reflections are analyzed.Simulation and analysis results show that,a higher frequency and a lower porosity result in higher amplitudes of thin-bed reflected PP-and PS-waves for fixed thin-bed polarity.In cases of low and medium porosities,the difference in seismic responses from the thin sand reservoir with different fluid types and saturations is very small.For high porosities,PP-wave amplitude shows an obvious gas-bearing anomaly.With the same porosity,the Poisson's ratio of gas-bearing sand reservoirs is smaller than that of non-gas-bearing sand reservoirs,and the Poisson's ratio of oil-bearing sand reservoirs is very similar to that of water-bearing reservoirs.This means that for the thin sand reservoir,it is reliable to distinguish whether the reservoir has gas or not using Poisson's ratio inversion,but there are not enough seismic anomalies to discern the oil-bearing case from the water-bearing case.
国家自然科学基金项目(41604119,41425017,41374131,41574126,41504107)以及国家科技重大专项“薄层地震波场特征与反演研究”(2016ZX05002005-008)联合资助。