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裂缝诱导的TTI介质固液解耦反射系数方程及裂缝和流体参数反演方法
Fracture-induced fluid-matrix decoupled reflection coefficient equation for TTI media and inversion method for fracture and fluid parameters
【摘要】 利用地震数据进行裂缝预测及流体识别对于裂缝性储层的勘探开发具有重要意义.针对单组旋转对称的倾斜裂缝诱导的TTI介质,基于各向异性Gassmann方程,推导了固液解耦纵波反射系数近似公式,分析了不同条件下近似公式的精度.根据实际研究工区裂缝储层的特征,选用高裂缝倾角近似公式,通过奇异值分解从方位弹性阻抗中估算裂缝密度和裂缝方位,进而分离和消除各向异性项,建立流体等效体积模量及孔隙度贝叶斯反演预测方法.模型试算表明,在信噪比大于2时,流体等效体积模量、孔隙度和裂缝参数的估计较为可靠,实际应用也验证了反演方法的有效性.
【Abstract】 Fracture prediction and fluid identification from seismic data are of great significance to the exploration and development of fractured reservoirs. Based on the anisotropic Gassmann model, a linearized fluid-matrix decoupled reflection coefficient equation for the Titled Transversely Isotropy(TTI) media induced by a single set of titled fracture was proposed. The accuracy of our approximate equation under different conditions was analyzed in detail. Then, according to the characteristics of the fractured reservoir in the field area, we employed a high-fracture-inclination approximate reflection coefficient equation to estimate fracture density and orientation from the azimuthal elastic impedance through a singular value decomposition. Further, a novel Bayesian EIVO inversion method was developed to estimate the effective fluid bulk modulus and porosity estimates by separating and eliminating the anisotropy term. Model test shows that our method can provide a reliably inverted result for the effective fluid bulk modulus, porosity and fracture parameters even with moderate noise. Field data test proves the effectiveness of our inversion method.
【Key words】 Titled Transversely Isotropy(TTI)media; Fluid-matrix decoupled approximation; Effective fluid bulk modulus; Fracture parameter; Fluid identification;
- 【文献出处】 地球物理学报 ,Chinese Journal of Geophysics , 编辑部邮箱 ,2023年10期
- 【分类号】P618.13;P631.4;TE311
- 【下载频次】4