【摘要】 杨氏模量和泊松比是表征岩石性质的重要弹性参数;地震叠前反演是获取地下弹性参数最有效的方法之一,其核心是描述地震波反射特点的反射系数方程。针对缺失大入射角的地震数据,经典三项式反射系数方程的反演不稳定性较突出的情况下,拟从减少参数维数入手,提高反演结果的稳健性。首先从Aki-Richards近似方程出发,通过引入密度幂指数经验近似模型拟合密度反射系数,推导得到直接反演杨氏模量和泊松比的两项式反射系数近似方程;然后,从正演与反演角度,利用多个参数化模型对新方程的稳定性与精度进行分析、验证,结果表明该方程具有计算精度高、适用性较强的特点;最后,依据新方程总结了一套适用于含气储层、能够直接反演岩体脆性参数的叠前反演方法,该方法较好地刻画了含气目标,为油气储层含气特征的识别提供了新的手段。更多还原

【Abstract】 Young’s modulus and Poisson ratio are two important rock parameters to indicate rock properties.Seismic prestack inversion is one of the most effective ways to obtain these parameters,and its core is reflection coefficient equation describing characteristics of seismic reflection.This article starts with introducing a variable parameter formula to Aki-Richards approximation equation,derive a new two-term reflection coefficient approximate equation in terms of Young’s modulus and Poisson ratio by reasonably fitting density reflection coefficient;and then analyzes the stability and precision of the new equation using different parametric models.Experimental results show that this equation is as accurate as the exact equation,and possesses good applicability.Finally,a new prestack seismic inversion procedure which is applicable to gas-bearing reservoirs is proposed for rock brittleness.Real data tests show that the proposed inversion method can well describe gas-bearing reservoirs.更多还原