薄储层的反射特性及其AVO属性分析

Reflection characteristics of thin reservoirs and its AVO attributes a- nalysis

针对薄储层地震反射模型,利用Gassmann流体置换方程分析了薄储层的孔隙度和含油、含气饱和度等因素对P波速度、S波速度和介质密度的影响;根据薄层反射动力学和粘弹各向异性理论,利用AVO技术研究了薄储层物性参数与地震反射特征之间的关系。研究结果表明,含气饱和度的变化使气体的可压缩性发生改变,P波速度随含气饱和度的增加由急剧降低转为缓慢升高;孔隙度的变化对P波速度、S波速度和介质密度的影响要大于含油、含气饱和度变化的影响;不同孔隙度薄层的AVO响应差异明显;孔隙度增加,AVO属性中的截距和梯度对含气饱和度的变化比对含油饱和度的变化敏感;薄层反射的AVO响应与薄层厚度有关,薄层厚度增加时,对其含油和含气饱和度的变化,梯度属性比截距属性更敏感。

Aiming at thin reservoir reflection model,the effect of porosity, oil and gas saturation on v_p,vS and media density are investigated by the Gassmann fluid substitution equation.In terms of thinbed reflection dynamics and viscoelastic anisotropic theory,AVO technology is used to study the relationship between thin reservoir properties and seismic reflection characteristics.The results show that the changes of gas saturation making the compressibility of gas altering,vP drops rapidly and then increases gently versus gas saturation increasing.The impact of changing porosity on v_p,v_s and media density is larger than changing oil and gas saturation.The difference of AVO response is obvious with different porosity.With porosity increasing,gradient and intercept of AVO attributes are more sensitive to the changes of gas saturation than oil saturation. AVO response of thin-bed reflection is related to the thickness, when thin-bed thickness is increasing,gradient is more sensitive to the changes of oil and gas saturation than intercept.