摘要
常规AVO分析是以单一界面为前提,用来分析薄层的AVO响应特征存在误差。Brekhovski给出的层状传播矩阵方程考虑了层内波的反射和透射以及层厚等影响因素,更适合用于讨论薄互层的地震响应特征。对薄层进行Brekhovski正演,发现不同入射角下振幅与厚度关系不同,与叠后全叠加振幅相比,截距P属性和薄层厚度之间的线性关系更强,说明P属性比全叠加振幅更有利于薄层厚度预测。不同薄互层模型的Brekhovski正演结果表明:净厚度和泊松比是影响AVO曲线特征的两个主要因素,净厚度越小,泊松比对截距P和梯度G属性的影响越小;当泊松比一定时,净厚度和P、G属性呈近似线性关系,P属性与净厚度关系更敏感,可用于薄互层净厚度预测。应用实例证明在薄互层区P属性用于砂地比预测效果比较好,叠后振幅和叠前反演的弹性阻抗预测的净砂岩厚度精度较差。
Conventional AVO analysis method based on single interface can result in errors in thin layer AVO response characteristics.The Brekhovski layered propagation matrix equation takes into account reflection and transmission of layer wave and thickness,therefore it is more suitable for discussing the seismic response characteristics of thin interbeds.We conducted Brekhovski forward modeling on thin layer and found different relationship between amplitude and thickness using different offsets.The results indicate that pitch attribute has stronger linear relationship with thickness comparing with post stack,full stack amplitude,and can be a good indicator for thin interbed thickness.In different thin interbed model tests by Brekhovski forward modeling,net thickness and Poisson's ratio are two main factors affecting AVO curve characters.Poisson's ratio has less influence on pitch and gradient attributes for small net thickness.While Poisson's ratio is constant,net thickness shows near linear relationship with pitch and gradient attributes,with pitch attribute more sensitive to net thickness,which means pitch attribute could be used for net thickness prediction.Testing results demonstrated that in thin interbed area,pitch attribute is promising for sandstone percentage prediction,whereas accuracy of net thickness prediction by poststack amplitude or prestack elastic impedance inversion is poor.
作者
陈珊
陆蓉
刘力辉
徐兴友
刘卫彬
白静
CHEN Shan;LU Rong;LIU Lihui;XU Xingyou;LIU Weibin;BAI Jing(Oil&Gas Survey,China Geological Survey,Beijing 100083,China;Unconventional Oil and Gas Engineering Technology Center,China Geological Survey,Beijing 100083,China;Beijing Rockstar Petroleum Technology Co.Ltd.,Beijing 100192,China)
出处
《地学前缘》
EI
CAS
CSCD
北大核心
2020年第4期98-109,共12页
Earth Science Frontiers
基金
中国地质调查局项目“大兴安岭西缘中生界油气战略选区调查”(DD20160202,DD201901)和“松辽盆地南部页岩油战略调查”(DD20190115)。
