基于地震物理模拟的碳酸盐岩溶洞储层流体识别

Fluid identification of carbonate cave reservoir based on seismic physical modeling

针对碳酸盐岩溶洞储层流体识别问题,开展了基于地震物理模拟数据的叠前AVO反演和叠前同步反演弹性参数属性交会分析流体识别方法研究。设计并制作了一个充填不同流体(气、油和水)的溶洞物理模型,模拟采集了溶洞模型的超声地震数据;通过模拟数据的叠前AVO反演和叠前同步反演,获得截距P、梯度G、纵波阻抗ZP、横波阻抗ZS、泊松比σ等多种弹性参数属性;对各种弹性参数属性分别进行两两交会分析,在交会图上划分出分别对应油、气、水的3个区域,将3个区域中的数据点投影到反演剖面中,实现溶洞不同充填流体的识别。结果表明,P-G交会、ZS-σ交会、μρ-σ交会、λρ-σ交会等识别油、气、水效果较好,因此它们均可以用于碳酸盐岩溶洞储层流体识别。

For fluid identification of carbonate cave reservoir,based on the seismic data by physical modeling,cross plotting is carried out on the elastic attributes obtained from prestack AVO inversion and prestack simultaneous inversion.A cave physical model fullfilled with different fluids （gas,oil and water） is constructed to acquire ultrasonic seismic data.Prestack AVO inversion and simultaneous inversion are adapted on the seismic data to obtain elastic attributes,such as AVO intercept P,AVO gradient G,P-wave impedance ZP,S-wave impedance ZS and Poisson？s ratio σ.Then these elastic attributes are analyzed by cross plotting with each other.Three areas of different fluids （oil,gas and water） are marked out on crossplots and then projected to an inversion profile to identify fluid within caves.Results verify that fluid identification by cross plotting analysis of P-G, ZS -σ,μρ-σ and λρ-σ is good,which can be effectively applied to fluid identification in carbonate cave reservoir.