三维孔洞储层建模及其地震波场正演模拟  

Geological modelling and seismic wave forward modelling in 3D cavity reservoir

作　　者：闵小刚[1,2] 陈开远[1] 顾汉明[3] 

机构地区：[1]中国地质大学(北京),北京100083 [2]中海石油研究中心,北京100027 [3]中国地质大学(武汉),武汉430074

出　　处：《地球物理学进展》2011年第4期1288-1297,共10页Progress in Geophysics

基　　金：国家重点基础研究发展计划(973计划)"碳酸盐岩孔洞型油藏开发基础研究"(2006CB202400)项目资助

摘　　要：本文研究的内容有二,一是针对塔河油田六区东中、下奥陶统碳酸盐岩孔洞储层发育的特征,通过精细的层位标定、构造解释与时深转换,搭建深度域等时地层框架模型,然后采用协克里金算法,将波阻抗反演体作为协变量,对孔洞储集体的三维孔隙度分布进行确定性建模;二是应用二维横向各向同性介质中的弹性波波动方程,基于交错网格差分格式,考虑初始条件、吸收边界条件以及野外实际地震观测系统,对三维孔洞储层模型逐线进行正演模拟和波场特征分析,总结地震响应规律.在常规叠加偏移处理的基础上,再把各二维偏移剖面并成三维体,并在频率域实现空间插值.结果表明,孔洞储集体在偏移剖面上表现为负-正-负三个相位的波形,但只能确定奥陶系风化面下第一个负相位是孔洞的发育位置,其下的"串珠"是孔洞的假象.风化面反射波与沿纵横向有一定分布的孔洞体的绕射波叠加,使得孔洞所在位置处风化面反射能量变弱,而孔洞底部与下覆围岩之间的正极性反射由于受风化面透射波的负值性续至波叠加,也变得较弱.This paper has two purposes. The first is to build isochronal stratigraphic framework in depth domain in the middle-lower Ordovician of work area 6, Tahe oil field, based on the reservoir character, careful calibration, structure interpretation, and time-to-depth conversion. Subsequently, the spatial distribution of cavity reservoir porosity is deterministic modelled by Co-kriging algorithm which takes the impedance inversion data as the covariance. Constrained by seismic information, the uncertainty of reservoir geological model has been effectively reduced, and the accuracy of geo modeling has been improved significantly. The second is to implement forward modelling of this geological model line by line just using finite difference of 2-D elastic wave equation for Transverse isotropic （TI） medium, analysis the wave field characteristic and summary the seismic response. In this process, the initial condition, absorbing boundary, seismic source, the practical data acquisition geometry and processing flow have been considered comprehensively. In solving 2-D elastic wave equation, the numerical dispersion can be decreased perfectly and the compute accuracy can be increased effectively, by combination the finite difference algorithm with the staggered grid technology, and using absorbing boundary and stability condition appropriately. At the same time, the compute efficiency can also be improved by using larger grid spacing, just considering the precondition of specific accuracy. Based on the ordinary stacking and migration processing, all the 2D migrated section is integrated into a 3D seismic body and spatial interpolated in frequency domain. The result has showed that： the cavity reservoir is a negative-positive-negative phase in migrated section, but only the first negative phase under the Ordovician basal surface is the real image, the subsequent paternoster reflection is the virtual image. The basal surface energy is weakens due to the interference between its own reflection and cavity diffraction, and t

关 键 词：碳酸盐岩 孔洞储层 确定性建模 有限差分 正演模拟 

分 类 号：P631[天文地球—地质矿产勘探]