利用VSP和跨孔走时反演横向各向同性介质中的弹性常数  

Deriving the elastic constants of transversal isotropic medium from VSP and crosshole travel times

作　　者：张文生[1] 何樵登[1] 

机构地区：[1]长春地质学院地球物理系

出　　处：《石油地球物理勘探》1997年第3期345-356,共12页Oil Geophysical Prospecting

摘　　要：横向各向同性介质（TI）是地下各自异性介质的最常见形式，它可由五个弹性常数来描述。在这种介质中，其对称轴和垂直对称轴附近的侵度面近似为椭圆面。根据这个特点，我们提出了用VSP和跨孔走时联合反演横向各向同性介质中弹性常数的方法。与以往的同类方法相比，采用本文方法，可估计多层TI介质中任意各向异性（不仅是弱各向异性）的弹性常数，且不用求解线性代数方程组，也不用计算准SV波的正常时差（NMO）速度。分析表明，对强各向异性介质，往往得不到正确的准SV波的NMO速度。理论模型处理结果表明，该方法具有适用性强和精度高的特点。Transversal isotropic medium is the most typical one of subsurface anisotropic media,and it can be described with 5 elastic constants. The slowness surface near symmetric axes in the medium approximates to an elliptic surface. On the basis of this characteristic, we put forward a new method for deriving elastic constants of transversal isotropic medium from VSP and crosshole travel times. The method can be used to estimate any anisotropic elastic constants of multilayer transversal isotropic medium,without both solving for any linear algebraic equation system and computing NMO velocity of quasi SV-wave. It is shown that correct NMO velocity of quasi SV-wave often can not be obtained in strong anisotropic medium. Theoretical result says that the method is very adaptable and accurate.

关 键 词：各向异性介质 横向各向同性 弹性常数 地震勘探 

分 类 号：P631.443[天文地球—地质矿产勘探]