TRAVELTIME ANALYSIS OF MULTIPLE REFLECTIONS IN SEISMIC PROSPECTING

Abstract

The seismic prospecting comprises of two basic techniques name]y the refraction and the reflection. In both these types of techniques seismic energy is generated through the detonation of ahelge underground or through the some other process. In the refraction prospecting the success of the method depends upon the criterion that the velocity changes in the increasing order from one layer to the layer below it. With this condition tb fulfill ll the waves incident at the critical angle travel along the boundhry and gives rise to the head waves which are recorded by the geophonea placed on the ground surface. Bowever,in this case if a low velocity layer is met along the patty of the ray' the waves travellirg along the boundrry would not be generated ,end as such the low velocity layer will be missed in the inter-pretetion dons on the basis of refraotionphooting. On the Qtb erk band_ thi reflection shooting will be found useful to derive information about such a layer. The only criterion to get a good reflection from a parti- cular interfrce. is that there should be good acoustic impedances contrast between the media 2 on the two sides of the interface. Are such the reflection method has been found much useful in the seismic prospect-trig work either In land or offshore........