S-wave velocity estimation using converted-wave VSP data

In three-component (3C) VSP data processing, first-break times of direct downgoing S-wave are commonly used for estimating the S-wave velocity. However, comparing to direct P-wave arrivals, the direct downgoing S-waves are usually too weak to be picked precisely. To mitigate this disadvantage, we present a new method of S-wave velocity estimation by using converted (P-to-S) waves in VSP data. Two synthetic examples as well as a real 3C VSP dataset are tested to demonstrate the effectiveness of this method. Results show that the proposed method can be a good alternative to conventional S-wave velocity estimation method using VSP data.