Abstract

Converted wave (PS) total field statics comprises of P wave shot statics and receiver shear statics.In multicomponent seismic data acquisition and processing computation of receiver statics for converted waves has been a challenge to the field crews and is often left for the processing center wherein the shear statics is estimated from indirect methods based on the data. Generally shear statics is estimated from shifts in shallow horizon or alternatively, in absence of trackable horizon by scaling PP receiver statics.Converted shear waves travel with very low velocity in near surface resulting in large static effects. Uphole surveys are used frequently for computation of near surface P wave velocity model and computation of PP statics. Uphole survey with 3C sensors offers a direct method of computing near surface shear wave velocity model. The main issue in this approach is identification of the shear events in the near surface and distinguishing it from surface waves. The paper demonstrates the methodology for acquisition of 3C uphole data and distinguishing the shear events from rayleigh waves. Uphole data of different areas of Gandhar and Kalol in Cambay Basin and Changmaigaon in Assam & Assam Arakan Basin were studied for the purpose. The velocities thus obtained in the Kalol area was used to derive shear statics. The stack after application of shear statics derived from uphole shows improvement when compared with stack with conventionally derived shear statics.