3D Seismic Refraction Analysis for Weathered Layer Delineation and Statics Computation in Khewari Area, Pakistan

Abstract

A total of one ninety-five (195) forward reverse-shooting seismic refraction lines and uphole survey data from one well have been analyzed, to compute weathered layer geophysical characteristics in "Khewari" Southern Indus Basin, Sindh, Pakistan. The time-intercept technique of seismic refraction interpretation was employed while the conventional method of well shooting analysis used in the uphole well surveys. Results of data interpretation revealed that the thickness of the weathered layer ranges from 2 m to 38 m at the north central location with a regional average of 24 m. The average weathered layer compressional wave velocity was about 640 m/s; ranging from 340 m/s to 880 m/s. The weathered layer has an average statics -55 m/s ranging from -100 m/s to -20 m/s. Rock physics analysis shows the variation in the lithology w.r.t wave velocities in subsurface.