Zero offset VSP processing of fiber optic cable (DAS) and geophone array at the CaMI Field Research Station
Adriana Gordon, Donald C. Lawton
Two Vertical Seismic Profiles (VSP) were acquired in May and July of 2017 at the Containment and Monitoring Institute Field Research Station (FRS) in Newell County, Alberta. These surveys were recorded using two different receiver types; a 24-level 3C geophones array and an integrated fiber optic cable (DAS and DTS). A zero-offset processing flow was completed for two shot points and an 80 m offset shot for both the fiber optic cable and geophone array. Before processing, a calibration step was necessary to estimate the exact depth for each trace in the fiber optic data set. There was an accurate result between the cross-correlation of the first and last geophone trace, a difference between 0 to 3 m or 0 to 12 traces was calculated from the calibration. After the processing flow was completed, a good match was obtained between the corridor stack of both the down-going and up-going segments of the fiber loop, as expected. A time difference of approximately 20 ms between the DAS and geophone data was also noticeable which might be caused to the difference between the signal recorded by the geophones and the fiber optic cable. A few tests for converting the DAS signals to particle velocity were evaluated and a similar calibration difference between the first and last geophone was obtained.