Quantitative quality of distributed acoustic sensing vertical seismic profile data

Abstract

Great advances have been made in distributed acoustic sensing (DAS) vertical seismic profile (VSP) data acquisition hardware and software. Here, we capture a quantitative assessment of the quality of DAS data at a single point in time. We apply comprehensive testing methods to determine the reliability of the data and its suitability as a supplement to geophone data or to gain access to wells where it would be difficult to deploy geophones. The test measurements are made on DAS and geophone data, which were collected at the same time and in the same well. We analyze the first breaks for waveform consistency, signal-to-noise (S/N) ratio, and slowness. Then, we examine the corridor stacks for waveform consistency and S/N ratio. Finally, we test the properties of the measurement, including linearity, repeatability, reliability, and response, as a function of the angle of incidence of a seismic wave to the fiber. The results show that the DAS VSP data provide accurate formation slowness logs and reliable amplitude information suitable for creating seismic images and corridor stacks.