A novel velocity band energy workflow for fiber-optic DAS interpretation and multiphase flow characterization

Distributed fiber-optic sensing continues to gain widespread adoption in the energy industry because of the numerous benefits it offers for real-time surface and subsurface monitoring of pipelines, wellbores, reservoirs, and storage infrastructure. In this study, we introduce a novel workflow to analyze optical fiber-based distributed acoustic sensor (DAS) data, which takes into account the speed of sound for a certain phase to filter the acoustic energy or signal contributed by that phase. This information is then utilized for the characterization of multiphase flow. The application of the proposed velocity band energy (VBE) workflow is demonstrated using a dataset acquired in a 5163-ft-deep wellbore, for estimating gas void fraction and real-time gas-liquid interface tracking across the length of the well. The workflow utilizes a series of signal processing and conditioning steps that aim to reduce noise and enhance the signals of interest. The insights from the new methodology will further assist in validating DAS-based flow monitoring algorithms, leak detection and quantification, and reservoir characterization.