# Monitoring Liquid Slugs Using Distributed Acoustic Sensing and an Air Gun

## TL;DR

This paper shows how sound-sensing fiber optic cables can track liquid slugs in oil wells using sound pulses, improving monitoring and flow management.

## Contribution

The study introduces using acoustic pulses with distributed acoustic sensing to effectively track liquid slugs in real-time.

## Key findings

- DAS with acoustic pulses can track liquid slug movement and estimate velocity, location, and body length.
- Relying on natural flow noise may not be sufficient for slug detection in complex flow environments.
- The method enables real-time monitoring for better well and flow management.

## Abstract

Distributed acoustic sensing sends laser pulses along a fiber optic cable and analyzes the backscattered light to identify acoustic signals along the entire fiber. Liquid slugs were produced in a 427 m vertical test well using surface-controlled gas lift valves. To enhance DAS monitoring, pressure pulses were induced by multiple acoustic shots from a fluid level gun. Visualization of the responses through frequency band energy plots and unfiltered phase shift measurements permitted tracking slug movement and estimating parameters such as velocity, location, and body length. The results demonstrate that DAS stimulated with acoustic pulses can effectively track liquid slugs in real-time. We observe that relying solely on flow-induced noise in multiphase flow environments may not provide sufficient signal strength for slug detection. Applications include real-time detection of liquid slugs for improved well monitoring and flow management.