Distributed Fibre Optic Sensors and Applications

Course Description

This course introduces standard optical fibres, including multimode and single-mode fibres, commonly used in telecommunications and sensing applications. It also provides an overview of optical fibre manufacturing processes. In previous editions of the course, site visits to optical fibre manufacturing facilities have been organised.

Key components used in optical fibre handling—such as different connector types and fusion splicing techniques—will be described. For in-person sessions, industry partners may also be invited to demonstrate fibre fusion splicing and optical loss measurements using an Optical Time Domain Reflectometer (OTDR).

The course explains the principles of distributed optical fibre sensing technologies that utilise different backscatter spectra. Important system performance parameters, including spatial resolution and gauge length, are also introduced.

For geophysical applications, the course derives methods for converting optical fibre phase measurements into particle velocity measurements (m/s) to enable comparison with conventional geophone data, while also considering the directional response of the optical fibre.

Examples of cable designs and installation methods for permanent, intervention, and subsea wells will be presented. The advantages of engineered fibre—which provides stronger and more efficient backscattered light for improved sensitivity and longer operating range compared with standard single-mode fibre—will also be discussed for advanced sensing applications.

Several key applications will be explored, including:

Flow profiling
Well integrity monitoring
Hydraulic fracture monitoring
Carbon Capture, Utilisation and Storage (CCUS)

The course also addresses the growing interest in low-frequency Distributed Acoustic Sensing (DAS) for geotechnical applications such as ground deformation and subsidence monitoring. Data processing techniques for measuring strain and temperature changes below 1 Hz frequency response will be introduced.

For the forthcoming fibre optic workshop, the course will include an additional module on DAS Vertical Seismic Profiling (VSP), to be presented by Sebastien Soulas from Avalon Sciences Ltd..

Course Outline

Session 1 Introduction to Optical Fibres
- Basic principles of optical fibres
o Different types of fibers such multimode and single-mode fibre
o How the fiber is made
o Operating temperature range
o Connectors
o Splicing

Session 2 Principles of Optical Fibre Distributed Sensors
- Distributed Fibre Optic Sensors
o Backscatter spectrum
o The measurement principles
o Sampling resolution, Spatial resolution, and gauge length
- Geophone comparison
o Conversion to geophone equivalent signal
o Frequency response as a function of gauge length
o Directionality response

Session 3 Installations and Applications
- Installation configurations
o Cable designs
o Permanent installation
o Intervention
o Subsea
- Applications
o Flow profiling
o Well integrity
o Frac monitoring
o Seismic
o Microseismic
o Low-frequency strain and frac hit detection

Session 4 Distributed Acoustic Sensing (DAS) for VSP applications 

o DAS principles 

o Motivation

o 2D VP imaging

o 3D VSP imaging o Case studies

Participants’ Profile

None

Prerequisites

None

About the Instructor

Mahmoud Farhadiroushan is a specialist tech founder and industry leader who helped pioneer modern distributed fibre-optic sensing systems. Mahmoud co-founded Silixa in 2007 and he is currently Executive Director. Prior to Silixa, he co-founded Sensornet in 1998 which was then received an investment from Shell Technology Ventures. Mahmoud worked as a Senior Research Fellow on non-linear fibre optic sensors at King’s College London from 1994 to1998. He successfully managed and completed a European project. From 1990 to 1994, he initiated and managed a Joint Industrial Project (JIP) in fibre optic sensing for oil and gas applications that led to the formation of Sensor Dynamics which was then acquired by Schlumberger in 2001. From 1986 to 1990 he was a Research Fellow at University College London working on fibre optic sensors, integrated photonics devices. He was a Joint winner of Metrology Award in 2000, British Telecom Award in 2001, Institute of Physics Innovation Award in 2015, and The Queen’s Award 2021 for Innovation on the behalf of Silixa.