Fiber Optic Sensing and Cabling Technologies

Fiber optic sensors work well in tight spots and applications with a high degree of electrical noise, but care must be taken when specifying these critical components.

Sensing part presence in machines, in fixtures, and on conveyors is an important component of industrial automation. Error-proofing assembly and controlling sequence based on the presence or absence of a part is often required. Many types of sensors are available, including inductive, magnetic, capacitive, and photoelectric. Each has its own strengths and weaknesses depending on the application.

Photoelectric sensors come with a variety of light-emission types (infrared, visible red, laser Class 1 and 2), sensing technologies (diffuse, background suppression, reflective, through-beam), and housing configurations (photo-eye or fiber optic). Fiber cabling is immune to electrical noise, and the electronics can be mounted away from the noise in a shielded enclosure.

Another very common application is small part assembly. These operations tend to be fully automated, and thus require multiple sensors to confirm part placement (seated) and assembly verification to confirm completion of an operation. Typically, the parts are moving in and out of a stage quickly on carriers or an indexing table. Because travel tolerance is minimal, precise measurement of position becomes essential.

A common issue in fiber optic installations concerns excessive flexing of the fibers. Since the fiber cables are bundles of individual fibers, they typically feel quite pliable, allowing an installer to easily bend the fibers beyond their recommended maximum bend radius. This can cause irrecoverable plastic deformation of the fibers, which will reduce the light transmission or, in the worst case, sever it entirely. The maximum bend radius, listed with all fibers, varies depending on fiber material, bundle size, and fiber dispersion in the bundle—and it must be adhered to in all cases.

Regardless of the application, machine builders must select the proper sensor technology. If fiber-optic sensors are used, amplifiers and fiber-optic heads must be carefully selected for the application to provide robust sensing performance.

Distributed fiber optic sensing (DFOS equipment) for oil & gas industry

Distributed fiber optic sensing (DFOS) presents a good ability for the oil and gas industry to operate and optimize its resources more effectively going forward. Expenses on DFOS by the oil and gas industry worldwide was $341.2m in 2015. The rise of expensive multilateral hydraulic fracturing, an ever-greater focus on improving oil recovery and the continued strength of capital expenditure on thermally enhanced oil recovery techniques provide the main markets for the uptake of DFOS over the next 10 years.

During the past five years distributed acoustic sensing (DAS) – one type of DFOS – has approved itself as a pipeline in-service surveillance and monitoring system. Moreover, distributed acoustic sensing as technology looks set to add value to DFOS monitoring solutions of wells and reservoirs. DTS (distributed temperature sensing) is already established as a well-monitoring technique and the complementary application of a DAS interrogation enhances the future business case. The last main type of DFOS equipment – distributed temperature and strain sensing (DTSS) – is competing for market share as well as being able to market itself as a solution that can anticipate structural problems with the oil and gas industry before they occur.

The application opportunities within the oil and gas industry for DFOS are poised to enable a substantive growth in spending on DFOS equipment. After well monitoring, permanent reservoir monitoring and seismic acquisition is an especially exciting venture market for DFOS, as is the use of fiber optics for monitoring offshore infrastructure and downstream process integrity. The use of DFOS as part of a 4D solution and vertical seismic profiling is the most deserving attention market space growth ability for DFOS equipment expenditure over the coming 10 years.

For emphasis: an oil price of $100 per barrel continues to enable exploration and production expenditure on unconventional oil and gas development, thermal enhanced oil recovery (EOR), and ever more IOR (Improved Oil Recovery) activity. Distributed fiber optic sensing is a part of this story: a tool to better the industry’s understanding of how to optimize recovery and improve development techniques.