Downhole Fiber-Optic Monitoring: An Evolving Technology
Authors: Jacobs Trent 
Published: February 2015

Fiber Optics

It has been an impressive comeback for a technology that once stood on the brink of failure. The upstream oil and gas industry has largely resolved crippling technical challenges that shortened the life of fiber-optic cables in downhole applications and is now working on a big encore. The developers of the technology have been successful in showing operators what can be gained by using permanent fiber-optic monitoring in a small number of wells. The next step is to broaden the market by expanding what the technology can do.

A number of research and development projects aimed at maturing new applications for fiber-optic systems are in progress. Taken together, they stand to improve the return on investment for operators as the technology slowly takes the shape of a central nervous system for oil and gas wells. Put simply, those working in the fiber-optic sector want to provide engineers with real numbers to enable managed production strategies that will increase overall production.

The most widely used form of fiber-optic technology today is by far distributed temperature sensing (DTS) and thus its development is relatively mature. Initially, many of Schlumberger’s customers viewed DTS as a niche product. But after pumping down more than 17 million ft of fiberoptic cable into more than 1,500 wells, the oilfield service company is experiencing greater global demand than ever, something it credits to better data.

“In the old days, the fiber data was marred by reliability, by fiber darkening, and those kinds of things. The big growth that we are seeing today is really because of the improved reliability, ease of data transmission, and customers having a lot more confidence in the data and being able to use that data,” said John Lovell, product line manager of distributed measurement and completions division at Schlumberger. “Now that we have good data going, you can start moving from a qualitative assessment to much more of a quantitative assessment.”

However, for all the benefits that downhole fiber optics is delivering, more breakthroughs are needed to bring about the next evolutionary step of the technology. Multiple companies are working on ways to adapt fiber optics to determine flow characteristics and related physical properties inside the pipe and near the wellbore. Managing the ever-growing sets of data being produced specifically through distributed acoustic sensing (DAS) is an ongoing problem that needs to be solved.

More work is under way to expand the computer systems and applications used by service providers so operators can use competing laser and optical receiving systems, known as interrogator units, and draw out the data in a universal format for interpenetration. Oil and gas companies also need more ways to integrate and correlate the fiber-optic data with conventional production data. And then there is the unresolved issue of how the data should be shared between the service providers and the operators. “These are all good problems to have,” said Zafar Kamal, manager of sensors and systems integration at BP. “I think they will be solved, it is just a question of how efficiently can we do it, how fast we can do it, and who gets there first.”