Well and Field Monitoring - Cased-Hole Log Analysis and Reservoir Performance Monitoring - page 239

DTS Applications
DTS technology (in the United States) was first applied by NASA. They used fiber
optics to monitor the fluid level inside fuel cells. As fluid levels within a cell vary
local temperature changes help determine the new fluid level. This was used to
obtain a good indication of fuel cell life. The same concept has since been adopted
in both the upstream and downstream sectors of the oil industry. Some of the appli-
cations are:
Gas lift monitoring (whether a gas lift valve is open or to what extent).
Pressure vessels (measurement of interior wall temperature and/or temperature
changes due to reactions).
Pipeline gas leak detection (fiber optic cable placed under the wrapper to monitor
temperature change).
Cement job quality (real-time monitoring of fracturing and detection of inter-zonal
communication).
Electric lines (overloading).
Packer seal (detection of fluid communication, i.e., under hydraulic fracturing pro-
cess in open-hole well completion).
Static and dynamic fluid levels (determination in a wellbore, for Sucker Rod, Gas
Lift & ESP applications).
Production in flow monitoring (real-time knowledge temperature distribution at
perforations allows for inflow performance optimization).
Enhanced recovery — thermal and non - thermal (steam distribution at both injec-
tors and producers can be monitored using DTS).
Electro submersible pumps ( ESP ) optimization (real-time monitoring of pump and
electrical cable temperatures allows for pump performance optimization).
Real - time stimulation monitoring (most facets of hydraulic fracturing operations
can be conveniently monitored including fracture height, well integrity, injec-
tion, packer seal efficiency as well as static and dynamic fluid levels).
Advantages of Fiber Optic Sensors
Fiber optic cables are essentially thin strands of glass and thus are made of electri-
cally insulating material. Their use obviates the need for any electric cables. Thus
they can be employed in high voltage environments since they are made from insu-
lating material. They are also chemically passive and not subject to corrosion. Yet
another added advantage is that a fiber optic cable is immune to electromagnetic
interference. Glass fibers also have a very wide operating temperature range making
them ideal for oilfield applications. Fiber optics are resistant to temperatures as high
as 1100 ﾰC. However, coating material resistance to such high temperatures may not