WorldOil

High-temperature fibers provide continuous DTS data in a harsh SAGD environment

Distributed Temperature Sensing (DTS) technology promises oil companies better well and reservoir management by allowing them to permanently monitor temperature profiles along entire wells, at user-selected intervals. The technology, traditionally based on multi-mode optical fiber, has particular application in Steam-Assisted Gravity Drainage (SAGD) and steamflood recovery methods, in which steam is injected into heavy oil reservoirs to reduce the viscosity of the hydrocarbon fluid so that it can flow more freely to a producing well. The fiber used in DTS technology normally contains dopants, such as germanium, designed to increase the refractive index of the fiber core. However, in the hydrogen-rich, corrosive environments of SAGD and steamflood applications, defects in dopant-enriched fiber may combine with hydrogen, exposing the fiber to a phenomenon known as “hydrogen darkening.” This occurrence reduces the ability of the fiber to refract light, thereby rendering it ineffective in monitoring temperature profiles.