Fiber Optical Sensors for Geothermal Purposes

摘要

First fiber optical sensors (FOS) were flexible endoscopes developed in the first half of 20th Century. Their conception and use created a revolution in medicine that continuous upon these days. The modern FOS era started in late 1970's with the development of ultra-low losses fibers. A wide variety and applications of FOS have been demonstrated over the last 30 years. Nevertheless, the use of FOS for geothermal applications has not been fully developed due to the aggressive-hostile environment that can be found in geothermal fields. In this work, we deal with FOS based on Fiber Bragg Gratings capable of measure Strain, Temperature, and Pressure in both static and dynamic conditions. Sensors working up to temperature as high as 700°C and with superior performances (regarding sensitivity, resolution, and bandwidth) to state-of-the-art commercial sensors will be discussed. All developed sensors were simulated and will be tested at reservoir conditions in rock samples of Mexican geothermal reservoirs. These tests at high pressure and temperature will be performed mainly in a GCTS tri-axial machine; this machine offers the possibility to include some corrosive liquids in the system. The obtained results from numerical simulations predict better performance than the electrical sensors used as a reference.