Dry hot rock geothermal monitoring system

Dry hot rock geothermal monitoring system

It is a real-time, online, and continuous temperature measurement system consisting of a temperature measurement host, a temperature sensing optical cable, and related accessories. It can accurately detect the temperature at any measurement point along the fiber optic cable, providing reliable and timely information for accurately monitoring the distribution of spatial temperature field. It has the advantages of real-time online, high temperature measurement accuracy, intrinsic safety, and no electromagnetic interference, and can monitor the distributed ground temperature of geothermal well walls in real-time for a long time.

Principle Overview

The distributed fiber optic temperature fire detector adopts the distributed fiber optic temperature sensing method, which utilizes the spontaneous Raman scattering principle and optical time domain reflectometry (OTDR) technology generated by laser transmission in the fiber optic to obtain spatial temperature distribution information. When a laser pulse of a certain energy and width is injected into an optical fiber, it continuously generates backward Raman scattering light while propagating forward in the fiber. The intensity of these backward Raman scattering lights is affected by the temperature of the scattering point on the fiber. After optical filtering, photoelectric conversion, amplification, and analog-to-digital conversion, the scattered backward Raman light is sent to a signal processor to calculate the temperature information in real time. At the same time, the temperature information is located based on the transmission speed of light in the fiber and the time of backward light echo. The principle is shown in the following figure:

Dry hot rock geothermal monitoring system