Distributed fiber optic sensor system used for temperature monitoring of geothermal deep well walls

Fib optik Tanperati optik Detèktè, Sistèm siveyans entelijan, Distribye fib manifakti optik nan peyi Lachin

Monitoring the temperature of geothermal deep well walls is a fundamental task in the development and utilization of geothermal resources. It is of great significance to grasp the dynamic changes of geothermal deep well thermal storage and its surrounding geological environment, and to ensure the long-term sustainable development and utilization of resources. The existing geothermal temperature monitoring generally uses electronic temperature sensors, which generate electrical signals that are susceptible to electromagnetic interference during transmission, and the lines are prone to corrosion, making it impossible to obtain real-time raw data on geothermal water temperature loss during drilling and development, the impact of geothermal well wall temperature, and cementing quality.

The distributed fiber optic temperature monitoring system and its method for geothermal deep well walls are used to solve the problem of real-time acquisition of geothermal water temperature loss and the influence of geothermal well wall temperature during the development and utilization process of geothermal drilling by existing technologies.
On the one hand, the embodiments of the present invention provide a distributed optical fiber temperature monitoring system for geothermal deep well walls, which is characterized in that it comprises a distributed optical fiber temperature testing device, a high-temperature resistant armored optical cable, and an optical cable crossing device; The distributed optical fiber temperature testing device is connected to the high-temperature resistant armored optical cable;

Technical indicators of geothermal distributed fiber optic temperature measurement

A distributed fiber optic temperature testing device is used to send laser signals to the high-temperature armored optical cable, receive Raman scattering light signals carrying temperature information returned by the high-temperature armored optical cable, and analyze and display them;
High temperature resistant armored optical cable, through the optical cable crossing device, enters the geothermal deep well and transmits the laser signal, collects temperature information at different wellbore positions in the geothermal deep well, and returns the temperature information to the distributed optical fiber temperature testing device in the form of Raman scattering light signal;

The technical challenge of distributed temperature monitoring of casing cannot be carried out in existing geothermal wells. High temperature resistant armored optical cables are inserted into the target depth position of the geothermal well along with the casing, achieving permanent monitoring of the wall temperature (or geothermal water temperature) of deep geothermal wells. Choose distributed fiber optic sensing technology as the temperature monitoring method to replace traditional electronic thermometers, because on the one hand, fiber optic transmission is a light wave signal, avoiding the defect of existing electronic temperature sensors in background technology being susceptible to electromagnetic interference, and fiber optic is not easily corroded, which can effectively ensure long-term stable operation in harsh environments; On the other hand, fiber optic sensing technology carries temperature information through reflected light. As a transmission and sensing element, fiber optic cables do not require specialized sensors and do not occupy more space. They are particularly suitable for the narrow linear space requirements of geothermal deep well walls and casings,
Improve the safety of project implementation. The coupling degree between different formations and casings in geothermal deep wells varies, resulting in different thermal energy losses. This is because different formations may have different amounts of thermal energy losses. The present invention adopts distributed temperature measurement technology, which can accurately obtain information on wellbore temperature or geothermal water temperature in different formations and at different depths of the same formation, providing richer data for geothermal research.

Monitoring the temperature of geothermal deep wells is a fundamental work for the development and utilization of geothermal resources. It is of great significance to grasp the dynamic changes of thermal storage and its surrounding geological environment, and to ensure the long-term sustainable development and utilization of resources. The existing geothermal temperature monitoring generally uses electronic temperature sensors, which generate electrical signals that are susceptible to electromagnetic interference during transmission, and the lines are prone to corrosion, making it impossible to obtain real-time raw data related to geothermal water temperature loss, geothermal well wall temperature impact, cementing quality, elatriye. during geothermal drilling and development and utilization.