Traditionally, geothermal plants have been located in areas where hot springs and other indicators of thermal activity can be seen at the surface. However, enhanced geothermal systems (EGS) may also be used in areas where hot rock is found at reasonable depths. To achieve geothermal energy, fluid is injected into the drilled wells, heated by contact with the hot rock, and removed to power turbines at the surface. The majority of EGS utilize steam turbines to convert geothermal energy into electricity.
Under the constant pressures to lower operational costs and raise the effectiveness of the EGS, a number of parameters need to be managed to ensure high efficiency and competitive electricity prices. The efficiency of a geothermal plant is entirely reliant on the amount of steam that can be retrieved from the well, therefore, the subsurface reservoir must be able to provide quality geothermal fluid in sufficient quantities over its service life.
In order to retain the needed pressure in the well and to extend its service life, geothermal fluid achieved by hydraulically fracturing the hot rock is re-injected. Consequently, it is crucial to understand where the fluid is going inside the well and where the fluids come from.
It is well known and documented that the use of distributed temperature sensing in geothermal energy applications has greatly improved the reliability and longevity of EGS. Distributed temperature sensing systems can also be combined with other sensors, like FBG pressure sensors, to provide a complete data set. The information – subsurface temperature and pressure – can be used in various ways, such as:
1. Estimation of the production potential in the new wells be measuring the temperature at the point of pressure
The rate at which the fluid pressure drops after the operator opens the tap at the surface allows the calculations of reservoir size, flow resistance between wells, well completion, etc.
2. Monitoring of the surface and subsurface scale buildup and chemical cleanup
The buildup of scale – a mineral residue precipitated from the geothermal fluid – can inhibit fluid flow and block a pipe. A better understanding of the severity of the scaling may improve the choice of mitigating options.
3. Integrity monitoring for casing and tubing leaks.
The compromised integrity of the casing and tubing may lead to contamination of ground and subsurface aquifers.
An installed DTS system provides many additional monitoring opportunities. The efficiency of the geothermal plants may be greatly improved by combining temperature data with subsurface point pressure data. Distributed temperature sensing channels may be added to monitor surface processes. Another geothermal energy application of DTS systems in localization of overheated areas that allows mitigating the hotspots.
If you would like to purchase DTS (Distributed Temperature System), please contact us: info@optromix.com or +1 617 558 98 58
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