Fiber optic DTS system application in the research of accumulation possibilities of thermal energy in the rock mass

Látal, Jan; Koudelka, Petr; Šiška, Petr; Skapa, Jan; Hanáečk, František; Vašinek, Vladimír; Vitasek, Jan; Hejduk, Stanislav; Bocheza, Jiri

doi:10.1117/12.887082

Cited by 5 publications

(3 citation statements)

References 2 publications

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“…DTS temperature measurements in oil and groundwater wells, production pipelines, and mining areas are well documented in previous studies (Majorowicz and Smith 1999;Kersey 2000;Johnson et al 2006;Nath et al 2006;Brown 2009;Inaudi and Glisic 2010;Frings and Walk 2011;Sanders 2011;Ukil et al 2012;Banks et al 2014;Lumens 2014;Hartog 2017) as well as the use within the scope of borehole heat exchanger installations for distributed thermal response tests (Fujii et al 2006(Fujii et al , 2009Acuña et al 2009;Latal et al 2011;Hartog 2017;Franco and Conti 2020). Regarding the use of DTS in geothermal wells, laboratory and field tests were carried out in the late 1980s to prove the ability of FO-techniques for temperature and pressure measurements (Angel et al 1986).…”

Section: Dtsmentioning

confidence: 67%

Monitoring cold water injections for reservoir characterization using a permanent fiber optic installation in a geothermal production well in the Southern German Molasse Basin

et al. 2021

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Fiber optic sensing has gained importance for wellbore monitoring and reservoir characterization in geothermal fields as it allows continuous, spatially highly resolved measurements. Distributed acoustic sensing (DAS) and distributed temperature sensing (DTS) technologies, among others, enable monitoring of flow regimes and heat transport inside the wellbore to describe the dynamical behavior of the reservoir. The technically challenging installation of a permanent fiber optic monitoring system in a geothermal production well over the entire wellbore length was conducted for the first time at the geothermal site Schäftlarnstraße in Munich, Germany. One cable with two DAS fibers, two DTS fibers, and one fiber for a downhole fiber optic pressure/temperature gauge were clamped to ¾-in. sucker rods and installed to 3.7 km measured depth to collect data from the wellbore after drilling, during testing, and during operations. We present DTS profiles during 3 months of well shut-in and show the results of two cold water injection tests conducted to localize inflow zones in the reservoir and to test the performance of the fiber optic setup. A vertical displacement in temperature peaks of approximately 1.5 m was observed during the injection tests, presumably resulting from thermal contraction of the sucker rod–cable setup. This was verified by analyzing the strain information from the DAS records over 1 h of warm-back after cold water injection with the calculated theoretical thermal contraction of DTS of the same period. We further verified the flowmeter measurements with a gradient velocity analysis of DTS profiles during injection. Intake to the major inflow zone was estimated to 93.5% for the first injection test, respective 94.0% for the second, intake of flowmeter was calculated to 92.0% for the same zone. Those values are confirmed by analyzing DTS profiles during the warm-back period after the well was shut.

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Section: Dtsmentioning

confidence: 67%

Monitoring cold water injections for reservoir characterization using a permanent fiber optic installation in a geothermal production well in the Southern German Molasse Basin

et al. 2021

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“…As mentioned at the beginning of the article, we have used the DTS system to measure temperature changes of the rock mass through measured thermal boreholes in a polygon [36][37][38]. The technology of the DTS system is based on the principle of optical reflectometer, i.e., a light impulse, at wavelength of 975 nm, 1064 nm or 1550 nm according to the type of DTS and width of 10 ns, is released into the filament.…”

Section: Used Methods and Devices For Measurements And Temperature Logging Of Bhesmentioning

confidence: 99%

“…The inquiry into the temperature changes of energetically utilized rock massive deals with the heat gained from the rocks at the upper part of the earth crust, whose main source is especially sunlight, as well as with the inner sources of the Earth (the heat released by the influence of tectonic and volcanic activity, radioactive decay of elements, etc.) [36]. Operation of a heat pump connected to a collector situated in a borehole disturbs the thermal equilibrium in the surroundings that leads to the transmission of heat inside the rock towards the borehole.…”

Section: Methodology Of Measurementsmentioning

confidence: 99%

Inquiry into the Temperature Changes of Rock Massif Used in Energy Production in Relation to Season

Клемпа

Látal

Grafova

et al. 2021

Sensors

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This research was undertaken to perform and evaluate the temperature measurement in the ground utilized as an energy source with the goal to determine whether significant temperature variations occur in the subsurface during the heating season. The research infrastructure situated on our University campus was used to assess any variations. The observations were made at the so called “Small Research Polygon” that consists of 8 monitoring boreholes (Borehole Heat Exchangers) situated around a borehole used as an energy source. During the heating season, a series of monthly measurements are made in the monitoring boreholes using a distributed temperature system (DTS). Raman back-scattered light is analysed using Optical Frequency Time Domain Reflectometry (OTDR). Our results indicate that no noticeable changes in temperature occur during the heating season. We have observed an influence of long-term variations of the atmospheric conditions up to the depth of a conventional BHE (≈100 m). The resulting uncertainty in related design input parameters (ground thermal conductivity) was evaluated by using a heat production simulation. Production data during one heating season at our research facilities were evaluated against the design of the system. It is possible to construct smaller geothermal installations with appropriate BHE design that will have a minimal impact on the temperature of the surrounding rock mass and the system performance.

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Optical fiber based distributed temperature systems deployment for measurement of boreholes temperature profiles in the rock massif

et al. 2016

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Fiber optic DTS system application in the research of accumulation possibilities of thermal energy in the rock mass

Cited by 5 publications

References 2 publications

Monitoring cold water injections for reservoir characterization using a permanent fiber optic installation in a geothermal production well in the Southern German Molasse Basin

Monitoring cold water injections for reservoir characterization using a permanent fiber optic installation in a geothermal production well in the Southern German Molasse Basin

Inquiry into the Temperature Changes of Rock Massif Used in Energy Production in Relation to Season

Optical fiber based distributed temperature systems deployment for measurement of boreholes temperature profiles in the rock massif

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