WO2018215868A1 - Système et dispositif permettant de déterminer la vitesse advective de la zone thermique affectée dans un aquifère - Google Patents

Système et dispositif permettant de déterminer la vitesse advective de la zone thermique affectée dans un aquifère Download PDF

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Publication number
WO2018215868A1
WO2018215868A1 PCT/IB2018/053303 IB2018053303W WO2018215868A1 WO 2018215868 A1 WO2018215868 A1 WO 2018215868A1 IB 2018053303 W IB2018053303 W IB 2018053303W WO 2018215868 A1 WO2018215868 A1 WO 2018215868A1
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WIPO (PCT)
Prior art keywords
temperature
well
aquifer
control point
inj ection
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Application number
PCT/IB2018/053303
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English (en)
Inventor
Glenda TADDIA
Elena CERINO ABDIN
Paolo DABOVE
Stefano LO RUSSO
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Politecnico Di Torino
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Publication of WO2018215868A1 publication Critical patent/WO2018215868A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24T—GEOTHERMAL COLLECTORS; GEOTHERMAL SYSTEMS
    • F24T10/00—Geothermal collectors
    • F24T10/20—Geothermal collectors using underground water as working fluid; using working fluid injected directly into the ground, e.g. using injection wells and recovery wells
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24—HEATING; RANGES; VENTILATING
    • F24T—GEOTHERMAL COLLECTORS; GEOTHERMAL SYSTEMS
    • F24T2201/00—Prediction; Simulation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/10—Geothermal energy

Definitions

  • the present invention relates to a system and a portable device for determining the advective velocity of the thermal affected zone related to aquifer re- inj ection of hot/cold water.
  • Direct measurement of the advective velocity of the heat related to low- enthalpy geothermal systems is an important parameter that fortifies the verification and validation of simulations of the propagation of heat related to aquifer re-inj ection of hot/cold water.
  • Such operations are carried out through the use of dedicated computational software.
  • simulations are often mandatory by law in order to obtain the authorization to build open-loop geothermal plants and also to obtain the renewal of the concession for use of the plant.
  • the application field of the solution described herein is low-enthalpy geothermics, and more specifically systems wherein aquifer re-inj ection of water occurs.
  • TEZ Thermal Affected Zone
  • FIG. 1 there is shown an example of temperature perturbation in the surroundings of a re-inj ection well.
  • hot water is re-inj ected, which, as can be seen, creates a zone of hotter water near the re- inj ection well.
  • the thermal affected zone may involve an "external" risk of interference with other systems or particular utilizations of the areas downstream of the return well, and also an "internal” risk of thermal feedback phenomena.
  • An open-loop geothermal system uses a production well from which underground water is extracted, which is made to circulate through a heat exchanger (heat pump); the water is then either re-inj ected in the aquifer through a re-inj ection well located downstream of the plant or discharged into a water body on the surface.
  • thermal energy in the form of heat can be either extracted from water taken from the subsoil (winter mode) or yielded to the aquifer (summer mode).
  • the ATES (Aquifer Thermal Energy Storage) technology is a particular type of thermal accumulation that exploits underground water as a tank by alternatively taking it, according to the season, from two different and sufficiently distant wells dedicated to different purposes, i.e. heating or cooling of buildings.
  • water is extracted from the "cold well” and used for cooling the buildings, and then, once it has acquired heat and warmed up, is delivered through the subsoil into the "hot well”.
  • extraction occurs from the "hot well" and the water, after having been used in the evaporator of the heat pump, i.e. after having released heat and cooled down, is delivered into the cold well, ready for the next summer season.
  • the heated water is re-inj ected into the aquifer, which creates a subterranean reservoir of hot water.
  • the pumping and re-injection scheme is reversed, so that hot water is extracted from the hot well and can be used for heating buildings (often in combination with a heat pump).
  • an ATES system operates by using the subsoil as a temporary buffer for compensating for seasonal variations in the heating and/or cooling demand.
  • Replacing heating and cooling systems using traditional fossil fuels with ATES systems may result in lower consumption of primary energy and lower CO2 emissions of a building.
  • This technology can be used to advantage in the presence of low or null aquifer velocity (De Carli et al., 2004).
  • the advective velocity of heat in an aquifer is calculated mainly through the use of analytical formulae or by numerical modelling.
  • V a the advective velocity value of the heat is analytically obtained from the undisturbed velocity of the aquifer, designated as V a and calculated with the following equation (Fetter, 1999): where V a is the flow velocity of the aquifer, expressed in meters per second [m/s], K is the conductivity of the aquifer, expressed in meters per second [m/s], n e is the effective porosity of the aquifer, and dh/dl is the hydraulic gradient.
  • thermal retardation factor which is given by the ratio between the volumetric thermal capacity of the porous medium (total phase) and the volumetric thermal capacity of water (mobile phase) according to the following equation (Shook, 2001): where p m Cm indicates the volumetric thermal capacity of the porous medium, pwCw indicates the volumetric thermal capacity of water, and n indicates the total porosity.
  • the advective velocity of the thermal affected zone is therefore equal to V p l lume _
  • Porosity of the aquifer determination by means of laboratory tests or by correlation between aquifer porosity, granulometry and lithology through table values expressed as a range of variation.
  • Laboratory tests involve difficulties in reconstructing existing physical conditions and in obtaining a sample representative of the entire aquifer, while table values are not site-specific.
  • Effective porosity of the aquifer determination by means of aquifer tests in variable conditions; in addition to the problems listed below, related to the pumping tests required for the conductivity calculation, such tests only allow determining the effective porosity of unconfined aquifers and have a tendency to underestimate the value, unless the tests are conducted for a very long time.
  • multi-well tracking tests may be conducted, which perhaps represent the most reliable, although most expensive, methodology.
  • the effective porosity datum can be obtained by correlation with granulometry and lithology; in this case, table values expressed as a range of variation will be obtained, as opposed to a site-specific value.
  • Hydraulic conductivity of the aquifer determined by constant-rate aquifer test (descent and possible reascent).
  • the constant-rate aquifer test is a pumping test which is generally carried out for the purpose of determining the hydrodynamic parameters of the aquifer, such as hydraulic transmissivity and the resulting hydraulic conductivity. Completion of this test normally requires many hours and high costs, so that it must be accurately programmed.
  • the test requires draining a well (active well) at a constant flow-rate (for at least 24-72 hours) and measuring the piezometric level at control points (piezometers/wells) both during the draining and after pumping, until the initial piezometric level is restored.
  • control points must affect the same aquifer of the active well, must have known geometric characteristics, and must be located at such a distance from the active well as to allows the measurement of significant level drops.
  • the well In order to carry out this test, the well must be equipped with a pump and possibly a generator set (if no connection to the electric grid is available), capable of keeping the flow-rate constant throughout the predefined time interval, a continuous-recording flowmeter, one or more well level meters (phreatimeters), and one or more chronometers.
  • the first problem relates to the necessity of shutting down the well in order to carry out the flow-rate test and to the fact that it may be impossible or economically or logistically disadvantageous for the owner to shut down the well or any other wells in the vicinity of the well to be tested.
  • Every test should, in fact, be conducted in initial conditions of undisturbed piezometry for at least 24 hours, i.e. in the absence of any draining, clearing or supply of water in the aquifer that might change the static level in the surroundings of the well and/or the observation wells or piezometers. Therefore, the well must not be used for at least 24 hours prior to the execution of the test and for the hours necessary for conducting the test (at least 24-72 hours).
  • the second problem is related to the implementation of an alternative discharge system for correctly causing the drained waters to flow away from the extraction point, so as to avoid any water supply in the aquifer from the surface, which might adversely affect the test.
  • the latter is measured in laboratory by means of a permeameter: the intrinsic limitation of this type of measurement lies in the representativeness of the sample and in the difficulty in reconstructing in laboratory stress conditions existing in situ.
  • Hydraulic gradient determination by means of hydrogeological maps of the aquifer of interest and piezometric measurements in wells/piezometers involving the aquifer in the area of interest. This requires the planning of a measurement campaign.
  • Thermal capacity of the soil determination by means of laboratory tests.
  • the invention described herein through the analysis of monitoring data relating to a period of operation of the plant of at least three months, recorded on an hourly basis, by means of the solution proposed herein, allows obtaining the value of the advective velocity of the heat related to aquifer re-inj ection of hot/cold water.
  • the use of this technique allows computing such parameter in a single step, resulting in extremely evident economical and logistic savings.
  • Figure 1 shows one example of implementation of a geothermal plant
  • Figure 2 shows an exemplary graph indicating the trend of the measured temperature
  • Figure 3 shows one example of implementation of a system according to the present description.
  • Figure 1 shows an example of temperature perturbation in the surroundings of a re-inj ection well.
  • This is a case of re-inj ection of hot water, which, as can be seen, creates a zone of hotter water, designated as zone A, in the vicinity of the re-inj ection well.
  • zone A propagates farther towards the right- hand part of the figure because of the direction of the aquifer flow, indicated by arrow F.
  • zone A corresponds to a temperature of 19°C.
  • Zones B, C and D extend in both directions starting from the re-inj ection well. Zones A, B, C and D have a greater extension in the direction of the water flow, indicated as F.
  • zone B corresponds to a temperature of 18°C
  • zone C corresponds to a temperature of 17°C
  • zone D which is the outermost one, corresponds to a temperature of 16°C.
  • control point which may be either a second well or a piezometer, located downstream of the re-inj ection well for a second measurement of the parameters.
  • the data acquired on both sites are collected in a computer PC and analyzed.
  • Figure 2 shows the results of the measurements at the re-inj ection well and at the control point, and in particular a graph with the analysis of the temperature of both sites.
  • the graph indicated by reference W (Well) concerns the time trend of the temperature detected by a sensor positioned in the re-inj ection well, while the graph indicated by reference CP (Control Point) concerns the time trend of the temperature detected by a sensor positioned at the control point.
  • W Well
  • CP Control Point
  • the solution described herein allows overcoming such problems by making it possible to obtain the advective velocity of heat in an aquifer only on the basis of temperature data experimentally measured directly on the geothermal system by using a common temperature measuring and monitoring probe, in a single computational step.
  • the probes S I and S2 serve to measure the temperatures of the two monitored sites (re-inj ection well and control point).
  • Such measured data are then sent to a computer PC, which processes and analyzes them.
  • the analyzed period of operation is at least three months.
  • the datum of the measured temperature is recorded during the normal operation of the well belonging to the open-loop system, thus avoiding the need for turning off the system for a few days. This provides a considerable cost saving.
  • the solution proposed herein allows recording the temperature datum related to the operation of the well, and it is therefore not necessary to remove the water with alternative systems, since it will follow the normal cycle and will be re-inj ected in the aquifer through the return well.
  • the portable device proposed herein allows determining, in a statistically rigorous and robust manner through the use of cross-correlation, the advective velocity of the thermal affected zone related to aquifer re-inj ection of hot/cold water, e.g. due to open-loop geothermal systems.
  • the advective velocity of the heat related to aquifer re-inj ection of water is obtained through the analysis of temperature monitoring data measured at the re-inj ection well and at a control point (piezometer or well) located downstream of the plant. Such monitoring data are measured by normal probes on an hourly basis for a period of at least three months.
  • the advective velocity value obtained by processing the collected data reflects what has been so far obtained through the use of analytical formulae, which however also require the knowledge, i.e. the measurement, of several other hydrodynamic parameters.
  • This device can be used in low-enthalpy geothermal systems through the use of cross-correlation algorithms.
  • the use of the device proposed herein allows for direct computation of the advective velocity in a single step on the basis of the measured data.
  • the processing algorithm employed written in a compilable programming language, can be compiled on different operating systems, such as, for example, Android and Windows.
  • the proposed solution comprises three interconnected modules exchanging data with one another.
  • the first module referred to as module 1 , consists of means for acquiring the temperature datum, to be positioned within the re-inj ection well, and another similar means to be positioned at the control point located downstream of the re-inj ection zone.
  • the second module consists of a device to be connected, through a suitable connector, to a means for real-time transmission of the temperature datum to a remote control center consisting of a computer, which represents the third and last module, referred to as module 3.
  • CCF cross- correlation value
  • the algorithm is based on a first phase of acquisition of the temperature measurements both in the re-inj ection well and at the downstream control point, which are subsequently used in order to compute the cross-correlation value.
  • This value represents the degree of similarity of two signals as a function of time (time shift) or space (displacement) applied to either one of the two.
  • the two temperatures can therefore be considered as two signals having real values x and y which only differ for a shift along the time axis (t).
  • the cross- correlation calculates how much the signal y must be anticipated in order to make it identical to x.
  • the formula essentially anticipates (or delays) the signal y along the time axis t, calculating the integral of the product by every possible shift value.
  • the value of (x*y) is greatest, because when the waveforms are aligned they contribute to the area computation only in a positive way.
  • the algorithm may be written in any programming language, depending on the operating system of the computer (e.g. Windows platform).
  • the system thus developed allows determining, in a statistically rigorous and robust manner through the use of cross-correlation, the advective velocity of the thermal affected zone related to aquifer re-inj ection of hot/cold water, for low-enthalpy geothermal systems.
  • Said algorithm determines the time shift of a signal (e.g. the temperature measured in the re-injection well) compared to another signal (the temperature measured at the control point).
  • the Authorization Body requires that such probes be installed in at least the control piezometer located downstream of the return well.
  • the system uses the datum relating to the normal operation of the re-inj ection well, so that it is not necessary to turn off the system.

Abstract

L'invention concerne un système permettant de déterminer la vitesse advective de la zone thermique affectée liée à une ré-injection d'eau aquifère dans des systèmes géothermiques, la vitesse advective étant obtenue par l'analyse de données mesurées par des dispositifs de surveillance de température, les dispositifs de surveillance de température étant positionnés dans un puits de ré-injection et au niveau d'un point de contrôle situé en aval du puits de ré-injection, par corrélation croisée desdites données mesurées. La corrélation croisée détermine le décalage temporel du signal se rapportant à la température mesurée dans le puits de ré-injection par rapport au signal se rapportant à la température mesurée au niveau du point de contrôle. Les dispositifs de surveillance de température comprennent des moyens permettant d'acquérir des données de température, ou des sondes, positionnées à l'intérieur du puits de ré-injection et à l'intérieur du point de contrôle situé en aval de la zone de ré-injection.
PCT/IB2018/053303 2017-05-23 2018-05-11 Système et dispositif permettant de déterminer la vitesse advective de la zone thermique affectée dans un aquifère WO2018215868A1 (fr)

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IT102017000055984 2017-05-23
IT102017000055984A IT201700055984A1 (it) 2017-05-23 2017-05-23 Sistema e dispositivo per la determinazione della velocità advettiva della plume termica in acquifero

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Publication number Priority date Publication date Assignee Title
CN110567176A (zh) * 2019-09-11 2019-12-13 吴镇宇 一种利用旧井开发地热能的方法

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US4577679A (en) * 1978-10-25 1986-03-25 Hibshman Henry J Storage systems for heat or cold including aquifers

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RUSSO ET AL: "Advective Heat Transport in an Unconfined Aquifer Induced by the Field Injection of an Open-Loop Groundwater Heat Pump", AMERICAN JOURNAL OF ENVIRONMENTAL SCIENCES, 1 March 2010 (2010-03-01), pages 253 - 259, XP055457123, Retrieved from the Internet <URL:http://thescipub.com/pdf/10.3844/ajessp.2010.253.259> [retrieved on 20180307], DOI: 10.3844/ajessp.2010.253.259 *
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110567176A (zh) * 2019-09-11 2019-12-13 吴镇宇 一种利用旧井开发地热能的方法

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