Method for managing, analysing and regulating a geothermal installation

Abstract

The present disclosure relates to a method for managing a geothermal installation, the geothermal installation being configured to respond to the heat or cold demands of at least one industrial or agricultural process or building, the method comprising: - measurement, at a certain sampling frequency, of hydraulic, thermal and / or chemical operating parameters of the installation, by at least one measuring device; - date-stamped estimation of an indicator as a function of at least one measured operating parameter; and - comparison between the indicator and at least one threshold relating to an extrinsic parameter to the geothermal installation, each threshold making it possible to differentiate between several hypotheses, of which at least one is a function of at least one cause external to the geothermal installation; and - selection, as a function of the result of the comparison, of at least one of these hypotheses, in order to characterize the origin of the anomaly.

Description

[0001]DESCRIPTION Method for managing, analyzing and regulating a geothermal installationTECHNICAL FIELDThe present invention relates to the field of geothermal energy. More particularly, it relates to the management of geothermal installations configured to meet a demand for calories or frigories from a building or industrial or agricultural process. STATE OF THE ARTIn order to meet the demands for calories or frigories from at least one building on the surface, it is possible to implement a geothermal installation. The geothermal installation may comprise a system of different types, such as, for example, a geothermal heat pump (HP) system on a water table,a heat pump system (HP) on vertical geothermal probes (SGV) or a geothermal heat pump system (HP) on baskets or walls… A geothermal installation circulates a heat transfer fluid in a borehole made in a basement to modify the temperature of the energy-consuming structure to which the geothermal installation is connected. The geothermal installation can thus heat the structure by transferring heat from the basement or cool the structure, by transferring the heat from the structure to the basement. However,malfunctions such as the clogging of a pipe or a variation in the thermal capacities of the subsoil may occur during the operation of the geothermal installation and cause deviations between the intended operation of the installation and the actual operation observed. The deviations reduce the efficiency of the geothermal installation and may require a temporary shutdown of the installation for maintenance, or even a permanent shutdown. GENERAL DISCLOSURE One aim of the disclosure is to avoid malfunctions or maintenance operations of the geothermal installation and thus allow continuous and efficient operation. To this end, according to one aspect of this disclosure, a method for managing a geothermal installation is proposed, the geothermal installation being configured to meet the demands for calories or frigories of at least one building or industrial or agricultural process, the method comprising: - a measurement,at a certain sampling frequency, of hydraulic, thermal and / or chemical operating parameters of the installation, by at least one measuring device;- a dated estimate of an indicator based on at least one measured operating parameter; and - highlighting of a possible operating anomaly of the installation by a comparison between the indicator and at least one threshold relating to a parameter extrinsic to the geothermal installation, each threshold making it possible to differentiate between several hypotheses, at least one of which is a function of at least one cause external to the geothermal installation; and- a selection, based on the result of the comparison, of at least one of these hypotheses, in order to characterize the origin of the anomaly. In particular, in the event of an anomaly, we determine - and if necessary we order - based on the result of the comparison,a corrective action on the installation. This method allows efficient operation of the geothermal installation and upstream management of the causes of possible malfunctions in order to avoid them. By continuous monitoring and independent analysis of each characteristic of the geothermal installation, the method makes it possible to identify the causes of the modification of a characteristic and thus avoid a malfunction by modifying the parameter in question. Advantageously, but optionally, the method described comprises at least one of the following characteristics,taken alone or in any combination:- the method comprises an implementation of a corrective action on the installation according to the detected anomaly and the selected hypothesis;- the reliability of the measurements of the operating parameters is tested in real time and the sampling frequency of these measurements is adapted according to the test results;- the real-time test of the reliability of the measurements of operating parameters implements the following processing: - discrete Fourier transform of the measurements of said operating parameter considered over a predetermined time interval, - calculation of a useful oscillating energy depending on the Fourier transform of said operating parameter, - determination of the sampling frequency according to this oscillating energy.- an estimated indicator is an indicator representative of a static level of the fluid in the subsoil,the estimation of said indicator being a function of a piezometric measurement in the geothermal installation as well as a previously determined theoretical static level;- the geothermal installation comprises at least one injection well and at least one production well and in which the estimation of the indicator representative of a static level implements:- a piezometric measurement of the level of the injection well and a piezometric measurement of the level of the production well;- a comparison between the two measurements, and in which the indicator is an interval which includes the interval between the piezometric measurement of the injection well and the piezometric measurement of the production well,if the difference between the two measurements is less than a first predetermined threshold.- the geothermal installation comprises at least one injection well and at least one production well and an estimated indicator is an indicator representative of a transmissivity between the production well and the injection well and the estimation of the indicator being a function of a flow rate of a fluid in the geothermal installation as well as a theoretical transmissivity previously recorded;- the estimation of the indicator representative of the transmissivity comprises:- a forecast of a piezometry of the level of the production well and / or the injection well as a function of the measured fluid flow rate and the transmissivity,- a comparison between the piezometry resulting from the forecast and a piezometric measurement of the injection well or a piezometric measurement of the production well,- a minimization of a difference resulting from the comparison;- an estimated indicator is an indicator representative of a clogging of the geothermal installation and is estimated as a function of a volume of fluid flowed in the geothermal installation as well as a previously recorded theoretical fluid flow rate;- the estimation (E2) of the indicator representative of the clogging includes:- an estimation of a future specific flow rate as a function of the volume of fluid flowed and the theoretical fluid flow rate as well as the characteristics specific to the fluid circulating in the geothermal installation, and - a calculation of a volume of fluid before shutdown as a function of the estimated specific flow rate;- the operating parameter is included in the following parameters: a flow rate of heat transfer fluid in the geothermal installation, a pressure of the fluid in a pipe of the geothermal installation,a volume of fluid having circulated in the geothermal installation; - the indicator for an open type geothermal installation is included in the following list: the specific flow rate, the ratio between the maximum flow rate of the installation and the specific flow rate, a static level of the fluid in the subsoil, a transmissivity between a production well and an injection well, an effective or apparent thermal conductivity of the soil or a thermal capacity of the soil, the pH, the temperature of the fluid in the production or injection wells, the indicator for a closed type geothermal installation is included in the following list: an estimated thermal conductivity, the minimum conductivity necessary to ensure the sustainability of the installation over a chosen period; - the extrinsic parameters of the geothermal installation analyzed are included in the following parameters: a permeability of the soil, a presence of biochemical elements,operating parameters of neighboring geothermal installations, an environment of the geothermal installation, a clogging of a pipeline, a meteorological evolution, an energy consumption, energy losses of the structure, the thermal conductivity, the thermal capacity, the surface temperature and the vertical gradient of the subsoil, the water table flows, or geological events; - the geothermal installation is a geothermal installation on water tables, or of the open type, or a geothermal installation on probe, or of the closed type, or a geothermal installation on compact exchangers. According to another aspect, there is provided an assembly comprising a geothermal installation configured to meet the demands for calories or frigories of at least one building or industrial or agricultural process and a system for managing the geothermal installation,the system comprising means for measuring the operating parameters of the geothermal installation and being suitable for implementing the method as previously described DESCRIPTION OF THE FIGURES Other characteristics, aims and advantages will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the attached drawings in which: Figure 1 illustrates a flowchart of the steps of a possible implementation of this presentation. DETAILED DESCRIPTION Geothermal energy is used to enable heat exchanges between a subsoil and a structure such as a building, a cold room for food warehouses, an industrial process (air conditioning and humidity control for production centers), an agricultural production greenhouse, any industrial process but at low temperature, swimming pool heating, etc. Subsequently,A building is the structure generally requiring a geothermal installation. Geothermal energy can be implemented by different geothermal installations. The geothermal installation allows the transport of heat between the subsoil and the building. A geothermal installation is therefore simply a device connecting a building and the subsoil. The geothermal installation is therefore connected to a building's heating network on the one hand and to the subsoil via a borehole, or well, on the other hand. The connections of the geothermal installation with the building and the subsoil are respectively configured to allow heat exchange,from one to the other and vice versa. Geothermal installationThe geothermal installation may include a circuit for a heat transfer fluid and an exchanger connected to the circuit. The circuit may include a pipe and a circulation pump to control the flow of the fluid in the pipe. The exchanger is, on the one hand, connected to the circuit to exchange heat with the heat transfer fluid present in the circuit and communicates thermally with the building on the other hand. The piping of the geothermal installation may include a network of injection / reinjection pipes carrying a fluid from the subsoil to exchange heat with the subsoil, we then speak of a geothermal installation on aquifer or groundwater. The piping of the geothermal installation may include a closed network of pipes to exchange heat with the subsoil using a heat transfer fluid enclosed in the geothermal installation,we then speak of geothermal installation on probe or probe fields. The piping of the geothermal installation can include a network of spiral pipes to exchange heat with the subsoil, we then speak of geothermal installation on compact exchangers. Whatever the geothermal installation, the heat is exchanged between the subsoil and the building, or vice versa, thanks to a heat transfer fluid circulating in the piping of the circuit of the geothermal installation. The fluid can:- be part of the installation and circulate in a closed loop in the piping in so-called closed geothermal installations, as in the case of geothermal installation on probe or on compact exchangers; or,- be pumped to pass into the circuit from a water table or an aquifer in so-called open geothermal installations,as in the case of a geothermal installation on a water table. The geothermal installation includes intrinsic parameters. Intrinsic parameters are the parameters that can be selected by a geothermal installation installer to configure the geothermal installation as such. Intrinsic parameters are, for example, a maximum flow rate of the circulation pump, a maximum exchange power of the exchanger, a pipe length, etc. The heat that the geothermal installation can exchange with the building in order to heat / cool it depends directly on several parameters, called operating parameters. The operating parameters are not intrinsic parameters of the geothermal installation but depend on the operation of the geothermal installation. The operating parameters can, for example, be: - the real-time flow rate of the fluid in the circuit or a piezometry in a well,the well being made to connect a pipe of the circuit to an underground water table, in the case of an open type geothermal installation, or - the flow rate, the inlet and outlet temperatures and the pressure variation of the fluid having circulated in the geothermal installation, in the case of a closed type geothermal installation. In so-called open geothermal installations, the temperature of the fluid is that of the water table fluid because the fluid is that of the water table. In so-called closed geothermal installations, the temperature of the fluid is close to that of the subsoil because the circuit communicates with the subsoil by a borehole and exchanges heat by conduction. The operating parameters of a geothermal installation can evolve or be modified over time due to elements external to the geothermal installation,called extrinsic parameters. Extrinsic parameters are for example: - characteristics of the subsoil: in practice the thickness of the water table, horizontal and vertical permeability, storage coefficient, spatial heterogeneity of these values, presence of wall (recharge via upper or lower water tables in hydraulic contact), recharge zone (river, canal, lake, etc.) or sealing (construction of foundations, tunnels, etc.); - characteristics of the well: quadratic head loss at the level of the screens, filter masses, and the close environment of the well, the skin effect of the well, the volume effect of the well, important for large diameters, etc., clogging; - characteristics of the water table: piezometry, flow gradient, chemical composition, solid fraction contained and biological; - thermal characteristics of the water table: temperature, heat capacity, thermal conductivity,the vertical gradient; - characteristics of the energy demand profile of the use: hot demand and cold demand, and especially the annual difference... - groundwater flows which can influence the apparent thermal conductivity of the subsoil by increasing exchanges by forced convection - Geological events, such as earthquakes, landslides or any event modifying the ground at the level of the probes which can lead to pipe ruptures, modification of flows or modification of the apparent thermal conductivity of the ground. The geothermal installation preferably includes detection means, such as sensors, to acquire measurements and means of recording the acquired measurements. The geothermal installation is preferably controlled by the building to which it is connected. The building advantageously includes a temperature regulation system which,in case of detection of need for heat or cold, will ask a geothermal installation regulation automaton to manage a flow of the circulation pump and thus allow a transfer of energy via the exchanger with a temperature difference ∆T = T2-T1, T1 being the temperature of the fluid at the exchanger inlet and T2 being the temperature of the fluid at the exchanger outlet: E, q. 1 : ^[^^] = 1,16 P being the power transmitted by the geothermal installation to the building and Q the flow rate of the fluid in the circuit. Open type geothermal installationThe geothermal installation can be an open geothermal installation or on aquifer.The open geothermal installation generally consists of several boreholes, having at least one production well and one injection well in order to draw the heat transfer fluid, in other words water, at ground temperature, to extract or communicate heat to it, in other words thermal energy, and to reintroduce it into the subsoil or the environment. The production well supplies the geothermal installation with fluid and the injection well evacuates the fluid from the geothermal installation. The water from the subsoil is pumped by the circulation pump into the production well and circulates in the circuit. This water is conveyed to the exchanger.Advantageously, the geothermal installation includes filters to remove any solid particles present in the fluid and other equipment such as a bladder, a flow meter and various temperature and pressure sensors, the latter being installed to monitor pressure drops in the filters in particular. By passing through one or more heat exchangers, the water will exchange heat with the building, either directly via low-temperature emitters such as underfloor heating or cooling or radiant panels, or through a heat pump to adapt the temperature to the end use. The water is then reinjected into the subsoil via at least one injection well. The geothermal installation may include sensors, such as energy meters and water volume meters. Each well is equipped with a piezometer that measures the water level in the well.Piezometric measurements may be taken in other wells, at a reasonable distance from the boreholes, allowing indirect measurement of the water table level. The geothermal installation circuit advantageously includes one or more temperature sensors to measure the temperature of the fluid and the temperature of the water table, in other words the subsoil. Advantageously, the flow rate in the circuit can vary from 5 to 500 m3 / h. The subsoil temperature is close to the average atmospheric temperature of the location, i.e. between 12 and 16°C (urban area) in France. The boreholes have a depth advantageously between 10 and 200 m, and preferably 50 m. The temperature difference between the production wells and the injection wells is typically 5°C (positive or negative) but can advantageously vary from 0 to 10°C.Each well generally consists of a watertight upper part (casing) made of a solid tube made of stainless steel, steel or plastic and a lower part made of a strainer (a tube with holes to allow water to pass through) placed at the level of the water table of interest. Around the strainer, a filter bed is placed, which is a cylinder of gravel or balls or other materials of small diameters. In a geothermal installation, sensors can be used to monitor the evolution of the static level. This monitoring, explained below, is an important indicator for the management of a geothermal installation. It is also possible to estimate the transmissivity between the boreholes. Transmissivity is the ease with which the soil allows fluid to pass through. If the transmissivity decreases, the fluid will become increasingly difficult to pump. This is the inverse of the resistance of the soil hydraulics. Monitoring transmissivity is therefore important in order to predict a possible future malfunction.The circulation of groundwater fluid in the circuit can cause the well to clog. Clogging is linked to fouling of the injection well. If the clogging is too severe, the geothermal installation will have to be shut down. It is therefore necessary to estimate and predict the time remaining before clogging. Closed-type geothermal installation The geothermal installation can be a closed geothermal installation, in other words on probes. The closed geothermal installation generally consists of several pipes connected to the closed-loop exchanger. The pipes are laid in the ground to receive and extract heat energy from the ground and thus increase the temperature of the heat transfer fluid circulating in the pipe. The heat transfer fluid in the pipe is therefore internal to the system and its pressure and flow rate can be controlled.In a non-exhaustive manner, the main anomalies listed for probe-type geothermal systems are as follows:- Subsoil freezing or water injection below legal limits, which in the case of France are -3°C. Indeed, subsoil freezing can lead to deterioration of the mechanical strength of the soil and lead to destruction. This case, which is quite frequent, therefore limits the use of the resource and the search for the cause is important.- Rapid loss of power, linked for example to a heat transfer fluid leak or a pump failure. The following table specifies the potential causes of these anomalies. The internal causes, which should also be considered for the sake of completeness, are also specified (int.).No. Anomaly Potential causes 1 / blockage of one or more probes by pinching, collapse Low threshold of 2 / modification of an underground flow of water table temperature 1 injection reached 3 / hot / cold imbalance of the use of the resource system shutdown (int.) 4 / non-turbulent flow reducing heat exchanges (int.) Sudden drop in 1 / Liquid leak 2 power 2 / Circulation pump failure (int.)Geothermal installation management processThe geothermal installation management process makes it possible to identify in real time one or more external causes of a development deemed unusual, in other words a drift, of an indicator. Once the external cause of a drift has been identified, the process is configured to manage the geothermal installation and possibly its environment and thus avoid a malfunction of the geothermal installation. The management process includes several steps which are detailed below.Measurement of an operating parameter The management method, as illustrated for example by Figure 1, includes a measurement (step E1), or acquisition, in real time of a change in the operating parameters. The measurement is carried out independently for each operating parameter. The measurement is made according to a sampling frequency. Sensors adapted to such acquisitions are implemented in the geothermal installation for this purpose. Advantageously, the management method also implements an analysis of the sampling frequency of each operating parameter, in other words of the sampling quality of each measured operating parameter. Indeed, the analysis makes it possible to modify the sampling frequency of each operating parameter according to a reliability criterion. The analysis of the sampling frequency is explained below.Such an analysis makes it possible to avoid a malfunction of the system by improving the reliability of the interpretation of the operating parameters and thus avoiding the selection of an incorrect indicator and therefore an erroneous cause at the origin of the anomaly. It also makes it possible to avoid a faulty highlighting of a possible anomaly due to a misinterpretation of the data. Depending on the needs of the use, the variations of the setpoints in the geothermal installation can be more or less rapid, with characteristic times sometimes very short (less than a minute) in the case of TOR (all or nothing) regulation or slower (variation in a few hours) if the regulation is proportional or adaptive. Thus the sampling frequency may or may not be adapted to qualitative management and lead to difficult or even erroneous interpretations of the measured operating parameters.It is then important to detect whether the sampling frequency allows a correct interpretation of the data in a given time interval. The method is done by using Discrete Fourier Transforms (DFT) and by setting up a useful oscillating energy indicator. After choosing a time interval to analyze, the signal x(t) to be analyzed is recovered over a duration NTe. The DFT X(n) of the signal is then carried out:. Only the first part of the coefficients (k=0 to N / 2) is useful because of frequency aliasing. Each coefficient e(k) = |X(k)| 2is interpreted as the energy of the signal x at the frequency f(k) = k / ( NTe ). Thus, e(0) corresponds to the average of the signal, e(1) corresponds to the fundamental frequency linked to the duration of the interval, which is of no use here, e(2) to e(N / 2) correspond to the total oscillating energy removed from the fundamental artifact. The really useful and interpretable frequencies are generally the frequencies lower than 10 times the sampling frequency, i.e. typically f(k) < fe / 10 (equivalent to k < N / 10), but the coefficient 10 can also be adapted typically from 2 to 20 according to the needs. Thus the useful oscillating energy (EOU) is equal to: The EOU value corresponds to a reliable criterion measuring the share of the useful and correctly sampled signal: the higher this parameter is, the more the signal is well sampled and easy to interpret. In other words, if the EOU value is higher than a predetermined threshold, the sampling frequency of the values ​​of the operating parameter considered is considered acceptable. The determination of the threshold for the EOU can be carried out in the following way: - for a given time interval or size of the time window, the value of EOU is determined for all the windows, - from a distribution function of the EOU values, we can identify the windows whose EOU is part of the 50% of the highest values. Typically, we will take values ​​between 20% and 80% as threshold. (the distribution function is a function which gives, as a function of an EOU value, the percentage of value lower than the EOU).Other methods can be used depending on the probability density of the EOU values: - if the probability density of the EOU is close to a Gaussian (1 peak), then the method described above is certainly the most suitable; - if the probability density of the EOU is binomial (2 peaks), then a Bayesian threshold is suitable. Furthermore, we will first remove the EOU values ​​lower than a predetermined significance threshold, linked to the measuring equipment used. If the measuring device has a measurement accuracy characterized by a measurement standard deviation ^, the threshold will be (^^)^ with m between 1 and 10, typically 5. Other methods can also be used such as the windowed Fourier transform or a threshold on the amplitude (difference between the max and min value) determined over a time window.Estimating the quality of the sampling thus makes it possible to improve the analysis of drifts thanks to a correct acquisition of the evolution of the operating parameters. Estimation of an indicator The management process then includes a step of estimation (E2) of one or more indicators. Each indicator is representative of an evolution, in real time, of one of the extrinsic parameters of the geothermal installation. The estimation is carried out in real time. The estimation can be a function of one or more operating parameters. The estimation can also be a function of the extrinsic parameters of the geothermal installation. For example, it is possible to estimate a static level of a water table to which the geothermal installation is connected by taking into account a piezometry in the installation's wells and a theoretical static level, as explained below.Another possibility is, for example, to estimate a transmissivity between the wells of the geothermal installation by taking into account a flow rate in the installation circuit and a theoretical transmissivity, as also explained below. Another possibility is, for example, to estimate an indicator representative of a clogging of the geothermal installation by taking into account a volume of fluid flowed in the geothermal installation as well as a theoretical fluid flow rate previously recorded, etc. Each type of installation can present its own indicators. Estimation of the static level In the case of an open geothermal installation (or on aquifers), the indicator corresponding to the static level of the water table is estimated in order to allow management of the geothermal installation, to detect an anomaly and to identify one or more external causes of the detected anomaly.The static level is therefore an extrinsic parameter to the geothermal installation whose indicator can be estimated based on one or more of the operating parameters of the geothermal installation. In order to estimate the static level indicator in real time, it is possible to take into account, as operating parameters, piezometry in the circuit of the open type geothermal installation as well as the theoretical static level previously recorded, as an extrinsic parameter.The water level, or piezometry, in a well varies according to many phenomena with time constants that vary depending on the case, typically:^ Pumping or injection of water respectively lowers and raises the water level: the time constant is linked to the flow calls of the geothermal system^ Natural variations of the water table: they are essentially cyclical with an annual period ^ Anthropogenic variations of the water table linked to pumping external to the geothermal installation: the time constants are here very variable but included a priori between the variations in pumping and the natural variations. The evolution of the piezometry influences the static level of the water table. In order to implement the prediction of the evolution of the water level, a solution can be to:- Determine a time window, typically between 1 and 30 days.- Record, in the time window, piezometry values ​​when the pumping or injection flow rate is zero or lower than the measurement noise (< 5 standard deviations of the measuring equipment typically);- Determine a minimum piezometry level (for the injection well) and / or a maximum piezometry level (for the pumping well): these values ​​will be candidate values ​​of the static level NSi and NSp which will be selected in the next step;- Calculation of the indicator value. The indicator is a value, but can possibly be an interval of values. This value is the estimate of the static level of the water table for the injection well NS. i or NSp production; and -Real-time comparison between these NSi and NSp values ​​of static levels: Si the estimate is deemed reliable, S i three cases can arise: a. Both estimates are wrong: > ^2 × ^ and|^^^(^) − ^^^(^ + ^)| > ^2 × ^ with z > 0 the smallest time such that ^^^(^ + ^)and ^^^(^ + ^) exist,b. It is the estimate at the injection well which is false and that of the production well which is good: it will be detected if < |^^^(^) − ^^^(^ + ^)| with z > 0 the smallest time such that ^^^(^ + ^) and ^^^(^ + ^) exist,c. It is the estimate at the production well which is wrong and that of the injection well which is right: we will detect it if |^^^(^) − ^^^(^ + ^)| < with z > 0 the smallest time such that ^^^(^ + ^) and^^^(^ + ^) exist. The thresholds S1 and S2 are interpreted as follows:^ S1 is the admissible static measurement error between the two wells, which can be associated with an error in determining the zero altitude, an underground flow, etc.; it can be determined as follows: o Method 1: ^1 = ^ + ^ ^ with m the absolute value of the time average of ^^^(^) − ^^^(^) and ^ the time standard deviation of ^^^(^) − ^^^(^). ^ is chosen between 0 and 10, typically 2. ^S2 is the maximum variation in meters per unit of time of the static level beyond which it cannot be a real cause but a measurement error: we can choose a threshold of 1m / day for example, but the values ​​of 0.1 and 10 m / day can be relevant.Taking into account the impact of an external parameter on the piezometry makes it possible to obtain a prediction of the evolution of the static level for the external parameter considered… In addition, the estimation of other indicators relating to a closed-type geothermal installation will be detailed below. Determination of thresholds The management process also includes a determination (E3) of one or more thresholds. Indeed, for each estimated indicator it is necessary to be able to know whether the value of the indicator and its evolution are the consequence of normal and usual use of the geothermal installation or whether the operation of the geothermal installation is malfunctioning or whether external causes, external to the installation, are present.To determine thresholds, in other words limit conditions or alert values, it is necessary to take into account the extrinsic parameter(s) linked to the operating parameter on which the indicator considered is a function as well as forecasts made previously and linked to forecasts of usual operation. For example, to determine a threshold for the indicator linked to the static level, it is possible to search in the piezometric chronicles of the water table, or in the Explore2070 simulation work, the typical natural variation of the water table, typically between 1 and 10 m depending on the case. It is possible to calculate, for each period with the variation in piezometric data typically from one week to another, or from one month to another and it will be compared to this threshold.Comparison of the indicator to the threshold To take the previous example relating to the indicator corresponding to the static level, we can, for example, note b, the natural beating of the water table over one year, which thus constitutes a threshold. We construct the following indicator: ∆^^ Eq. 17: Water table variation index 1 =. With Δns the variation of the static level in the time interval Δt in days. If this indicator is less than 1, the variation of the water table is natural, if it is greater than 1, and especially in cases where it is much greater than 1, we can assume an anthropogenic action of the variation of the water table piezometry. In this example, we consider the following indicator ^ ∆^^ ×^^^∆^ ^, derived from the previous one with the same notations. In the proposed method, a possible operating anomaly of the installation is highlighted by a comparison (E4) of the indicator in question with at least one threshold relating to a parameter extrinsic to the geothermal installation.In the proposed method, a possible operating anomaly of the installation is highlighted by a comparison (E4) of the indicator in question with at least one threshold relating to a parameter extrinsic to the geothermal installation.In this case, the extrinsic parameter is the natural beating of the water table over one year. The threshold is a value noted b. It is relative to the theoretical annual beating of the water table. The threshold b can be determined by sufficiently long chronicles (at least one year) nearby, for example using the BRGM databases (https: / / ades.eaufrance.fr / ), or from the piezometric maps published for example by SIGES Seine Normandie (https: / / sigessn.brgm.fr / ) which provides high water (HE) and low water (BE) piezometric maps for almost the entire Paris basin, allowing by difference the estimation at the drilling point of the parameter b (m). The threshold b thus makes it possible to differentiate between: - a first hypothesis linked to an external cause. In this case the external cause is the presence of an anthropogenic action which would cause significant variations in the beating of the water table, and - a second hypothesis which is that of a natural movement of the water table, the beating of which would then remain within the classic limits of this water table at the location considered. This comparison therefore makes it possible to select the probable cause of the anomaly (see the table below). IndicatorHypothesis / causeThreshold (E3 / E4)Corrective actions (E6) (E2) external Too great variation Search for the cause in the >. bto be of natural origin, neighborhood and discussion with it is therefore linked to an action ∆ ^^ × 365the entity at the origin of the cause ^ ^ anthropogenic ∆^ Taking into account this Natural movement of the <= b stress in the conditions of use of the installation In another embodiment, the rise of the water table which can cause the shutdown of the geothermal installation by activation of the anti-overflow safety device can also be linked to a clogging of the injection well, in which case it is also appropriate to consider a second indicator in order to select the correct cause at the origin of the anomaly. In order to estimate in real time the necessary indicator, it is necessary to estimate ^^^(^) from the operating parameters, the fluid flow rate in the circuit of the open type geothermal installation as well as the piezometry in the production or injection wells. For a geothermal doublet and in the Jacobs approximation, this indicator verifies the following relationship (it is also commonly called the specific flow rate in m2 / s or m2 / h) :^^^(^) = Δ^(^) / Δℎ(^)With delta Q the variation in flow rate and Δℎ the variation in piezometry in the well considered. Different numerical methods allow to estimate ^^^(^) as a function of regular measurements of Q and h, typically over a time window of the order of a day. It is for example possible to use the least squares method, minimization functions or the gradient method of the functional distance between Q and Qsp x (h-h0), Qsp and possibly h0 (static level during the time window considered). The method may optionally include a digital filtering step using a first-order low-pass F filter, or several to improve the robustness of the method.It is possible to refine the theoretical model of the well (Theis, Hantush theory and adding clogging effects, skin effects, etc.) The piezometry in the well is the addition of the static level ns(t) and a rise in the water table due to the operation of the installation r(t) = Q(t) / Qsp, with Q(t) being the reinjection flow rate and Q. sp the specific flow rate estimated as described above with a frequency of the order of the day. The level in the well is therefore equal to Pi = ns(t) + r(t). We therefore construct two indicators (E2):^ the indicator Qmax / Qsp which is the maximum rise in meters at the maximum flow rate of the installation, with Qmax the maximum flow rate of the installation and Qsp defined above, and ^the indicator which is the variation of the piezometric level in m / dayThe threshold of the Qmax / Qsp indicator which is Rmax is determined from an extrinsic parameter: the transmissivity T of the subsoil. Transmissivity is the product of the power of the water table (its thickness in meters) and the permeability in m / s. This information is either determined by direct measurement during long-term pumping tests and loop tests in particular (for a complete description of the methods see document 72-SGN-273-AME.pdf of the BRGM), or from BRGM databases or the bibliography (see for example the site https: / / infoterre.brgm.fr / ). The maximum nominal flow rate of the installation (Qmax) as well as the distance between wells (d) and the radius of the wells (r) are also used via the following formula: Safety coefficients can be added to this threshold to make the conclusions more robust. The table below explains the different thresholds and the related hypotheses allowing to select the external cause(s) at the origin of the anomaly. Indicators (E2) Qmax / Qsp Thresholds (E3 / E4) ≤ Rmax > Rmax A: A variation B: The clogging of the well ≤ b natural of the injection layer is the cause is the cause. (EXT) ∆ ^^ × 365 ^ ^ ∆^C: a drilling D: There is a double cause: anthropogenic clogging and influence > bproximity influence of an anthropogenic drilling the installation (EXT) (INT and EXT)In cases A and C, the hypotheses are based on causes external to the installation. In case D, a calculation based on indicators and thresholds makes it possible to estimate the relative share between the impact of clogging and the impact of static level variation on the anomaly by comparing the values ​​of the static level and the rise in water table linked to the injection. Furthermore, we can continue to add indicators in order to specify the internal or external origin of the clogging. Indeed, it can be linked to external causes (change in water composition, its pH (hydrogen potential) or its temperature) modifying the conditions of carbonate precipitation for example, or come from an excessive increase in injection temperature in summer causing chemical (carbonates) or biochemical (bacterial development) precipitates.Management process for a closed type installationIn the same way, in the case of a closed geothermal installation, indicators (E2) allow us to select (E5) the possible external causes at the origin of an anomaly. For example, an indicator can inform us about the thermal drift of the subsoil linked to the thermal imbalance of the demand. Indeed, by recording the heat flows injected and extracted from the subsoil since commissioning (E1), we can model the drift of the subsoil temperature in the future by considering an identical thermal demand thereafter. The minimum temperature reached by the fluid after a period of 10, 20, 30, 40 or 50 years, for example, depending on the chosen sustainability objective, can then be estimated for a given thermal conductivity value of the subsoil.If this value noted ^^^^(30 ^^^) for the minimum temperature of the fluid in 30 years, is lower than the regulations or good practices (in France, the GMI regulations frame the temperature of the fluid between -3°C and 40°C), the difference between the needs of heat and cold does not allow a sustainable use of the resource. This value is inversely proportional to the thermal conductivity of the subsoil: −3°^ < ^^^^(30 ^^^) =1 ^^^^^(30 ^^^, ^, ^) With ^ the thermal conductivity, Fmin is a function whose value depends on the history of the flow rate measurements (Q) and temperatures (T) mentioned above.We can thus calculate an indicator (E2) which is the minimum conductivity necessary for the installation to remain sustainable over a period of 30 years so that the ground does not freeze or complies with the regulations (here -3°C): Similarly, we can construct an equivalent indicator from ^^^^(30 ^^^) which is the maximum temperature of the fluid in 30 years which must not exceed the upper threshold of good practices or the GMI (Medium-Sized Geothermal) regulations:. For these two indicators ^^^^(30 ^^^) and ^^^^(30 ^^^), the thresholds (E4) are the same and are determined with an extrinsic parameter which is the thermal conductivity of the soil. If ^^^^(30 ^^^) is lower than the thermal conductivity of the subsoil, which is an extrinsic parameter, then the hypothesis is that the demand on the subsoil by the building is sustainable, otherwise, the hypothesis is that it is not: the demand for heat is too high, or the heat recharge of the subsoil is insufficient. Similarly for ^^^^(30 ^^^): if this indicator is lower than the thermal conductivity of the subsoil, which is an extrinsic parameter, then the demand on the subsoil by the building is sustainable, otherwise, it is not: the demand for cold is too high, or the cold recharge of the subsoil is insufficient (which is an external cause).The modeling methods for estimating the indicators ^^^^(30 ^^^) and ^^^^(30 ^^^) are well described, notably in the article Claesson et al, Volume 13, Issue 6(https: / / www.sciencedirect.com / journal / energy / vol / 13 / issue / 6), June 1988, Pages 509-527 for example. Another indicator constructed from regular measurements of temperature and flow rate (E1) of the fluid passing through the probes makes it possible to estimate an indicator of the apparent thermal conductivity (E2) of the subsoil and thus to detect as a possible external cause at the origin of an anomaly, a change in the nature of the terrain, such as for example the modification of an underground flow, influencing thermal exchanges by adding a convective effect, or possible ground movement leading to a modification of the same type (E4 / E5).For example, we can proceed as follows to determine the conductivity of the subsoil from the measurements, and at the same time other parameters of interest such as the average temperature of the soil and the heat capacity. We estimate the algebraic power injected into the soil by ^(^) = 1.16^(^)(^^^(^) − ^^^^(^)) in Watts and the average temperature of the circulating fluid by ^^(^) =. ^ ^^ (^)^^ ^^^ (^) ^ , the thermal system being linear, we have the following relation: With h(t) the impulse response of the thermal probe system, ^ ^the sampling time typically of the order of a minute, but can vary from 10 s to 1 h and Np the order of the impulse response, typically chosen so that ^^^^ ≈ 72 ℎ, but can also vary from a few hours to a month. The function h(t) can be determined using the least squares approximation method from the data ^^(^) and ^(^) over a sufficient duration, of the order of ^^^^ ≈ 72 ℎ. The short-term response of a probe field can be approximated in the case of a power step, for example, by the equations used for TRT (Thermal Response Test) or other more comprehensive approaches described for example in Eskilson 1987. The response to a unit power step being equal to ^(^^^) = ∑^ ^ ^^ ℎ(^^^) , we therefore have: With ^ the average conductivity of the subsoil, L the active probe length, r the probe radius, gamma the Euler constant, a the thermal diffusion coefficient of the subsoil and ^ ^the resistance of the probe between the fluid and the edge of the probe. It is easy to determine^ knowing L and H(t) by plotting for example H(t) as a function of ln(t) and estimating the slope coefficient of the straight line obtained, or by other methods using the minimization of a criterion, such as mean square error. Thus we have constructed an indicator as a function of the measurements that can be estimated periodically over a period of approximately 2 days in the example below:^̅(^ ± 1 ^^^^^) = ^(^, ^^^, ^^^^)With ^̅(^ ± 1 ^^^^^) the average conductivity of the subsoil estimated between t - 1 days and t+1 days. If we use least squares methods, we can estimate an error of the indicator, for example by estimating an interval corresponding to a 95% chance of corresponding to the true value. The thresholds are then defined around the initial conductivity of the site ^^^^^^^^^(extrinsic parameter) with a safety margin ^ depending on the precision of the estimate.The table below shows the indicators, the thresholds to which they can be respectively compared and the resulting hypotheses: No. Hypotheses / Corrective actions Indicator (E2) Thresholds (E4) External causes (E6) In the absence of storage, nothing to do, as it is favorable. Increase in flow rate. In the presence of >^^^^^^^^^ + ^water table if present, favorable thermal storage, in the absence of storage increase the compensatory thermal quantities 1^̅(^ ± 1 ^^^^^) Reduction in the flow rate of Taking into account the new characteristics of the subsoil for the site management <^^^^^^^^ − ^water table if present, reduction of the piezometric characteristics of the subsoil for the control Use of the resource Recharge the subsoil with heat >^^^^^^^^^ + ^non-sustainable by 30 in summer, reduce the needs of 2^^^^(30 ^^^) years for example: surplus heat in winter of demand for heat <. ^Sustainable use of the ^^^^^^^^ − ^resource Use of the resource Recharge the subsoil with cold in >^^^^^^^^^ + ^non-sustainable by 30 winters, reduce needs by 3^^^^(30 ^^^) years for example: surplus cold in summer demand for cold < ^ ^^ − Sustainable use of the ^ ^^^^^ ^resourceThus, the selection (E5) makes it possible to identify one or more of the external causes that may be at the origin of the anomaly.Management of the installation As mentioned previously, the management process then includes a step of highlighting a possible anomaly in the operation of the installation. Highlighting is obtained by comparing the estimate of the indicator considered with one or more thresholds relating to one or more parameters extrinsic to the geothermal installation. As mentioned previously, the management process then includes a step of selecting, based on the result of the comparison, one or more of the hypotheses, in order to characterize the external cause at the origin of the anomaly. The selection is made from the measurements of one or more indicators and the thresholds determined for each indicator considered. The selected hypothesis is the external cause that makes it possible to characterize the origin of the anomaly.The identification of an anomaly therefore makes it possible to select (step E5) the cause(s) of the anomaly. The determined cause is associated with one of the extrinsic parameters or with a malfunction of the installation:^ external cause associated with an extrinsic parameter: anthropogenic or natural modification of the water table, modification of the hydrogeological characteristics of the subsoil linked to new human constructions, increase in the temperature of the water table by anthropogenic or natural effect… ^malfunction of the installation: clogging, imbalance in the demands for heat and cold…Advantageously, the method also comprises a step of implementing a corrective action (E6) of the geothermal installation. The management step makes it possible to avoid any malfunction of the installation.Management influences the operating parameters and / or the external causes identified in order to resolve the anomaly detected in the evolution of one of the indicators linked to an extrinsic parameter. Thus the process makes it possible to remedy operating anomalies which are linked to the operating parameters of the installation as well as external causes modifying the extrinsic parameters.

Claims

CLAIMS1. Method for managing a geothermal installation, the geothermal installation being configured to meet the calorie or frigory demands of at least one building or industrial or agricultural process, the method comprising:- a measurement (E1), at a certain sampling frequency, of hydraulic, thermal and / or chemical operating parameters of the installation, by at least one measuring device;- a dated estimate (E2) of an indicator as a function of at least one measured operating parameter; and- a highlighting of a possible operating anomaly of the installation by a comparison (E4) between the indicator and at least one threshold relating to a parameter extrinsic to the geothermal installation, each threshold making it possible to differentiate between several hypotheses, at least one of which is a function of at least one cause external to the geothermal installation; and- a selection (E5), as a function of the result of the comparison (E4),of at least one of these hypotheses, in order to characterize the origin of the anomaly.

2. Method according to claim 1, comprising an implementation of a corrective action (E6) on the installation as a function of the detected anomaly and the selected hypothesis.

3. Method according to any one of claims 1 and 2, in which the reliability of the measurements of the operating parameters is tested (E11) in real time and the sampling frequency of these measurements is adapted as a function of the test results.

4. Method according to claim 3, in which the real-time test of the reliability of the measurements of operating parameters implements the following processing:- discrete Fourier transform of the measurements of said operating parameter considered over a predetermined time interval, - calculation of a useful oscillating energy as a function of the Fourier transform of said operating parameter,-determination of the sampling frequency as a function of this oscillating energy.

5. Method according to any one of claims 1 to 4, in which an estimated indicator is an indicator representative of a static level of the fluid in the subsoil, the estimation of said indicator being a function of a piezometric measurement in the geothermal installation as well as a previously determined theoretical static level., 6. Method according to claim 5, in which the geothermal installation comprises at least one injection well and at least one production well and in which the estimation (E2) of the indicator representative of a static level implements: - a piezometric measurement of the level of the injection well and a piezometric measurement of the level of the production well; - a comparison between the two measurements, and in which the indicator is an interval which includes the interval between the piezometric measurement of the injection well and the piezometric measurement of the production well, if the difference between the two measurements is less than a first predetermined threshold.7.Method according to any one of claims 1 to 4, in which the geothermal installation comprises at least one injection well and at least one production well and an estimated indicator is an indicator representative of a transmissivity between the production well and the injection well and the estimation of the indicator being a function of a flow rate of a fluid in the geothermal installation as well as a theoretical transmissivity previously recorded.

8. Method according to claim 7, in which the estimation (E2) of the indicator representative of the transmissivity comprises:- a forecast of a piezometry of the level of the production well and / or of the injection well as a function of the measured fluid flow rate and the transmissivity,- a comparison between the piezometry resulting from the forecast and a piezometric measurement of the injection well or a piezometric measurement of the production well, - a minimization of a difference resulting from the comparison.9.Method according to any one of claims 1 to 4, in which an estimated indicator is an indicator representative of a clogging of the geothermal installation and is estimated as a function of a volume of fluid flowed in the geothermal installation as well as a previously recorded theoretical fluid flow rate.

10. Method according to claim 9, in which the estimation (E2) of the indicator representative of the clogging comprises: - an estimation of a future specific flow rate as a function of the volume of fluid flowed and the theoretical fluid flow rate as well as the characteristics specific to the fluid circulating in the geothermal installation, and - a calculation of a volume of fluid before shutdown as a function of the estimated specific flow rate.

11. Method according to any one of claims 1 to 10, in which the operating parameter is included in the following parameters: a flow rate of heat transfer fluid in the geothermal installation, a pressure of the fluid in a pipe of the geothermal installation, a volume of fluid having circulated in the geothermal installation. 12.Method according to any one of claims 1 to 4, wherein the indicator for an open-type geothermal installation is included in the following list: the specific flow rate, the ratio between the maximum flow rate of the installation and the specific flow rate, a static level of the fluid in the subsoil, a transmissivity between a production well and an injection well, an effective or apparent thermal conductivity of the soil or a thermal capacity of the soil, the pH, the temperature of the fluid of the production or injection wells, the indicator for a closed-type geothermal installation is included in the following list: an estimated thermal conductivity, the minimum conductivity necessary to ensure the sustainability of the installation over a chosen period. 13.Method according to any one of claims 1 to 12, wherein the extrinsic parameters of the geothermal installation analyzed are included in the following parameters: a permeability of the ground, a presence of biochemical elements, operating parameters of neighboring geothermal installations, an environment of the geothermal installation, a clogging of a pipeline, a meteorological evolution, an energy consumption, energy losses of the structure, the thermal conductivity, the thermal capacity, the surface temperature and the vertical gradient of the subsoil, the water table flows, or geological events.

14. Method according to one of claims 1 to 5 and 9 to 11, wherein the geothermal installation is a geothermal installation on water tables, or of the open type, or a geothermal installation on probe, or of the closed type, or a geothermal installation on compact exchangers. 15.Assembly comprising a geothermal installation configured to meet the calorie or frigory demands of at least one building or industrial or agricultural process and a system for managing the geothermal installation, the system comprising means for measuring the operating parameters of the geothermal installation and being suitable for implementing the method according to any one of claims 1 to 14.

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