Process for managing, analyzing and regulating a geothermal installation

Abstract

This disclosure relates to a method for managing a geothermal installation, 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 measuring devices; a dated estimate of an indicator depending on at least one measured operating parameter;and highlighting a possible operating anomaly of the installation by comparing the estimate of the indicator with a plurality of boundary conditions, said boundary conditions being a function of different hypotheses relating to parameters extrinsic to the geothermal installation, and a selection, depending on the result of this comparison, of at least one of these hypotheses, in order to characterize the external cause at the origin of the anomaly. Figure for the abstract: Fig. 1;

Description

Title of the invention: Method for managing, analyzing and regulating a geothermal installation Technical field

[0001] The 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 ART

[0002] In order to meet the calorie or frigory demands of at least one surface building, it is possible to implement a geothermal installation.

[0003] The geothermal installation can comprise a system of different types such as for example a geothermal heat pump system (PAC) on a water table, a heat pump system (PAC) on vertical geothermal probes (SGV) or a geothermal heat pump system (PAC) on baskets or walls...

[0004] A geothermal installation circulates a heat transfer fluid in a borehole made in a subsoil 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 to it from the subsoil or cool the structure, by transferring the heat from the structure to the subsoil.

[0005] 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 planned 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 STATEMENT

[0006] One aim of the disclosure is to avoid malfunctions or maintenance operations of the geothermal installation and thus to enable continuous and efficient operation.

[0007] To this end, according to one aspect of the present disclosure, a method for managing a geothermal installation is proposed, the geothermal installation being configured to meet the calorie or frigories demands of at least one building or industrial or agricultural process. The method comprises: - 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 a possible operating anomaly of the installation by comparing the estimate of the indicator with a plurality of boundary conditions, said boundary conditions being a function of different hypotheses relating to parameters extrinsic to the geothermal installation, and a selection, depending on the result of this comparison, of at least one of these hypotheses, in order to characterize the external cause at the origin of the anomaly.

[0008] In particular, in the event of an anomaly, a corrective action (E6) on the installation is determined - and if necessary ordered - based on the result of the comparison.

[0009] This process allows efficient operation of the geothermal installation and upstream management of the causes of possible malfunctions in order to avoid them.

[0010] 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.

[0011] Advantageously, but optionally, the method described comprises at least one of the following characteristics, taken alone or in any combination: - an implementation of a corrective action on the installation as a function of the operating anomaly detected and the selected hypothesis;

[0012] - a real-time test of the reliability of the measurements of the operating parameters and the sampling frequency of these measurements is adapted according to the test results;

[0013] - real-time testing of the reliability of operating parameter measurements 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;

[0014] - an estimated indicator is an indicator representative of a static level, 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;

[0015] - 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 measures,

[0016] and wherein the indicator is an interval which comprises 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;

[0017] - the geothermal installation comprises at least one injection well and at least one production well and an 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;

[0018] - the estimation of the representative indicator of transmissivity includes: - 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 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;

[0019] - an indicator is an indicator representative of a clogging of the installation geothermal and is estimated based on a volume of fluid flowing through the geothermal installation as well as a previously recorded theoretical fluid flow rate;

[0020] - the estimation of the indicator representative of the clogging includes: - an estimate of a future specific flow rate based on 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 stopping as a function of the estimated specific flow rate;

[0021] - 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 system;

[0022] - the indicator is included in the following list: 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;

[0023] - the extrinsic parameters of the geothermal installation analyzed are included in the following parameters: soil permeability, presence of biochemical elements, operating parameters of neighboring geothermal installations, environment of the geothermal installation, clogging of a pipeline, meteorological developments, energy consumption or energy losses of the structure;

[0024] - the geothermal installation is a geothermal installation on a water table, or open type, or a geothermal installation on probe, or closed type, or a geothermal installation on compact exchangers.

[0025] According to another aspect, there is provided an 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 capable of implementing the method described above. DESCRIPTION OF FIGURES

[0026] 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 appended drawings in which:

[0027] [Fig.l] illustrates a flowchart of the steps of a possible implementation of this disclosure. DETAILED DESCRIPTION

[0028] Geothermal energy is used to enable heat exchanges between a subsoil and a structure such as a building, a cold room in 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, the structure generally requiring a geothermal installation will be called a building.

[0029] 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 quite simply a device connecting a building and the subsoil. The geothermal installation is therefore connected with a heating network of the building on the one hand and with 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 an exchange of heat, from one to the other and vice versa.

[0030] Geothermal installation

[0031] The geothermal installation may comprise a circuit for a heat transfer fluid and an exchanger connected to the circuit. The circuit may comprise a pipe and a circulation pump for controlling the flow rate 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.

[0032] The piping of the geothermal installation may include a network of injection / reinjection pipes to exchange heat with the subsoil; this is then referred to as a geothermal installation on a water table or aquifer.

[0033] The piping of the geothermal installation may comprise a closed network of pipes to exchange heat with the subsoil; this is then referred to as a geothermal installation on a probe or probe fields.

[0034] The piping of the geothermal installation may include a network of spiral pipes to exchange heat with the subsoil; this is then referred to as a geothermal installation on compact exchangers.

[0035] 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 pipe of the geothermal installation circuit. The fluid can: - be part of the installation and circulate in a closed loop in the pipeline in so-called closed geothermal installations, as in the case of geothermal installations on probes 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 geothermal installations on a water table.

[0036] The geothermal installation includes intrinsic parameters. Intrinsic parameters are the parameters that can be selected by an installer of the geothermal installation 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.

[0037] 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 a underground water table, in the case of an open-type geothermal installation, or - the flow rate, inlet and outlet temperatures and pressure variation of the fluid circulating in the geothermal installation, in the case of a closed-type geothermal installation.

[0038] 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 via a borehole and exchanges heat by conduction.

[0039] The operating parameters of a geothermal installation may change 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, its horizontal and vertical permeability, the storage coefficient, the spatial heterogeneity of these values, the presence of a wall (recharge via upper or lower water tables in hydraulic contact), a recharge zone (river, canal, lake, etc.) or waterproofing (construction of foundations, tunnels, etc.); - well characteristics: quadratic pressure drop at the level of the strainers, 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; - characteristics of the energy demand profile of the use: heating demand and cooling demand, and especially the annual difference...

[0040] The geothermal installation preferably comprises detection means, such as sensors, for acquiring measurements and means for recording the acquired measurements.

[0041] The geothermal installation is preferably controlled by the building to which it is connected. The building advantageously comprises a temperature regulation system which, in the event of detection of a need for heat or cold, will request a geothermal installation regulation controller to manage a flow rate of the circulation pump and thus allow a transfer of energy via the exchanger with a difference temperature AT = T2-T1, Tl being the temperature of the fluid entering the exchanger and T2 being the temperature of the fluid leaving the exchanger:

[0042] Eq. 1:p[kW] = 1.16 x AT[ 0 C or °Æ] xô[f]

[0043] P being the power transmitted by the geothermal installation to the building and Q the flow rate of the fluid in the circuit.

[0044] Open type geothermal installation

[0045] The geothermal installation may be an open geothermal installation or an 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 makes it possible to supply the geothermal installation with fluid and the injection well makes it possible to evacuate the fluid from the geothermal installation.

[0046] 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.

[0047] The geothermal installation may include sensors, such as energy meters and water volume meters. Each well is equipped with a piezometer which 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 circuit of the geothermal installation advantageously includes one or more temperature sensors in order to measure the temperature of the fluid and the temperature of the water table, in other words the subsoil.

[0048] Advantageously, the flow rate in the circuit can vary from 5 to 500 m3 / h. The temperature of the subsoil 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.

[0049] 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 allowing.

[0050] 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.

[0051] It is also possible to estimate the transmissivity between 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 soil hydraulics. Monitoring transmissivity is therefore important in order to predict possible future malfunctions.

[0052] The circulation of the water table fluid in the circuit can cause clogging of the well. Clogging is linked to fouling of the injection well. If the clogging is too significant, the geothermal installation will have to be shut down. It is therefore necessary to estimate and predict the time remaining before clogging.

[0053] Management method

[0054] The method for managing the geothermal installation makes it possible to identify in real time one or more causes of a development deemed unusual, in other words a drift, of an indicator. Once the cause of a drift has been identified, the method is configured to manage the geothermal installation and possibly its environment and thus avoid a malfunction of the geothermal installation. The management method comprises several steps which are detailed below.

[0055] Measurement of an operating parameter

[0056] The management method, as illustrated for example by [Fig. 1], comprises 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 suitable for such acquisitions are implemented in the geothermal installation for this purpose.

[0057] 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 parameter operating according to a reliability criterion. The analysis of the sampling frequency is explained below.

[0058] 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.

[0059] Thus the sampling frequency may or may not be suitable for 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 correct interpretation of the data in a given time interval.

[0060] The method is done by using Discrete Fourier Transforms (DFT) and setting up a useful oscillating energy indicator.

[0061] 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:

[0062] Eq.

[0063] Only the first part of the coefficients (k=0 to N / 2) is useful because of the frequency aliasing. Each coefficient e(k) = IX(k)l2 is 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(l) corresponds to the fundamental frequency linked to the duration of the interval, which is not useful 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.

[0064] Thus the useful oscillating energy (EOU) is equal to:

[0065] Eq.3:£Or=I^ix(^

[0066] 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 judged to be acceptable.

[0067] The determination of the threshold for the EOU can be carried out in the following manner: - 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 among the 50% of the highest values. We will typically take values between 20% and 80% as thresholds. (the distribution function is a function which gives, as a function of an EOU value, the percentage of value lower than the EOU).

[0068] Other methods can be used depending on the probability density of the EOU values: - if the probability density of the EOUs is close to a Gaussian (1 peak), then the method described previously is certainly the most suitable; - if the probability density of the EOU is binomial (2 peaks), then a Bayesian thresholding is suitable

[0069] Furthermore, the EOU values below a predetermined significance threshold, linked to the measuring equipment used, will be removed beforehand. If the measuring device has a measurement accuracy characterized by a measurement standard deviation, the threshold will be (me)2 with m between 1 and 10, typically 5.

[0070] Other methods can also be used such as the windowed Fourier transform or thresholding on the amplitude (difference between the max and min value) determined over a time window.

[0071] Estimating the quality of the sampling thus makes it possible to improve the analysis of drifts thanks to correct acquisition of the evolution of the operating parameters.

[0072] Estimation of an indicator

[0073] The management method then comprises a step (E2) of estimating one or more indicators. Each indicator is representative of a change, in real time, in one of the extrinsic parameters of the geothermal installation.

[0074] The estimation is carried out in real time. The estimation may be a function of one or more operating parameters as well as extrinsic parameters of the geothermal installation.

[0075] It is for example 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 wells of the installation 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 circuit of the installation 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 previously recorded theoretical fluid flow rate etc.

[0076] Estimation of static level

[0077] In the case of an open geothermal installation (or on water tables) the indicator corresponding to the static level of the water table is estimated in order to enable management of the geothermal installation, to detect an anomaly and to identify one or more external causes of the detected anomaly.

[0078] The static level is therefore a parameter extrinsic to the geothermal installation, the indicator of which can be estimated as a function of 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.

[0079] The water level, or piezometry, in a well varies according to numerous phenomena with time constants that vary depending on the case, typically: • Pumping or injecting water lowers and raises the water level respectively: the time constant is linked to the flow rate calls of the geothermal system • Natural variations in the water table: they are essentially cyclical over an annual period • Anthropogenic variations in the water table linked to pumping external to the geothermal installation: the time constants here are very variable but a priori between the variations in pumping and natural variations.

[0080] 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: - 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 NS; and NSp which will be selected in the next step; - Calculation of the indicator value. The indicator is a value, but can optionally be a value interval.

[0081] This value is the estimate of the static water table level for the NS injection well; or NSP production well; and - Real-time comparison between these NS values; and NSP of static levels:

[0082] If 1^5,-(7) -NSp(t) | is less than a first threshold SI, the estimate is deemed reliable,

[0083] If \NSff) -NSp(t) | is greater than the first threshold SI, three cases can arise: a. Both estimates are false: |NSP(t) -NSP(t + z) | > 52 xz and | NSj (t) -NSft + z) \ > S2 xz with z > 0 the smallest time such that NSp(t+z) and NSft+z) exist, b. It is the estimate at the injection well that is wrong and that of the production well that is right: it will be detected if |NSP(t) -NSP(t + z) | < |NSj(t) -NSj(t + z) | with z > 0 the smallest time such that 2V5p(7 + z) and NSj(t+z) exist, c. It is the estimate at the production well that is wrong and that of the injection well that is right: it will be detected if | / V5;(7) -NSjtt + z) | < |N5P(7) -NSp(t + z) | with z > 0 the smallest time such that NSp(t + z) and NSj(t + z) exist.

[0084] The thresholds SI and S2 are interpreted as follows: • SI is the permissible 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: • Method 1: SI = m + fi <7 with m the absolute value of the time average of NSfJf -NSp(t) and the time standard deviation of NSj(t) -NSpït). fi 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 Im / d for example, but the values of 0.1 and 10 m / d can be relevant.

[0085] Taking into account the impact of an external parameter on piezometry makes it possible to obtain a prediction of the evolution of the static level for the external parameter considered...

[0086] Estimation of transmissivities of producing and injecting wells and

[0087] Transmissivity is the ease with which the soil allows water to pass through: if transmissivity decreases, pumping is less efficient and the efficiency of the geothermal installation is reduced. Transmissivity is therefore the inverse of the resistance of the soil hydraulics.

[0088] Transmissivity is therefore a parameter extrinsic to the geothermal installation, the indicator of which can be estimated as a function of one or more of the parameters of

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095]

[0096]

[0097] operation of the geothermal installation. Estimating the transmissivity indicator helps improve the management of the geothermal installation. In order to estimate in real time the indicator of the actual transmissivity it is possible to take into account, as operating parameters, the fluid flow rate in the circuit of the open type geothermal installation as well as the theoretical transmissivity previously recorded. Variables description Pi, Piezometer n°i, actual value P^n Piezometer n°i, value measured by the sensor Pi. Piezometer n°i, value recorded in the memory T * if Temperature n°i, actual value Temperature n°i, value recorded in the memory Q Flow rate n°i, actual value Q Flow rate n°i, value measured by the sensor For the pumping well: ^^,,(0=-5,2-^-4^(¾) ^-^2^,(0 = -^(¾) For the injection well: Eq ' 6 '2' 22 (O =s2g+c2g 2 + 4^Tv(^) Eq' 7 'QRn(t) With : - if > 0 the skin effect and linear clogging, - > 0, the quadratic pressure loss coefficient also linked to clogging, - T; the transmissivity of the water table near well no. i, - S the storage coefficient, - t the time, - rijla distance such that if i = j, it is the radius of well no. i, if i* j, the distance between wells i and j, and - W, a typical function of the structure of the sheet. The function W(u) is calculated classically according to the hypotheses of Theis, Jacobs or Hantush for example, depending on whether we have a homogeneous and isotropic medium, a homogeneous and isotropic medium for long times, and a homogeneous and isotropic medium with a wall. Other models exist simulating the presence of a recharge or a watertight wall, whether the water table is captive or free, etc.

[0098] The method may optionally comprise a digital filtering step using a first-order low-pass filter F, or several to improve the robustness of the method.

[0099] In summary, the estimation of the representative indicator of the transmissivity of producing and injecting wells includes: - the prediction of a piezometry of a well of the geothermal installation according to the measured fluid flow rate and the transmissivity, - a comparison between the estimated piezometry and a piezometric measurement of an injection well or a piezometric measurement of a production well, - a minimization of a difference resulting from the comparison, the difference implementing a modification of the parameters of a model for the forecast.

[0100] This makes it possible to estimate in real time the indicator of the transmissivity of the geothermal installation.

[0101] Estimated time remaining before circuit clogging

[0102] The clogging of the circuit is due to the presence of particles in the reinjected water. As a result, a layer of material (cake) will form on the strainer, thus increasing the hydraulic resistance of the structure. Clogging (or "fouling" or "clogging" according to Anglo-Saxon terminology) can be broken down into reversible clogging (the "cake" once removed allows the initial resistance to be restored) or irreversible clogging (even after washing and treatment, additional resistance persists).

[0103] In order to estimate the circuit clogging indicator in real time, it is possible to take into account ... (operating parameter) of the geothermal installation as well as ... (extrinsic parameter such as the purity of the water table...).

[0104] Let Kg be the permeability of the cake, S the surface area of the strainer, Cg the mass concentration of comatating particles in the water, dg their mass density in the form of cake and Qsp(0) the initial specific flow rate. In addition:

[0105] Eq. 8: s

[0106] is the total volume flowed into the well. Finally, we have:

[0107] Eq. 9: _j_ Qsft) “

[0108] With “_ c“ 1 Kgdgs

[0109] By definition, T es,co

[0110] We can easily set a maximum threshold at l] Q (or minimum at beyond from which the installation must be stopped. In fact, we know from the dimensions of the well, the maximum possible drop in piezometric pressure to avoid dewatering the water table or flooding the upper parts of the installations (parking, garden, basement, etc.). Let QF"1 be this value equal to the required flow rate divided by the maximum piezometry variation in the well.

[0111] We therefore have a linear relationship between the volume injected into the well, and the inverse of the specific flow rate, which is homogeneous to a resistance. Thus by regularly measuring [ j Q by the methods seen previously, we can predict by linear interpolation the volume which will lead to a fault in the installation; knowing the water consumption of the installation, we can deduce a forecast date of forced shutdown of the installation.

[0112] This method will also make it possible to estimate the effectiveness of unclogging because unclogging will lower the value of [j Q by removing the filter cake.

[0113] In summary, the estimation of the indicator representative of clogging includes: - an estimate of a future specific flow rate based on 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 stopping as a function of the estimated specific flow rate.

[0114] It is possible to simplify the knowledge model to a single parameter. For this, we assume that the transmissivities are identical on each well (T i = - T) and in posingr = ri i ~ the radius of the wells and d - rn = ^21 the distance between wells, we arrive at the following simplifications:

[0115] For the pumping well we have:

[0116] Eq. 10: Pu, = ECpP* +

[0117] With: __). In the case of long times the Jacobs approximation is valid (jy ( _ 0.577 - ln(u)) for captive, homogeneous and isotropic water tables and with a perfect well. We also have S the storage coefficient, r the radius of the well and T the transmissivity. We also neglect the quadratic pressure losses (c=0).

[0118] And for the injection well:

[0119] Eq. 11: P2(. = ECpPs + a2

[0120] With: )

[0121] Thus the knowledge model is reduced to a parameter a for each well; 1 / a is interpreted as the specific flow rate of the installation. If we know the transmissivity initial water table, which can also be estimated with the minimum value in absolute value of ai with the following relation:

[0122] Eq. 12: ~ ln«) 1 init ~ 2 / r miri^

[0123] We are able to estimate the linear clogging of each well:

[0124] Eq. 13: ÿi=

[0125] Eq. 14:^-^.--

[0126] if has the unit [s / m2] and is homogeneous to a hydraulic resistance. This characterizes the resistivity linked to clogging. We can construct a clogging indicator which is worth 0 when the clogging is negligible and 1 when the totality of the apparent hydraulic resistance is associated with the clogging:

[0127] Eq. 15: Cost index^ 1 —

[0128] We can also define a clogging index which represents the logarithmic ratio between the apparent resistance of the well and the initial resistance:

[0129] Eq. 16 . clogging 2 = = log-^^

[0130] It is equal to 0 when there is no clogging, 1 when the apparent resistance is 10 times stronger than the initial resistance, 2 for 100 more.

[0131] Determination of boundary conditions

[0132] The management method further comprises a determination (E3) of boundary conditions. Indeed, for each estimated indicator it is necessary to be able to know whether the values of the indicator and their 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, extrinsic to the installation, are present.

[0133] To determine boundary conditions, in other words thresholds or alert values, it is necessary to take into account the extrinsic parameter linked to the indicator considered as well as forecasts made previously and linked to usual operating hypotheses.

[0134] For example, to determine the boundary conditions of 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, the variation in piezometry typically from one week to another, or from one month to another, and it will be compared to this threshold.

[0135] For example, b is the natural beating of the water table over one year. The following indicator is constructed: J— / *-£• ± / . 4. Water table variation index 1 = — 365

[0137] With Ans the variation of the static level in the time interval At 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 anthropic action of the variation of the piezometry of the water table.

[0138] Installation control

[0139] As mentioned above, the management method then comprises a step of highlighting a possible operating anomaly of the installation. The highlighting is obtained by comparing the estimate of the indicator considered with a plurality of boundary conditions. The boundary conditions being a function of different hypotheses.

[0140] The assumptions relate to one or more parameters extrinsic to the geothermal installation.

[0141] As mentioned above, the management method then comprises 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 boundary conditions determined for each indicator considered. The selected hypothesis is the cause of the anomaly highlighted.

[0142] Highlighting the 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: • 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, etc. • malfunction of the installation: clogging, imbalance in the demands for heat and cold, etc.

[0143] Advantageously, the method further 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. The 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.

[0144] Thus the method makes it possible to remedy operating anomalies which are linked to the operating parameters of the installation as well as to external causes modifying the extrinsic parameters.

Claims

Claims

1. Method for managing a geothermal installation, the geothermal installation being configured to respond to the demands for calories or frigories of at least one building or industrial or agricultural process, the method comprising: - a measurement (El), 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 - highlighting a possible operating anomaly of the installation by a comparison (E4) of the estimate of the indicator with a plurality of boundary conditions, said boundary conditions being a function of different hypotheses relating to parameters extrinsic to the geothermal installation, - and a selection (E5), depending on the result of this comparison, of at least one of these hypotheses, in order to characterize the external cause at 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 operating 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 (El 1) in real time and the sampling frequency of these measurements is adapted according to 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 comprises 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 previously recorded theoretical transmissivity.

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 of 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 flowing in the geothermal installation as well as a theoretical fluid flow rate previously recorded.

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. A method according to any one of claims 1 to 4, wherein the estimated indicator is included in the following list: a static fluid level in the subsoil, a transmissivity between a production well and an injection well, an effective or apparent soil thermal conductivity or a soil heat capacity.

13. Method according to any one of claims 1 to 12, in which 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 or energy losses of the structure.

14. Method according to one of claims 1 to 13, in which the geothermal installation is a geothermal installation on a water table.

15. Method according to one of claims 1 to 5 and 9 to 11, in which the geothermal installation is an open type installation, or a geothermal installation on probe, or a closed type installation, or a geothermal installation on compact exchangers.

16. 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 capable of implementing the method according to any one of claims 1 to 15.

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