Method and device for monitoring the operation of a well or drilling

Abstract

The present invention relates to a method and device for monitoring the operation of a well or a borehole. In particular, the proposed method comprises: a determination (S200) of specific flow rates (Qs1-QsM) from water levels (N1-NN) and flow rates (Q1-QN) measured during the operation of the well or borehole; a selection (S300) of a plurality of specific flow rates (Qs1-QsP) from the determined specific flow rates (Qs1-QsM); a determination (S400) of an operating state (FST) of the well or borehole from the selected specific flow rates (Qs1-QsP). Figure for abstract: Fig. 2

Description

Title of the invention: Method and device for monitoring the operation of a well or drilling Technical field

[0001] The present invention relates to the field of wells and boreholes. More particularly, the present invention relates to a method and a device for monitoring the operation of a well or borehole, as well as a system for operating a well or borehole, and an associated computer program. The present invention finds a particularly advantageous, although in no way limiting, application for monitoring the operation of a well and planning maintenance operations thereon. Prior art

[0002] In the current state of the art, it is known to monitor the operation of a well from specific flow rate measurements. We recall that the specific flow rate corresponds to a pumping rate related to a drawdown, the latter being equal to the difference between the static water level and the dynamic water level in the well.

[0003] Patent EP3184731B1 illustrates such a solution for monitoring a well. This patent proposes to monitor a well by determining specific flow rate values and to plan a well maintenance operation based on these specific flow rate values. More specifically, to make reliable comparisons of well performance and plan a maintenance operation, this patent proposes to select the specific flow rate values measured with similar static water levels.

[0004] However, the reliability of the solution proposed in patent EP3184731B1 is not fully satisfactory, since the use of this solution leads to numerous false positives. In other words, when this solution is implemented, unnecessary maintenance operations are planned. In particular, selecting specific flow rate values measured with similar static water levels is not sufficient to make reliable comparisons of well performance.

[0005] Consider, for example, a catchment field grouping together several water catchment devices in the same water table. The different wells of the catchment field influence each other and significant interference can occur between these wells. Also, for such a catchment field, the solution proposed in patent EP3184731B1 does not allow the operation of a well to be reliably monitored and could lead to the planning of unnecessary maintenance operations.

[0006] Therefore, there is a need for a solution for reliably determining the operating status of a well or borehole. Statement of the invention

[0007] The present invention aims to remedy all or part of the drawbacks of the prior art, in particular those set out above.

[0008] According to one aspect of the invention, there is provided a method for monitoring the operation of a well or a borehole comprising: - a determination of specific flow rates from water levels and flow rates measured during operation of the well or drilling, the determination of each specific flow rate including: • obtaining a so-called static water level measured during a filling phase (during which the pump is stopped), a so-called dynamic water level measured during a pumping phase (during which the pump is running) following the filling phase, and a pumping flow rate measured during the pumping phase, so that: • an indicator of instability of the static water level is lower than a first threshold, this indicator being determined from a difference between the static water level and a water level measured at a previous time of the filling phase; and / or • a dynamic water level instability indicator is lower than a second threshold, this indicator being determined from a difference between the dynamic water level and a water level measured at a previous time in the pumping phase; • a calculation of said specific flow rate from the static water level, the dynamic water level, and the pumping flow rate; - a selection of a plurality of specific flow rates from among the determined specific flow rates, each selected specific flow rate satisfying the criteria according to which: • a difference between: a reference static water level; and the static water level associated with said selected specific flow rate, is less than a given percentage of a reference water height; and • a difference between: a reference pumping flow rate; and the pumping flow rate associated with said selected specific flow rate, is less at a given percentage of the reference pumping rate; and a determination of an operating condition of the well or borehole from selected specific flow rates.

[0009] The present invention proposes to monitor the operation of a well by carrying out specific flow rate measurements and analyzing them.

[0010] On the one hand, the proposed solution makes it possible to obtain reliable well performance measurements. Indeed, the specific flow rates are calculated by ensuring that the static and dynamic water levels are stable. Specifically, it is verified that the static and dynamic water levels have instability indicators below thresholds. These indicators make it possible to verify the stability of the water body during the measurements of the static and dynamic water levels. This guarantees that the static and dynamic water levels are measured during established regimes (respectively filling and pumping), and not during transient regimes. In particular, for a catchment field, the use of instability indicators makes it possible to ensure that another well is not started during the measurements of the static and dynamic water levels.

[0011] On the other hand, the proposed solution allows reliable comparisons of well or drilling performance measurements. In fact, to determine whether the well is functioning properly or not (e.g. the well is clogged), it is proposed to select specific flow rates measured under similar operating conditions. Two criteria are used to select the specific flow rates from which the operating status will be determined.

[0012] Similar to the solution of patent EP3184731B1, a first selection criterion implies that the selected specific flow rates are measured for similar static water levels (i.e. in a given range around a reference static level). It is important to note that the reference water height, used to define this first selection criterion, may in particular correspond to a reference aquifer power (i.e. a thickness of the saturated zone of the aquifer), or to the reference static water level.

[0013] Furthermore, and unlike the solution of patent EP3184731B1, a second selection criterion implies that the specific flow rates selected are measured for similar pumping flow rates (i.e. in a given range around a reference pumping flow rate).

[0014] By selecting specific flow rates measured under similar operating conditions, the proposed solution ensures that comparisons of well performance are reliable. Thus, the present invention makes it possible to reliably determine the operating status of the well. This makes it possible to determine whether the well is operating properly or not, or even whether its operation is degrading over time. For example, the proposed solution can be used to determine whether the well is plugged or not.

[0015] Compared to existing solutions, and in particular that of the patent EP3184731B1, the proposed solution makes it possible to improve the reliability of monitoring the operation of a well and to reduce the number of false positives, i.e. incorrect detections of a malfunction of the well. This improvement results in particular from the joint use of instability indicators for static and / or dynamic water levels, and the selection criteria for the specific flow rates proposed.

[0016] According to one embodiment, the given percentage of the reference water height and / or the given percentage of the reference pumping rate are fixed according to the well or borehole.

[0017] In this embodiment, it is proposed to adapt the selection criteria for the specific flow rates according to the well. In other words, the given ranges around the reference static water level and the reference pumping flow rate, used to select specific flow rates considered comparable, are defined according to the well.

[0018] This implementation mode thus makes it possible to adapt the proposed operational monitoring solution to different well configurations or topologies. This contributes to improving the reliability of operational monitoring.

[0019] For information purposes, the given percentage of the reference water height may be equal to 5%, 10% or 15%; and the given percentage of the reference pumping flow rate may be equal to 5%, 10% or 15%.

[0020] According to one embodiment, for each specific flow rate determined: the static water level is measured after a filling time greater than or equal to 1 hour; and / or the dynamic water level is measured after a pumping time greater than or equal to 1 hour.

[0021] By setting the pumping duration to at least one hour, this implementation method ensures that the dynamic water level is measured during an established pumping regime, and not during a transient regime (e.g. the start of pumping). The same applies to the static water level. Consequently, this implementation method contributes to improving the reliability of the proposed solution for monitoring the operation of a well.

[0022] According to one mode of implementation, for each specific flow rate determined, the dynamic water level is measured after a given pumping duration (i.e. fixed, predetermined).

[0023] According to this implementation mode, each dynamic level used to calculate a specific flow rate is measured after a fixed pumping duration. Thus, the dynamic levels are measured after similar pumping durations, which makes it possible to ensure that the specific flow rates are measured under similar operating conditions. This implementation mode therefore makes it possible to obtain comparable measurements of well performance and contributes to the reliability of the proposed solution.

[0024] According to one embodiment, for each specific flow rate determined, an indicator of instability of the pumping flow rate is less than a third threshold, this indicator being determined from a difference between: an instantaneous pumping flow rate measured at the instant of measurement of the dynamic water level; and an instantaneous pumping flow rate measured at a previous instant of the pumping phase.

[0025] To perform a specific flow rate measurement of the well, it is proposed in this embodiment to ensure not only that the static and dynamic water levels are stable, but also that the pumping rate is stable. This embodiment makes it possible to obtain reliable performance measurements of the well.

[0026] According to one embodiment, the determination of the operating state of the well or drilling comprises a detection of a clogging from the selected specific flow rates.

[0027] This implementation method makes it possible to reliably detect a clogging of the well. As mentioned above, the proposed solution makes it possible to make reliable comparisons of the well's performance. Thus, compared to existing solutions, the proposed solution makes it possible to reduce the number of false positives, i.e. erroneous detections of clogging. The proposed solution is therefore particularly advantageous in that it makes it possible to avoid planning unnecessary maintenance operations.

[0028] According to one embodiment, a clogging is detected if a difference between: a specific reference flow rate; and one of the selected specific flow rates, is greater than a given percentage of the specific reference flow rate.

[0029] According to this embodiment, a clogging of the well is detected if (and only if) the specific flow rate of the well drops significantly compared to the reference specific flow rate. It thus makes it possible to reliably detect a clogging of the well.

[0030] More particularly, the given percentage of the specific reference flow rate can be set according to the well or the drilling, which makes it possible to adapt the detection of a clogging to the configuration and the topology of the well. The given percentage of the specific reference flow rate can in particular be equal to 15% or 30%.

[0031] According to one embodiment, the determination of the operating state of the well or drilling comprises a prediction (i.e. a determination) of specific flow rates for later times (i.e. later than the times of the selected specific flow rates) from the selected specific flow rates.

[0032] It is proposed here to predict the future values of the specific flow rate of the well. Note that the prediction of the specific flow rate values only exploits the selected specific flow rates, i.e. reliable and comparable well performance measurements. Therefore, the proposed solution makes it possible to reliably evaluate the future evolution of the specific flow rate of the well. It can thus be used to determine a future operating state of the well.

[0033] The prediction of the specific flow rates of the well is carried out using a regression model. This may, for example, be a linear regression model. Alternatively, it could also be envisaged to use a non-linear regression model, or an artificial neural network to carry out this prediction.

[0034] According to one embodiment, the determination of the operating state of the well or drilling comprises, if (and only if) a prediction quality indicator is greater than a fourth threshold: - a determination of a later time at which a difference between: a reference specific flow rate; and a predicted specific flow rate, is greater than a given percentage of the reference specific flow rate.

[0035] As mentioned previously, the given percentage of the reference specific flow rate can be set according to the well or borehole, which makes it possible to adapt to the configuration and topology of the well.

[0036] This implementation method makes it possible to determine the date on which a maintenance operation will be necessary. Indeed, the predicted values of the specific flow rate are used here to determine whether a significant drop in the specific flow rate of the well is to come. For example, this implementation method can be used to detect the formation of a well blockage and determine the date on which a maintenance operation will be necessary to remedy it.

[0037] It is important to note that the proposed solution determines whether a maintenance operation will be necessary only when the prediction quality indicator is above a threshold. This ensures that the conclusions about the future operating state of the well are based on a regression model accurately describing the evolution of the specific flow rate of the well over time.

[0038] In particular, the prediction quality indicator is determined from differences between specific determined flow rates (i.e. calculated from measurements) and specific predicted flow rates (i.e. calculated by the regression model). For example, when a linear regression is used, this indicator may correspond to the coefficient of determination, commonly noted R2. Alternatively, it could also be the root-mean-square error.

[0039] According to one embodiment, the prediction of specific flow rates is carried out (only) if the number of specific flow rates selected is greater than a fifth threshold.

[0040] This mode of implementation makes it possible to ensure that the number of specific flow rate values selected is sufficient to reliably predict the future evolution of the specific flow rate of the well.

[0041] According to one embodiment, the water levels and flow rates are measured with a sampling interval of less than or equal to 15 minutes.

[0042] By using a sampling interval of less than or equal to 15 minutes to measure the water level and the pumping rate of the well, this implementation method makes it possible to carry out precise monitoring of the operation of the well over time.

[0043] According to one embodiment, a said reference value is a value measured or determined following commissioning of the well or drilling, or following a maintenance operation of the well or drilling.

[0044] By "reference value", we mean here: the reference static water level, the reference water height, the reference pumping rate, and / or the reference specific rate. For example, a reference value is measured or determined during a pumping test (e.g., a step test pumping) carried out following the last maintenance operation on the well.

[0045] This mode of implementation is particularly advantageous in that it allows reliable comparisons of the well's performance to be made. Indeed, the reference values used to compare the well's performance are those measured during commissioning or the last maintenance operation on the well. In other words, the proposed solution determines the operating state of the well (i.e. correct operation or malfunction) by referring to an operation of the well considered to be correct, or even optimal, by the operator at that given moment (i.e. a reference state).

[0046] According to one aspect of the invention, a device is proposed for monitoring the operation of a well or a borehole, the device comprising means configured to implement a method in accordance with the invention.

[0047] The operation monitoring device may be configured to implement any of the modes of implementation of a method according to the invention. In particular, for each step of a method according to the invention, the proposed device may be configured to implement said step, or comprise a module configured to implement said step.

[0048] According to another aspect of the invention, there is provided a system for operating a well or a borehole comprising: at least one pump; a water level sensor (i.e. a probe); at least one volumetric meter or flow meter; and an operating monitoring device in accordance with the invention.

[0049] According to one aspect of the invention, there is provided a computer program comprising instructions for implementing the steps of a method according to the invention, when the computer program is executed by at least one processor or or- diner.

[0050] The computer program may be formed of one or more sub-parts stored in the same memory or in separate memories. The program may use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code, such as in a partially compiled form, or in any other desirable form.

[0051] According to one aspect of the invention, there is provided a computer-readable information medium comprising a computer program according to the invention.

[0052] The information carrier may be any entity or device capable of storing the program. For example, the carrier may comprise a storage means, such as a non-volatile memory or ROM, for example a CD-ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a floppy disk or a hard disk. Furthermore, the storage medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by a telecommunications network or by a computer network or by other means. The program according to the invention may in particular be downloaded onto a computer network. Alternatively, the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question.

[0053] The proposed operation monitoring device, operating system, computer program and information medium have the advantages described above in connection with the operation monitoring method. Brief description of the drawings

[0054] Other characteristics and advantages of the present invention will emerge from the description provided below, illustrating embodiments of the invention given by way of example and without any limiting character, with reference to the attached drawings:

[0055] [Fig.l] represents the architecture of a well operating system according to an embodiment of the invention;

[0056] [Fig.2] represents steps of a method for monitoring the operation of a well according to an embodiment of the invention;

[0057] [Fig.3] represents steps of a method according to an embodiment of the invention for determining a specific flow rate of the well;

[0058] [Fig.4] represents water levels of a well over time used to determine a specific flow rate of the well;

[0059] [Fig.5] represents steps of a method according to an embodiment of the invention for selecting specific flow rate values; and

[0060] [Fig.6] represents steps of a method according to an embodiment of the invention for determining an operating state of a well. Description of the embodiments

[0061] [Fig.l] represents the architecture of a well operating system according to one embodiment of the invention. In particular, [Fig.l] is described below to introduce the present invention and to exemplify an application thereof.

[0062] The SYS system for operating a well comprises at least: a PMP pump; a set of SENS sensors; and an APP device for monitoring operations. In particular, the SYS system may be a SCADA type system (for “Supervisory Control And Data Acquisition” in English).

[0063] The PMP pump is configured to extract (i.e. capture) water from an aquifer. This is controlled by CMD control signals which trigger the starting or stopping of the PMP pump. As illustrated in [Fig.l], the CMD control signals can be emitted by the APP device. However, it could be envisaged that the CMD control signals are emitted by a separate device.

[0064] The set of sensors SENS comprises at least: a water level sensor WLS (i.e. a level probe); and at least one volumetric sensor or a flow meter FMS. The set of sensors SENS is thus configured to provide water level values NrNN and flow rate values QrQN measured during operation of the well. These values are provided to the APP device.

[0065] In addition to the water level values Nl-NN and flow rates Ql-QN, the APP device is configured to obtain the changes of state (i.e., starting or stopping) of the PMP pump, so as to be able to identify the pumping phases of the well (i.e. pump running) and the filling phases of the well (i.e. pump stopped).

[0066] The SYS system may also include a display device DISP as illustrated in [Fig.l]. The display device DISP may, for example, be used to display to a user specific flow rates QsrQsM of the well determined by the APP device. It could also be used to signal to a user that a well maintenance operation is considered necessary or will be necessary.

[0067] The APP device monitors the operation of the well. The APP device is thus configured to automatically determine specific flow rates QsrQsM of the well during its operation. To do this, it uses in particular the Ni-Nn water levels and the QrQN flow rates measured, as well as the changes in state of the PMP pump.

[0068] The APP device is further configured to determine the operating status of the well (e.g. correct operation, operation in the process of degrading, or well clogged) from the specific flow rates QsrQsM. The operational monitoring carried out by the APP device is described in more detail below with reference to [Fig.2].

[0069] The APP device comprises, according to the embodiment illustrated by [Fig.l]: at least one processing unit or processor PROC; and at least one memory MEM.

[0070] More particularly, the APP device has the hardware architecture of a computer according to one embodiment. The memory MEM constitutes an information medium in accordance with the invention, readable by a computer and by the processor PROC, on which a computer program PROG in accordance with the invention is recorded. The program PROG comprises instructions for carrying out steps of a method in accordance with the invention, when the program PROG is executed by the processor PROC.

[0071] As illustrated by [Fig.l], the APP device has a communication module COM configured to communicate with at least one of the following elements: the pump PMP; the set of sensors SENS; and the display device DISP. No limitation is attached to the nature of the communication interfaces between these devices, which can be wired or wireless, and can implement any protocol known to those skilled in the art.

[0072] The architecture of the well operating system SYS having been introduced, we describe below the operating monitoring carried out by the APP device with reference to the following figures.

[0073] [Fig.2] represents steps of a method for monitoring the operation of a well according to an embodiment of the invention.

[0074] As illustrated by [Fig.2], the proposed method comprises at least one of the steps S100 to S500 described below. These steps are implemented by the APP device.

[0075] Note that the proposed method may comprise a plurality of iterations of each of its steps. The steps of the method may be repeated at a given frequency, for example every day, every week, or every month.

[0076] In step S100, the APP device obtains the water levels NrNN and the flow rates QrQN measured during operation of the well by the set of sensors SENS. The APP device may in particular receive these values from the set of sensors SENS. Alternatively, the APP device could obtain these values from a storage device.

[0077] The measured water levels NrNN and flow rates QrQN are time-stamped. Hereinafter, we denote TrTN the times of measurement of these values. In particular, the water levels Ni-Nn and the flow rates Qi-Qn are measured using a fixed sampling frequency.

[0078] According to one embodiment, the sampling interval is less than or equal to 15 minutes. It may for example be equal to 5 minutes, 10 minutes or 15 minutes. This embodiment makes it possible to carry out precise monitoring of the operation of the well during the time.

[0079] The flow rates QrQN can be obtained directly from a flow meter, but could also be calculated from information provided by a volumetric meter.

[0080] In step S200, the APP device determines specific flow rates QsrQsM of the well from the water levels NrNN and the flow rates QrQN measured during operation of the well. The implementation of step S200 is described in more detail with reference to FIGS. 3 and 4.

[0081] Thus, the APP device has performance measurements of the well over time. These performance measurements are then used by the APP device to determine the operating state of the well.

[0082] In step S300, the APP device selects a plurality of specific rates Qsi-QsP from among the determined specific rates QsrQsM.

[0083] In fact, the APP device selects in step S300 specific flow rates measured under similar operating conditions, which allows reliable comparisons of the well performance measurements. The implementation of step S300 is described in more detail with reference to [Fig.5].

[0084] In step S400, the APP device determines an operating state FST of the well using specific flow rates comprising only the selected specific flow rates Qsi-Qsp. It is important to note that the APP device does not use, during step S400, the specific flow rates not selected in step S300. The implementation of step S400 is described in more detail with reference to [Fig.6].

[0085] The APP device can determine, during this step, a current FST operating state of the well. For example, it can determine that the well is operating correctly or, on the contrary, that its operation is abnormal (e.g. the well is clogged), or that the operation of the well is degrading.

[0086] However, it may alternatively be a future FST operating state of the well. For example, from the selected specific flow rates, the APP device can predict the evolution of the specific flow rate of the well. This makes it possible in particular to determine whether a maintenance operation will be necessary in the future and, if so, the date before which this maintenance operation must be carried out.

[0087] Obviously, other operating parameters can be taken into account to determine the operating condition of the well. We can cite, for example, water quality indicators, or pump performance indicators, or even indicators relating to the presence of bacteria in the water, etc.

[0088] In step S500, the APP device provides a SIG signal. The SIG signal may indicate the FST operating status of the well, and / or include the specific flow rate values QsrQsM of the well. This SIG signal could further indicate that an operation of maintenance is considered necessary and the date before which this operation must be carried out.

[0089] As illustrated in [Fig.l], the SIG signal can be sent by the APP device to the DISP display device to be returned to a user (e.g. a person responsible for controlling the operation of the well). Also, this SIG signal could be provided to a control device, or to a storage device.

[0090] As detailed below, the proposed solution enables reliable monitoring of well operation. By using specific flow rates measured under similar operating conditions, the proposed solution ensures that comparisons of well performance are reliable and therefore that conclusions about the operating condition of the well are correct.

[0091] We describe below the implementation of steps S200, S300 and S400 with reference to the following figures.

[0092] [Fig.3] and [Fig.4] respectively represent steps of a method according to an embodiment of the invention and water levels of a well over time.

[0093] More specifically, these figures detail the implementation of step S200 previously introduced with reference to [Fig.2]. We recall that in step S200 the APP device determines specific flow rates QsrQsM of the well from the Ni-Nn water levels and the QrQN flow rates.

[0094] Each specific flow rate Os; is associated with a pumping cycle E; comprising: a filling phase (i.e. non-pumping) during which the PMP pump is stopped; immediately followed by a pumping phase during which the PMP pump is running. We also refer to a pumping cycle by the expression “filling-pumping sequence”.

[0095] Such a pumping cycle E; is illustrated by [Fig.4]. In this figure, the PMP pump is stopped at time Tt and started at time Tu. Thus, the PMP pump is stopped during the filling phase from time Tt to time Tu; and the PMP pump is running during the pumping phase from time Tu.

[0096] The APP device determines a specific flow rate Qs; associated with a pumping cycle E i if (and only if): the filling phase of this cycle E; is of a duration greater than a given duration (eg 1 hour); and if the pumping phase of this cycle E; is of a duration greater than a given duration (eg 1 hour). This makes it possible to ensure that the static and dynamic water levels are measured during established regimes.

[0097] It is important to note that the frequency of pumping cycles (i.e., filling-pumping sequences) may vary depending on the well or borehole. For example, pumping cycles may occur at least once a day for a given well. In this case, the APP device determines a specific flow rate for the pumping cycle having the longest filling phase of the day and satisfying the criteria of filling and pumping times stated above.

[0098] Alternatively, the pumping cycles may occur less than once per day. In which case, the APP device determines a specific flow rate for any pumping cycle satisfying the filling and pumping duration criteria set forth above.

[0099] However, within the scope of the invention, other embodiments could also be envisaged. The APP device could determine a specific flow rate for each of the pumping cycles (i.e. each of the filling-pumping sequences) occurring during the operation of the well.

[0100] In step S200, and according to the embodiment of [Fig.3], the APP device implements steps S210 to S240 for each specific flow rate to be determined. We detail below the determination of a specific flow rate value Qs; associated with a pumping cycle E;.

[0101] In step S210, the APP device obtains a static water level N]s measured during the filling phase of the cycle E;. To do this, the APP device carries out steps S211 to S213.

[0102] In step S211, the device APP determines the static level N$ More precisely, the static level N$ corresponds to the last level measured during the filling phase, i.e. the level measured before the start of the pump PMP.

[0103] As mentioned above, the static level Nf is measured after a filling of a duration R; greater than or equal to 1 hour. This makes it possible to ensure that the static level is measured during an established filling regime. Furthermore, it should be mentioned that the longer the filling duration, the more the filling regime will be established.

[0104] In step S212, the APP device determines an instability indicator I? of the static level N? - This indicator I? is determined from a difference between: the static water level N?; and the water level measured at the previous instant.

[0105] According to one embodiment, the indicator I? is calculated using the following expression: ,sJ^ L- RT '

[0106] where Nf is the static level, is the level preceding the static level, and RT is the total rise of the filling phase. The total rise RT of the filling phase is equal to the difference between: the water level at the start of the filling phase; and the water level at the end of the filling phase. Note that the indicator I? is greater than or equal to 0 since an absolute value is used to calculate it.

[0107] In step S213, the APP device verifies that the instability indicator I? of the static level Nf is lower than a threshold Xs. In particular, the threshold Xs is set according to the well or the drilling. It can for example be equal to 5% or 10%.

[0108] If the result of this verification is positive (i.e. the measured static level is stable), the method continues at step S220. Otherwise, the calculation of the specific flow rate associated with the cycle Ei is interrupted; and step S200 continues to determine another specific flow rate Qsi+iassociated with a following pumping cycle Ei+ien resuming at step S210.

[0109] In step S220, the APP device obtains a dynamic water level nP measured during the pumping phase of cycle E;. To do this, the APP device implements steps S221 to S223.

[0110] In step S221, the APP device determines the dynamic level. In particular, the dynamic level nP corresponds to the water level measured after a given pumping duration Po (eg 1 hour, or 2 hours). Thus, the dynamic level N® is measured at the instant TV=TU+PO.

[0111] Measuring the dynamic level Np after a given pumping duration Po has two advantages. On the one hand, when this duration is greater than or equal to 1 hour, this makes it possible to ensure that the dynamic level is measured in a stable pumping regime. For certain wells, it may be envisaged to use a pumping duration PO greater than 1 hour, for example 2 hours, to ensure that the pumping regime is established.

[0112] On the other hand, this allows comparable measurements of well performance to be obtained. Indeed, it is important that the dynamic levels are measured after similar pumping durations so that the specific flow rates are comparable.

[0113] In step S222, the APP device determines an instability indicator iP of the dynamic level. This indicator iP is determined from a difference between: the dynamic level nP measured at time Tv; and the water level measured at the previous time Tv_i.

[0114] According to one embodiment, the indicator ]P is calculated using the following expression: TD_INP-Nfl “RT'

[0115] with: N?, the dynamic level; N'P, the water level preceding the dynamic level; and RT, the total rise. Note that the indicator iP is greater than or equal to 0 since an absolute value is used to calculate it.

[0116] In step S223, the APP device verifies that the instability indicator iP of the dynamic level ND is lower than a threshold XD. In particular, the threshold XD is set according to of the well or drilling. For example, it can be equal to 5% or 10%.

[0117] If the result of this verification is positive (i.e. the measured dynamic level is stable), the method continues at step S230. Otherwise, the calculation of the specific flow rate associated with the cycle E; is interrupted; and step S200 continues to determine another specific flow rate Qsi+iassociated with a following pumping cycle Ei+i by resuming at step S210.

[0118] In step S230, the APP device obtains a pumping flow rate Q; measured during the pumping phase of cycle E;. To do this, the APP device implements steps S221 to S223.

[0119] In step S231, the APP device determines the pumping flow rate Q;. This may be an instantaneous flow rate measured at time Tv (i.e. the time of measurement of the dynamic level). Alternatively, the pumping flow rate Q; may be an average flow rate measured since the start of the pumping phase (i.e. from time Tu to time Tv).

[0120] In step S232, the APP device determines an instability indicator jQ of the pumping flow rate Q;. This indicator tQ is determined from a difference between: an instantaneous flow rate measured at the instant Tv of measurement of the dynamic level; and the instantaneous flow rate measured at the previous instant Tv.i.

[0121] According to one embodiment, the indicator jQ is calculated using the following expression: TQ JO^'J h - q_ »

[0122] with: Q;, the instantaneous flow rate measured at time Tv; and Q^, the instantaneous flow rate at the previous time Tv.i. Note that the indicator jQ is greater than or equal to 0 since an absolute value is used to calculate it.

[0123] In step S233, the APP device verifies that the instability indicator jQ of the pumping flow rate Q; is less than a threshold XQ. In particular, the threshold XQ is set according to the well or the drilling. It can for example be equal to 5% or 10%.

[0124] If the result of this verification is positive (i.e. the measured pumping flow rate is stable), the method continues at step S240. Otherwise, the calculation of the specific flow rate associated with the cycle E; is interrupted; and step S200 continues to determine another specific flow rate Qsi+iassociated with a following pumping cycle Ei+i by resuming at step S210.

[0125] In step S240, the APP device calculates the specific flow rate Qs; from the static level of the dynamic level N?, and the pumping flow rate Q;. The specific flow rate Qsi is calculated using the following expression: HAS -

[0126] The proposed solution makes it possible to calculate the specific flow rate values of the well during its operation, while ensuring that the measured static levels, dynamic levels and pumping rates are stable. More specifically, the use of instability indicators makes it possible to verify the stability of the water body during measurements of static and dynamic water levels and the stability of pumping rates. Thus, the proposed solution makes it possible to obtain reliable well performance measurements.

[0127] We describe with reference to the following figures the use of these performance measurements to determine the operating state of the well.

[0128] [Fig.5] represents steps of a method according to an embodiment of the invention. This figure details the implementation of step S300 previously introduced with reference to [Fig.2]. We recall that step S300 relates to the selection of a plurality of specific rates QsrQsP from among the determined specific rates Qsi-Qsm.

[0129] In fact, it is proposed to select only specific flow rates measured under similar operating conditions, which will then make it possible to reliably determine whether the well is functioning properly or not.

[0130] More precisely, the proposed solution is based on two selection criteria CRT_NS and CRT_Q. The first criterion CRT_NS ensures that the selected specific flow rates are measured for similar static water levels (i.e. in a given range around a reference static level). And, the second criterion CRT_Q ensures that the selected specific flow rates are measured for similar pumping rates (i.e. in a given range around a reference flow rate). For a specific flow rate to be selected, it must satisfy these two criteria.

[0131] In step S300, the APP device implements steps S310 and S320 for each specific flow rate Qsj among the determined specific flow rates QsrQsM. The APP device thus checks whether the specific flow rate Qsj satisfies the selection criteria CRT_NS and CRT_Q. If this is the case, the specific flow rate Qsj is selected; otherwise, it is excluded.

[0132] Note that steps S310 and S320 can be implemented by the APP device in parallel, or consecutively.

[0133] In step S310, the APP device determines the difference between: a reference static water level Nq; and the static water level jq? used to determine the specific flow rate Qsj. It then verifies that the difference IjqJ - NqI is less than a given percentage of a reference water height. This reference water height may correspond to an aquifer power (i.e. a thickness of the saturated zone of the aquifer). Alternatively, the reference water height could correspond to the reference static water level.

[0134] In particular, the given percentage of the reference water height is fixed according to the well. It can for example be equal to 5%, 10%, or 15%. This makes it possible to adapt the CRT_NS selection criterion according to the configuration or topology of the well.

[0135] As mentioned above, the reference water height corresponds, according to one embodiment, to a reference aquifer power. This embodiment is particularly advantageous in that it makes it possible to define the selection criterion CRT_NS independently of the altitude of the well. In other words, the given range around the reference static level, used to select the specific flow rates, is defined independently of the altitude of the well.

[0136] Consider, for example, a well whose static reference level is 1500 m above mean sea level and whose base (i.e. the wall) is located at 1400 m above mean sea level. For this well, the aquifer capacity (i.e. the thickness of the saturated zone of the aquifer) is therefore 100 m. With a given percentage of 10% of the reference height, the given range of selection is 10% x 100 m = 10 m, if the aquifer capacity is used as the reference height. On the other hand, the range of selection is 10% x 1500 m = 150 m, if the static reference level is used as the reference height. Thus, by using the aquifer capacity as the reference height, rather than the static reference level, this embodiment ensures that the specific flow rates selected for this well actually have similar static levels.

[0137] In step S320, the APP device determines a difference between: a reference pumping flow rate Qo; and the pumping flow rate Q; used to calculate the specific flow rate Qsj. The APP device verifies that the difference IQj-Qol is less than a given percentage of the reference pumping flow rate Qo.

[0138] Similarly, the given percentage of the reference flow rate Qo is fixed according to the well. It can be equal to 5%, 10% or 15%. This makes it possible to adapt the selection criterion CRT_Q according to the configuration or topology of the well.

[0139] The proposed solution described herein allows for the selection of specific flow rates measured under similar operating conditions and thus the selection of comparable well performance measurements.

[0140] Furthermore, it is important to mention that the reference static level, the reference water height, and the reference pumping flow rate Qo are measured during a pumping test carried out following the commissioning of the well, or following the last maintenance operation. Also, and as detailed below, the proposed solution uses a specific reference flow rate Qs0 measured during this pumping test.

[0141] The proposed solution thus selects specific flow rates measured in operating conditions similar to those of the specific reference flow rate (similar static levels, similar pumping rates, and similar pumping durations). Therefore, to determine the operating state of the well, the proposed solution uses only well performance measurements comparable to the well's performance at the time of its commissioning or last maintenance operation.

[0142] We detail, with reference to the following figure, the determination of the operating state of the well from the specific flow rates selected.

[0143] [Fig.6] represents steps of a method according to an embodiment of the invention. This figure details the implementation of step S400 of determining the FST operating state of the well, previously introduced with reference to [Fig.2],

[0144] According to the embodiment of [Fig.6], step S400 comprises at least one of steps S410 to S430 described below.

[0145] In step S410, the APP device determines whether the well is clogged from specific flow rates comprising only the selected specific flow rates QsrQsp. More particularly, the APP device detects a clogging of the well if a difference between: the reference specific flow rate Qs0; and one of the selected specific flow rates QsrQsp, is greater than a given percentage of the reference specific flow rate Qs0.

[0146] The given percentage of the specific reference flow rate is fixed according to the well, which makes it possible to adapt the detection of a clogging to the configuration and topology of the well. This given percentage can in particular be equal to 15% or 30%.

[0147] The proposed solution thus detects a clogging of the well if (and only if) a significant drop in the specific flow rate is measured. This drop in specific flow rate is defined in relation to the reference specific flow rate, a measure of the performance of the well when it was put into service or during the last maintenance operation. The drop in specific flow rate is thus measured in relation to an operation considered correct by the operator.

[0148] It should be emphasized that the proposed solution allows for reliable detection of well clogging. The reliability of the proposed solution results from the fact that it uses only specific flow rates measured under similar operating conditions to detect clogging.

[0149] Compared to existing solutions, the proposed solution reduces the number of false positives, i.e. erroneous detections of clogging. The proposed solution is therefore particularly advantageous in that it makes it possible to avoid planning unnecessary maintenance operations.

[0150] In step S420, the APP device predicts (i.e. determines) specific flow rates Qsm+i -Qsm+k for later (i.e. future) instants from specific flow rates comprising only the specific selected QsrQsP rates.

[0151] According to one embodiment, the prediction step S420 is carried out only if the number of selected specific flow rates QsrQsP is greater than a fifth threshold. This makes it possible to ensure that the number of selected specific flow rate values is sufficient to reliably predict the future evolution of the specific flow rate.

[0152] Prediction of specific well flow rates can be performed using a linear regression model. It could also be considered to use a non-linear regression model, or an artificial neural network to perform this prediction.

[0153] To make this prediction, the proposed solution uses only the selected specific flow rates, therefore reliable and comparable well performance measurements. As a result, the proposed solution makes it possible to reliably evaluate the future evolution of the specific flow rate of the well. It can thus be used to determine a future operating state of the well, as described below.

[0154] In step S430, the APP device determines, from the predicted specific flow rates Qs m+i-Qsm+k, a date on which a well maintenance operation is considered necessary. For this purpose, and according to the embodiment of [Fig.6], step S430 comprises steps S431 to S433.

[0155] In step S431, the APP device determines a prediction quality indicator Ip. This indicator is calculated from differences between determined specific flow rates QsrQsM; and predicted specific flow rates (i.e. calculated by the regression model).

[0156] The Ip indicator thus characterizes the accuracy of the regression model. In other words, it characterizes the ability of the regression model to describe and predict the specific flow rate of the well.

[0157] When a linear regression is used to make the prediction, the IP indicator can correspond to the coefficient of determination R2, or to the root-mean-square error.

[0158] No limitation is attached to the type of prediction quality indicator used. In the context of the invention, it may be envisaged to use any type of prediction quality indicator.

[0159] In step S432, the APP device verifies that the prediction quality indicator Ip is greater than a fourth threshold XP. If the result of this verification is positive, the method continues to step S433; otherwise, step S430 is interrupted.

[0160] The APP device thus verifies that the regression model used for the prediction is capable of accurately describing the evolution of the specific flow rate of the well over time.

[0161] In step S433, the device determines a later time TN+k at which a difference between: the reference specific flow rate Qs0; and the specific flow rate QsN+k predicted for the instant TN+K, is greater than a given percentage of the reference specific flow rate Qs0.

[0162] Advantageously, the proposed solution makes it possible to determine the date on which a maintenance operation will be necessary. Indeed, the predicted values of the specific flow rate are used here to determine whether a significant drop in the specific flow rate of the well is to come. The proposed solution can thus be used to detect the formation of a well blockage and determine the date on which a maintenance operation will be necessary to remedy it.

[0163] Obviously, if no specific flow rate drop is observed, the APP device can indicate that no maintenance operation is considered necessary.

[0164] Compared to existing solutions, the proposed solution determines whether a maintenance operation will be necessary only when the prediction quality indicator is above a threshold. This ensures that conclusions about the future operating state of the well are based on a regression model accurately describing the evolution of the specific flow rate of the well over time.

[0165] Additional variants: It should be noted that the order in which the steps of a method according to the invention are carried out, in particular with reference to the attached drawings, constitutes only an example of embodiment without any limiting character, variants being possible. In particular, a method according to the invention may comprise one or more iterations of the steps described above, in particular with reference to the attached drawings. Furthermore, the reference signs do not limit the scope of the protection, their sole function being to facilitate the understanding of the claims.

[0166] A person skilled in the art will understand that the embodiments and variants described above constitute only non-limiting examples of implementation of the invention. In particular, a person skilled in the art will be able to envisage any adaptation or combination of the embodiments and variants described above in order to meet a very specific need.

Claims

Claims

1. Method for monitoring the operation of a well or drilling comprising: a determination (S200) of specific flow rates (QsrQsM) from water levels (NrNN) and flow rates (QrQN) measured during operation of the well or drilling, the determination of each specific flow rate (Qs;) comprising: • obtaining (S210, S220, S230) a so-called static water level (A^) measured during a filling phase, a so-called dynamic water level (A^P) measured during a pumping phase following the filling phase, and a pumping flow rate (Q;) measured during the pumping phase, such that: • an instability indicator ( / ?) of the static water level (A / f) is lower than a first threshold (Xs), this indicator ( / $) being determined from a difference between the static water level (Af) and a water level measured at a previous instant (Tu_i) of the filling phase; and / or • an instability indicator ( / P) of the dynamic water level (Nf) is lower than a second threshold (XD), this indicator ( / P) being determined from a difference between the dynamic water level (A / P) and a water level measured at a previous instant (Tv.i) of the pumping phase; • a calculation (S240) of said specific flow rate (Qs;) from the static water level (Af), the dynamic water level (N^), and the pumping flow rate (Q;); a selection (S300) of a plurality of specific flow rates (Qsi -QsP) from among the determined specific flow rates (QsrQsM), each selected specific flow rate (Qsj) satisfying the criteria (CRT_NS, CRT_Qs) according to which: • a difference between: a reference static water level (A^); and the static water level (A^) associated with said selected specific flow rate (Qsj), is less than a given percentage of a reference water height; and • a difference between: a reference pumping flow rate (Qo); and the pumping flow rate (Q;) associated with said selected specific flow rate (Qs;), is less than a given percentage of the reference pumping flow rate (Qo); and - a determination (S400) of an operating state (FST) of the well or borehole from the selected specific flow rates (QsrQsp).

2. A method according to claim 1, wherein the given percentage of the reference water height and / or the given percentage of the reference pumping flow rate (Qo) are set as a function of the well or borehole.

3. Method according to claim 1 or 2, in which for each determined specific flow rate (Qs;): the static water level (N?) is measured after a filling time (R;) greater than or equal to 1 hour; and / or the dynamic water level (ND) is measured after a pumping time (Po) greater than or equal to 1 hour.

4. Method according to any one of claims 1 to 3, in which for each determined specific flow rate (Qs;), the dynamic water level (N^) is measured after a given pumping duration (Po).

5. Method according to any one of claims 1 to 4, in which for each determined specific flow rate (Qs;), an instability indicator QÇ) of the pumping flow rate (Q;) is less than a third threshold (XQ), this indicator Qô) being determined from a difference between: an instantaneous pumping flow rate measured at the instant of measurement of the dynamic water level (N?); and an instantaneous pumping flow rate measured at a previous instant (Tv.i) of the pumping phase.

6. Method according to any one of claims 1 to 5, wherein the determination (S400) of the operating state (FST) of the well or borehole comprises a detection (S410) of a clogging from the selected specific flow rates (QsrQsP).

7. The method of claim 6, wherein a clogging is detected (S410) if a difference between: a reference specific flow rate (Qs0); and one of the selected specific flow rates (QsrQsP), is greater than a given percentage of the reference specific flow rate (Qs0), this given percentage being fixed according to the well or drilling.

8. A method according to any one of claims 1 to 7, wherein the determination (S400) of the operating state (FST) of the well or borehole comprises a prediction (S420) of specific flow rates (QsM+rQs m+k) for later times from the selected specific flow rates (QsrQsp).

9. Method according to claim 8, in which the determination (S400) of the operating state (FST) of the well or drilling comprises, if a prediction quality indicator (Ip) is greater than a fourth threshold (XP): - a determination (S433) of a later instant (TN+k) at which a difference between: a reference specific flow rate (Qs0); and a predicted specific flow rate (QsN+k), is greater than a given percentage of the reference specific flow rate (Qs0).

10. The method of claim 8 or 9, wherein the prediction (S420) of specific flow rates (Qsm+i-Qsm+k) is performed if the number of selected specific flow rates (QsrQsP) is greater than a fifth threshold.

11. Method according to any one of claims 1 to 10, in which the water levels (NrNN) and the flow rates (Qi-Qn) are measured with a sampling step less than or equal to 15 minutes.

12. Method according to any one of claims 1 to 11, in which a said reference value (2Vq, Qo, S0) is a value measured or determined following commissioning of the well or drilling, or following a maintenance operation of the well or drilling.

13. Device (APP) for monitoring the operation of a well or drilling, the device (APP) comprising means (PROC, MEM, COM) configured to implement a method according to any one of claims 1 to 12.

14. System (SYS) for operating a well or a borehole comprising: - at least one pump (PMP); - a water level sensor (WLS); - at least one volumetric meter or flow meter (FMS); and - an operating monitoring device (APP) according to the re- indication 13.

15. Computer program (PROG) comprising instructions for implementing the steps of a method according to any one of claims 1 to 12, when said computer program (PROG) is executed by at least one processor (PROC).

16. Computer-readable information medium (MEM) comprising a computer program (PROG) according to claim 15.

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