Probe for measuring gas in-situ, method for assembling a probe and autonomous use of the probe

Abstract

The measuring probe, which is intended to be buried in a piece of ground with a view to obtaining concentrations of a gas, such as dihydrogen, or some other similar characteristic, includes internally, in its hollow bottom part (2), an intake compartment (01) where a gas flow (FG), typically an ascending gas flow, forms, and a compartment (02) that is rendered seal-tight with respect to liquids. A measuring device (4) is housed internally in the compartment (02) at a large distance from the top of the probe. A barrier to liquids interposed between the two compartments is formed by a filtering element (EF), which lets a purified gas flow diffuse into the compartment (02) where measurements are carried out by a selective electrochemical sensor of the device (4). An auxiliary sensor of the device is connected to a collecting part with a view to obtaining control data and allowing a level of reliability of the measurements carried out in situ by the electrochemical sensor to be determined.

Description

In-situ gas measurement probe, probe assembly method and autonomous probe use technical field

[0001] The present invention relates to the field of equipment fitted with sensors for detecting fluids in the ground. More particularly, it proposes a probe capable of detecting a gas in a buried position underground, a method for assembling the probe, and the use of a data collection device within an underground probe. Previous technique

[0002] Solutions have been developed to determine the presence of a gas, such as hydrogen, in underground pockets in the soil of a region, using probes installed below the surface at a depth that generally does not exceed 3 or 4 meters, thus minimizing the drilling equipment required. Such probes can be installed for extended periods, for example, several months, which can create challenges in terms of autonomy and / or integrity.

[0003] Document WO 202 / 161431 describes a measuring device that circulates gas admitted at depth, at the lower end of the probe, to a detection unit using a pump. Repeated communication is required for data transmission. This equipment is energy-intensive, which severely limits the autonomy of such a measuring device, unless an external power source such as solar panels is used. Moreover, the measurements taken by this type of device are very imprecise. The measurement method is not compatible with high temporal resolution: the sampling rate is limited, with a sampling interval typically on the order of half an hour and at best about one minute.

[0004] One difficulty with this type of measurement lies in the variability of soil types, particularly with regard to the risk that the probe's sensing element may be submerged in a water retention area or other type of zone unsuitable for obtaining reliable measurements. A gas detection sensor can give inaccurate results, especially when used outside its operating range.

[0005] Furthermore, specific probes have been designed for measuring gases dissolved in liquids. This type of probe, such as the one described in US document 2008 / 0216591 A1, does not allow for repeatable measurements: the probe is unsuitable for the type of application considered above and clearly belongs to a different category of measuring devices.

[0006] There is therefore room for improvement in providing suitable detection solutions for autonomous operation and compatible with discreet integration (limiting the risks of degradation), particularly in remote or wild areas, without operator intervention during measurements, while providing reliable detection data over a long measurement period. Technical solution

[0007] To improve the situation, a measuring probe is proposed, designed to be buried in the ground to detect at least one gas in that ground; the probe comprises: - a rigid body extending from an upper end of the probe and suitable for being buried in the ground; - a hollow part supported by the rigid body, perforated and / or porous to gases and liquids, and delimiting an intake compartment through which a gas flow is admitted into the probe; - a passage opening that allows a gas flow to circulate from the intake compartment to a measurement area; - a measuring device, located in the measurement zone which is in fluidic communication with the intake compartment via the passage opening; and - a link with a measurement acquisition module from one or more sensors of the measurement device; knowing that the measurement device, which can be housed internally in the probe at a distance from the upper end, is located in an instrumented compartment sealed, with respect to the liquids present in the inlet compartment, by means of filtration, so that the measurement device makes it possible to measure in situ one or more characteristics of a filtered gaseous fluid (corresponding to the flow only / exclusively gaseous which could have passed through the means of filtration), preferably continuously, this measurement device including a means of electrochemical, selective, detection of a gaseous component of the purified / filtered gaseous flow.

[0008] Thus, the measuring probe can carry part of the instrumentation necessary to carry out measurements for a given period, with a reliability in the measurements which is optimized simply because these measurements are carried out in situ (at depth, several tens of centimeters below the ground) with the admitted gas flow which flows / diffused naturally, without the need for pumping which is likely to destabilize the environment and the natural circulation of the gas.

[0009] The instrumented compartment can be completely separated from the outside, by being located in an internal zone of the probe which is, for example, a zone into which gas can only reach through the filter media(s) belonging to the filtration system, via the inlet compartment which forms an upstream zone (of the probe) in relation to the filtration means. Here, the term "upstream" is understood by reference to the filtration of the gas flow diffusing inside the probe from the perforated and / or porous region, it being understood that the gas admitted, on the upstream side, may be loaded with particles and / or liquids by being able to rise / circulate in the inlet part before reaching the instrumented compartment.

[0010] The purified gas stream was filtered before diffusing into the downstream zone (downstream of the filtration means), which is the zone where the measuring device is located. To limit the amount of water in the instrumented compartment, and therefore to limit humidity, the filtration means are typically interposed between the inlet compartment and the instrumented compartment, sealing the passage opening to form a liquid barrier that allows the gas stream to flow towards the measuring device as the purified / filtered gas stream. The relative humidity level in the instrumented compartment can be easily regulated or controlled by taking advantage of filtration and typically sensors with optional integration of dehydration means in the probe: regulation can be advantageous to maintain operation in accordance with the requirements of the electronic components mounted in the instrumented compartment.

[0011] The hollow section can be stepped, with the filtration elements forming part of a transition / passage zone between the lower intake compartment and the instrumented compartment. The top of the hollow section can correspond to a connector section or mounting bracket for the measuring device.

[0012] Advantageously, a control data collection device is provided in the probe / in connection with the measuring device, allowing the determination of a level of reliability of the measurements (during the measurement period, typically very long) carried out by means of electrochemical detection, on the basis of data retrieved by at least one auxiliary sensor of the measuring device. The measurement from the sensor or electrochemical detection device can thus be verified by at least one additional data point detected in real time. The measurement frequency of this detection method can be less than 10 seconds, or optionally on the order of one second to achieve continuous measurement.

[0013] The electrochemical detection method may incorporate an electrochemical measuring unit, equipped with an electrolyte, for example by having a detection cell equipped with a solid electrolyte (which is preferably ionically conductive). The solid electrolyte may include a polymer. The probe's sensor(s) can be assembled on a common support, for example in the form of a support plate, optionally oriented along a plane longitudinal in the probe. This support extends into the instrumented compartment, for example by extending perpendicularly to a filter cloth or layer of the filtration means.

[0014] The measuring device can be part of a pre-assembled component. The manufacturing cost of the probe can be optimized, while still incorporating at least three sensors, including: - one measures a gas concentration, for example dihydrogen or another gaseous component whose molecular weight (molar mass) is less than or equal to 30 or 50 g / mol, - and possibly at least one other measure of temperature and / or pressure. A measurement or determination of a local humidity level in the instrumented compartment is carried out by using one or more sensors, which may belong to the pre-assembled component.

[0015] The probe can operate autonomously, which is an advantage in isolated areas far from urban centers, where there is no communication network (such as "white zones"). The probe can be of the transmitter-less type (no fragile communication antenna is required), as the measurement data is stored by the acquisition module. This improves battery life. The probe can continuously record, potentially with high temporal resolution, the emissions of the subsoil's gaseous component. It is well-suited for complete burial, rendering it invisible at the surface and thus less vulnerable to vandalism and accidental damage, for example by wildlife.

[0016] One particular feature of the probe is its compact design, which can limit its radial dimensions, for example, with an external diameter of no more than 7 cm for the hollow section. The rigid body can form the upper end of the probe, incorporating a metallic outer lateral surface without any openings or communication channels to either or both compartments. The rigid body can constitute a main section of a probe pole, possibly having a length greater than or equal to 50 or 60 cm, as a non-limiting example.

[0017] The probe is configured to limit the flow of gas, internally from the intake compartment to the instrumented compartment, to a passive flow, without any mechanical / moving drive parts. With a simple assembly of parts and the use of pre-assembled electronics, the probe can have an optimized cost, both for its production and for its reuse (possibly with some parts needing replacement, such as the filter elements, or with the cartridge assembly needing replacement before reuse). With an optimized cost price, it is possible to consider a large number of probes deployed on site, which makes it possible to improve the coverage of a region to be explored.

[0018] In some embodiments, the relative humidity inside the probe is regulated to remain below a certain humidity threshold, for example below 95% humidity, at least in the instrumented compartment. At least one desiccant may be housed in a cavity communicating with the measurement area, thus trapping water to lower the humidity level in the instrumented compartment. In the case where the gaseous component to be detected is dihydrogen for example, such a threshold can be chosen to correspond to the limit case beyond which the measurement of dihydrogen is no longer possible due to risks of condensation on the electrochemical cell or where applicable on the electronic components present inside the measurement chamber (instrumented compartment).

[0019] More generally, the probe has a housing for trapping water (typically water in vapor form). Optionally, each desiccant can be mounted in the probe via a top access port which is then sealed. Preferably, this housing is accessible, during probe operation, only via a lower passage that communicates with the instrumented compartment: the water vapor thus rises in the probe to reach this housing, where it is trapped. The housing for trapping the water is equipped with one or more desiccant elements, preferably each containing a desiccant material. When the desiccant element includes a filter envelope to retain the desiccant material within a closed volume, it is understood that the envelope is permeable to water vapor, so that each desiccant element traps water within this internal / closed volume. The closed volume is optionally elongated, possibly along a central / longitudinal axis of the probe, with each envelope potentially being at least two or three times taller than it is wide.

[0020] It is understood that the probe can be buried (with the rigid body or the probe shaft fully buried), possibly without requiring external protection. The probe is well protected, retaining the recorded measurements through the use of a storage memory provided in the acquisition module. In some embodiments, the probe incorporates one or more of the following features: - the hollow portion is configured to form or include a lower end of the probe, the inlet compartment being a lower compartment of the probe that extends into or to the lower end. - the instrumented compartment is an upper compartment superimposed on the compartment lower. - the passage opening allows the admitted gas flow to be directed back towards the instrumented compartment. - the instrumented compartment can be an upper compartment of the hollow part, typically extending under the body. - the hollow part, which may form a tip or a point at the bottom of the probe, may be a removable part or contain a removable module. - Access to the measuring device is permitted after the removal of the removable part or module. - one and / or the other of the compartments is less wide than an external diameter of the probe body. - the intake compartment is delimited by a section of outer wall (tubular section) which is for example thicker than the section of wall (tubular section) surrounding the measuring device (this allows to lengthen a radial component of the conduits forming the orifices. - the openings in the perforated part can be of a calibrated type, for example by having an internal diameter not exceeding 1.5 mm or 2 mm.

[0021] To limit the risk of disturbance due to humidity in the instrumented compartment, the probe design may include at least one of the following features: - the filtration means are of the thin wall type, fabric or membrane (vapor barrier fabric). - the filtration means are hydrophobic, for example in the form of a fabric made of hydrophobic material or by including a hydrophobic layer or fabric on an external face intended for the side of the intake compartment. - the filtration means include a flexible fabric or layer of a filtering medium, for example with a peripheral edge / margin perimeter pinched between two rigid clamping parts, these two parts being made of gas-impermeable material. - the flexible fabric or layer is held between two annular support pieces which are connected to each other by clamping means arranged around the periphery of a part of the filtration means. - the fabric or flexible layer contains or consists of polytetrafluoroethene (PTFE). - the flexible layer contains or consists of a ceramic membrane (porous to allow gas to pass through). - the filtration means separate the intake compartment from the instrumented compartment, for example by being arranged in the central hollow of an insertion head / male organ which forms a portion of connection with a complementary connector carried by or made integral with the elongated rigid body. - the fabric or flexible layer is arranged perpendicular to an axis of elongation of the probe (a hydrophobic structure or a hydrophobic side, which is a lower side for this fabric or flexible layer, may be provided). - the filtration means are extractable / removable with the hollow part or with a subset of the hollow part.

[0022] The probe can be designed to operate without communication of measurement data, therefore without a transmitter. Regardless of whether measurement data is transmitted remotely, the probe can perform a series of measurements at a high rate, for example, with an interval of less than 10 seconds between successive measurements. High temporal resolution can be achieved with, for example, a measurement rate of every 4 seconds, or even approximately every second (with measurements taken every second).

[0023] In optional configurations, an electronic unit of the probe can implement an optimized recording routine, writing data only if the measurement differs from the previous one. This electronic unit can control the acquisition module and include a measurement data comparison module to compare successive measurements obtained using electrochemical detection.

[0024] A setting can be configured to define a threshold (minimum threshold) or a rule to activate a new recording. The electronic unit can be configured to implement an optimized recording routine by writing data to the acquisition module only when the comparison module detects a variation exceeding a given minimum threshold in successive measurements made by the electrochemical detection method.

[0025] This can increase battery life, for example, to reach or exceed two months with reliable measurements, at least under favorable temperature conditions (positive temperatures or above 15-20°C), which is possible in warm or temperate regions. Positioning the sensor at a depth of approximately one meter avoids day / night variations, while burying the battery (which can be shallower) can prevent the risk of accelerated discharge in cold weather.

[0026] In assembly examples for integrating the instrumented compartment into the probe and the filtration means, in a manner compatible with achieving gas tightness around the measurement area, one or more of the following features may be used: - The hollow part includes a connection section allowing the intake compartment, or at least a lower section or end piece, to be connected and disconnected. of the probe, perforated and / or presenting porosity for the admission of the gas flow, which delimits at least part of the intake compartment. - the connection portion allows for maintenance or replacement of the filtration means. - the annular or tubular connection portion, so as to delimit a hollow internal space. - the intake compartment is separable from the instrumented compartment, for example by making a disconnection which uses the connecting portion. - the connection portion provides a rigid fixing from below (i.e. on the opposite side to the upper end of the probe) by coupling with a complementary connector element provided in the probe. - rigid fixing is achieved by locking the coupling by a relative rotation between the connecting portion and the complementary connecting element. - Rigid fixing is achieved by axially locking a coupling position, by one or more elastically deformable elements to allow a snap-in. - the annular or tubular connection portion is either provided with rotational indexing means, allowing guidance or a keying effect, preventing rotation during locking of the connection of the end section, or adapted to allow connection independently of the relative angular position between the connection portion and the complementary connecting element. - the connection using the connecting portion forms a peripheral junction, which is provided with a sealing element to form a lateral barrier opposing the entry of water and also opposing, preferably, the entry of gas through this peripheral junction. - the connection portion includes the passage opening and is integral with a perforated tubular section which delimits the intake compartment, for example when the connection is made. - in a mounted state of the probe, a sealing element made of elastic material (typically elastically deformable) surrounds the connection portion and the complementary connector element or makes an annular sealing contact against the connection portion and against the complementary connector element.

[0027] In its mounted state, the instrumented compartment of the probe may only be accessible from below, for example, through a single access point formed by the passage opening. The instrumented compartment is isolated from the outside of the probe by the absence of a top opening or lateral communication channel.

[0028] Any type of junction can be used to allow selective removal of a lower section of the probe, enabling the replacement of all or part of the components involved in creating the humidity-lowering barrier effect (typically a hydrophobic barrier). To force the gas reaching the measuring device to pass through the filtration means, For example, one can plan the internal construction of a water separation stage in a first zone, under the compartment instrumented by the filtration means, by adding a peripheral seal around or on the peripheral junction, in a second zone radially offset outwards from the first zone.

[0029] According to one particular feature, when assembled with the sealing element integrated into the peripheral junction, the probe is designed to allow selective gas admission below the junction (only below this junction). The junction, whether or not combined with the aforementioned sealing element, provides gas (and liquid) tightness. In another variant, the peripheral junction can be adapted to form an additional admission zone, for example, by incorporating porosity. In this latter case, instead of the sealing element integrated into or overlapping the junction, an annular seal is provided in a different position: for example, above the peripheral junction and below the instrumented compartment to prevent upward moisture propagation.Alternatively or in addition, filtration means may be provided to form / integrate such an annular seal, for example by a peripheral frame or edge connected in a hermetically sealed manner to an external side wall structure which extends above the junction.

[0030] Depending on one particular feature, the sealing element, surrounding a longitudinal axis of the probe, is chosen from: - a heat-shrinkable sleeve or film suitable for wrapping an overlapping area between the connection portion and a complementary connector element of the probe; and - an annular compression seal, covered laterally by an external wall of the probe and on which an axial clamping is exerted. The complementary connecting element, which can extend lower than the electrochemical detection means, is preferably provided with a compressible material and / or can be covered, on the outside, with a heat-shrink sleeve or film.

[0031] In some embodiments of the probe, the auxiliary sensor(s) are chosen to enable real-time detection of a parameter (e.g., temperature, pressure, and / or humidity) that could interfere with the measurement performed by the electrochemical detection method, and potentially with other measurements. For example, the control data collection device (which may include or consist of a control device / unit) monitors the reliability of the measurements performed by the electrochemical detection method by: - retrieving measurements from at least one auxiliary sensor to determine a parameter representative of the humidity level in the instrumented compartment, - and / or by performing anomaly detection under physical conditions encountered during measurements, with detection enabled by at least one auxiliary sensor of the device measurement. A simple pressure measurement can be part of, or constitute, this anomaly detection, given that it allows us to know in particular: - if the probe is submerged, because in this case a sudden pressure increase will be observed (a pressure increase typically associated with precipitation), - whether the arrival of the gases is associated with pressure variations or not, thus qualifying the process as diffusion or not.

[0032] To minimize the risk of situations where the measurements of the electrochemical detection means are distorted by excess humidity, for example to ensure operation at a humidity level of less than or equal to 95%, the measuring device can be placed next to a desiccant gel or any suitable desiccant, placed in the instrumented compartment or in a downstream area relative to the filtration means and in fluidic communication with the instrumented compartment. More broadly, anomaly detection can help to make measurements taken in the probe more reliable, whether these measurements are taken by electrochemical detection or by other sensors.

[0033] In the event of rain, it is understood that the buried placement of the probe helps to avoid or limit the risk of water saturation in the environment. The elongated rigid body, preferably with an outer face of annular or cylindrical section, has for example a length of at least 50 centimeters, being adapted to keep the measuring device at least 50 cm below ground level when the rigid body is fully buried.

[0034] The rigid body of the probe can be made of robust inorganic material, for example, metal. This body forms, for example, a rod with a lower connector that connects and holds the hollow part (delimiting the intake compartment) in line with an internal housing of the rod. The internal housing of the stem can advantageously be used to trap water by being filled with dehydration means, for example in solid or gel form, which may consist of a gel and / or granular desiccant component. After purification via filtration means, the gas stream can therefore be dried, in order to avoid an undesirable effect of accumulation of water molecules and condensation in the instrumented compartment.

[0035] The electrochemical detection method can provide dihydrogen gas concentration measurements at a very high rate, with a link to the acquisition module for data writing / acquisition which will subsequently allow, after the long measurement period, the provision of precise and accurate readings. passing by, not missing a brief passage of dihydrogen. This is applicable to other types of gases detectable by an electrochemical detection cell or means.

[0036] The acquisition module can be a data logger with a data processing interface that connects to one or more of the sensors of the measuring device, including the electrochemical detection system. Data acquisition is controlled by dedicated software. An electronic board can integrate the circuit(s) and the measuring components / sensors, miniaturizing the instrumented section housed within the instrumented compartment. The acquisition module is for example connected to an autonomous power supply, preferably protected in a box connected from above to the probe via a cable.

[0037] At least in the case where the instrumented compartment is adjacent to / near the intake compartment, preferably located more than fifty centimeters from the top of the constant cross-section part of the rigid body, at least one of the following arrangements can be provided: - the rigid body, which incorporates the cable, is connected in a gas-tight manner to the hollow part and has an external delimitation in two parts with: a first part, tubular, creating a lateral barrier to gas; and a second part, surmounting the first tubular part of the rigid body. - an axial gas-tight barrier, preventing gases from escaping the probe by rising beyond the second instrumented compartment, is provided in the form of an internal partition of the probe or in the second part. - the first part extends to the hollow part. - a support for the measuring device is mounted in / attached to the first tubular part. - the hollow part is designed as a part separable from the rest of the probe, preferably by separating / disconnecting from a connector element included in the first part of the rigid body. - the measuring device is surrounded by a portion of the hollow part which is permanently fixed to the rigid body, for example by being welded to the first part. - the probe may consist of a power supply unit, an upper grippable part and a probe rod (of generally circular cross-section for example, constant) which includes the instrumented compartment and the intake compartment, possibly with at least one connection-disconnection interface at the lower end where the intake compartment is formed.

[0038] According to another aspect, a method for assembling a measuring probe is proposed, in particular as presented above, the assembly method comprising: - the supply of the elongated rigid body and a hollow part, which is perforated and / or porous to gases and liquids by delimiting an intake compartment through which a gaseous flow can be admitted into the probe; - the mounting of a measuring device in one of the rigid body and the hollow part, on at least one support which allows a power supply from an electrical power source via a cable or link (cable / electrical link), the cable or link also allowing the measuring device to be connected to a control device or unit and to a module for acquiring measurements made by one or more sensors of the measuring device; - the watertight connection of the hollow part to a lower annular section of the rigid body, after placing the cable in the rigid body and filtration means in the hollow part, respectively, whereby the filtration means separate an instrumented compartment where the measuring device extends from the inlet compartment, forming a barrier to liquids allowing a gaseous flow, admitted into the inlet compartment, to flow towards the measuring device in the form of a purified gaseous flow, knowing that the measuring device has a means for the selective electrochemical detection of a gaseous component of the purified gaseous flow, while at least one auxiliary sensor is also integrated into the measuring device to allow the collection of control data retrieved by the device or control unit using this auxiliary sensor.

[0039] The control device or unit constitutes or forms part of a collection device, which is thus configured to control a level of reliability of measurements made by means of electrochemical detection on the basis of data (the control data) retrieved using at least one auxiliary sensor of the measuring device.

[0040] Such an assembly makes it possible to provide a robust probe, suitable for a long period of autonomous operation, typically without communication with the outside. In some configurations, a temporary communication module (possibly removable) can be installed, allowing initial data to be retrieved from outside the borehole where the probe is located. This short-range communication takes advantage of the presence of an operator (who may be the same person who installed the probe at depth). This can enable the immediate detection of a significant malfunction related to the installation, for example, by implementing a test routine that demonstrates the probe's functionality.

[0041] More generally, the operator can establish a routine to ensure everything is in order immediately after installation. With the operator still present, and equipped with a communication / verification module that signals a malfunction, they can then react and typically modify the installation accordingly, drilling in a different location, if necessary after drying the sensitive / instrumented area (in the part hollow) or a replacement for it. The communication module for such provisional communication is subsequently disconnected and transported elsewhere, to conserve battery power, so that the probe will not lose any energy activating an external data transmission once the operator has left.

[0042] Optionally, the assembly process includes the placement of one or more desiccant elements inside the probe, for example, at a level higher than the filtration means. For this purpose, the process may include: - the supply of the desiccant element(s) (possibly in a stackable unit format or one that can be placed side by side), each having a desiccant material and a filter envelope, to allow water to be trapped in an internal volume of the envelope where the desiccant material is located; and - the insertion of the desiccant element(s) into the instrumented compartment and / or into a central hollow (which defines a housing) of the rigid body. When the housing for this / these desiccant element(s) is located in the central hollow of the rigid body, such a housing preferably extends over a portion of electrical and mechanical connection which allows the rigid body and the hollow part to be connected (together, for example directly one on top of the other) in a separable manner.

[0043] According to another aspect, it is proposed to use the probe of the aforementioned type, the probe having its body buried in the ground and extending to the hollow part which is perforated and / or porous to gases and liquids in order to allow the admission of a gas flow into the probe's inlet compartment, which is a gas taken in situ at a lower end of the probe, in which the measuring device, when placed in the instrumented compartment provided in the probe to be separated from the inlet compartment by filtration means, by being connected to the measurement acquisition module by a (non-fluidic) link, serves to provide: - by an electrochemical gas concentration sensor, preferably a solid electrolyte sensor, constituting the electrochemical detection means, of the first measurements in the measurement zone where the gas flow purified by the filtration means circulates; and - by at least one auxiliary sensor for the second set of measurements; and in which the acquisition module records measurement data whose reliability level is evaluated by a control device or unit, preferably housed in a casing that also contains the acquisition module, thereby enabling the probe to operate for several days or weeks without communication with externally, by accumulating the first measurements whose level of reliability can be verified with regard to the second measurements.

[0044] The probe can be used autonomously for detecting a gas, for example, at least one gas such as dihydrogen, which tends to rise along the probe by diffusion. The probe is specifically designed for energy efficiency, operating without transmitting measurement data and therefore without a transmitter.

[0045] With this application, it is possible to retrieve data stored in the probe's memory, typically on a removable part of the probe. This data consists of electrochemical detection data, which is validated using control data or measurements from auxiliary sensors. Optionally, secondary measurements from auxiliary sensors are digitized and / or processed as control data. The control data may include a parameter representing the humidity level in the instrumented compartment and / or at least one data point representing the detection of anomalies in physical conditions encountered during measurements in the instrumented compartment.

[0046] Such data allows for the selective disqualification of measurements taken when the control device detects, using one or more detection thresholds applied to the control data, a loss of measurement reliability. This can potentially be done in real time, with the option of not recording defective measurements—thus saving the energy associated with writing data to the probe's onboard memory (in the instrumented compartment).

[0047] The improved protection of the instrumented compartment makes the analysis efficient, while allowing data to be collected autonomously and passively with regard to the flow / diffusion of the gas flow: The measurement period, of a duration of at least 1 month for example, is carried out passively, without pumping (the instrumented compartment being of the pump-free type).

[0048] The internal cavity of the probe can only be accessed by gases through the lower perforated / porous part, so that all the gas present in the instrumented compartment has passed through the intake compartment and then the filtration means. A pre-filter stage, possibly with a coalescing medium, separate from the filtration means which separate the water, may be provided in the receiving / inlet compartment (which is a lower compartment in the probe). Brief description of the drawings Other features, details, and advantages will become apparent upon reading the detailed description below and analyzing the attached drawings, on which: Figure 1 is a longitudinal cross-sectional view, showing the bottom of a probe, with a measuring device embedded in a chamber sealed against liquids, this device being close to a filter element equipping an access passage to the sealed chamber from a lower compartment. Figure 2 is an exploded perspective view of the openwork lower end and a mounting interface for internally incorporating a filter element. Figure 3 is a cross-sectional view along a longitudinal plane of the probe in the measurement area, illustrating an example of an embodiment that integrates the lower compartment and the instrumented compartment in the hollow part. Figure 4A schematically shows an example of instrumented compartment layout with sealing using at least one annular gasket and one annular weld. Figure 4B illustrates, by means of an exploded perspective view, an example of the assembly of an electronic board bringing together a control device and several sensors including an electrochemical detection cell sensor. Figure 5 schematically illustrates the installation of a probe designed without a transmitter, in a borehole with complete burial to prevent damage. Figure 6 shows a flowchart of steps that can be taken to achieve a recording / acquisition of measurements with a level of reliability without requiring communication or intervention during the measurement period, which extends over several weeks or months. Figure 7 shows, by a view similar to figure 3, a part of the probe with a heat-shrink sleeve placed on the outer side wall. Description of the implementation methods

[0049] Several examples of non-limiting embodiments are described in detail below. In the various figures, identical reference numerals indicate identical or similar elements. Some dimensions may be exaggerated for illustrative purposes.

[0050] In the drawings, the direction of an arrow Z indicates a downward direction in a vertical path through the ground S. The terms "upper" and "lower" in this description refer to an arrangement substantially along the vertical direction, considering a direction along the length of the elongated device or probe 1. The length L of a probe 1 can reach or exceed 80 cm, for example.

[0051] With reference to figures 1 and 5, a probe 1 is presented according to an example of an embodiment, adapted to be buried below the ground level S, in a borehole to cross a subsoil strip SS which can be on the order of 1 meter or more in some embodiments. As clearly visible here, probe 1 can extend longitudinally between a lower end E1 and an upper end E2, in a straight line or at least along a longitudinal axis A. This structure allows the probe 1 shaft to be installed in a borehole of suitable depth, for example, a hole deeper than 50 or 80 cm and less than 1.6 m. In practical applications, the length of probe 1 can be chosen according to the tool, which may be a handheld tool used to perform the drilling.

[0052] The probe can be narrow, not exceeding 6 or 7 centimeters in external diameter in some embodiments, and typically not exceeding 5 cm. The drilling zone ZF (Figure 5) can be easily constructed, and the gripping section, arranged as a handlebar with two aligned handles or grips 1d, for example, can also be concealed so as not to protrude from the ground or be subject to movement.

[0053] Probe 1 is a measuring instrument with an internal instrumented compartment, C2, positioned downwards relative to ground level S, for in-situ measurements. Thus, probe 1 is designed and configured to detect a gas and typically measure its concentration at a distance from ground level S, i.e., several tens of centimeters below the surface. As illustrated in particular in Figure 1, the probe 1 is rigid, having a shaft that includes a rigid body 1a, elongated from the upper end E2 of the probe. The body 1a can be completely buried in the ground, i.e. below the ground surface level S, allowing the isolation / enclosure of an internal volume V1 (Figure 5) of the probe 1 from the top of the probe 1 and from the area of ​​soil or subsoil SS surrounding the upper end E2 of the probe 1.

[0054] In some embodiments, where there is no top access to the internal volume V1, the probe 1 may have a hollow section 2 supported by the rigid body 1a, which is perforated and / or porous to any gases and liquids that may be present (without, however, allowing such liquids to spread within the probe, as described later). The hollow section 2 may include a segment with a connector interface TC, which serves to support at least one sensor of the probe 1. The external wall of the hollow section may be made of multiple materials and / or be composed of several nested segments, preferably without a hatch or side door. In some alternatives, a housing in the hollow part can initially be accessed laterally and then sealed gas-tight by a part of cover. Where appropriate, such a housing is sealed by a sensor and / or filter holder cartridge, which can serve as a functional stage to form a sub-part of the instrumented compartment, possibly by forming a transverse partition that can only be crossed through a water separator filtration medium.

[0055] The hollow part 2 extends for example to a bottom 3a (domed or pointed for example) of the probe 1, so as to include a lower end 3 of the probe 1 where through orifices 03 are provided which allow gas to enter a lower compartment, hereafter called the intake compartment C1, which may be a sub-part of the internal volume V1. The lower end 3 may correspond to an inlet stage (where gas diffusion begins inside the probe), this stage typically lacking gas measurement sensors, which are located in the instrumented compartment C2. The instrumented compartment may be offset, here axially (vertically) offset, above this lower end 3, which is the only part of the probe through which gases can enter the internal volume V1 to reach compartment C2.

[0056] The hollow section 2 can be designed separately from the body 1a and then connected to a lower end of this body 1a, opposite the upper end E2. In Figure 1, a central hollow 12 is provided in the rigid body 1a, which has a tubular structure at least in an area adjacent to the hollow section 2. The inlet compartment C1 is distinct from this central hollow 12, being surrounded / delimited by a part or end piece of the hollow section 2 that rigidly connects to the rest of the probe 1. A fluidic communication, without the passage of liquid, can nevertheless be achieved so that a gaseous flow FG admitted via the orifices 03 can flow internally into the probe 1, for example, with the possibility of reaching the central hollow 12 during in-situ operation of the probe 1.

[0057] In some options, the rigid body 1a can be directly perforated in addition to the hollow part 2 or can have a perforated section, for example with lateral openings forming the orifices 03, to delimit the lower compartment 01. The hollow part 2 can then be supported by the body 1a by constituting an end of this body 1a, or at least a section far from the upper end E2 (measurement zone in depth, surrounded by a subsoil strip SS).

[0058] At the upper end E2, the probe 1 has a self-contained power supply, such as a battery. Figures 4 and 5 show a housing B that contains and protects this self-contained power supply. A connection 10, possibly in the form of a flexible cable, connects this housing B to a head 1f that fits over the body 1a of the probe shaft and which may be: - traversed by a common axis to the handles 1d, the longitudinal axis A, - and / or crossed by the longitudinal axis A.

[0059] Regardless of the specific external structure adopted to make it self-contained and installed in a borehole, the probe 4 forms a measuring device by allowing internal gas diffusion through its inlet compartment C1, which can be contained within a monolithic block of the probe, optionally removably connected to the rest of the probe from below, as in the non-limiting case illustrated in Figures 1 to 3. A central circulation channel CC forms a zone within the inlet compartment C1 through which the gas flow FG ascends towards the filtration means EF. All channels with a radial component, formed by the orifices 03, can open into this central channel CC. Figures 2 and 3 show an example of a rigid part used to form the lower end 3 with the base 3a and a plurality of orifices 03 distributed both over different angular sectors of the circumference of this end 3 (at least 8 or 9 different angular sectors can be provided with such orifices 03) and also distributed vertically (Z direction), for example, forming regularly spaced vertical rows Rv of holes / orifices. An axial / vertical spacing dv can be provided between the highest orifice(s) 03 and a lower face of the filtration means EF.

[0060] Although this example illustrates orifices 03 positioned near the bottom 3a and formed in a single piece that includes this bottom 3a, it is possible to have an alternative bottom 3a, designed separately from a section or segment that is perforated with this type of hole for gas intake. In this case, the intake compartment C1 can be axially offset from the bottom 3a. In some embodiments, the bottom 3a may have an extension, possibly pointed, formed at the bottom of the probe 1. As an alternative or complement to designs using a plurality of orifices 03 for the admission of gas internally into the probe 1, a fluid-porous layer can be provided, which allows the liquid and gases to pass through a porous structure which does not have radial holes or through orifices with a purely radial component.

[0061] The probe 1 includes sensors 20 and 6 and can house these sensors in a zone that is distinct from the inlet compartment C1 and separated from it by filtration means EF, thus limiting the influx of water molecules into the gas flow circulating / diffusing along the sensors 20 and 6. The probe 1 has an electronic component for data acquisition, some of which represents gas concentration measurements or other gas characterization parameters. In particular, an electrochemical detection means 20 is provided in a zone of circulation or diffusion of the gas flow that has passed through a wall of the probe at the lower end 3. This electrochemical detection means 20 allows the determination of a concentration of a particular gas, for example dihydrogen as a non-limiting example.

[0062] In some designs, the electrochemical detection means 20 is an electrochemical sensor, for example, using solid electrolyte (polymer) electrochemistry technology and amperometric detection. In the instrumented compartment C2, the electrochemical detection means includes at least one measuring electrode (where the gas to be detected forms the analyte). One or more electrochemical sensors are provided, given that the electrochemical detection means 20 has high sensitivity for detecting, for example, trace gases, with concentrations up to 40,000 ppm, 10,000 ppm, or less. The probe can be equipped with several electrochemical sensing elements, for example each covering a different detection range (measurement range / target concentration). At least one pressure sensor (specific sensor for example) may be provided, possibly two pressure sensors, where appropriate with a pressure sensor located in the instrumented compartment.

[0063] The type of sensor forming the electrochemical detection means 20 is relatively robust and suitable for underground measurement conditions. It offers an optimized signal-to-noise ratio, especially since probe 1 is free of a pump or system to force gas or fluid circulation.

[0064] Referring to Figure 3, the probe 1 integrates a measuring device 4 into an electronic assembly, for example, combining the measuring device 4 and other components, including a data acquisition module 14, on a single substrate 4p. The measuring device 4 may optionally have a card, which may constitute all or part of the substrate 4p, including a digitizer and an additional component for determining temperature and humidity levels. This additional component (which may include several sensors / sensitive detection parts) is referred to as the auxiliary sensor 6 in the following text. Of course, an arrangement with independently connected sensors, for obtaining measurements or determinations of similar parameters, may also be suitable. Example of gas filtration passing through the instrumented compartment

[0065] The mechanical design of the probe section adjacent to the C1 intake compartment and housing the C2 instrumented compartment is designed to prevent both the ingress of liquid water and the accumulation of excess water vapor / humidity. Ideally, the probe should achieve an IP67 rating for water and particle protection, while ensuring optimal gas flow (which rises from the intake compartment C1). Thus, probe 1 can be temporarily immersed underwater without the measuring device 4 and associated electronics being degraded.

[0066] Internally in the external envelope of the probe which brings together body 1a and the underlying hollow part 2, there is typically a passage opening 3c which allows a gas flow to circulate from the intake compartment C1 to the measurement area, here to the instrumented compartment C2 which is superimposed on the lower end 3 including the orifices 03 and allowing the intake. The measuring device 4, arranged in the measurement zone, is thus in fluidic communication with the inlet compartment C1, via the passage opening 3c, but is located downstream of the filtration means EF which close this passage opening 3c. In other words, the measuring device 4 can be subjected to a purified gas flow (which will reach the measuring electrode(s) or sensitive parts of the sensors), the water content of which can be minimized due to passage through the filter media(s) belonging to the filtration means.

[0067] This arrangement is compatible with an electrochemical sensor or detection device 20 configured to perform measurements with high temporal resolution (high measurement rate, for example less than or equal to 10 seconds, possibly on the order of 1 second for dihydrogen detection). One or more characteristics of the purified gaseous fluid can thus be recorded during a long period of probe 1 installation, which will constitute the measurement period.

[0068] Referring to Figure 1, it can be seen that the probe 1 can be made watertight around the instrumented compartment C2, while still allowing the lower end 3 to be separated for inlet. To achieve this, the filtration means EF can first be mounted on an annular insertion element 3b, formed opposite the bottom 3a, which belongs to the lower end 3 of the probe, and then inserted internally into an intermediate section 2b (which can serve as an extension for the rigid body 1a).

[0069] With reference to Figure 2, the following is illustrated, but not limited to, the case of filtration means in the form of a hydrophobic fabric or membrane pinched and / or compressed at its edge using clamping rings 35a, 35b, with at least one seal J1 integrated into the stack of these parts and in direct contact with the filtration means EF to prevent water from bypassing the filter radially from the outside. The rings 35a, 35b, with a common central hole 35c, allow the extension of the central channel CC (visible in Figure 7) into which the orifices 03 open radially inwards and which is covered, here axially at its upper end for example, by the hydrophobic fabric or membrane. As described later, a removable assembly of the filtration part and an assembly Removable parts of the hollow section 2 are preferred. Fastening elements, such as screws or similar removable anchoring elements MF1, concealed when the probe 1 is mounted / assembled, can be provided to achieve the clamping configuration for the filtration means EF. These anchoring elements MF1 are accessible from above, for example, by being positioned on the insertion element 3a or similar upper portion of the lower end 3a which includes the through-holes 03.

[0070] More generally, the filtration stage, with the filtration means EF, is placed in the hollow part 2 and in such a way that the lower end can be separated from the body 1 a by making these filtration means EF accessible for dismantling and replacement. Next, a seal can be achieved by sealing a junction between the lower end 3 and the rest of the probe. A gasket J3, for example made of silicone, can optionally be added in the junction area, against a stop or connection part provided in the lower end 3.

[0071] In the embodiment shown in Figures 1 and 3, achieving this seal includes a step of wrapping the hollow part 2 with a heat-shrink sleeve or film 15 (also wrapping any gasket J3). The area to be enclosed by the sleeve 15 corresponds to the bottom junction / connection of the rigid body 1a or its extension, with the lower end 3. The sleeve 15, in its operational position, forms a sheath enclosing a tubular area through which gases could reach the instrumented compartment, bypassing the internal upstream area (upstream of the filtration means) where the intake compartment is located. Here, the insertion member 3b engages against a thinned and / or flexible area of ​​the extension (intermediate section 2b), with the insertion member 3b locking, for example by snapping into place (via internal lugs 2r or similar features), in an external annular groove G (Figure 2) which is axially interposed between the perforated tubular portion and the insertion member 3b. The external diameter of the insertion member 3b may be larger than that of the groove G but smaller than the maximum diameter of the lower end 3. A screw connection (without snapping) may also be provided. In practice, and as can be seen in particular in Figure 3, the maximum diameter of the lower end 3 may correspond to an external diameter D1, kept essentially constant, of the probe 1.

[0072] When hot, the sleeve 15 contracts, covering the junction, here overlapping the area between the lower end 3 and the extension which, for the hollow part 2, completes the lower end 2. In Figure 1, it can be seen that the chamber for the sensor 6, which is delimited by the intermediate section 2b (when the instrumented compartment C2 is located on this side, above the junction allowing the removal of components such as the filter), can be centrally accessed. through the opening 3c equipped with the filter / means EF. In some embodiments, this chamber cannot be supplied by other means or interstices between the tubular parts 3, 2b, TC constituting the hollow part 2.

[0073] In an alternative design, as seen for example in Figure 4A, a J15 seal can be appropriately pinched or clamped in the junction area, being covered by at least one annular section of the probe's outer wall. Such an elastically deformable J15 seal is axially compressed by a shoulder or similar seating surface, sufficiently to achieve a gas- and water-tight seal. A rotational coupling can be applied to lock the connection and ensure substantial compression on the J15 seal.

[0074] Regardless of the method of obtaining a seal, opposite this junction with the lower open end 3, the hollow part 2 may have an axial tip, forming an upper end 2a of this hollow part 2, which does not prevent gas exchange with an additional compartment or housing 12 provided in a hollow of the probe body 1a.

[0075] MF2 fastening means can also allow the measuring device 4 to be removably mounted in compartment C2, for example using screws 4f and 4g and a mounting element S4 that forms a hollow adapter. In the non-limiting case of Figure 3, the filtration portion (means EF) is to be fixed to the section that forms the lower end, with a top fixing, and conversely, the measuring device 4 is to be fixed from below, to an upper portion / end 2a of the hollow part 2. The intermediate section 2b can be fixed to the elongated rigid body 1a, for example by welding or other watertight fixing, preferably permanent, to the annular lower end 1c of the body 1a before or after the measuring device is connected by the MF2 fastening means.These MF2 fixing means can be complementary to a cable, or alternatively constitute an interface for mechanical, electrical and information or measurement signal transmission (this can allow, possibly, the grouping of measurement signals into vectors or in another way, when it is necessary to correlate or associate measurements that have been made at the same time).

[0076] In order to limit the humidity in the instrumented compartment C2 without interfering with the natural upward flow of a gaseous flow FG from the intake part / compartment C1, the probe can integrate means to trap water, with a dehydration effect, away from the measuring device 4 but in a sub-zone of the area downstream of the water filtration / separation carried out by the filtration means EF. Housing 12, delimited by a lower section of the rigid body 1a, is provided above the TC connector interface section and above the extension or section Intermediate 2b. Housing 12 can serve as a storage location for one or more desiccant elements 8. In this case, housing 12 can typically be accessible only via a lower passage, preferably axial (to avoid increasing the radial footprint), which communicates with the instrumented compartment C2 by means of a cable 9 or electrical connection, which can serve as a power supply (downward direction) and data transfer (upward direction). A desiccant material can thus be stored to a certain height along the rigid body 1a of the probe, in an internal volume V1 isolated from the outside.

[0077] An annular weld ZW (Figure 4A) provides a seal for the connection, in this case permanent, of the intermediate section 2b to the rigid body 1a. This design, with an intermediate section 2b belonging to the hollow portion surrounding the instrumented compartment C2, can facilitate the initial assembly of the measuring part 21, for example, by avoiding the use of the longest component, namely the extended rigid body 1a. The tubular intermediate section 2b can include a shoulder adapted to accommodate an annular mounting element S4, which allows for a central gas flow channel CC' despite the constrained radial space (the probe can thus be thin and drilling simplified).The diameter De at the upper part / end 2a can thus be sufficient to facilitate the flow and convey gas to the water / moisture trapping area (housing 12), while corresponding to a reduction in cross-section compared to an internal diameter provided in the measurement area where the support 4a extends (which is here wider than the diameter De).

[0078] The electronic board of the measuring device 21 can be easily inserted and secured onto such a mounting element S4, which can be incorporated into a pre-assembled version of the measuring device 21. Regardless of the above, whatever the design of the probe 1, an intermediate section 2b can be provided, located higher than the lower end equipped with the inlet compartment C1. This section can have thinner walls than either of the two sections to which it connects, as can be clearly seen in Figure 3, for example. This allows for an enlargement of the internal cross-section to accommodate the support structure (plate 4p) of the measuring device 4, in particular the removable mounting structure with the fastening means MF2.

[0079] As can be seen in Figure 1 for example, the housing 12 can be located higher than the measuring device 4, and higher than an MF2 connector interface (interface which may include an MC connector module at the top of the hollow part 2, as in Figure 4A) carried by the TC section to ensure the electrical and data link between the measuring device 4 of the instrumented compartment C2 and a higher area, typically corresponding to the housing B, where one and / or the other of the control unit UC and the acquisition module 14 can be located (see Figure 5). A structure with an insertion member 2i, at the annular upper end of the TC section, may be preferred, which can allow the formation of an internal axial stop in this insertion member 2i. The dehydration element(s) 8 can then bear against this axial stop Bt which narrows the passage section (for example with the diameter De), without preventing the connection with the measuring device 4, via the annular mounting element S4.

[0080] As shown in Figure 4B, this mounting element S4 forms part of a connection interface, optionally in the form of fastening means MF2 allowing for disconnection. It can form a connection with two arms b1, b2, spaced apart by a distance e to allow gas circulation, to rigidly support the measuring device 21 (via the plate 4p). A set of screws 4f, 4g, or equivalent fastening elements, allows the measuring device 4 to be fixed to the section TC. The screws 4g secure the measuring device 4 to the mounting element S4 (here via the longitudinal arms b1, b2), while the screws 4f anchor the upper annular ring of this element S4 to a seat surface provided with holes receiving these screws 4f.

[0081] The acquisition module 14 records the measurements (or corresponding data) from the detection means 20 and / or, optionally, from each of the other sensors of the measuring device 4. This acquisition module 14 is part of the probe 1, occupying the instrumented compartment C2, which is watertight. The measuring device 4 and the electrochemical sensor / detection means 20 can be mounted on or connected to the electronic board used to digitize the signal and / or equipped with the acquisition module 14, which records the digitized signal.

[0082] This digitized signal is then transmitted via cable 9 to the typically sealed housing B, which contains the rest of the instrumentation. In some embodiments, the acquisition module 14 continuously records the measurement parameters in this housing B. These parameters include, for example, the concentration of hydrogen or other gas measured by the electrochemical detection device 20, the relative humidity, and the temperature at the bottom of the probe (typically in compartment C2). The sampling frequency can be adjusted as needed, making it easy to achieve one measurement point per second for the measured gas concentration. The data, for example recorded on a portable card (e.g., in SD format, short for "Secure Digital") or similar memory, is typically retrievable via a standard connection port or directly from the card. The probe and its housing form a system that can be completely buried to be entirely invisible on the surface, which ensures safety. With reference now to Figure 6, a sequence of operations is presented for a (non-limiting) example of using a probe 1 according to the invention. During a preparation phase 40, a first step 41 may consist of excavating the soil S and drilling a borehole. The borehole may be approximately 1 m deep, with a width suitable for the passage of the probe 1, this width typically being much less than 10 cm, given the small diameter of the probe 1. An operator may then proceed to a step 42 of installing the probe 1 to obtain the buried configuration of this probe 1, such that the inlet compartment C1 is located approximately 1 meter below the level of the soil S, or more broadly at any sufficient vertical distance, which may be greater than 50 or 60 cm, with the lower end 3 embedded in the subsoil SS. This type of drilling does not require heavy machinery when the ground is relatively soft. The method typically involves placing the probe rod in the borehole to fill it. The measuring device 4, equipped with an electrochemical sensor, for example, to form the detection means 20, is located in the last (deepest) third of the borehole, but not in the lowest compartment, which corresponds to the intake compartment C1.

[0083] The probe 1, once powered, can then begin continuous measurements during a step 61 that starts the measurement period. During this period, the buried measuring device 4 repeatedly sends signals that are digitized and recorded to provide, for example, at least one month later, complete information on the presence of the gas to be detected. In operation as shown in Figure 6, the control device UC can analyze or verify the reliability level of the measurements performed by the electrochemical detection means 20, using, for example, representative information on the humidity level obtained with the help of the auxiliary sensor(s) 6 of the measuring device 4.

[0084] A control step 62 is typically performed before recording the data (recording step 63), which can save a time-consuming write operation. In one embodiment, this control step 62 may include a comparison that reflects whether or not there has been a change in the conditions and / or measurement results. Alternatively, all sensor data is recorded, allowing for time stamping. In this case, the humidity information can be recorded and matched / associated with the gas concentration result as determined by electrochemical detection.

[0085] More generally, the probe with its instrumentation is adapted to provide contextual data for the measurement performed, which may be a concentration measurement gas obtained by electrochemical means, these data being used by the control unit UC which forms a control device allowing to make the measurement results collected reliable when they are retrieved: the results linked to conditions not well suited to the measurement may have been deleted (at least in part) or may be identified as doubtful due to the data from the auxiliary sensor(s) 6. Phenomena of pressure variation and / or other physico-chemical parameters can be retrieved in a similar way, in order to provide control data and to optimize or report on a level of reliability of the measurements.

[0086] Probe 1 thus advantageously integrates an optimized data collection equipment, allowing in situ measurement and local recording of one or more characteristics of the gaseous fluid arriving in the instrumented compartment, for a period that can be very long (several days or several weeks) without communication with the outside, with a cost that can be minimized despite autonomous operation.

[0087] When the control data includes a parameter representing a humidity level in compartment C2 and possibly at least one other data point representing the detection of anomalies in physical conditions encountered during measurements (in this compartment C2), it is understood that the control unit (CU) intervenes so that the equipment collecting such data allows the end user or subsequent processing software to assess the reliability of the measurements. This makes it possible to reconstruct the measurement context of the retrieved data (gas concentration) and to selectively disqualify measurements taken when this device / control unit detects, possibly using one or more detection thresholds applied to the control data, a loss of measurement reliability.Pressure measurements (to indicate in particular the pressure in compartment C2), possibly temperature, in addition to and / or as an alternative to the humidity parameter may be part of these control data. Regarding the humidity control data, this can also help determine, depending on the installation location, whether the quantity of dehydration elements 8 needs to be adjusted. If it takes 1 or 2 months to exceed 90 or 95% humidity according to the data collected, this may indicate that these dehydration elements 8 are effective. Example(s) of electrochemical detection

[0088] The detection of the gaseous component, for example H2, CO2, CH4 or H2S (this list is not exhaustive), can be carried out using a sensor forming the detection means 20, for example in the form of an electrochemical detection cell which integrates A solid electrolyte. This is, for example, a solid polymer within a sensitive area that allows for an electrochemical catalytic reaction. Continuous detection can be achieved by placing a solid electrolyte between two electrodes.

[0089] The electrochemical cell or sensor of the detection means 20 is for example mounted on an electronic board which has a converter or similar processing means to digitize the signal provided by the sensor 20. The electronic board can be pre-programmed in order to easily / automatically detect the sensor(s), typically by configuring a coupling with this or these sensors, thus allowing automatic recording of the information or signals delivered by this / these sensors.

[0090] Of course, the measuring device 4 can be adapted to avoid saturation situations, for example by having (among the sensors arranged in compartment C2) two separate electrochemical sensors to measure the concentration of the same gas. In one option, the resolution of the first sensor is 1000 ppm and the resolution of the other electrochemical sensor is 20,000 or 40,000 ppm. One or more carbon dioxide gas sensors, such as carbon monoxide, can be included / integrated. More broadly, other additional electrochemical sensors can also be present for measuring another gas or several other gases.

[0091] The fineness of a filter material, in EF filtration means, can be adapted to separate very fine particles, with the specificity of preventing water from rising back up into the tube / into the instrumented compartment.

[0092] The probe 1 can be used in particularly humid environments despite the presence of an electrochemical sensor which loses its reliability when too much humidity is present in the instrumented compartment C2. The probe stem, formed by the body 1a with the hollow part 2 where the measurements are taken, can be completely watertight and particle-proof, while ensuring proper gas circulation through the filter element EF, placed internally in the stem.

[0093] Probe 1 is well suited to allow continuous recording, where appropriate with high temporal resolution, of the emanations of the gaseous component of the subsoil SS such as dihydrogen. Probe 1 can be used to monitor leaks in underground gas storage areas, such as hydrogen storage, as well as natural upwelling from geological reservoirs. It can facilitate mapping operations to identify naturally occurring hydrogen in the ground, typically at depths exceeding 50 or 60 cm. This allows for the identification of areas with potential for the extraction / exploitation of this gas, which constitutes a carbon-free energy source.

[0094] The embodiments described above are examples used to describe one or more ways of obtaining the device, without limitation. Furthermore, each part of this disclosure is not limited to the corresponding embodiment, and various variations may be made within the same technical framework.

Claims

Demands

1. A measuring probe (1) intended to be buried in soil (S) to detect at least one gas in that soil, the probe (1) comprising: - a rigid body (1a) elongated from an upper end (E2) of the probe and suitable for being buried in the ground (S); - a hollow part (2) carried by the rigid body (1a), perforated and / or porous to gases and liquids, and delimiting an intake compartment (C1) through which a gaseous flow (FG) is admitted into the probe (1); - a passage opening (3c) which allows a gas flow to circulate from the intake compartment (01) to a measurement zone; - a measuring device (4), provided in the measuring zone which is in fluidic communication with the intake compartment (01) via the passage opening (3c); and - a connection with a module (14) for acquiring measurements from one or more sensors of the measuring device (4); characterized in that the measuring device (4) is housed internally in the probe (1) at a distance from the upper end (E2), in an instrumented compartment (02) sealed, with respect to the liquids present in the inlet compartment (01), by filtration means (EF) which: - are interposed between the intake compartment (01) and the instrumented compartment (02); and - close the passage opening (3c) to form a barrier to liquids which allows the gas flow to flow towards the measuring device (4) in the form of a filtered gas flow, so that the measuring device allows one or more characteristics of the filtered gas flow to be measured in situ, preferably continuously, and in that the measuring device (4) includes a means for the selective electrochemical detection (20) of a gaseous component of the filtered gas flow, the probe (1) further comprising a control data collection device enabling the determination of a level of reliability of the measurements carried out by the electrochemical detection means (20), on the basis of data retrieved by at least one auxiliary sensor (6) of the measuring device (4).

2. Probe according to claim 1, wherein the hollow portion (2) is configured to form or include a lower end (3) of the probe (1), the inlet compartment (01) being a lower compartment of the probe extending into or to the lower end (3), and wherein the instrumented compartment (02) is an upper compartment superimposed on the lower compartment, the passage opening (3c) allowing the admitted gas flow to be directed upwards to the instrumented compartment (02).

3. Probe according to claim 1 or 2, wherein the filtration means (FE) comprise a flexible cloth or layer of a filter medium, held between two annular support pieces which are connected to each other by clamping means arranged on the periphery of a filtration portion of the filtration means.

4. Probe according to any one of the preceding claims, comprising an electronic unit (CU) controlling the acquisition module (14) and having a measurement data comparison module for comparing successive measurements made by the electrochemical detection means (20), the electronic unit (CU) being configured to implement an optimized recording routine by writing data to the acquisition module (14) only in the case where the comparison module determines a variation, exceeding a given minimum threshold, in successive measurements made by the electrochemical detection means (20).

5. Probe according to any one of the preceding claims, wherein the hollow part (2) has a connection portion (3b), annular or tubular, allowing the inlet compartment (C1) to be connected and disconnected from below a complementary connector element provided in the probe and allowing maintenance or replacement of the filtration means (EF), wherein the connection portion (3b) includes the passage opening (3c) and is integral with a perforated tubular section which delimits the inlet compartment (C1), and wherein, in an assembled state of the probe (1), a sealing member (15; J15) made of elastic material surrounds the connection portion (3b) and the complementary connector element or makes an annular sealing contact against the connection portion (3b) and against the complementary connector element.

6. Probe according to claim 5, wherein, in the mounted state of the probe (1), the instrumented compartment (C2) is accessible only from below, through a single access formed by the passage opening (3c), the instrumented compartment (C2) being isolated from the outside of the probe (1) by absence of a top outlet or lateral communication channel.

7. Probe according to claim 5 or 6, wherein the sealing element (15; J15), surrounding a longitudinal axis (A) of the probe (1), is selected from: - a heat-shrinkable sleeve or film (15) suitable for wrapping an overlapping area between the connection portion (3b) and a complementary connector element of the probe; and - an annular compression joint (J 15), covered laterally by an external wall of the probe (1 ) and on which an axial clamping is exerted.

8. Probe according to any one of the preceding claims, wherein the control data collection device is configured to control the reliability level of measurements performed by the electrochemical detection means (20) by: - retrieving measurements from at least one auxiliary sensor (6) allowing the determination of a parameter representative of a humidity level in the instrumented compartment (C2), - and / or by performing anomaly detection in physical conditions encountered during measurements, the detection being enabled by at least one auxiliary sensor of the measuring device.

9. Probe according to any one of the preceding claims, comprising a housing (12) for trapping water, accessible only through an underpass which communicates with the instrumented compartment (C2), the housing (12) allowing to house one or more desiccant elements (8), preferably containing a desiccant material.

10. Probe according to any one of the preceding claims, wherein the acquisition module (14) is connected to a self-contained power supply, preferably protected in a housing (B) connected from above to the probe (1) via a cable (9), and wherein the rigid body (1), which incorporates the cable (9), is connected in a gas-tight manner to the hollow part (2) and has an external boundary in two parts with: - a first, tubular section, forming a lateral barrier to gases; and - a second part, surmounting the first tubular part of the rigid body (1a), knowing that an axial barrier hermetic to gases, preventing gases from escaping from the probe (1) by rising beyond the second instrumented compartment (C2), is provided in the form of an internal partition of the probe or in the second part.

11. A method for assembling a buried gas detection probe, preferably constituting the probe (1) according to any one of the preceding claims, comprising: - the supply of an elongated rigid body (1a) and a hollow part (2) that is perforated and / or porous to gases and liquids which delimits an inlet compartment (C1) through which a gas flow (FG) can be admitted into the probe (1); - the mounting of a measuring device (4) in one of the rigid body (1 a) and the hollow part (2), on at least one support (4a) which allows supply from an electrical power source via a cable (9) or link, the cable (9) or link also allowing the measuring device (4) to be connected to a control device or unit (UC) and to a module (14) for acquiring measurements made by one or more sensors of the measuring device (4); - the watertight connection of the hollow part (2) to a lower annular section (1 c) of the rigid body (1 a), after placing the cable (9) in the rigid body (1 a) and, respectively, filtration means (EF) in the hollow part (2), whereby the filtration means (EF) separate an instrumented compartment (C2) where the measuring device (4) extends from the intake compartment (C1), forming a barrier to liquids allowing a gaseous flow, admitted into the intake compartment (C1), to flow towards the measuring device (4) as a filtered gaseous flow, knowing that the measuring device (4) has a means for the selective electrochemical detection (2) of a gaseous component of the filtered gaseous flow, while at least one auxiliary sensor (6) is also integrated into the measuring device (4) to allow the collection of control data retrieved by the control device or unit (UC) using this auxiliary sensor (6).

12. Assembly method according to claim 11, further comprising: - the supply of one or more desiccant elements (8), each having a desiccant material and a filter jacket, to allow water to be trapped in an internal volume of the jacket where the desiccant material is located; and - the insertion of the desiccant element(s) (8) into the instrumented compartment (C2) and / or into a central hollow which defines a housing (12) for the rigid body (1 a), preferably above a portion of electrical and mechanical connection which allows the rigid body (1 a) to be connected in a separable way to the hollow part (2).

13. Use of the probe (1) according to any one of claims 1 to 10, the probe having its body (1a) buried in the ground (S) and extending to the hollow portion (2) which is perforated and / or porous to gases and liquids to allow the admission of a gas flow (FG) into the inlet compartment (C1) of the probe, which is a gas taken in situ at a lower end (3) of the probe (1), in which the measuring device (4), when disposed in the instrumented compartment (C2) provided in the probe to be separated from the inlet compartment by the filtration means (EF), by being connected to the measurement acquisition module (14) by a non-fluidic link, serves to provide: - by an electrochemical gas concentration sensor, preferably a solid electrolyte sensor, constituting the electrochemical detection means (20), of the first measurements in the measurement zone where the gas flow circulates after being filtered by the filtration means; and - by at least one auxiliary sensor (6) of the second measurements; and in which the acquisition module (14) records measurement data whose reliability level is evaluated by a control device or unit (CU), preferably provided in a housing (B) which also contains the acquisition module (14), thereby enabling the probe to operate for several days or weeks without external communication, accumulating initial measurements whose reliability can be verified against subsequent measurements.

14. Use according to claim 13, wherein the subsequent measurements are digitized and / or processed as control data, which include: - a parameter representative of the humidity level in the instrumented compartment (C2), - and / or at least one representative data point of anomaly detection in physical conditions encountered during measurements in the instrumented compartment (C2), said control data allowing the selective disqualification of the first measurements taken when the control device or unit (UC) detects, using one or more detection thresholds applied to the control data, a loss of reliability of the measurements.

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