Monitoring a subsurface medium and identifying object and anomalies therein

Abstract

A subsurface anomaly detection system comprises static sensor arrays positioned in boreholes along a region of interest. The arrays contain electromagnetic and / or electrode sensors distributed along each borehole length. Adjacent arrays form neighboring couples enabling signal transmission between arrays and reflection within arrays. A processing circuitry operates selected couples to generate and detect signals, and generating sensed data that is analyzed to identify anomalies in the subsurface between the couples.

Description

[0001] MONITORING A SUBSURFACE MEDIUM AND IDENTIFYING OBJECT AND ANOMAEIES THEREIN

[0002] TECHNOEOGICAE FIELD

[0003] The present disclosure is in the field of subsurface monitoring.

[0004] BACKGROUND ART

[0005] References considered to be relevant as background to the presently disclosed subject matter are listed below:

[0006] - US9568635

[0007] Acknowledgement of the above references herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter.

[0008] GENERAL DESCRIPTION

[0009] The present disclosure provides a solution for continuous measurement of undersurface medium, i.e. undersurface soil and rock environment, for detecting and localizing anomalies. The unique approach uses large-scale sensor arrays that continuously monitor the subsurface. These arrays may be equipped with both Seismic, electromagnetic and resistivity methods sensors, enabling seismic detection and hyper- tomographic electromagnetic and electric imaging through both transmission and reflection methods. The system detects and maps subsurface anomalies, providing realtime data on subsurface conditions and, for example, detection of hostile / non legitimate operation.

[0010] The sensor arrays are static arrays of sensory elements that are constantly disposed within boreholes. The sensory elements are spread over the length of the borehole, either in constant or varying distances between each two adjacent sensory elements. The static arrays are arranged along a path of interest for undersurface detection. The path can be a border or a perimeter of a secured facility. Each undersurface portion along the path is confined between two adjacent static arrays and measurements by these two adjacent static arrays, together or each alone, provide a mapping of the undersurface that can indicate whether there are any anomalies. Two types of measurements are performed by the two adjacent static arrays - a transmission profde measurement, in which a signal from sensory elements of a first member of the adjacent static arrays is propagating through the medium portion between the two static arrays and detected by sensory elements of a second member of the adjacent static arrays; a reflection profile measurement, in which a signal from sensory elements of a first member of the adjacent static arrays is reflected from a medium portion between the two static arrays and detected by sensory elements of the same member, namely the first member. By performing these measurements by the sensory elements of the two adjacent static arrays, the undersurface mapping is created, and anomalies are identified and localized.

[0011] Each individual sensory element (whether configured as a transmitter, receiver, or transceiver) within a borehole array participates in signal exchange with one or more sensory elements in neighboring boreholes.

[0012] Therefore, a first aspect of the present disclosure provides a system for monitoring and identifying anomalies, e.g. tunnels, in a subsurface medium, i.e. soil or rock. The system comprises a plurality of static arrays of sensory elements configured to apply signals and detect response of the signals. The sensory elements comprise at least one of: (a) electromagnetic transmitters and electromagnetic receivers or (b) electrodes. Each array is accommodated within a borehole out of a plurality of boreholes arranged along a region of interest, namely each array is disposed constantly in its own borehole. The arrays define together an underground sensory fence along the region of interest. The sensory elements of each array are spread over different locations along the length of borehole to allow measurements along the entire length of the borehole. The plurality of static arrays of sensors define a plurality of neighboring couples, each neighboring couple comprises a first member and a second member out of the static arrays such that a signal, e.g. an electromagnetic transmission of electromagnetic transmitters, and / or electric electrodes, applied by sensory elements of the first member is receivable by sensory elements, e.g. electromagnetic receivers, of the second member to thereby allow measurement of transmission profile of the applied signals, e.g. electromagnetic radiation, and / or electric electrodes, between array in one borehole to an array in another, neighboring borehole. The system further comprises at least one processing circuitry configured for: (i) operating selected one or more neighboring couples for applying signals by the sensory elements of the first member and detecting response of the signal by sensory elements of the first member or sensory elements of the second member and generate sensed data based thereon. Namely, the processing circuitry is configured to operate the arrays to obtain two types of measurement: (1) the first type is a transmission profile measurement obtained by transmitting electromagnetic radiation from a transmitter in the first member and receiving the radiation in the second member; (2) the second type is a reflection profile measurement obtained by transmitting electromagnetic radiation from a transmitter, either in the first or in the second member, and receiving the radiation reflected from the soil in the same member. The receiving of the radiation can be in a different location than of the transmission. The processing circuitry is further configured for (ii) analyzing said sensed data to identify anomalies in a part of soil between the one or more neighboring couples.

[0013] The neighboring couples can be configured such that signals propagate between the first and second members along the region of interest. This propagation occurs through the subsurface medium, with each sensor element capable of detecting signals from multiple sensor elements in the adjacent array.

[0014] It is to be noted that any combination of the described embodiments with respect to any aspect of this present disclosure is applicable. In other words, any aspect of the present disclosure can be defined by any combination of the described embodiments.

[0015] In some embodiments of the system, said operating comprises obtaining measurements of (1) transmission of electromagnetic radiation between the first member and the second member, and (2) reflection of electromagnetic radiation transmitted from the first and second members and received in the same member. It is to be noted that a transmission or reflection of electromagnetic radiation can be sensed by more than one sensory element in each member.

[0016] In some embodiments of the system, said operating comprises obtaining measurements of (1) transmission of electric currents between the first member and the second member, and (2) reflection of electric currents transmitted from the first and second members and received in the same member. It is to be noted that a transmission or reflection of electric currents can be sensed by more than one sensory element in each member.

[0017] In some embodiments of the system, the sensory elements comprise at least one of: electromagnetic transmitters, electromagnetic receivers, electromagnetic transducers, electric current electrodes, voltage potential electrodes, electric current or voltage potential transducers, seismic sensors or a combination thereof.

[0018] The seismic sensors can be highly sensitive 1 -axial and / or 2-axial and / or 3 -axial Seismographs and accelerometers positioned closer to the anticipated treat direction to provide real-time triangulated detection of tunneling and or subsurface anomalies connected to hostile activity activities. The sensitivity vs subsurface conditions will allow detection distance of least several tens of meters using P-waves and S-Waves analysis, possibly Surface-waves as well.

[0019] In some embodiments of the system, the sensory elements are configured to perform ground penetrating radar (GPR) measurements, frequency domain electromagnetic (FDEM) measurements, time-domain electromagnetics (TDEM) measurements, electrical resistivity (ERT) measurements, or any combination thereof.

[0020] GPR or Borehole Radar Mapping (BHR) is a wave method, highly based upon mapping and detecting of changes the changes in Dielectric Constants (also known as Dielectric Permittivity, a function of the Waves Velocity) and energy decay (a function of the Waves Attenuation) of the subsurface medium. The GPR sensory elements may operate at the local resonant frequency of the soil or, for example, at a center frequency vary from 20MHz to 500MHz.

[0021] FDEM is an induction method, highly based upon mapping and detecting of changes in Electrical Conductivity (EC) and Magnetic Susceptibility (MS) imaging of the subsurface in selected frequencies. The FDEM sensory elements may operate, for example, at a frequency between 30 Hz to 60 kHz.

[0022] In some embodiments, the system comprises a tube extending throughout the borehole, on which the sensory elements are mounted. The tube can be filled with materials matching soil conductivity, permittivity, and permeability to ensure minimal reflection and refraction of electromagnetic radiation.

[0023] In some embodiments of the system, at least some of the sensory elements are housed together in a shared enclosure that comprises adequate shielding to prevent mutual interference. This is relevant, for example, when housing together GPR sensory elements and FDEM sensory elements.

[0024] In some embodiments, the system comprises a central processing circuitry configured to manage data acquisition from all sensory elements. The central processing circuitry is configured to synchronize data collection, perform processing, and storing data.

[0025] In some embodiments of the system, the sensed data comprises time stamps for associating each data piece of the sensed data with a time of collection of said data piece.

[0026] In some embodiments of the system, said analyzing comprises analyzing a time variation of the sensed data of a selected neighboring couple, namely a variation of the sensed data when sampled in different times, and identifying temporal signatures indicative of said anomalies to thereby identifying the anomalies. Namely, the analyzing comprises monitoring of variation of the sensed data in x, y, z, t coordinates to identify anomalies.

[0027] In some embodiments of the system, said analyzing a time variation of the sensed data comprises comparing at least two measurements obtained in different times. The analysis of the changes in the subsurface environment may be carried out by using algorithms of pattern recognition or Al-based algorithms. The comparison of the sensed data is performed for determining variations in amplitude, phase, frequency or bandwidth of the detected signals by the member in similar locations in different times of measurements.

[0028] In some embodiments of the system, said operating selected one or more neighboring couples comprises sequentially operating a first neighboring couple and a second neighboring couple. It is to be noted that the order of the sequence of operation is not important. The rationality behind the sequential operation is to ensure that the measurements do not interfere with each other, and clean measurements can be obtained. The second neighboring couple comprises a common member of the first neighboring couple, therefore, ambiguity of reflection measurements can be overcome. By obtaining additional measurements from a neighboring couple, the origin of the reflection measurement of the first or second neighboring couple can be determined.

[0029] In some embodiments of the system, said operating selected one or more neighboring couples further comprises sequentially operating a third neighboring couple. It is to be noted that also in this embodiment the order of the sequence of operation is not important. The measurements of the first neighboring couple, the second neighboring couple and the third neighboring couple can be taken in any desired order. The third neighboring couple comprises a common member of the second neighboring couple other than the common member of the first and second neighboring couples, therefore, other ambiguities of reflection measurements can be overcome.

[0030] More specifically, in some scenarios, when sensor elements at specific vertical positions along an array within a single borehole detect reflected signals from an anomaly, the measurement alone cannot determine whether the anomaly is located to the left or right of the borehole. This ambiguity arises because electromagnetic or acoustic waves can reflect from anomalies on either side of the array with similar signal characteristics, making it difficult to determine the direction of the reflecting object using data from a single neighboring couple alone.

[0031] In some embodiments, three consecutive static arrays from first and second neighboring couples sharing a common member (static array) can be operated sequentially to generate measurements from both neighboring couples. In particular, three consecutive arrays comprising a first side array, an intermediate array, and a second side array, positioned in adjacent boreholes. These form two neighboring couples: the first couple comprises the first side array and the intermediate array, while the second couple comprises the intermediate array and the second side array, with the intermediate array serving as the common member between them. When sensor elements at specific vertical positions along the intermediate (common) array detect reflection signals, there may be ambiguity regarding the location of the reflecting anomaly with respect to the intermediate array, namely, whether the reflecting anomaly is located in the region between the first side array and the intermediate array or in the region between the intermediate array and the second side array at those specific vertical positions.

[0032] The ambiguity can be resolved, according to the technique of the present disclosure, by analyzing the complete set of measurements from both neighboring couples at the relevant vertical positions. If an anomaly exists between the first side array and the intermediate array at specific vertical positions, several distinctive patterns emerge: the transmission profiles between sensors at corresponding vertical positions along the first side array and the intermediate array will show signal modification (e.g., attenuation or distortion) due to the anomaly's presence, while the transmission profiles at the same vertical positions between the intermediate array and the second side array will remain relatively unaffected. Additionally, sensors at similar vertical positions along the first side array may detect reflection signals from the same anomaly, providing corroborating evidence. Conversely, if the anomaly is located between the intermediate array and the second side array, the opposite pattern occurs: the transmission between sensors at corresponding vertical positions along the intermediate array and the second side array shows disruption while the transmission between the first side array and the intermediate array remains unaffected, and sensors at the relevant vertical positions along the second side array may register additional reflections.

[0033] The specific order of sequential operation is not critical. The temporal separation guarantees that when sensor elements at specific vertical positions along the intermediate array participate in measurements with corresponding sensor elements along the first side array, there is no simultaneous activity from sensor elements along the second side array that could corrupt the signals, and vice versa. Through this systematic approach of overlapping measurements with shared array members, the system transforms ambiguous reflection data from specific vertical positions into precise anomaly locations, significantly enhancing the reliability and accuracy of subsurface monitoring.

[0034] In some embodiments of the system, the anomalies comprise variation in soil or rock characteristics, voids, tunnels, water contents, water salinities, water qualities, contaminants, hydrocarbons, or any combination thereof.

[0035] In some embodiments of the system, each sensory element is registered with an underground depth indicative of its position underground. Said analyzing comprises using said underground depth to evaluate an underground position of an identified anomaly. In other words, the sensed data comprises also information of the depth of each collected measurement in addition to its geographic location, any data piece of the sensed data is correlated with X, Y, Z coordinates. This allows to create a 3D map of the sensed data and identify anomalies anywhere in the 3D map. Therefore, if an anomaly is detected by a sensory element, the associated depth of the sensory element assists in the evaluation of the depth of the identified anomaly by that sensory element and its geographical location.

[0036] In some embodiments of the system, the sensory elements comprise first sensory elements configured to perform ground GPR measurements, and a second sensory elements configured to perform FDEM measurements; wherein the at least one processing circuitry is configured to synchronize between the operation of the first sensory elements and the second sensory elements to avoid interference between them. In some embodiments of the system, the sensory elements are encapsulated by electromagnetic shielding encapsulation for preventing the first sensory elements from interfering with the second sensory elements and vice versa.

[0037] In some embodiments of the system, said operating comprises sequentially applying signals from one or more selected sensory elements of the first member, wherein said one or more selected sensory elements are distanced from one another such that signals applied from a first selected sensory element do not interfere with signals applied from a second selected sensory element. In other words, the processing circuitry is configured to operate the sensory elements of the first member to apply signals in different time windows. In each time window, a number of sensory elements are operated simultaneously, and they are selected such that there will not be any interference of their signals when they are applied simultaneously. Typically, a vertical difference of several sensory elements between two sensory elements that operate simultaneously is sufficient.

[0038] In some embodiments, the system further comprises seismic sensors accommodated in seismic boreholes, which are the same or different than the plurality of boreholes, each seismic borehole is geographically associated with at least one array of sensory elements. The seismic sensors are configured to sense acoustic signals and generate acoustic data based thereon. The at least one processing circuitry is configured for analyzing said acoustic data and determine a potential threat associated with a specific seismic borehole, wherein said selected or more neighboring couples are selected based on a geographical association with said specific seismic borehole.

[0039] In some embodiments of the system, said analyzing said acoustic data comprises performing triangulation of the potential threat to determine a location of the potential threat that is associated with a specific seismic borehole, enabling detection of the X, Y, Z, coordinates of a treat at a distance from the front line of the sensors array.

[0040] In some embodiments of the system, said selected one or more neighboring couples are neighboring couples that are distanced from one another such that obtaining measurements from one selected neighboring couple does not interfere with obtaining measurements from another neighboring couple.

[0041] Yet another aspect of the present disclosure provides a method for monitoring and identifying anomalies, e.g. tunnels, in a subsurface medium including, for example, soil and rock. The method comprises inserting a plurality of arrays of sensory elements, each into an own borehole out of a plurality of boreholes arranged along a region of interest thereby obtaining a plurality of static arrays within boreholes, namely each array is disposed constantly in its own borehole. The arrays define together an underground sensory fence along the region of interest. The sensory elements of each array are spread over different locations along the length of borehole to allow measurements along the entire length of the borehole and are configured to apply signals and detect response of the signals, wherein the sensory elements comprise at least one of: (a) electromagnetic transmitters and electromagnetic receivers or (b) electrodes. The plurality of static arrays of sensors define a plurality of neighboring couples, each neighboring couple comprises a first member and a second member out of the static arrays such that a signal, e.g. an electromagnetic transmission of electromagnetic transmitters, applied by sensory elements of the first member is receivable by sensory elements, e.g. electromagnetic receivers, of the second member to thereby allow measurement of transmission profile of the applied signals, e.g. electromagnetic radiation, between array in one borehole to an array in another, neighboring borehole. The method further comprises operating selected one or more neighboring couples for applying signals by the sensory elements of the first member and detecting response of the signal by sensory elements of the first member or sensory elements of the second member and generating sensed data based thereon. Namely, the method comprises operating the arrays to obtain two types of measurement: (1) the first type is a transmission profile measurement obtained by transmitting electromagnetic radiation from a transmitter in the first member and receiving the radiation in the second member; (2) the second type is a reflection profile measurement obtained by transmitting electromagnetic radiation from a transmitter, either in the first or in the second member, and receiving the radiation reflected from the soil in the same member. The receiving of the radiation can be in a different location than of the transmission. The method further comprises analyzing said sensed data to identify anomalies in a part of soil between the one or more neighboring couples.

[0042] In some embodiments of the method, said operating comprises obtaining measurements of (1) transmission of electromagnetic radiation between the first member and the second member, and (2) reflection of electromagnetic radiation transmitted from the first and second members and received in the same member.

[0043] In some embodiments of the method, said operating comprises obtaining measurements of (1) transmission of electric currents between the first member and the second member, and (2) reflection of electric currents transmitted from the first and second members and received in the same member. It is to be noted that a transmission or reflection of electric currents can be sensed by more than one sensory element in each member.

[0044] In some embodiments of the method, the sensory elements comprise at least one of: electromagnetic transmitters, electromagnetic receivers, electromagnetic transducers, electric current electrodes, voltage potential electrodes, electric current or voltage potential transducers, seismic sensors or a combination thereof.

[0045] In some embodiments of the method, the sensory elements are configured to perform ground penetrating radar (GPR) measurements, frequency domain electromagnetic (FDEM) measurements, time-domain electromagnetics (TDEM) measurements, electrical resistivity (ERT) measurements, or any combination thereof.

[0046] In some embodiments of the method, said analyzing comprises analyzing a time variation of the sensed data of a selected neighboring couple and identifying temporal signatures indicative of said anomalies. Namely, the analyzing comprises monitoring of variation of the sensed data in x, y, z, t coordinates to identify anomalies.

[0047] In some embodiments of the method, said analyzing a time variation of the sensed data comprises comparing at least two measurements obtained in different times.

[0048] In some embodiments of the method, said operating selected one or more neighboring couples comprises sequentially operating a first neighboring couple and a second neighboring couple. The second neighboring couple comprises a common member of the first neighboring couple, therefore, ambiguity of reflection measurements can be overcome. By obtaining additional measurements from a neighboring couple, the origin of the reflection measurement of the first or second neighboring couple can be determined.

[0049] In some embodiments of the method, said operating selected one or more neighboring couples further comprises sequentially operating a third neighboring couple. The third neighboring couple comprises a common member of the second neighboring couple other than the common member of the first and second neighboring couples.

[0050] In some embodiments of the method, the anomalies comprise variation in soil or rock characteristics, voids, tunnels, water content, water salinity, water quality, contaminants, hydrocarbons, or any combination thereof.

[0051] In some embodiments of the method, each sensory element is registered with an underground depth indicative of its position underground, wherein said analyzing comprises using said underground depth to evaluate an underground position of an identified anomaly.

[0052] In some embodiments of the method, the sensory elements comprise first sensory elements configured to perform ground GPR measurements, and a second sensory elements configured to perform FDEM measurements; wherein the method further comprises synchronizing between the operation of the first sensory elements and the second sensory elements to avoid interference between them.

[0053] In some embodiments of the method, the sensory elements are encapsulated by electromagnetic shielding encapsulation for preventing the first sensory elements from interfering with the second sensory elements and vice versa.

[0054] In some embodiments of the method, said operating comprises sequentially applying signals from one or more selected sensory elements of the first member, wherein said one or more selected sensory elements are distanced from one another such that signals applied from a first selected sensory element do not interfere with signals applied from a second selected sensory element. In other words, the method comprises operating the sensory elements of the first member to apply signals in different time windows. In each time window, a number of sensory elements are operated simultaneously, and they are selected such that there will not be any interference of their signals when they are applied simultaneously. Typically, a vertical difference of several sensory elements between two sensory elements that operate simultaneously is sufficient.

[0055] In some embodiments, the method further comprises inserting seismic sensors into seismic boreholes, which are the same or different than the plurality of boreholes, each seismic borehole is geographically associated with at least one array of sensory elements. The seismic sensors are configured to sense acoustic signals and generate acoustic data based thereon. The method further comprises analyzing said acoustic data and determine a potential threat associated with a specific seismic borehole, wherein said selected or more neighboring couples are selected based on a geographical association with said specific seismic borehole.

[0056] In some embodiments of the method, said analyzing said acoustic data comprises performing triangulation of the potential threat to determine a location of the potential threat that is associated with a specific seismic borehole, enabling detection of the X, Y, Z, coordinates of a treat at a distance from the front line of the sensors array. In some embodiments of the method, said selected one or more neighboring couples are neighboring couples that are distanced from one another such that obtaining measurements from one selected neighboring couple does not interfere with obtaining measurements from another neighboring couple.

[0057] BRIEF DESCRIPTION OF THE DRAWINGS

[0058] In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

[0059] Figs. 1A-1D are schematic illustrations of non-limiting examples of top view of deployment arrangement of static arrays of sensory elements along a desired path.

[0060] Figs. 2A-2B are schematic illustrations showing different non-limiting examples of measurements schemes by the sensory elements of the static arrays.

[0061] Figs. 3A-3B are schematic illustrations of cross-sectional views exemplifying the measurements by the sensory elements of adjacent static arrays.

[0062] DETAILED DESCRIPTION

[0063] The following figures are provided to exemplify embodiments and realization of the invention of the present disclosure.

[0064] Reference is first being made to Figs. 1A-1D, which are schematic illustrations of different non-limiting examples of top view of deployment arrangement of static arrays of sensory elements along a desired path. The desired path can be a straight line or a curved line, as shown in Fig. IB. Figs. 1A-1D show a plurality of static arrays 102, each array is disposed in its own borehole and comprises one or more types of sensory elements 103. The term “static arrays” should be understood as an array of sensors that is constantly disposed within a borehole and that the position of each sensory element of the array is constant at a certain vertical position along the borehole, during the lifespan of the arrays. The sensory elements may comprise ground penetrating radar (GPR) sensors, frequency domain electromagnetic (FDEM) sensors, time-domain electromagnetics (TDEM) sensors, electrical resistivity (ERT) sensors, or any combination thereof. The sensory elements 103 are disposed at different vertical locations along the borehole such that they allow measurement of the undersurface generally along the entire length of the borehole. The sensory elements are mounted on a carrying element that spans the entire length of the borehole and is also used for delivering the data sensed by the sensory elements and transferring energy to the sensory elements. The energy is transferred from an energy source, e.g. a battery, that is disposed at a location along the borehole, typically at the top of the borehole. The static arrays are arranged such that each static array has at least one neighboring static array adjacent thereto, defining together a neighboring couple. A neighboring couple is defined such that transmitted signals from sensory elements of a first member of the neighboring couple are received by sensory elements of a second member of the neighboring couple. In other words, the signals transmitted from sensory elements of the first member of the neighboring couple pass through the undersurface medium and being sensed by sensory elements of the second member of the neighboring couple, thereby a measurement of the transmission profile of the signal is obtained. Therefore, the sensory elements 103 are capable of transmitting signals to the undersurface soil they are associated with, and the signals are detectable, after passing through the undersurface medium, either it is soil, rock or other medium, by either sensory elements of the same static array to measure the reflection profile of the signal, or by sensory elements of a neighboring static array to measure the transmission profile of the signal. The sensory elements may either apply signals of electromagnetic radiation or signals of electric current or electric field to the undersurface medium they are associated with. The medium associated with the sensory elements should be understood as the undersurface medium that the signals either pass therethrough or reflected therefrom.

[0065] The sensory elements may be either (1) a collection of transmitters and receivers, wherein the transmitters transmit the signals, and the receivers sense the response of the signal after interacting with the undersurface medium, (2) a collection of transceivers that are capable of both transmitting the signals and sensing their response, or (3) a combination of (1) and (2).

[0066] In the examples presented in Figs. 1A-1B, acoustic sensors 104, i.e. seismic sensors are also included in some of the static arrays. It is to be noted that acoustic sensors are not necessarily found in every borehole and can be included in only some of the boreholes. The acoustic sensors 104 sense acoustic signals from the underground soil they are associated with and by analyzing detected signals from one or more acoustic sensors 104, evaluation of the undersurface area from which the acoustic signals arrived can be obtained. For example, by triangulation of detected acoustic signals from a plurality of acoustic sensors an estimated location of the source of the acoustic signal can be determined, enabling detection of the X, Y, Z, coordinates of a treat at a distance from the front line of the sensors array. The estimated location is associated with one or more static arrays disposed in boreholes and the detection of the signal from the estimated location triggers measurement by the one or more static arrays associated with the estimated location.

[0067] The sensory elements 103 are operated by one or more processing circuitries, i.e. processing units or control units that are capable of operating the sensory elements to transmit signals and to detect the response of these signals after their interaction with the undersurface medium. All the static arrays may be operated by a single central processing circuitry or by a plurality of synchronized processing circuitries that together control the operation of all the sensory elements of the static arrays in synchronization.

[0068] Figs. 1A-1B show examples of a plurality of static arrays, each disposed in its own borehole and comprises GPR and FDEM sensors. Furthermore, as mentioned above, in some of the boreholes are also included acoustic sensors such as geophone sensors. Fig. 1C exemplifies three lines of static arrays, each line comprises static arrays comprising a different type of sensory elements. The first line comprises acoustic sensors, the second line comprises GPR sensors, and the third line comprises FDEM sensors. Therefore, the three lines of static arrays ensure that any anomaly in the undersurface medium will be detected by at least one line of the static arrays. Fig. ID exemplifies two lines of static arrays, the first line comprises acoustic sensors, and the second line comprises GPR and FDEM sensors.

[0069] Reference is now made to Figs. 2A-2B, which are schematic illustrations showing different non-limiting examples of measurements schemes by the sensory elements 203. Fig. 2A exemplifies the use of transmitters 203A and receivers 203B, namely different sensory elements for transmitting and sensing. Each individual transmitter 203A within a borehole array is configured to transmit signals to multiple receivers 203B in neighboring boreholes, while each receiver 203B is configured to receive signals from one or more transmitters 203 A in neighboring boreholes.

[0070] Fig. 2B exemplifies the use of transceivers for performing the measurements, namely the same sensory elements for transmitting and sensing. Signals applied by sensory elements of either the first member or the second member are receivable by sensory elements of the other member such that the signals propagate between the first and second members along the region of interest, enabling bidirectional transmission measurements through the subsurface medium.

[0071] Each individual sensory element 203 within a borehole array is configured to both transmit signals to and receive signals from one or more sensory elements in neighboring boreholes, creating a network of transmission paths through the subsurface medium. This bidirectional capability enables coverage of the subsurface volume between neighboring arrays, as signals propagate in both directions along the region of interest between the first and second members of each neighboring couple.

[0072] The resulting transmission profile between any two neighboring arrays therefore can include many individual transmission paths, each providing unique information about the subsurface medium it traverses. When an anomaly is present between two boreholes, it affects multiple transmission paths differently depending on the specific sourcereceiver geometry. Transmission paths that pass directly through the anomaly show maximum attenuation or distortion, while paths that graze the anomaly's edges show partial effects, and paths that miss the anomaly entirely remain unaffected. By analyzing this complete set of transmission measurements - where each sensor at depth X in the first borehole has its signals measured, for example, by sensors at depths Yi, Y2, Y3...Ynin the second borehole - the processing circuitry can reconstruct a detailed three-dimensional image of any anomalies present.

[0073] Reference is now made to Figs. 3A-3B, which are schematic illustrations of cross- sectional views exemplifying the measurements by the sensory elements 303. A set of measurements is performed with the participation of two adjacent static arrays defining together a neighboring couple 306. Signals, e.g. electromagnetic radiation, are applied from a first member 308 of a neighboring couple 306 and from a second member 310 of a neighboring couple 306. The signals are interacting with the undersurface medium and either transmitted to the other member to be sensed by one of its sensory elements or reflected from a part of the undersurface medium and sensed by one of the sensory elements of the same member that transmitted the signal. It is to be noted that the measurements are synchronized such that application of signals by a first member of a neighboring couple will not interfere with application of signals by a second member of a neighboring couple. The synchronization can be a time synchronization, with application of signals in different time windows, or a wavelength synchronization, in which different wavelengths are used by different sensory elements. As mentioned above, the operation of the static arrays is controlled by one or more processing circuitries to allow these synchronized measurements.

[0074] Figs. 3A-3B exemplify the detection of tunnels formed between neighboring couples. The tunnels cause some of the electromagnetic radiation to reflect and also affect the transmission profde of the electromagnetic radiation that passes through the tunnels. By analyzing the sensed signals in the surrounding of the tunnel in the neighboring couple, an anomaly can be identified indicating that there may be a tunnel and its location can be determined by crossing the data from a plurality of sensory elements surrounding the tunnel.

[0075] The processing circuitry can be configured to sequentially operate multiple neighboring couples, collecting both transmission and reflection measurements from sensor elements at various vertical positions along each couple, and analyzing the transmission profiles at specific vertical positions. The processing circuitry can be configured to correlate detected responses (reflections and / or transmissions) from sensory elements at corresponding vertical positions across different arrays to localize anomalies. More specifically, analyzing transmission profiles between sensory elements at corresponding vertical positions in neighboring arrays; determining a vertical position of an anomaly based on which specific transmission paths between corresponding vertical positions show signal attenuation or distortion; identifying which specific sensory elements detect reflection signals at specific vertical positions; and correlating both the transmission profiles and reflection signals from corresponding vertical positions to determine three-dimensional locations of anomalies.

[0076] By identifying which transmission paths between sensors at corresponding vertical positions show attenuation or distortion with respect to which remain unaffected, and correlating this with reflection signals detected by individual sensor elements at specific vertical positions along the arrays, the processing circuitry determines the precise location of anomalies. For example, the processing circuitry can be configured to distinguish between anomalies located between different array pairs at specific vertical positions via pattern recognition schemes, transforming ambiguous reflection data from specific sensor elements into unambiguous three-dimensional positional information.

Claims

CLAIMS:

1. A system for identifying anomalies in a subsurface soil, comprising: a plurality of static arrays of sensory elements configured to apply signals and detect response of the signals, wherein the sensory elements comprise at least one of: (a) electromagnetic transmitters and electromagnetic receivers or (b) electrodes, wherein each array is accommodated within a borehole out of a plurality of boreholes arranged along a region of interest and the sensory elements of each array are spread over different locations along the length of borehole; wherein the plurality of static arrays of sensors define a plurality of neighboring couples, each neighboring couple comprises a first member and a second member out of the static arrays such that a signal applied by sensory elements of the first member is receivable by sensory elements of the second member; at least one processing circuitry configured for:(i) operating selected one or more neighboring couples for applying signals by the sensory elements of the first member and detecting response of the signal by sensory elements of the first member or sensory elements of the second member and generate sensed data based thereon; and(ii) analyzing said sensed data to identify anomalies in a part of soil between the one or more neighboring couples.

2. The system of claim 1, wherein said operating comprises obtaining measurements of (1) transmission of electromagnetic radiation between the first member and the second member, and (2) reflection of electromagnetic radiation transmitted from the first and second members and received in the same member.

3. The system of claim 1 or 2, wherein the sensory elements comprise at least one of: electromagnetic transmitters, electromagnetic receivers, electromagnetic transducers, electric current electrodes, voltage potential electrodes, electric current or voltage potential transducers, seismic sensors or a combination thereof.

4. The system of any one of claims 1-3, wherein the sensory elements are configured to perform ground penetrating radar (GPR) measurements, frequency domain electromagnetic (FDEM) measurements, time-domain electromagnetics (TDEM) measurements, electrical resistivity (ERT) measurements, or any combination thereof.

5. The system of any one of claims 1-4, wherein said analyzing comprises analyzing a time variation of the sensed data of a selected neighboring couple and identifying temporal signatures indicative of said anomalies.

6. The system of claim 5, wherein said analyzing a time variation of the sensed data comprises comparing at least two measurements obtained in different times.

7. The system of any one of claims 1-6, wherein said operating selected one or more neighboring couples comprises sequentially operating a first neighboring couple and a second neighboring couple, wherein the second neighboring couple comprises a common member of the first neighboring couple.

8. The system of claim 7, wherein said operating selected one or more neighboring couples further comprises sequentially operating a third neighboring couple, wherein the third neighboring couple comprises a common member of the second neighboring couple other than the common member of the first and second neighboring couples.

9. The system of any one of claims 1-8, wherein the anomalies comprise variation in soil or rock characteristics, voids, tunnels, water contents, water salinities, water qualities, contaminants, hydrocarbons, or any combination thereof.

10. The system of any one of claims 1-9, wherein each sensory element is registered with an underground depth indicative of its position underground, wherein said analyzing comprises using said underground depth to evaluate an underground position of an identified anomaly.

11. The system of any one of claims 1-10, wherein the sensory elements comprise first sensory elements configured to perform ground GPR measurements, and a second sensory elements configured to perform FDEM measurements; wherein the at least one processing circuitry is configured to synchronize between the operation of the first sensory elements and the second sensory elements to avoid interference between them.

12. The system of claim 11, wherein the sensory elements are encapsulated by electromagnetic shielding encapsulation for preventing the first sensory elements from interfering with the second sensory elements and vice versa.

13. The system of any one of claims 1-12, wherein said operating comprises sequentially applying signals from one or more selected sensory elements of the first member, wherein said one or more selected sensory elements are distanced from one another such that signals applied from a first selected sensory element do not interfere with signals applied from a second selected sensory element.

14. The system of any one of claims 1-13, comprising seismic sensors accommodated in seismic boreholes, which are the same or different than the plurality of boreholes, each seismic borehole is geographically associated with at least one array of sensory elements; wherein the seismic sensors are configured to sense acoustic signals and generate acoustic data based thereon; wherein the at least one processing circuitry is configured for analyzing said acoustic data and determine a potential threat associated with a specific seismic borehole, wherein said selected or more neighboring couples are selected based on a geographical association with said specific seismic borehole.

15. The system of claim 14, wherein said analyzing said acoustic data comprises performing triangulation of the potential threat to determine a location of the potential threat that is associated with a specific seismic borehole.

16. The system of any one of claims 1-15, wherein said selected one or more neighboring couples are neighboring couples that are distanced from one another such that obtaining measurements from one selected neighboring couple does not interfere with obtaining measurements from another neighboring couple.

17. A method for identifying anomalies in a subsurface soil, comprising: inserting a plurality of arrays of sensory elements, each into an own borehole out of a plurality of boreholes arranged along a region of interest thereby obtaining a plurality of static arrays within boreholes, wherein the sensory elements of each array are spread over different locations along the length of borehole and are configured to apply signals and detect response of the signals, wherein the sensory elements comprise at least one of: (a) electromagnetic transmitters and electromagnetic receivers or (b) electrodes; wherein the plurality of static arrays of sensors define a plurality of neighboring couples, each neighboring couple comprises a first member and a second member out of the static arrays such that a signal applied by sensory elements of the first member is receivable by sensory elements of the second member; operating selected one or more neighboring couples for applying signals by the sensory elements of the first member and detecting response of the signal by sensory elements of the first member or sensory elements of the second member and generating sensed data based thereon; and analyzing said sensed data to identify anomalies in a part of soil between the one or more neighboring couples.

18. The method of claim 17, wherein said operating comprises obtaining measurements of (1) transmission of electromagnetic radiation between the first member and the second member, and (2) reflection of electromagnetic radiation transmitted from the first and second members and received in the same member.

19. The method of claim 17 or 18, wherein the sensory elements comprise at least one of: electromagnetic transmitters, electromagnetic receivers, electromagnetic transducers, electric current electrodes, voltage potential electrodes, electric current or voltage potential transducers, seismic sensors or a combination thereof.

20. The method of any one of claims 17-19, wherein the sensory elements are configured to perform ground penetrating radar (GPR) measurements, frequency domain electromagnetic (FDEM) measurements, time-domain electromagnetics (TDEM) measurements, electrical resistivity (ERT) measurements, or any combination thereof.

21. The method of any one of claims 17-20, wherein said analyzing comprises analyzing a time variation of the sensed data of a selected neighboring couple and identifying temporal signatures indicative of said anomalies.

22. The method of claim 21, wherein said analyzing a time variation of the sensed data comprises comparing at least two measurements obtained in different times.

23. The method of any one of claims 17-22, wherein said operating selected one or more neighboring couples comprises sequentially operating a first neighboring couple and a second neighboring couple, wherein the second neighboring couple comprises a common member of the first neighboring couple.

24. The method of claim 23, wherein said operating selected one or more neighboring couples further comprises sequentially operating a third neighboring couple, wherein the third neighboring couple comprises a common member of the second neighboring couple other than the common member of the first and second neighboring couples.

25. The method of any one of claims 17-24, wherein the anomalies comprise variation in soil or rock characteristics, voids, tunnels, water contents, water salinities, water qualities, contaminants, hydrocarbons, or any combination thereof.

26. The method of any one of claims 17-25, wherein each sensory element is registered with an underground depth indicative of its position underground, wherein said analyzing comprises using said underground depth to evaluate an underground position of an identified anomaly.

27. The method of any one of claims 17-26, wherein the sensory elements comprise first sensory elements configured to perform ground GPR measurements, and a second sensory elements configured to perform FDEM measurements; wherein the method further comprises synchronizing between the operation of the first sensory elements and the second sensory elements to avoid interference between them.

28. The method of claim 27, wherein the sensory elements are encapsulated by electromagnetic shielding encapsulation for preventing the first sensory elements from interfering with the second sensory elements and vice versa.

29. The method of any one of claims 17-28, wherein said operating comprises sequentially applying signals from one or more selected sensory elements of the first member, wherein said one or more selected sensory elements are distanced from one another such that signals applied from a first selected sensory element do not interfere with signals applied from a second selected sensory element.

30. The method of any one of claims 17-29, comprising inserting seismic sensors into seismic boreholes, which are the same or different than the plurality of boreholes, each seismic borehole is geographically associated with at least one array of sensory elements; wherein the seismic sensors are configured to sense acoustic signals and generate acoustic data based thereon; wherein the method further comprises analyzing said acoustic data and determine a potential threat associated with a specific seismic borehole, wherein said selected or more neighboring couples are selected based on a geographical association with said specific seismic borehole.

31. The method of claim 30, wherein said analyzing said acoustic data comprises performing triangulation of the potential threat to determine a location of the potential threat that is associated with a specific seismic borehole.

32. The method of any one of claims 17-31, wherein said selected one or more neighboring couples are neighboring couples that are distanced from one another such that obtaining measurements from one selected neighboring couple does not interfere with obtaining measurements from another neighboring couple.

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