Methods and systems for wireless downhole sensing

Abstract

Embodiments herein generally relate to methods and systems for downhole sensing. In at least one example, the system for downhole wireless sensing comprises: a power supply electrically connected to a conductive portion of a well, and configured to provide input electric current through the conductive portion; a wireless sensor unit electrically connected to the conductive portion to receive the input electric current, the wireless sensor unit connecting to an output ground node and configured to transmit an output sensor signal through the output ground node; a ground signal receiver for detecting an electromagnetic signal, travelling through ground, corresponding to the output sensor signal; and at least one processor coupled to the ground signal receiver for receiving the detected output sensor signal.

Description

METHODS AND SYSTEMS FOR WIRELESS DOWNHOLE SENSINGCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] The present application claims priority to, and benefit from, United States Provisional Patent Application No. 63 / 581,055, titled “METHODS AND SYSTEMS FOR WIRELESS DOWNHOLE SENSING”, filed on September 7, 2023.FIELD

[0002] The present invention generally relates to downhole sensors for oil and gas and geotechnical applications, and more particularly, to methods and systems for wireless downhole sensing.BACKGROUND

[0003] Downhole monitoring systems (e.g., sensors) are often used in oil and gas, as well as geotechnical applications, for monitoring or controlling subsurface assets. Traditional methods of deploying downhole sensors require the use of an insulated conductor(s). These insulated conductor(s) are cabled and extend between surface equipment and the downhole sensor deployed inside or around the well. The cables supply power to the downhole sensor, as well as carry -up output signals generated by the sensor.

[0004] Cable-based sensors, however, suffer from a number of drawbacks. These primarily relate to the cost and complexity of running and installing cables within deep wells. Wireless sensors, accordingly, are increasingly used as an alternative to cable-based sensors. Wireless sensors transmit sensor data to above ground equipment using a variety of wireless telemetry techniques which do not otherwise rely on cables. Examples of common wireless telemetry techniques include acoustic telemetry, electromagnetic or radio telemetry, as well as pressure / flow telemetry.

[0005] Downhole wireless sensors, however, also suffer important challenges. Without cables for supplying power, the wireless sensors require an alternate source of power. The alternate power source is usually in the form of downhole battery packs coupled to the wireless sensors. Battery packscan deplete and require recharging or replacement. Further, once the wireless sensors are installed, it can be difficult to retrieve the wireless sensors to replace or recharge their battery packs.SUMMARY OF VARIOUS EMBODIMENTS

[0006] In accordance with one broad aspect, there is provided a system for downhole wireless sensing comprising: a power supply electrically coupled to at least one conductive portion of a well extending through a subsurface formation, wherein the power supply provides electrical current through the at least one conductive portion; at least one wireless sensor electrically coupled to the at least one conductive portion, and configured to receive the electric current, wherein, the at least one wireless sensor generates an output sensor signal comprising at least one measured downhole parameter, and the at least one wireless sensor further comprising an output ground node coupled to ground, the output ground node configured for transmitting an output electromagnetic (EM) sensor signal through the ground, the output EM sensor signal corresponding to the output sensor signal; a ground signal receiver coupled to the ground for receiving the output EM sensor signal; and at least one processor coupled to the ground signal receiver for receiving a received sensor signal corresponding to the output EM sensor signal.

[0007] In some examples, the at least one conductive portion comprises a casing of the well extending through the subsurface formation.

[0008] In some examples, the output sensor signal is an alternating current signal modulated to encode data about the at least one measured downhole parameter.

[0009] In some examples, the ground signal receiver comprises an antenna.

[0010] In some examples, the at least one measured downhole parameter comprises one or more of pressure and temperature data.

[0011] In some examples, the at least one wireless sensor comprises a vibrating wire sensor.

[0012] In some examples, the vibrating wire sensor comprises: at least one electromagnetic assembly electrically coupled to the at least one conductive portion of the well, and receiving the electrical current; and a vibrating wire extending proximal the at least one electromagnetic assembly, wherein the electrical current, passing through the at least one electromagnetic assembly, inducesvibration of the vibrating wire, which induces the output sensor signal through the at least one electromagnetic assembly.

[0013] In some examples, the at least one processor is configured for processing the received sensor signal to determine the at least one measured downhole parameter.

[0014] In some examples, the at least one processor is configured for analyzing one or more signal waveform properties, in the received sensor signal, to determine the at least one measured downhole parameter.

[0015] In some examples, the at least one wireless sensor comprises a plurality of wireless sensors, each coupled to the at least one conductive portion.

[0016] In accordance with another broad aspect, there is provided a method for downhole wireless sensing comprising: generating electrical current through at least one conductive portion of a well extending through a subsurface formation; receiving an output electromagnetic (EM) sensor signal generated by at least one wireless sensor coupled to the at least one conductive portion, wherein the output EM sensor signal comprises at least one measured downhole parameter; and processing a received sensor signal, corresponding to the output EM sensor signal, to determine the at least one downhole parameter.

[0017] In some examples, the at least one conductive portion comprises a casing of the well extending through the subsurface formation.

[0018] In some examples, the electrical current is provided by a power supply.

[0019] In some examples, the output EM sensor signal is detected using a ground signal receiver.

[0020] In some examples, the at least one downhole parameter comprises one or more of pressure and temperature.

[0021] In some examples, the at least one wireless sensor comprises a vibrating wire sensor.

[0022] In some examples, the method further comprises analyzing one or more signal waveform properties, in the received sensor signal, to determine the at least one measured downhole parameter.

[0023] In some examples, the at least one wireless sensor comprises a plurality of wireless sensors, each coupled to the at least one conductive portion.

[0024] In some examples, the processing is performed by a controller.

[0025] In some examples, the method further comprising demodulating the received sensor signal to determine the at least one downhole parameter.

[0026] Other features and advantages of the present application will become apparent from the following detailed description taken together with the accompanying drawings. It should be understood, however, that the detailed description and the specific examples, while indicating preferred embodiments of the application, are given by way of illustration only, since various changes and modifications within the spirit and scope of the application will become apparent to those skilled in the art from this detailed description.BRIEF DESCRIPTION OF THE DRAWINGS

[0027] For a better understanding of the various embodiments described herein, and to show more clearly how these various embodiments may be carried into effect, reference will be made, by way of example, to the accompanying drawings which show at least one example embodiment, and which are now described. The drawings are not intended to limit the scope of the teachings described herein.

[0028] FIG. 1 A shows an example environment for deploying a system for wireless downhole sensing.

[0029] FIG. IB shows another example environment for deploying a system for wireless downhole sensing, using multiple downhole wireless sensors.

[0030] FIG. 1C shows still another example environment for deploying a system for multiwireless downhole sensing, using multiple downhole wireless sensors.

[0031] FIG. ID shows another example environment for deploying a system for multi -wireless downhole sensing, using multiple downhole wireless sensors.

[0032] FIG. IE shows still yet another example environment for deploying a system for multiwireless downhole sensing, using multiple downhole wireless sensors.

[0033] FIG. IF shows another example environment for deploying a system for multi-wireless downhole sensing, using multiple downhole wireless sensors.

[0034] FIG. 2 is a simplified schematic showing the flow of electric current in a system for wireless downhole sensing.

[0035] FIG. 3 is a simplified illustration of an example vibration wire sensor that can be used in a system for wireless downhole sensing.

[0036] FIG. 4 is a process flow for an example method for wireless downhole sensing.

[0037] FIG. 5 is a simplified hardware block diagram for an example controller.DETAILED DESCRIPTION OF THE EMBODIMENTS

[0038] Embodiments described herein generally relate to methods and systems for wireless downhole sensing.I. GENERAL OVERVIEW

[0039] FIG. 1A is an example environment (100a) for deploying a system for wireless downhole sensing.

[0040] As shown, environment (100a) includes a well (102) drilled below ground (104), and into a subsurface formation (106). In some examples, well (102) is used for accessing and recovering hydrocarbon deposits, or more generally, any gas or oil reservoir.

[0041] As known in the art, well (102) may be constructed from various nested components. These nested components can extend, at different depths, into the subsurface formation (106). For example, well (102) can include a conductor pipe (110), a surface casing (112), an intermediate casing (114), a production casing (116) as well as a production tubing (118). During well production, fluid (120) flows within the production tubing (118), as well as between the production tubing (116) and the production casing (118).

[0042] In the course of well completion and production, it is often necessary to monitor downhole well conditions. As shown in FIG. 1A, the monitoring is usually effected through one ormore downhole sensor units (130). The sensor units (130) measure downhole parameters, including temperature, strain, pressure, load and weight, humidity, acceleration and vibration.

[0043] As stated previously, wireless sensors have become more prevalent over the years as a cost-effective alternative to cable-based sensors. However, a common challenge encountered with wireless sensors is the requirement for downhole batteries to supply power. More generally, once a downhole sensor's battery depletes, the sensor is rendered effectively in-operational. Further, it can be challenging for well operators to retrieve the wireless sensor in order to substitute or recharge its battery. Accordingly, to conserve battery charge, it is often the case that the wireless sensors are purposefully configured for suboptimal performance, including low sampling rates as well as low transmission frequencies.

[0044] In view of the foregoing, and to mitigate at least some of the drawbacks associated with downhole wireless sensors, examples herein provide for wireless downhole sensing which does not rely on cables, or alternatively, downhole power sources (e.g., batteries), to provide downhole power. As explained herein, the disclosed technology uses electricity conducted through the well (102) to supply power to the downhole sensors, as well as return ground signals to communicate sensor data back above-ground.II. SYSTEM FOR WIRELESS DOWNHOLE SENSING

[0045] As shown best in FIG. 1A, the disclosed system can include a controller (150). Controller (150) can be located above ground (104), and proximal the well (102). In other examples, controller (150) can be located anywhere else relative to the well (102), including below or partially- below ground.

[0046] Controller (150) includes a power or energy supply (506) (FIG. 5) for producing electric current. Power supply (506) can be any suitable source for DC and / or AC power. For example, power supply (506) can be one or more batteries supplying DC current.

[0047] While the power supply (506) is exemplified as being part of the controller (150), this is not necessarily always the case. For example, it is possible that the power supply (506) is completely or partially separate from the controller (150). This is the case, for instance, where the power supply (506) comprises a source of AC power, such as the electric grid. In these cases, controller (150) maystill connect to the power supply, directly or in-directly, to control its output power. In some examples, it is also possible that the controller (150) is not coupled to the power supply (506).

[0048] Power supply (506) is coupled (e.g., electrically coupled) to a conductive portion (180) of the well (102) (FIG. 1A). In the illustrated example, the conductive portion (180) corresponds to the production casing (116), which is formed partially or fully from electrically conductive material (e.g., metal). Accordingly, electric current (154) from power supply (506) may flow into and through the production casing (116).

[0049] To that end, the power supply (506) can electrically couple to the well's conductive portion (180) directly or in-directly. In the illustrated example, the power supply (506) couples to the production casing (116), indirectly, via an extended conductor (152).

[0050] A wireless sensor (130) is installed, and otherwise electrically coupled to the conductive well portion (180). In this example, the wireless sensor (130) is therefore also coupled to the production casing (116), e.g., an outside surface of the production casing. Electric current (154), from power supply (506), flows through the production casing (116) and is received by the downhole wireless sensor (130). This, in turn, allows powering and / or activating the wireless sensor (130). In some examples, the input electric current (154), delivered to the sensor (130), is in the range of a few millivolts.

[0051] As described in further detail below, the wireless sensor (130) is grounded to the earth, as is the controller (150), thereby completing the power circuit.

[0052] In other examples, the power supply (506) and wireless sensor (130) are coupled to any other conductive portion of the well structure, e.g., other than the production casing (116). That is, any other conductive portion can be used to electrically couple, and transmit electric power between power supply (506) and the wireless sensor (130) located inside a subsurface formation. For example, any one of the surface and intermediate casings can be used as the conductive portion (180). In these cases, the sensor (130) and power supply (506) are both electrically coupled to the intermediate casing. In some examples, the sensor (130) and power supply (506) are coupled to the same conductive portion (180).

[0053] More broadly, as used herein, the "conductive portion" (180) of the well (102) refers to one or more components (or elements) of the well, that together form a continuous conductive pathfor relaying electric power from the power supply (506) to the downhole wireless sensor (130). There is no limitation on how the conductive path is formed through the well components, and it does not necessarily require the well components to be physically abutting. In some examples, as shown in FIGs. ID and IE, the conductive portion may comprise the production tubing (118).

[0054] The conductive portion (180) may also include an external component coupled to the well and / or sensor. For instance, in FIG. ID, a cable (170) couples the production tubing (118) to the sensor (130). For instance, the cable (170) can extend partially in the well (e.g., below the wellhead) and then the remaining casing / tubing forms the remainder of the conductive portion (180) to complete the signal to surface.

[0055] Typically, the power supply (506) is coupled to a first area of the conductive portion (180), e.g., located at or above ground. Further, the wireless sensor (130) is coupled to a second area of the conductive portion (180), e.g., that is distal to the first area and located further downhole, below ground, and inside the well (102).

[0056] The amount of input power delivered to the wireless sensor (130) may be controllable, or otherwise adjustable. For example, controller's processor (502) can couple to the power supply (506), and control the amount of output power, as required. This can accommodate different wireless sensors (130), which may have different power demands, e.g., depending on the type of sensor used as well as its use application. Any circuit component known in the art can be used for regulating the power output of power supply (506) (e.g., voltage regulators, current limiters, etc.).

[0057] Once the sensor (130) is powered and / or activated via electrical current (154), it can monitor downhole parameters (e.g., temperature, pressure, etc.). In turn, the sensor (130) can generate a corresponding output electric sensor signal. In some examples, the output sensor signal is modulated to carry or encode information (e.g., data) about the measured downhole parameters.

[0058] As exemplified, the wireless sensor (130) is coupled to a ground output node (182), which directly contacts ground earth (106). This allows the output electrical sensor signal to travel through the ground node (182), and transform into an output electromagnetic (EM) sensor signal (156) that travels through ground (106).

[0059] As shown, the output EM sensor signal (156) travels through ground (106) and is detected (e.g., received) by a ground signal receiver (158). Ground signal receiver (158) can be anantenna or the like (e.g., any conductive rod), and is at least partially implanted into the ground (106) to detect the EM sensor signal (156).

[0060] The signal receiver (158) couples to the controller (150), and converts the EM sensor signal (156) back into a received electrical sensor signal (162), which is then relayed to controller (150). In this example, signal receiver (158) couples to the controller (150) via one or more conductors (160).

[0061] Controller (150) receives the received sensor signal (162), and extracts (e.g., decodes and / or demodulates) the signal to resolve the measured downhole parameters. It will be understood that the controller (150), or processor (502), which controls the power supply (506), can be the same or different from the controller (150) or processor (502) which receives the received sensor signal (162).

[0062] FIG. 2 shows a schematic representation (200) of the flow of electric current and EM signals through the system (100a). As shown, by virtue of the ground node (182), a feedback circuit is completed as between the controller (150) and the wireless sensor (130).

[0063] More generally, an input electric current (154), provided or generated by power supply (506), travels through the conductive portion (180) from the controller (150) (or power supply (506)) to the downhole sensor (130). Downhole sensor (130) receives the input electric current (154), and generates an output electric sensor signal (204) with sensed data corresponding to measured downhole parameters (e.g., temperature data, pressure data, etc.). The modulation technique used by the downhole sensor (130) can be any modulation technique known in the art, including various frequency, amplitude and phase modulation techniques known to the skilled person.

[0064] The output electrical sensor signal (204) travels to the ground node (182), and is carried through ground (106) as an electromagnetic (EM) wave (156) to the signal receiver unit (158). In at least one example, the output signal (204) is an AC signal, which induces an EM signal (156) through ground.

[0065] Signal receiver unit (158) receives the EM sensor signal (156) and converts it into a received electric sensor signal (162). Electric sensor signal (162) is transmitted to the controller (150). Controller (150) can demodulate the modulated sensor signal (162) to extract the sensor data contained therein.

[0066] In some examples, the controller (150) can apply a demodulation technique, to the received sensor signal (162), based on the known modulation technique applied by the sensor (130), e.g., as stored in the controller memory (504) (FIG. 5). That is, controller (150) can apply a demodulation technique corresponding to the known modulation technique applied by the sensor (130). In other cases, the output signal (204), generated by the wireless sensor (130), can include embedded data on the type of modulation used. This embedded data is communicated to the abovesurface controller (150) to allow it to apply the correct demodulation technique.

[0067] In view of the foregoing, the disclosed system allows powering and / or activating the downhole wireless sensor (130) without using any cabling, or otherwise, any downhole power source (e.g., batteries). This is because power is delivered to the wireless sensor unit (130) through the conductive portion (180) of the well. Further, the wireless sensor unit (130) can be placed at any depth, insofar as it electrically couples to the conductive well portion (180) to receive power therefrom.III. EXAMPLE WIRELESS VIBRATING WIRE SENSOR

[0068] In at least one example, the disclosed examples use a wireless downhole sensor (130) comprising a vibrating wire sensor. The exemplified vibrating wire sensor can be used alone, or in combination with any of the features of systems described herein.

[0069] FIG. 3 shows an example illustration of a vibrating wire sensor (130) which is adapted for use in the disclosed examples. The exemplified vibrating wire sensor (130) is adapted to monitor changes in pressure.

[0070] As known in the art, a vibrating wire sensor can include a number of components housed within a steel housing (320). These components include a moving diaphragm (302) connected to a vibrating wire (304) (e.g., a conductive wire). The vibrating wire (304) is tensioned, and extends between and proximal a "plucking" electromagnetic assembly (306) and a "pickup" electromagnetic assembly (308). In some cases, the plucking and pickup assemblies are one of the same. Further, the electromagnetic assemblies (306), (308) can comprise coils or the like. The sensor may also include a filter (310).

[0071] As shown, the plucking assembly (306) is coupled to a conductive wire (316). Wire (316) extends through a conductor cable (312) and electrically couples to the conductive portion (180)of the well (102). For example, the conductive portion (180) can be the well's production casing (116). In this manner, the input electric current (154), travelling through the conductive portion (180), flows through the plucking assembly (306). In turn, this induces an EM field, that induces vibration of the tensioned wire (304). The wire (304) is induced to vibrate at its natural frequency when under tension. In some examples, the input electric current (154) is an AC signal which induces cyclical plucking of the wire (304) (FIG. 2).

[0072] As the tensioned wire (304) vibrates, it further induces a corresponding output electric signal in the opposing pickup electromagnetic assembly (308). This is a result of the electric current running the wire (304), which generates a further EM field in the pickup assembly (308), e.g., as the tensioned wire vibrates or oscillates. This output electric signal, generated in the pickup assembly (308), corresponds to the output sensor signal (204) (FIG. 2). In some examples, output sensor signal is an oscillating AC signal, which corresponds to the wire’s oscillating frequency after plucking (FIG. 2).

[0073] The output electrical signal, generated by vibrating wire (304), varies depending on the surrounding pressure conditions. The varying pressure conditions deforms the shape of diaphragm (302) coupled to a distal end of the wire (304). Accordingly, as the diaphragm (302) deforms to different extents (e.g., pushes inwardly or outwardly), the diaphragm (302) tensions or de-tensions the wire (304) to different degrees. This tensioning and de-tensioning affects the resonating frequency of the wire (304) when plucked by the plucking assembly (306). This change to the resonating frequency of the wire (304) is then reflected in the waveform of the output sensor signal (204), e.g., at the pickup assembly (308).

[0074] As further shown in FIG. 3, the pickup assembly (308) connects to the ground node (182), e.g., via an output wire (202). This allows the output sensor signal (204) to travel through the ground node (182), and transform into an EM signal that is transmitted back to the above-surface controller (150). It is appreciated that the generation of an EM signal is facilitated by the output of the sensor (130) being an oscillating AC signal, and not merely a DC signal.

[0075] In other examples, rather than being configured for monitoring pressure, the vibrating wire sensor is configured to measure any other suitable downhole parameter. For example, this includes measuring temperature, strain, load / weight, liquid level, humidity and / or accel erati on / vibrati on .

[0076] For instance, in some examples, the design of FIG. 3 is varied to measure temperature. This may be accomplished by removing the diaphragm (302), and using specific material for the vibrating wire (304) that oscillates at known frequencies at different temperatures.

[0077] To this effect, different designs for a vibrating wire sensor, adapted to measure different types of parameters, will be known to the skilled person.

[0078] At a more general level, it is appreciated that the vibrating wire sensor (130) is adapted for use in systems (100a) - (100c) because it is: (i) powered by the input electrical signal (154); (ii) generates an output sensor signal that modulates the measured downhole parameters via frequency modulation, and (iii) generates an oscillating AC signal that induces an EM wave to travel through ground (106) and to the controller (150).

[0079] In these examples, once the controller (150) receives the output signal (162) (FIG. 2), it may resolve or extract the measured downhole parameters by analyzing the waveform of the sensor signal (162). For example, the controller (150) can store predefined reference data that associates (i) difference oscillating waveforms generated by vibrating sensor (130), and (ii) corresponding tension properties of the vibrating wire (130).

[0080] In at least one example, the controller (150) analyzes the received sensor signal (162) for various waveform properties. The waveform properties can include: (i) frequency content, e.g., determined via a fast Fourier Frequency Transform (FFT); (ii) dampening ratio; and (iii) signal amplitude properties (e.g., maximum and minimum amplitude). The controller (150) may then store predefined mappings between: (i) one or more (or any combination) of the signal waveform properties, and (ii) known wire tensions that result in these properties. The wire tension properties, determined by controller (150), are then mapped to known downhole parameters (e.g., pressure or temperature readings) that correlate or result in these wire tension properties.IV. SYSTEMS FOR WIRELESS DOWNHOLE SENSING USING A PLURALITY OF WIRELESS SENSOR UNITS

[0081] FIG. IB shows an example environment (100b) which includes a system for multisensor downhole sensing.

[0082] The environment (100b) is generally analogous to the environment (100a), with the exception that environment (100b) includes more than one downhole sensor (130), e.g., sensors (130a) - (130c). The plurality of sensors (130) can be used for monitoring the same and / or different downhole parameters. Further, sensors (130) can be the same type, or different types of sensors. Sensors (130) can also be installed at the same or different locations.

[0083] In this example, all of the sensors (130) are coupled to the production casing (116), and therefore, receive the same input electric signal (154) transmitted therethrough. The power supply (506) can be configured, or controlled, to supply input electric current (154) with sufficient power to accommodate the power demands of each of the plurality of sensors (130).

[0084] As shown, each sensor (130) can transmit its own output sensor signal (156a) - (156c) through ground (106), to be received by the signal receiver (158). In at least one example, each sensor (130a) - (130c) is configured to transmit at a different frequency, e.g., a sensor-specific frequency. In this manner, the sensors (130) can transmit concurrently, while allowing the controller (150) to distinguish between the separate signals. In other examples, the sensors transmit at the same frequency, but at different times.

[0085] While not illustrated, it is also possible that different sensors (130) are coupled to different conductive portions (180) of well (102). For example, different sensors (130) can couple to different conductive casings in well (102) such that the system includes multiple conductive portions. In these examples, each casing is electrically coupled to the power supply (506) to receive an input electric signal therefrom.

[0086] FIG. 1C shows still another example environment (100c) which includes a system for wireless sensor downhole sensing, using multiple wireless sensors (130). Environment (100c) is generally analogous to environment (100b), but includes more than one controller (150a), (150b).

[0087] In this example, each controller (150) communicates with a different one of the sensors (130). For example, controller (150a) is tuned to receive signals emitted by sensor (130a), whilecontroller (150b) is tuned to receive signals emitted by sensor (130b). The sensors (130a) - (130b) can receive power from the same, or different power sources (506).V. EXAMPLE METHOD

[0088] FIG. 4 shows an example method (400) for wireless downhole sensing. In at least one example, method (400) is executed fully or partially by the processor (502) of controller (150).

[0089] As shown, at (402), the power supply (506) is operated to generate an input electric current, for powering or activating at least one downhole wireless sensor (130). As explained previously, the input electric signal travels through a conductive portion (180) of well (102), e.g., the production casing, and is received by the wireless sensor (130) which electrically couples to the conductive portion (180).

[0090] At (404), the controller (150) monitors for any received electrical sensor signal detected via the ground signal receiver (158).

[0091] At (406), a determination is made whether a sensor signal is received. If not, the controller (150) can continue the monitoring.

[0092] Otherwise, at (408), the controller (150) can process the received sensor signal to determine or extract (e.g., demodulate, decode, etc.) the monitored downhole parameters. In some cases, prior to processing the received signal, the signal is pre-processed using various signal processing hardware (e.g., noise amplifiers, digital-to-analog converters (DAC), etc.).VI. SPECIFIC AND / OR ALTERNATE EXAMPLES

[0093] While examples herein relate to using a battery-less wireless sensor (130), in other examples, the wireless sensor (130) can also include a battery, such as a rechargeable battery. For instance, the wireless sensor (130) can include a rechargeable battery that electrically couples to the conductive portion (180). This allows the rechargeable battery to recharge using the input electric current (154). In turn, this enables use of ordinary wireless sensors which communicate with an abovesurface controller in the ordinary course (e.g., using wireless telemetry techniques that require a downhole battery). To this effect, the wireless sensor can use the rechargeable battery in alternativeof, or in addition to, the operational modes described herein using EM signals (156) transmitted through ground (106).

[0094] In other examples, the sensor includes a battery, but is not necessarily electrically coupled to conductive portion (180). This still allows the sensor to transmit signals through ground as explained previously, based on the power supplied by the battery.

[0095] In some examples, as best shown in FIG. IF, the tubing / casing may by partially insulated by insulation (172) from ground / earth (104).

[0096] In at least some cases, also shown in FIG. IF, the system (lOOf) is used in a thermal well (SAGD) in an observation well. In observation wells, the power cabling for a wired sensor is typically cemented by cement (174) to an outside of the tubing casing. However, this can result in gas travelling up through the cement and exiting the surface. This is a liability and the use of a wireless sensor (130) without any cables allows for an improved cement job.

[0097] In some examples, the use of a wireless sensor (130) allows for higher transmission frequencies. Typical data frequencies in mud pulse telemetry or electromagnetic telemetry systems are less than 100 Hz. However, the disclosed wireless sensor can achieve frequencies in higher ranges, e.g., 1,000 Hz to 6,000 Hz. Accordingly, in some examples, the wireless sensor (130) is operated to transmit data and signals in a higher frequency range (e.g., 1,000 Hz to 6,000 Hz). This is also possible if the sensor (130) includes a downhole battery, as explained previously.VII. EXAMPLE HARDWARE CONFIGURATION FOR CONTROLLER

[0098] FIG. 5 shows a simplified block diagram for an example controller (150). As shown, controller (150) can include a processor (502) coupled to a memory (504), as well as one or more of a power supply (506), a signal receiver unit (508) and a communication interface (510).

[0099] Processor (502) refers to one or more electronic devices that is / are capable of reading and executing instructions stored on a memory to perform operations on data, which may be stored on a memory or provided in a data signal. The term "processor" includes a plurality of physically discrete, operatively connected devices despite use of the term in the singular. Non-limiting examples of processors include devices referred to as microprocessors, microcontrollers, central processing units(CPU), and digital signal processors. Processor (502) is also referred to herein as "at least one processor".

[0100] Memory (504) refers to a non-transitory tangible computer-readable medium for storing information in a format readable by a processor, and / or instructions readable by a processor to implement an algorithm. The term "memory" includes a plurality of physically discrete, operatively connected devices despite use of the term in the singular. Non-limiting types of memory include solid- state, optical, and magnetic computer readable media. Memory may be non-volatile or volatile. Instructions stored by a memory may be based on a plurality of programming languages known in the art, with non-limiting examples including the C, C++, Python ™, MATLAB ™, and Java ™ programming languages.

[0101] To that end, it will be understood by those of skill in the art that references herein to a computing system (e.g., controller (150)) as carrying out a function or acting in a particular way imply that the corresponding processor (502) is executing instructions (e.g., a software program) stored in memory (504) and possibly transmitting or receiving inputs and outputs via one or more interfaces.

[0102] Power supply (406) can be any suitable source for generating electric current and power, and is coupled to the conductive portion of the well (102) (e.g., via one or more conductors).

[0103] Signal receiver unit (408) is coupled to the ground signal receiver and include various electronic components for signal pre-processing, such as low noise amplifiers (LNAs), as well as an analog to digital converter (DAC).

[0104] Communication interface (410) can include any suitable interface (e.g., an antenna) for receiving and / or transmitting data, e.g., over a network.VIII. INTERPRETATION

[0105] Various systems or methods have been described to provide an example of an embodiment of the claimed subject matter. No embodiment described limits any claimed subject matter and any claimed subject matter may cover methods or systems that differ from those described below. The claimed subject matter is not limited to systems or methods having all of the features of any one system or method described below or to features common to multiple or all of the apparatusesor methods described below. It is possible that a system or method described is not an embodiment that is recited in any claimed subject matter. Any subject matter disclosed in a system or method described that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicants, inventors or owners do not intend to abandon, disclaim or dedicate to the public any such subject matter by its disclosure in this document.

[0106] Furthermore, it will be appreciated that for simplicity and clarity of illustration, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. In addition, numerous specific details are set forth in order to provide a thorough understanding of the embodiments described herein. However, it will be understood by those of ordinary skill in the art that the embodiments described herein may be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the embodiments described herein. Also, the description is not to be considered as limiting the scope of the embodiments described herein.

[0107] It should also be noted that the terms “coupled” or “coupling” as used herein can have several different meanings depending in the context in which these terms are used. For example, the terms coupled or coupling may be used to indicate that an element or device can electrically, optically, or wirelessly send data to another element or device as well as receive data from another element or device. As used herein, two or more components are said to be “coupled”, or “connected” where the parts are joined or operate together either directly or indirectly (i.e., through one or more intermediate components), so long as a link occurs. As used herein and in the claims, two or more parts are said to be “directly coupled”, or “directly connected”, where the parts are joined or operate together without intervening intermediate components.

[0108] It should be noted that terms of degree such as "substantially", "about" and "approximately" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed. These terms of degree may also be construed as including a deviation of the modified term if this deviation would not negate the meaning of the term it modifies.

[0109] Furthermore, any recitation of numerical ranges by endpoints herein includes all numbers and fractions subsumed within that range (e.g. 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.90, 4, and 5). It is also to be understood that all numbers and fractions thereof are presumed to be modified bythe term "about" which means a variation of up to a certain amount of the number to which reference is being made if the end result is not significantly changed.

[0110] The present invention has been described here by way of example only, while numerous specific details are set forth herein in order to provide a thorough understanding of the exemplary embodiments described herein. However, it will be understood by those of ordinary skill in the art that these embodiments may, in some cases, be practiced without these specific details. In other instances, well-known methods, procedures and components have not been described in detail so as not to obscure the description of the embodiments. Various modification and variations may be made to these exemplary embodiments without departing from the spirit and scope of the invention, which is limited only by the appended claims.

Claims

CLAIMS:

1. A system for downhole wireless sensing comprising: a power supply electrically coupled to at least one conductive portion of a well extending through a subsurface formation, wherein the power supply provides electrical current through the at least one conductive portion; at least one wireless sensor electrically coupled to the at least one conductive portion, and configured to receive the electric current, wherein, the at least one wireless sensor generates an output sensor signal comprising at least one measured downhole parameter, and the at least one wireless sensor further comprising an output ground node coupled to ground, the output ground node configured for transmitting an output electromagnetic (EM) sensor signal through the ground, the output EM sensor signal corresponding to the output sensor signal; a ground signal receiver coupled to the ground for receiving the output EM sensor signal; and at least one processor coupled to the ground signal receiver for receiving a received sensor signal corresponding to the output EM sensor signal.

2. The system of claim 1, wherein the at least one conductive portion comprises a casing of the well extending through the subsurface formation.

3. The system of any one of claims 1 or 2, wherein the output sensor signal is an alternating current signal modulated to encode data about the at least one measured downhole parameter.

4. The system of any one of claims 1 to 3, wherein the ground signal receiver comprises an antenna.

5. The system of any one of claims 1 to 4, wherein the at least one measured downhole parameter comprises one or both of pressure and temperature data.

6. The system of any one of claims 1 to 5, wherein the at least one wireless sensor comprises a vibrating wire sensor.

7. The system of claim 6, wherein the vibrating wire sensor comprises: at least one electromagnetic assembly electrically coupled to the at least one conductive portion of the well, and receiving the electrical current; and a vibrating wire extending proximal the at least one electromagnetic assembly, wherein the electrical current, passing through the at least one electromagnetic assembly, induces vibration of the vibrating wire, which induces the output sensor signal through the at least one electromagnetic assembly.

8. The system of any one of claims 1 to 7, wherein the at least one processor is configured for processing the received sensor signal to determine the at least one measured downhole parameter.

9. The system of claim 8, wherein the at least one processor is configured for analyzing one or more signal waveform properties, in the received sensor signal, to determine the at least one measured downhole parameter.

10. The system of any one of claims 1 to 9, wherein the at least one wireless sensor comprises a plurality of wireless sensors, each coupled to the at least one conductive portion.

11. A method for downhole wireless sensing comprising: generating electrical current through at least one conductive portion of a well extending through a subsurface formation; receiving an output electromagnetic (EM) sensor signal generated by at least one wireless sensor coupled to the at least one conductive portion,wherein the output EM sensor signal comprises at least one measured downhole parameter; and processing a received sensor signal, corresponding to the output EM sensor signal, to determine the at least one downhole parameter.

12. The method of claim 11, wherein the at least one conductive portion comprises a casing of the well extending through the subsurface formation.

13. The method of any one of claims 11 or 12, wherein the electrical current is provided by a power supply.

14. The method of any one of claims 11 to 13, wherein the output EM sensor signal is detected using a ground signal receiver.

15. The method of any one of claims 11 to 14, wherein the at least one downhole parameter comprises one or both of pressure and temperature.

16. The method of any one of claims 11 to 15, wherein the at least one wireless sensor comprises a vibrating wire sensor.

17. The method of any one of claims 11 to 16, the method further comprising analyzing one or more signal waveform properties, in the received sensor signal, to determine the at least one measured downhole parameter.

18. The method of any one of claims 11 to 17, wherein the at least one wireless sensor comprises a plurality of wireless sensors, each coupled to the at least one conductive portion.

19. The method of any one of claims 11 to 18, wherein the processing is performed by a controller.

20. The method of any one of claims 11 to 19, further comprising demodulating the received sensor signal to determine the at least one downhole parameter.

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