EA025452B1 - System and method for remote sensing - Google Patents

Abstract

A system for monitoring conditions in a borehole and a method therefor. Well tubing and casing act as a conductive pair for delivering power to one or more downhole active sensors. At the surface, power and signal are isolated so that the same conductive pair may act to transmit the sensor signals to the surface. In an embodiment, the sensor signals are RF signals and the surface electronics demodulate the RF signals from the sensor power.

Description

The application for this invention claims the priority of provisional patent application US 61413,179, filed November 12, 2010, which is fully incorporated herein by reference.

Technical field

The present invention relates, in General, to remote measurement and, more specifically, to the measurement of pressure and temperature in the environment of the bottomhole zone of the well.

In mining, it may be useful to monitor various conditions in locations remote from the observer. In particular, it may be useful to provide temperature and pressure control at a depth in the wellbore drilled for exploration or production. Since such wellbores can travel several miles, it is often not practical to replace power supplies for sensors installed in the wellbore.

SUMMARY OF THE INVENTION

An aspect of an embodiment of the present invention includes an apparatus for monitoring conditions in a wellbore. The tubing string and casing act as an electrically conductive pair to supply power to one or more downhole active sensors. On the surface, the power and signal are isolated, so that one conductive pair can act by transmitting the sensor signals to the surface.

An aspect of an embodiment of the present invention includes a system for measuring environmental conditions in a borehole bottomhole zone underground, including a source configured and configured to transmit a power signal using a drill string in a wellbore, a sensor module electrically coupled to the source using drill string, and the sensor module containing an oscillator having a resonant frequency that varies with changing conditions in the environment of the bottomhole zone of the well, the sensor module ignored and configured to receive power from the source and generate a sensor signal in response to a condition in the environment of the bottomhole zone of the well and transmit the signal using the drill string to the surface, as well as a detector electrically connected to the sensor module using the drill string and configured and configured with the ability to receive a sensor signal.

An aspect of an embodiment of the present invention includes a system for monitoring conditions in a wellbore. The tubing string and casing act as an electrically conductive pair to supply power to one or more downhole active sensors. Both on the surface and on the sensor, the power and sensor signals are isolated, so that one conductive pair can act by transmitting the sensor signals to the surface.

Another aspect of an embodiment of the present invention includes a method for monitoring conditions in a wellbore. The power signal is transmitted using the drill string to one or more downhole active sensors. The sensor signal is transmitted using the drill string to the surface. Both on the surface and in the sensor, the power and sensor signals are isolated.

Aspects of embodiments of the present invention include a tangible computer-readable medium with computer-executable instructions for performing any of the above methods and / or for controlling any of the above devices or systems.

Description of drawings

Other features described herein should be apparent to a person skilled in the art from the detailed description with the accompanying drawings.

In FIG. 1 schematically shows a system for acquiring downhole environment data in a well bore underground according to an embodiment of the present invention.

In FIG. 2 shows an electrical diagram of a circuit configured to provide DC power to the sensor in place in the bottomhole zone of the well and receive input from the sensor for transmission to the surface.

In FIG. 3 is a diagram of an embodiment for an alternating current power and signal transmission system for a remote sensor.

In FIG. 4 is a diagram of an embodiment for a direct current power and signal transmission system for a remote sensor.

In FIG. 5 is a block diagram of a transformer connection system according to an embodiment of the present invention.

In FIG. 6 is a block diagram of an assembly of a sensor module according to an embodiment of the present invention.

In FIG. 7 is a block diagram of an interface of a sensor module according to an embodiment of the present invention.

In FIG. 8 is a block diagram of an isolated system according to an embodiment of the present invention.

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Detailed description

In FIG. 1 shows an example of an apparatus 100 for monitoring conditions in an underground wellbore. The device 100 includes an electromagnetic transmission channel, such as a conductive line 102 for transmitting electromagnetic energy through a wellbore. One skilled in the art will appreciate that the conductive line 102 may take various forms or embodiments, depending on the condition of the wellbore. For example, the conductive line 102 may comprise a production tubing string in a completed well, or a drill string in a well under construction. Near the top of the conductive line 102, a transformer 104 is provided for connecting the conductive pipe to a source of electromagnetic energy. Alternative methods of connecting to transformer 104 may be used. For example, a transmission line may be directly connected to a coaxial cable or any other suitable cable.

As shown in an example embodiment, the transformer 104 includes a stack of ferrite rings 106 and a wire 108 wound around the rings. The wire 108 includes terminal leads 110 that can be coupled to a signal generator 112, which can be configured to produce a pulsed or continuous waveform as necessary or desired. The wire 108 may additionally be connected to the receiver 114. The receiver 114 may be made in the form of a computer, including a bus for receiving signals from the device 100 for storage, processing and / or display. In this case, the computer 114 may be equipped with a display 118, which may include, for example, a graphical user interface.

Computer 114 may be programmed to process received sensor signals to provide a measured parameter value. Computer 114 may perform any necessary processing of the recorded signal, including, without limitation, statistical analysis (e.g., Fourier) of the signal, deconvolution of the signal, correlation with another signal, or the like. There are commercially available products known to those skilled in the art that can be used to perform any suitable frequency detection. Alternatively, the computer may be provided with a correspondence table in a storage device or in an accessible medium that correlates the received modulated signals with the measured parameters of the conditions in the wellbore.

In a typical application in drilling in the wellbore, there must be a casing 120 of the well that is used to secure the wellbore. This casing 120 is often made of a conductive material such as steel, in which case the casing works together by line 102 to form a coaxial transmission line, and there is no need to create any additional conductive means. If the casing is not conductive, a conductive sleeve (not shown) can be created in the casing to form a coaxial structure. To maintain the clearance between line 102 and casing 120, device 100 may include dielectric rings 122 spaced along a conductive line 102.

The separators can, for example, be made as isolated centralizers, which are disks of any suitable material, including, without limitation, nylon or polytetrafluoroethylene (PTFE). Although the illustrated embodiment uses a coaxial transmission line, it is contemplated that alternative embodiments of the transmission line, such as a single wire line, paired wire lines or waveguide, can be used. For example, the casing may act autonomously as a waveguide for certain frequencies of electromagnetic waves. In addition, lengths of coaxial cable can be used in the entire line or in part. Such a coaxial cable can be especially useful when the insulating fluid cannot be used in the casing 120 (for example, when mineralized water or other conductive fluid is present in the casing 120).

The probe portion 124 is located near the far end of the device 100. In principle, the probe portion can be located at any point along the length of the data line. In fact, several such probe sections can be installed at intervals along the length. In principle, wavelength multiplexing in a coaxial line can be used to provide multiple probes from the same communication line without interfering with each other.

The probe portion includes an opening 126 configured to transmit the pressure and temperature of the surrounding fluid present in the wellbore to a probe where a sensor can measure it (not shown in FIG. 1). Under the probe, packer 128 and packer teeth 130 are shown.

In FIG. 2 shows an electrical diagram of a downhole section of an embodiment of a system according to the invention. Resistive-capacitive terminal device 200 is designed to reduce or eliminate reflected waves at the end of the line. From the end of the line, the path of the power signal depends on whether the signal is a DC signal or an AC signal. The applied direct current must pass along the upper path 202 through a high inductance inductor 204 (which may be, for example, about 1 mH) and pass through a diode 206, arriving at the site

- 2 025452 DC power output circuit 208 on the right in the figure. On the other hand, the applied alternating current must pass through a relatively low inductance inductor 212 (which may be, for example, about 17 μH). AC energy passes through a power transformer 214 and a bridge rectifier 216 to receive DC power in the same portion of the DC power input circuit 208. The sensors generate a signal (in general, a radio frequency (RF) signal) that is received at the input portion of the radio frequency sensor circuit 218 and connects back to the conductive pair for transmission to the surface.

The inventors have determined that an electrically isolated borehole string should provide the best match for the impedance of the borehole string with respect to the transmitted radio frequency (RF) signal. In addition, and at the same time, such an electrical insulator should provide AC and DC power transmission along the tubing string for power supply when performing functions in the bottomhole zone of the well. The method and device for passive power switching provides selective connection of power to circuits and loads in the bottomhole zone of the well.

The physical implementation of a well string DC insulator in general requires strong mechanical components that, when combined into an assembly, can reliably carry up to 200,000 pounds of load of the tubing string of the tubing, withstand high fastening torques and meet operating requirements for exposure to chemicals and the environment .

In theory, an insulator can be nothing more than a dielectric break in a solid part of a tubing. In practice, such an insulator should enter well casing with sufficient clearance, have a low through capacitance, be able to withstand the applied potential difference of hundreds of volts, and, most importantly, be accepted by the drilling foreman with confidence in trouble-free operation. Built-in uptime elements may also be useful, or required for user acceptance.

According to an embodiment of the invention, the DC isolation technique includes ceramic or other non-conductive insulators inserted in series with the borehole tubing. An insulator can, for example, be built into a 4-foot tubing section, commonly referred to as a sub.

Ceramic parts and tubing parts can be connected to each other by clamps and should be connected without electrical shorting of the tubing parts to each other. An insulation coating can be applied to the inner and outer surfaces of the assembly as protection against electrical breakdown in the gap.

In an embodiment, the RF connection (sensor signal) and the DC connection (power) are performed on the tubing in the form of a common connection, with the signal being separated by an electronic device outside the well.

Numerous structures of mechanical joints and assemblies have already been designed and built. Many of them show electrical resistance values that are too low for practical use. In practice, insulation resistance values of 2,000 ohms or more are useful.

An installation example according to an embodiment of the invention is shown schematically in FIG. 3. In the example of FIG. 3, a surface-generated power signal is an AC signal transmitted to input 300. An AC signal is transmitted to a pair of conductors through power cores 302 of the ferrite type transformer described above, shown in FIG. 1. In FIG. 4 shows an alternative solution in which the power signal is a direct current signal.

As shown in FIG. 3 and 4, the main difference is the use of a transformer, which can be, for example, a toroidal transformer made with spiral tape cores on the borehole tubing string slightly below the wellhead equipment and above the set of radio frequency ferrite cores 304. In this approach, a small the number of turns is the main transformer, with a borehole tubing constituting the secondary winding of the transformer. In the example, this may be a single-turn secondary winding. The solution with the sensor module 310 and the spring centralizer 312 used in the DC isolator does not change in the AC application.

In this method, the power signals generated by the power source 318 are supplied to the sensor module 310 from the lower transformer 304. In the reverse direction, the sensor module 310 generates communication signals that are transmitted to the lower transformer 304. The communication signals are conducted upstream of the tubing string to the upper transformer 302 and then transmitted to the receiver 320 of the ground system 500 (as shown in FIG. 5). The electrical path is completed by grounding the tubing string on the unused sides of the upper and lower transformers and grounding the system on the surface and sensor module 310. In practice, the casing is generally grounded. Thus, the tubing string above the top transformer can be grounded by connecting the tubing string to the casing string through wellhead equipment. The tubing string below the bottom transformer 304 may be grounded by connecting the tubing string to the casing through a spring centralizer 312, for example.

In an embodiment, the transformers are made using a tubing string as one of the windings of each transformer. For example, on the top transformer, the power signal from the system on the surface is transmitted to the primary winding of a toroidal transformer installed around the tubing string. The tubing string itself is one turn of the transformer secondary winding for the power circuit. Similarly, the bottom transformer is another toroidal transformer surrounding the tubing string and includes a primary winding for the power circuit, which is the tubing string itself, and a secondary winding that connects to the sensor module 310. In the communication circuit, the signals are transmitted using only transformers, although (in comparison with the power circuit) the primary and secondary windings in each transformer change roles.

In an embodiment, the AC isolation technique includes an insulator mounted on a short section of a steel tubing containing AC magnets and radio frequency magnets. Separate electrical connections (300, 314, respectively) of alternating current and RF can be performed with passage through the wellhead equipment suspension 316. A suitable impedance for the RF signal can be set by selecting the RF magnetic material. The appropriate impedance for the AC source can be set by selecting the characteristics of the AC transformer.

In this approach, the RF impedance established by the RF magnets is also affected by the presence of AC magnets, which represent a very high RF impedance. In this case, it may be necessary to create an electrical path around the AC magnets to the wellhead equipment for RF currents passing up the borehole from the sensor unit 310. In this case, two different electrical connections to the wellhead equipment are required.

In practice, the supply frequencies can be between 5 and 200 kHz, for example. On the other hand, radio frequencies of data transmission can have a range between 3 and 8 MG c. In an embodiment, power is supplied at a frequency in the range between 1 and 10 KHz, and a frequency modulation scheme in the frequency range between 15 and 30 KHz is used in data transmission. Power frequencies above the radio frequency (RF) range are theoretically applicable. Sensor data frequencies can also be selected outside of these ranges. Since the power and transmitter frequencies of the sensors are different, their separation is possible using filtering either in the surface system 500 and / or in the sensor module 310.

As a result of power and data transmission based on the use of a transformer through the drill string, the need for current-limiting or current-guiding devices (i.e., devices providing a current flow either up or down the tubing string) can be eliminated. Since there is no requirement for the direction of power and data transmission through the tubing string, the transmission becomes less susceptible to attenuation than if the necessary current-guiding devices are used. This, in turn, ensures the use of low-power sensors (for example, less than 10 V) in the sensor module. These low-power sensors allow the system as a whole to withstand significant attenuation between the power source and downhole sensors.

In FIG. 6 is a block diagram of an assembly of a sensor module 600 according to an embodiment of the present invention. As should be clear, the sensor module 600 is similar to the device shown in FIG. 2 and represents an alternative approach illustrating similar concepts.

The sensor module 600 is connected to the lower transformer via a bus 602, which transmits both a power signal and a sensor data signal. A low-pass filter 604 passes a low-frequency power signal into the power circuit of the sensor module, which is composed of a transformer 606, a rectifier 608, and a voltage regulator 610. Power is supplied to the microprocessor 612 and to one or more digital measuring devices 614, each of which may be, for example, an OiaP / duplex® measuring device. which is mass-produced and supplied by OiaP / Jups. 1ps., 8a11 bake ΟίΙν, ϋΤ. Such measuring instruments constitute a quartz resonator and are often equipped with the supplied oscillatory circuit and a processor (for example, a frequency meter), and may include base and temperature piezoelectric crystals together with the corresponding oscillatory circuit.

The output signals of the measuring devices 614 are supplied to a processor 612, which processes the data and provides a communication signal through a frequency modulator 616. The communication signal is transmitted back to the tubing string using bus 602 and a lower transformer. The high-pass filter 618 (which may be a capacitor), in conjunction with the low-pass filter 604, isolates the communication signal from the power path.

A portion of the ground system 500, which acts as a meter interface module, is shown in block diagram form in more detail in FIG. 7. Bus 702 communicates with top transformer 302. Serial input 704 is powered by a power source (not shown). A microprocessor unit 706 controls the power input and outputs power using a low-pass filter 708, a step attenuator 710, and a power amplifier 712. The power monitor 714 measures the output power and returns the measured power data to the microprocessor unit 706. A second low-pass filter 716, which in the shown embodiment is an inductor, passes the power signal to the bus 702 and excludes higher frequency data signals that are returned from the module sensor. Instead, the data signals pass through a high-pass filter 718 to the demodulator 720 and from it to the microprocessor unit 706. The output from the microprocessor unit can pass through a connection 722 ECSGPSO or another type of connection.

In FIG. 8 shows a block diagram of an arrangement similar to the device shown in FIG. 4, and an alternative approach is presented to illustrate similar concepts. As described above, this approach uses ceramic insulated pipe tubing sub to isolate a portion of the tubing string. One isolating sub forms the upper insulator 319, and the other forms the lower insulator 321. The intermediate section 802 of the tubing string becomes the signal and power transmission line in the system. Similar to the embodiment of the transformer, the tubing string conducts power signals from a connection point located directly below the upper ceramic insulated sub of the tubing string (upper insulator 319) to a connection point located directly above the lower ceramic insulated sub of the tubing (lower insulator 321). Power signals are transmitted to the assembly 310 of the sensor module / measuring device from the connection point located directly above the lower insulator 321. In the opposite direction, the sensor module 310 generates communication signals that are transmitted to the connection point located directly above the lower insulator 321. The communication signals are transmitted up the tubing string to a connection point located directly below the upper insulator 319 and then transferred to the surface system 500. The electrical path is terminated by grounding the tubing string above the upper ceramic insulated tubing string sub and below the lower ceramic insulating tubing string sub and grounding the system on the surface and the sensor module. In practice, the casing is generally grounded. Thus, the tubing string above the upper ceramic insulated tubing sub can be grounded by connecting the tubing string to the casing through wellhead equipment. The tubing string below the lower ceramic insulated tubing string sub can be grounded by connecting the tubing string to the casing through a shorting spring centralizer, for example.

In an experimental test, the inventors arranged up to 17,000 feet of coaxial cable corresponding to the field test loss (i.e., simulated the depth of a typical deep well). A remote half-wave power rectifier / AC filter was provided at the end of the cable to provide DC power to amplify the sensor signal.

A 60 Hz low frequency AC voltage was transmitted down the cable. In this case, a voltage of about 10 V DC (from the rectifier / filter) was applied at the end of the cable. An amplified sensor signal (frequency peak) was received at the surface using a high-frequency (HF) radio detector. This equipment provides reception of more than 120 samples per second on the surface.

In an embodiment, parameters, such as pressure or temperature, are measured (one at a time or at the same time) at great depth using technical means by the well of the column, both as a way to power sensors (and other related devices) and as a way to transmit data signals from sensors. Essentially, this technique uses one system for both supplying power and creating a signal path for transmitting these parameters. The applied power can be direct and / or alternating current with different frequencies to perform several functions in low-power remote control equipment or in high-power equipment as part of artificial-lift systems (pumps).

This technique uses a tubing string and casing as a conductive pair to supply power down to a set of remote, powered sensors or related devices. This is accomplished by connecting an alternating current with a magnetic core (like a transformer) or element 319 with insulation of the tubing string directly below the suspension of the tubing string (on the surface) and a similar element 321 with insulation of the tubing string near the far end of the string tubing for direct current. The tubing is held in the center of the borehole casing with ring insulating spacers (centralizers) so that the electrically conductive pair (tubing string and casing) do not short-circuit with each other. At the end of the tubing string, below the bottom tubing insulation element, there should be an electrically conductive packer or spring centralizer 312 or other mechanism for making contact with the casing to close the circuit.

As should be clear, with the help of electronic separation / isolation of power and signal, this one pair of conductors can work as a way to equip the wellhead for processing data from a set of sensors. One skilled in the art should understand the selective frequency filtering methods used here to separate power from a signal and function from function. In this method, sensors are used that transmit a parameter of interest to a low-power radio frequency transmitter. The carrier of each transmitter is modulated to transmit embedded data to ground-based instrumentation. The RF carrier is then demodulated on ground electronic equipment for use.

The second purpose of the layout of the electrically conductive pair of downhole equipment described in this document is to power the electric centrifugal submersible pump (ESP) system for the mechanized production of fluids in the production zone. The electric power supplied to the ESP through the tubing string can be used to power the attached sensor systems, while the signals from such sensors use the same electrically conductive pair as the RF path back to the ground instrumentation.

In an embodiment, control methods for various functions in the downhole zone of the well can be performed by selecting a specific supply frequency that must perform various separate remote control operations (i.e., controlling valves in several zones, etc.) using resonant frequency switching networks to remote valve location.

One skilled in the art will appreciate that the embodiments described herein are only examples and that numerous variations thereof should exist. The invention is limited only by claims that encompass the embodiments described herein, as well as those that are obvious to those skilled in the art. In addition, it should be clear that the design features or steps of the method shown or described in any embodiment of this document can also be used in other embodiments.

Claims (15)

CLAIM 1. A system for measuring the internal parameters of the environment in the bottomhole zone of the well below the surface, containing a power source electrically connected to the drill string; a sensor module electrically connected to the power source through the drill string, the sensor module containing an oscillator having a resonant frequency that varies with changing conditions in the environment of the bottomhole zone of the well, the sensor module is configured and configured to receive power from the power source and generate a sensor signal in depending on the conditions in the environment of the bottomhole zone of the well and signal transmission through the drill string to the surface; a detector electrically connected to the sensor module through the drill string, configured and configured to receive the sensor signal. 2. The system of claim 1, further comprising an overhead transformer configured and configured to receive a power signal from a source and connect a power signal to the drill string and receive a sensor signal from the drill string and connect the sensor signal to the detector; a lower transformer configured and configured to receive a power signal from the drill string and connect the power signal to the sensor module and receive a sensor signal from the sensor module and connect the sensor signal to the drill string. 3. The system of claim 1, further comprising a top insulator configured and configured to electrically isolate the drill string portion from the surface; a lower insulator configured and configured to electrically isolate the drill string section from the distal end of the drill string, with the upper insulator and lower insulator forming the respective ends of the drill string conduit for transmitting a power signal and a sensor signal. 4. The system of claim 1, wherein the sensor module further comprises a power conversion circuit. 5. The system according to claim 1, in which the sensor module further comprises a filter designed and configured to separate power signals and data. - 6,025452 6. The system of claim 5, wherein the filter comprises a low-pass filter configured and configured to pass a power signal through a power conversion circuit to an oscillator, and wherein the sensor module further comprises a frequency modulator configured and configured to modulate the sensor signal for transmissions to the detector; a high-pass filter configured and configured to bypass the modulated sensor signal and attenuate parts of the power signal, which otherwise could be transmitted to the detector. 7. The system according to claim 1, in which the detector and the source together comprise a system on the surface and in which the system on the surface further comprises a filter designed and configured to separate the power and data signals. 8. The system of claim 7, wherein the filter comprises a low-pass filter configured and configured to pass a power signal from a source to a power conversion circuit, and in which the surface detector of the system further comprises an additional low-pass filter configured and configured to skipping the power signal from the power conversion circuit to the drill string and attenuating portions of the sensor signal that might otherwise be transferred to the power conversion circuit; a high-pass filter configured and configured to attenuate the power signal and pass the sensor signal to the demodulator, the demodulator configured and configured to demodulate the sensor signal and pass the demodulated sensor signal to the detector. 9. The system of claim 1, further comprising a short circuit installed in the wellbore under the sensor module and connecting the drill string to the wellbore casing. 10. The method of measuring the internal parameters of the medium in the bottomhole zone of the well below the surface using the system according to claim 1, comprising the steps of supplying power to the sensor module from the power source through a drill string in the wellbore, which comprises an oscillator having a resonant frequency that varies with a change in the internal parameters of the medium in the bottomhole zone of the well, and installed in the environment of the bottomhole zone of the well; register the sensor signal on the surface. 11. The method according to claim 10, in which the separation of the power signal and the sensor signal comprises the step of filtering the signals based on frequency. 12. The method according to claim 10, in which the separation of the power signal and the sensor signal comprises the step of passing through the low-pass filter the combined power signal and the sensor signal before transmitting the power signal. 13. The method of claim 10, wherein the separation of the power signal and the sensor signal comprises the step of passing the combined power signal and the sensor signal through the high-pass filter before detecting the sensor signal on the surface. 14. The method according to claim 10, further comprising the step of isolating the drill string section used in transmission using appropriate assemblies of the insulating sub on the top of the section and the bottom of the section. 15. The method according to claim 10, in which the power and sensor signals are connected to the drill string using a pair of transformers, one transformer forming the upper portion of the drill string used in the transmission, and the other transformer forming the lower portion.