Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B47/00—Survey of boreholes or wells
  • E21B47/06—Measuring temperature or pressure
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B47/00—Survey of boreholes or wells
  • E21B47/12—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B47/00—Survey of boreholes or wells
  • E21B47/12—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling
  • E21B47/13—Means for transmitting measuring-signals or control signals from the well to the surface, or from the surface to the well, e.g. for logging while drilling by electromagnetic energy, e.g. radio frequency

Definitions

• the present invention relates generally to remote sensing and more particularly to sensing pressures and temperatures in a down hole environment.
• An aspect of an embodiment of the present invention includes an apparatus for monitoring conditions in a borehole.
• the well tubing and casing act as a conductive pair for delivering power to one or more downhole active sensors.
• power and signal are isolated so that the same conductive pair may act to transmit the sensor signals to the surface.
• An aspect of an embodiment of the present invention includes a system for measuring a condition in a downhole environment in a borehole beneath a surface, including a source, configured and arranged to transmit a power signal via a drillstring in the borehole a sensor module, in electrical communication with the source via the drillstring, the sensor module comprising an oscillator having a resonant frequency that varies with changes in the condition in the downhole environment, the sensor module being configured and arranged to receive power from the source and to produce a sensor signal in response to the condition in the downhole environment and to transmit the signal, via the drillstring, toward the surface, and a detector, in electrical communication with the sensor module via the drillstring and configured and arranged to receive the sensor signal.
• An aspect of an embodiment of the present invention includes a system for monitoring conditions in a borehole.
• the well tubing and casing act as a conductive pair for delivering power to one or more downhole active sensors.
• power and sensor signals are isolated so that the same conductive pair may act to transmit the sensor signals to the surface.
• Another aspect of an embodiment of the present invention includes a method of monitoring conditions in a borehole.
• a power signal is transmitted via the drillstring to one or more downhole active sensors.
• the sensor signal is transmitted via the drillstring to the surface. At each of the surface and the sensor, power and sensor signals are isolated.
• aspects of embodiments of the present invention include tangible computer readable media encoded with computer executable instructions for performing any of the foregoing methods and/or for controlling any of the foregoing apparatuses or systems.
• Figure 1 is a schematic illustration of a system for interrogating a downhole environment in a borehole beneath a surface in accordance with an embodiment of the present invention
• Figure 2 is an electrical schematic diagram illustrating a circuit configured to provide DC power to a sensor in a down hole location and to accept input from the sensor for transmission to the surface;
• Figure 3 is a schematic diagram illustrating an alternating current embodiment of a transmission system for power and signal for a remote sensor
• Figure 4 is a schematic diagram illustrating a direct current embodiment of a transmission system for power and signal for a remote sensor
• FIG. 5 is a block diagram of a transformer coupling system in accordance with an embodiment of the present invention.
• Figure 6 is a block diagram of a sensor module assembly in accordance with an embodiment of the present invention.
• Figure 7 is a block diagram of a sensor module interface in accordance with an embodiment of the present invention.
• FIG. 1 illustrates an example of an apparatus 100 for monitoring a condition in a subsurface borehole.
• the apparatus 100 includes an electromagnetically transmissive medium, such as a conductive line 102, for conducting electromagnetic energy through the borehole.
• a conductive line 102 may take different forms or embodiments, depending on the state of the borehole.
• the conductive line 102 may comprise a production tubing string in a completed borehole or a drillstring in a borehole under construction.
• a transformer 104 is provided to couple the conductive pipe to a source of electromagnetic energy. Alternate coupling methods to the transformer 104 may be employed.
• the transmission line may directly couple to a coaxial cable or any other suitable cable.
• the transformer 104 includes a stack of ferrite rings 106, and a wire 108 wound around the rings.
• the wire 108 includes leads 110 that may be coupled to a signal generator 112 which may be configured to produce a pulsed or a continuous wave signal, as necessary or desirable.
• the wire 108 may further be coupled to a receiver 114.
• the receiver 114 may be embodied as a computer that includes a bus for receiving signals from the apparatus 100 for storage, processing and/or display.
• the computer 114 may be provided with a display 118 which may include, for example, a graphical user interface.
• the computer 114 may be programmed to process the received sensor signals to provide a measure of the sensed characteristic.
• the computer 114 may perform any desired processing of the detected signal including, but not limited to, a statistical (e.g., Fourier) analysis of the signal, a deconvolution of the signal, a correlation with another signal or the like.
• a statistical (e.g., Fourier) analysis of the signal e.g., a deconvolution of the signal, a correlation with another signal or the like.
• Commercial products are readily available and known to those skilled in the art that can be used to perform any suitable frequency detection.
• the computer may be provided with a look-up table in memory or in accessible storage, that correlates received modulated signals to sensed conditions in the borehole.
• the borehole will be lined with a borehole casing 120 which is used to provide structural support to the borehole.
• This casing 120 is frequently made from a conductive material such as steel, in which case it will cooperate with the line 102 in order to form a coaxial transmission line, and it is not necessary to provide any additional conductive medium.
• a conductive sleeve (not shown) may be provided within the casing in order to form the coaxial structure.
• the apparatus 100 may include dielectric rings 122 disposed periodically along the conductive line 102.
• the spacers can, for example, be configured as insulated centralizers which can be disks formed from any suitable material including, but not limited to, nylon or polytetrafluoroethylene (PTFE).
• PTFE polytetrafluoroethylene
• the illustrated embodiment makes use of a coaxial transmission line, it is contemplated that alternate embodiments of a transmission line may be employed, such as a single conductive line, paired conductive lines, or a waveguide.
• the casing alone may act as a waveguide for certain frequencies of electromagnetic waves.
• lengths of coaxial cable may be used in all or part of the line. Such coaxial cable may be particularly useful when dielectric fluid cannot be used within the casing 120 (e.g., when saline water or other conductive fluid is present in the casing 120).
• the probe portion may include a port 126 that is configured to communicate ambient pressures and/or temperatures from fluid present in the borehole into the probe where it may be sensed by the sensor (not shown in Figure 1). Below the probe is illustrated a packer 128 and packer teeth 130.
• the AC energy passes through a power transformer 214 and a bridge rectifier 216 to produce DC power at the same DC power out portion of the circuit 208.
• the sensors produce a signal (generally an RF signal) that is accepted at the RF sensor input portion of the circuit 218 and coupled back to the conductive pair for transmission to the surface.
• a signal generally an RF signal
• the inventors have determined that an electrically isolated wellstring would enable better matching of the wellstring impedance with regard to an RF signal being propagated. Additionally, and concurrently, such an isolator would enable the transmission of AC and DC power along the tubing to power functions deeper in the well.
• a passive power switching method and apparatus allows selective application of power to down hole circuits and loads.
• an isolator may be nothing more than a dielectric break in an otherwise solid piece of tubing.
• such an isolator needs to fit within well casings with sufficient clearance, exhibit low end-to-end capacitance, be able to standoff many hundreds of volts of applied potential, and perhaps most importantly, be received by wellsite managers with confidence that it will not fail.
• Built-in failsafe design features may also be useful, or required for acceptance by users.
• a technique for DC isolation includes a ceramic or other non-conductive insulator inserted in series with well tubing. This may be, for example, built-in to a 4 foot section of tubing, commonly referred to as a "sub".
• the ceramic and tubing parts may be clamped together and should be connected without electrically shorting the tubing parts together.
• An insulating coating may be applied to the internal and external surfaces of the assembly as electrical breakdown protection across the gap.
• the RF (sensor signal) and DC (power) connection is made to the tubing thru a common connection, with signal separation handled electronically outside the well.
• Multiple mechanical topologies have been drawn and built. Many have exhibited values of electrical resistance too low for practical use. In practice, isolation values of 2,000 ohms or greater have proven useful.
• FIG. 3 An example of a set-up in accordance with an embodiment of the invention is schematically illustrated in Figure 3.
• the power signal generated at the surface is an AC signal delivered to input 300.
• the AC signal is coupled into the conductor pair via power cores 302 which may be of the ferrite transformer type described above in relation to Figure 1.
• Figure 4 illustrates an alternate approach in which the power signal is a DC signal.
• a primary difference is the use of a transformer which may be, for example, a toroidal transformer made with tape wound cores on the wellstring tubing just below the wellhead and above a set of RF ferrite cores 304.
• a transformer which may be, for example, a toroidal transformer made with tape wound cores on the wellstring tubing just below the wellhead and above a set of RF ferrite cores 304.
• a small number of turns make up the primary of the transformer, with the well tubing making up the secondary winding of the transformer.
• it may be a single turn secondary winding.
• the sensor module 310 and bowspring centralizer 312 used in the DC isolator approach remains unchanged in such an AC application.
• the power signals generated by power supply 318 are provided to the sensor module 310 from the lower transformer 304.
• the sensor module 310 generates communication signals that are transmitted to the lower transformer 304.
• the communication signals are conducted up the tubing string to the upper transformer 302 and then transmitted to the receiver 320 of the surface system 500 (as illustrated in Figure 5).
• the electrical path is completed by grounding the tubing string on unused sides of the upper and lower transformers and by grounding the surface system and sensor module 310.
• the casing is generally grounded.
• the tubing string above the upper transformer may be grounded by coupling the tubing string to the casing through the wellhead.
• the tubing string below the lower transformer 304 may be grounded by connecting the tubing string to the casing via the bowspring centralizer 312, for example.
• the transformers are formed by formed by using the tubing string as one of the windings of each transformer.
• the power signal from the surface system is transmitted to the primary winding of a toroidal transformer positioned around the tubing string.
• the tubing string itself is the single turn secondary winding of the transformer for the power circuit.
• the lower transformer is another toroidal transformer surrounding the tubing string and includes, for the power circuit, a primary winding that is the tubing string itself and a secondary winding that is connected to the sensor module 310.
• signals are transmitted using the same transformers, though (as compared to the power circuit) the roles of the primary and secondary windings in each transformer are reversed.
• the RF impedance, established by the RF magnetics is also affected by the presence of the AC magnetics, which represent a very high impedance to the RF. As such, it may be necessary to provide an electrical path around the AC magnetics to the wellhead for the RF currents travelling up the wellstring from the sensor package 310. In that case, two different electrical connections to the wellhead would be required.
• the power frequencies may be between 5kHz and 200kHz, for example.
• the RF frequencies for data may be between 3MHz and 8 MHz.
• power is supplied in a range between 1 and 10kHz and data is transmitted using a frequency-shift keying modulation scheme at frequencies in the range between 15 and 30kHz.
• Power frequencies above the RF range are, in theory, usable.
• Sensor data frequencies may also be selected outside the foregoing ranges. Because the transmission frequencies of the power and sensor signals are different, it is possible to separate them using filtering at either the surface system 500 and/or at the sensor module 310.
• FIG. 6 is a block diagram of a sensor module 600 assembly in accordance with an embodiment of the present invention. As will be appreciated the sensor module 600 is similar to the arrangement illustrated in Figure 2 and represents an alternate approach to illustrating similar concepts.
• the sensor module 600 connects to the lower transformer by way of a bus 602 that carries both the power signal and the sensor data signal.
• a low pass filter 604 passes the low frequency power signal to the sensor module power circuitry which is made up of a transformer 606, a rectifier 608, and a voltage regulator 610.
• Power is supplied to a microprocessor 612 and to one or more digital gauges 614, each of which may be, for example, a Quartzdyne® gauge, available from Quartzdyne, Inc. of Salt Lake City, UT. Such gauges constitute a quartz resonator and are often packaged along with an
• Output from the gauges 614 is provided to the processor 612 which processes the data and outputs a communication signal through a frequency modulator 616.
• the communication signal is passed back to the tubing string by way of the bus 602 and the lower transformer.
• a high pass filter 618 (which may be a capacitor), in conjunction with the low pass filter 604, isolates the communication signal from the power pathway.
• a bus 702 communicates with the upper transformer 302.
• a serial input 704 obtains power from a power supply, not shown.
• An MPU 706 manages the input power and outputs the power by way of a low pass filter 708, digital attenuator 710, and power amplifier 712.
• a power monitor 714 senses the output power and returns data on the sensed power to the MPU 706.
• a second low pass filter 716 which in the illustrated embodiment is an inductor, passes the power signal to the bus 702 and excludes the higher frequency data signals that are being returned from the sensor module. The data signals instead pass through a high pass filter 718 to a demodulator 720 and thence to the MPU 706.
• Output from the MPU may be passed via an Ethernet connection 722, or other type of connection.
• FIG 8 is a block diagram illustrating an arrangement similar to that illustrated in Figure 4 and represents an alternate approach to illustrating similar concepts. As described above, this approach makes use of ceramic insulated tubing subs in order to isolate a portion of the tubing.
• One insulating sub forms the upper isolator 319 while another forms the lower isolator 321.
• An intermediate tubing portion 802 becomes the transmission line for signals and power in the system.
• the tubing string conducts power signals from a connection point located just below the upper ceramic insulated tubing sub (upper insulator 319) to a connection point located just above the lower ceramic insulated tubing sub (lower insulator 321).
• the power signals are provided to a sensor module/gauge assembly 310 from the connection point located just above the lower insulator 321.
• the sensor module 310 In the reverse direction, the sensor module 310 generates communication signals that are transmitted to the connection point located just above the lower insulator 321.
• the communication signals are conducted up the tubing string to the connection point located just below the upper insulator 319 and then transmitted to the surface system 500. .
• the electrical path is completed by grounding the tubing string above the upper ceramic insulated tubing sub and below the lower ceramic insulated tubing sub and by grounding the surface system and sensor module.
• the casing In practice, the casing is generally grounded.
• the tubing string above the upper ceramic insulated tubing sub may be grounded by coupling the tubing string to the casing through the wellhead.
• the tubing string below the lower ceramic insulated tubing sub may be grounded by connecting the tubing string to the casing via a bowspring shorting centralizer, for example.
• a low frequency 60 hertz AC voltage was transmitted down the cable. It provided about 10 volts DC (out of the rectifier/filter) at the cable terminus.
• An amplified sensor signal (frequency peak) was received at the surface using an HF radio detector. This setup allowed receipt of over 120 readings per second at the surface.
• parameters such as pressure or temperature are measured (singularly or simultaneously) at great depth using the well string hardware as both the path to power the sensors (and other associated devices), and to transport data signals from the sensors.
• this technique uses the same conduction system for both electrical power and the signal path for the parameter data.
• Applied power can be DC and/or AC power at various frequencies to accommodate a multitude of lower powered remote functions or higher powered uses including artificial lifting systems (pumps).
• This technique uses the well tubing and casing as a conductive pair (CP) to carry the power down to the remote, powered sensor set or associated devices. This is
• centralizers such that the conductive pair (tubing and casing) do not electrically short to each other.
• a conductive "packer” or bow-spring centralizer 312 or other mechanism to make contact with the casing to complete the circuit.
• a second use of the CP arrangement of the well hardware described herein is to power an electrical submersible pump (ESP) system for artificial lifting of fluids in the producing zones.
• Electrical power sent to the ESP, via the tubing string, can be used to power attached sensor systems with the signals from those sensors using the same CP as the RF path back to surface instruments.
• methods for commanding various functions down-hole might be accomplished by selecting a specific power frequency that would perform various separate remote operations (i.e. multiple zone valve control, etc.) by using resonant, frequency selective networks at the remote valve location.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Life Sciences & Earth Sciences (AREA)
• Mining & Mineral Resources (AREA)
• Geology (AREA)
• Remote Sensing (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• Geophysics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Electromagnetism (AREA)
• Arrangements For Transmission Of Measured Signals (AREA)
• Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
• Geophysics And Detection Of Objects (AREA)

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• 2011
  • 2011-11-11 CA CA2817593A patent/CA2817593C/en active Active
  • 2011-11-11 BR BR112013011709-5A patent/BR112013011709B1/pt active IP Right Grant
  • 2011-11-11 WO PCT/US2011/060454 patent/WO2012065118A2/en active Application Filing
  • 2011-11-11 MX MX2013005021A patent/MX2013005021A/es active IP Right Grant
  • 2011-11-11 AU AU2011325931A patent/AU2011325931B2/en not_active Ceased
  • 2011-11-11 EA EA201390692A patent/EA025452B1/ru not_active IP Right Cessation
  • 2011-11-11 CN CN2011800541736A patent/CN103221635A/zh active Pending
  • 2011-11-11 EP EP11806009.4A patent/EP2638244B1/en active Active
  • 2011-11-14 US US13/295,784 patent/US20120211278A1/en not_active Abandoned

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