WO2015030743A1 - Système et procédé de détermination de localisation de défaut - Google Patents

Système et procédé de détermination de localisation de défaut Download PDF

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Publication number
WO2015030743A1
WO2015030743A1 PCT/US2013/056965 US2013056965W WO2015030743A1 WO 2015030743 A1 WO2015030743 A1 WO 2015030743A1 US 2013056965 W US2013056965 W US 2013056965W WO 2015030743 A1 WO2015030743 A1 WO 2015030743A1
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WIPO (PCT)
Prior art keywords
fault
input impedance
calibration unit
signal
signals
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PCT/US2013/056965
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English (en)
Inventor
Brian Clark
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Intelliserv, Llc
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Publication of WO2015030743A1 publication Critical patent/WO2015030743A1/fr

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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
    • E21B47/12—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
    • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
    • E21B17/003—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings with electrically conducting or insulating means

Definitions

  • WDP wireless drill pipe
  • a system employing WDP for communication may include hundreds of individual wired drill pipes connected in series. Repeater subs may be interspersed among the WDPs to extend communication range. If one WDP (or repeater sub) has an electrical fault, then the entire communication system may fail.
  • an intermittent fault occurs while drilling, but disappears as the drill string is removed from the borehole.
  • Such intermittent faults may be due to downhole pressures, downhole temperatures, shocks, rotating and bending, or other environmental effects that are not present when the drill pipe is retracted from the wellbore.
  • the fault cannot be traced to within a few joints of WDP, then large sections of WDP may have to be replaced.
  • the repeater subs are spaced apart by 500 meters, then an intermittent fault may only be beatable to within the 500 meter section below the lowest repeater sub known to be operational. This uncertainty in the location of the fault may require large numbers of WDP joints to be available on the drilling rig. Each failure might require 500 meters of drill pipe to be replaced. If the fault only occurs under drilling conditions, then it may be impossible to identify exactly which drill pipe is failing at the rig site. Therefore, it is desirable to locate an intermittent fault while drilling, that is - with the WDP in the borehole.
  • a method includes disposing a drill string comprising a plurality of wired drill pipes in a borehole.
  • the input impedance of the wire drill pipes is measured while drilling.
  • a propagation constant for the wire drill pipes is determined. Based on the input impedance, whether a fault in the wired drill pipe is an open circuit or a short circuit is determined.
  • an apparatus for drilling a borehole in formations includes a drill string comprising a plurality of wired drill pipes, and a wired drill pipe fault monitor coupled to the wired drill pipes.
  • the fault monitor includes an impedance measuring system configured to measure an input impedance of the wired drill pipes while drilling the borehole, and a fault locator.
  • the fault locator is configured to determine a propagation constant for the wired drill pipes.
  • the fault locator is also configured to determine, as a function of the input impedance and the propagation constant, a location of a fault in the wired drill pipes.
  • a fault location system includes a plurality of conductively coupled media sections, impedance measurement electronics, and a fault locator.
  • Each media section includes a length of conductive media and conductive couplers communicatively connected to opposing ends of the conductive media.
  • the impedance measurement electronics is configured to measure an input impedance of the media sections.
  • the fault locator is configured to determine a propagation constant for the media sections, and to analyze the input impedance and determine, as a function of the input impedance and the propagation constant, a location of a fault in the media sections.
  • a channel characterization system includes a first calibration unit, a second calibration unit, a conductive medium coupling the first calibration unit to the second calibration unit, and a processor coupled to the first calibration unit and the second calibration unit.
  • the first and second calibration units are configured to exchange characterization signals via the conductive medium, to measure amplitude and phase of the characterization signal received via the conductive medium from the other calibration unit, and to provide the amplitude and phase measurements to the processor.
  • the processor is configured to determine a propagation constant of the conductive medium based on the measurements.
  • a method for characterizing a communication channel includes splitting, by a first calibration unit, a calibration signal transmitted by a second calibration unit via a conductive medium connecting the first and second calibration units into a first two signals.
  • a first of the first two signals is mixed by the first calibration unit with a first oscillator signal generated by the first calibration unit to produce a first mixed signal.
  • a second of the first two signals is mixed by the first calibration unit with a second oscillator signal generated by the first calibration unit to produce a second mixed signal.
  • the first and second oscillator signals generated by the first calibration unit have a same frequency and quadrature phase offset.
  • a sum of the first of the first two signals and the first oscillator signal is filtered from the first mixed signal to produce a first filtered signal.
  • a sum of the second of the first two signals and the second oscillator signal is filtered from the second mixed signal to produce a second filtered signal.
  • the first filtered signal is integrated over time to generate a first integrated signal.
  • the second filtered signal is integrated over time to generate a second integrated signal.
  • a propagation constant for the conductive medium is computed based on the fist and second integrated signals.
  • Figure 1 shows a drilling system that includes wired drill pipe and wired drill pipe fault location in accordance with principles disclosed herein;
  • Figure 2 shows a longitudinal cross-section of a conductively coupled pair of wired drill pipes in accordance with principles disclosed herein;
  • Figure 3 shows a block diagram of a wired drill pipe fault monitoring system in accordance with principles disclosed herein;
  • Figure 4 shows a schematic diagram of a wired drill pipe impedance measurement system in accordance with principles disclosed herein;
  • Figure 5 shows a transmission line model of wired drill pipe in accordance with principles disclosed herein;
  • Figures 6A and 6B show a block diagrams of a channel characterization system including a pair of repeater subs configured to determine the propagation constant of wired drill pipe connecting the repeater subs in accordance with various embodiments;
  • Figure 7 shows a flow diagram for a method for determining the propagation constant for wired drill pipe in accordance with various embodiments
  • Figure 8 shows a flow diagram for a method for determining the location of a fault in wired drill pipe in accordance with principles disclosed herein;
  • Figure 9A shows a schematic diagram of wired drill pipe cable and contacts for determining attenuation and phase velocity in accordance with principles disclosed herein;
  • Figure 9B shows a graphical depiction of the characteristic impedance of a string of wired drill pipes
  • Figure 10 shows a flow diagram for a method for determining the distance to a fault in wired drill pipe in accordance with principles disclosed herein;
  • Figure 11 shows a plot of real and imaginary parts of wired drill pipe impedance measurement for wired drill pipe including a short circuit in accordance with principles disclosed herein;
  • Figure 12 shows a plot of real and imaginary parts of wired drill pipe impedance measurement for wired drill pipe including an open circuit in accordance with principles disclosed herein;
  • Figure 13 shows normalized input impedance of wired drill pipe in the presence of a short located 100 meters from the fault monitor
  • Figure 14 shows inverted distances to the short versus frequency computed in accordance with principles disclosed herein;
  • Figure 15 shows a flow diagram for another method for determining the distance to a fault in wired drill pipe in accordance with principles disclosed herein;
  • Figure 16 shows normalized input impedance of wired drill pipe in the presence of a short located 500 meters from the fault monitor;
  • Figure 17 shows identification of a zero-crossing in the imaginary part of the normalized impedance to determine distance to the fault in accordance with principles disclosed herein;
  • Figure 18 shows a flow diagram for yet another method for determining the distance to a fault in wired drill pipe in accordance with principles disclosed herein;
  • Figure 19 shows normalized input impedance of wired drill pipe in the presence of a short located 2000 meters from the fault monitor
  • Figure 20 shows normalized impedance data fit to impedance functions in accordance with principles disclosed herein.
  • FIG 1 shows a drilling system 100 that includes wired drill pipe (WDP) 118 and wired drill pipe fault location in accordance with principles disclosed herein.
  • WDP wired drill pipe
  • a drilling platform 102 supports a derrick 104 having a traveling block 106 for raising and lowering a drill string 108.
  • a kelly 110 supports the drill string 108 as it is lowered through a rotary table 112.
  • a top drive is used to rotate the drill string 108 in place of the kelly 110 and the rotary table 112.
  • a drill bit 114 is positioned at the downhole end of the tool string 126, and is driven by rotation of the drill string 108 or by a downhole motor (not shown) positioned in the tool string 126 uphole of the drill bit 114. As the bit 114 rotates, it removes material from the various formations 136 and creates the borehole 116.
  • a pump 120 circulates drilling fluid through a feed pipe 122 and downhole through the interior of drill string 108, through orifices in drill bit 114, back to the surface via the annulus 140 around drill string 108, and into a retention pit 124. The drilling fluid transports cuttings from the borehole 116 into the pit 124 and aids in maintaining the integrity of the borehole 116.
  • the drill string 108 includes a plurality of lengths (or joints) of wired drill pipe 118 that are communicatively coupled end-to-end.
  • a surface sub 130 communicatively couples the wired drill pipes 118 to surface processing systems, such as the drilling control/analysis computer 128.
  • the drill string 108 may also include a bottom hole assembly (BHA) interface 134 and repeater subs 132.
  • BHA interface 134 communicatively couples the WDP 118 to the tool of the bottom hole assembly.
  • the repeater subs 132 are interspersed among with the wired drill pipes 118, and may boost the WDP signal transmitted through the drill string 108.
  • the spacing between the repeater subs 132 may be related to the efficiency (i.e.
  • Repeater subs 132 may be individually addressable, so that a command can be sent from the surface computer 128 to a selected repeater sub 132. In response to the command, the selected repeater sub 132 may transmit an acknowledgement to the surface computer 128.
  • Such individual addressability and command/response protocol can be used to verify that the WDPs 118 (i.e., the WDP system) are working correctly between the surface and the selected repeater sub 132.
  • FIG. 2 shows a longitudinal cross-section of a mated pair of wired drill pipes 118 (or a sub 130, 132, 134 and a WDP 18) in accordance with principles disclosed herein
  • Each WDP 1 18 includes a communicative medium 202 (e.g., a coaxial cable, twisted pair, etc.) structurally incorporated or embedded over the length of the pipe 1 18, and an interface 206 at each end of the pipe 118 for communicating with an adjacent pipe 1 18, sub, or other component.
  • the communicative medium 202 is connected to each interface 206.
  • the interface 206 may include a conductive contact 204 (e.g., an annular conductive contact) for forming a conductive connection with the adjacent component.
  • the conductive contact 204 may be embedded in insulating material (i.e., insulator) 208.
  • Figure 2 shows a pin end 210 of a first wired drill pipe 1 18 mated to a box end 212 of a second wired drill pipe 1 18 such that conductive contacts 204 of the wired drill pipes 1 18 electrically connect the cables 202 of the two wired drill pipes 118.
  • the high bandwidth of the wired drill pipes 1 18 allows for transfers of large quantities of data at a high transfer rate.
  • the cable 202 that links the two ends of the wired drill pipe 1 18 has well defined electrical properties, such as characteristic impedance, phase velocity, and attenuation that may be relatively independent of frequency. Because the contacts 204 are short compared to the cable 202, the reactive effects of the contacts 204 are small. The contacts 204 modify the properties of WDP 118 such that there are only relatively benign effects on the WDP transmission line properties.
  • the contacts 204 can affect the WDP transmission properties through hard failures or soft failures.
  • Common hard failure modes for WDPs 118 include an open circuit and a short circuit.
  • An open circuit may be due to a gap between the two contacts 204, a break in the cable 202, or a bad connection between the cable 202 and the contact 204.
  • An open circuit is represented by a high equivalent load impedance (e.g., thousands of ohms).
  • a short circuit may be due to mechanical failure of the insulation 208 between the contact 204 and the drill pipe 1 18. a mechanical failure of the connection between the contact 204 and the cable 202, or by a metal wire or metal flake bridging the insulation between the contact 204 and the shoulder of the drill pipe 1 18.
  • a short circuit is represented by a low equivalent load impedance (e.g., zero ohms). Such hard failures may be induced by harsh downhole conditions.
  • An intermittent open circuit caused by shock is a common type of fault in the WDPs
  • Soft failures can cause excessive attenuation that results in lost communication. Soft failures may be caused by poor electrical connection between contacts 204 of adjacent WDPs 118, or due to a conductive path between a contact 204 and the drill pipe 118. High contact resistance between two contacts 204 might result from corrosion, dried mud, lost circulation material, sand, or other debris on the faces of the contacts 204. A low shunt resistance between the contact 204 and the drill pipe 118 might result from conductive drilling fluids and gaps between the insulators 208.
  • Embodiments of the drilling system 100 are configured to precisely locate faults in the wired drill pipes 118 of the drill string 108.
  • Figure 3 shows a block diagram of a wired drill pipe fault monitoring system 300 in accordance with principles disclosed herein.
  • the fault monitor 300 may be disposed in whole or in part in the repeaters subs 132, the surface sub 130, and/or the BHA interface 134 for locating faults in the joints of wired drill pipe 118 uphole or downhole of the fault monitor 300.
  • the surface computer 128 may implement a portion of the fault monitor 130.
  • embodiments of the drilling system 100 can locate a fault in wired drill pipes 118 from two directions, thereby improving fault location accuracy.
  • Embodiments of the fault monitoring system 300 locate a fault to within a few drill pipes 118. Thus, embodiments require that only a few drill pipes be removed from the drill string, thereby reducing the time and expense associated with correcting a fault in wired drill pipe 118.
  • Embodiments are also applicable to locating faults in various other types of conductive communication systems that employ multiple sections of conductively coupled media with conductive couplers disposed at terminal ends of each section.
  • the fault monitor 300 includes WDP interface 302, impedance measurement system 304, and fault locator 306.
  • the WDP interface 302 connects the impedance measurement system 304 to the cable 202 and/or the contacts 204 of the sub including the fault monitor 300 (e.g., the repeater sub 132).
  • the WDP interface 302 may selectively and/or periodically connect the impedance measurement system 304 to the cable 202 and/or the contacts 204 via, for example, switches or relays, in other embodiments, the WDP interface 302 may fixedly connect the impedance measurement system 304 to the cable 202 and/or the contacts.
  • the impedance measurement system 304 includes electronic circuitry that measures the impedance of a section of wired drill pipes 118 connected to, and either uphole or downhole of, the fault monitor 300.
  • Figure 4 shows a schematic diagram of a wired drill pipe impedance measurement system 304 in accordance with principles disclosed herein.
  • the WDP impedance measurement system 304 includes a signal generator 402, a resistor 404, and one or more vector voltmeters 406.
  • the signal generator 402 produces an oscillating signal of frequency / , and angular frequency ⁇ - 2 ⁇ .
  • the signal generator 402 may produce frequencies over the entire transmission bandwidth of the WDP 1 18.
  • the section of WDPs 118 driven by the impedance measurement system 304 is assumed to have a characteristic impedance ⁇ ) , and is terminated by a load impedance Z t ⁇ ) .
  • the voltage input to the WDP section is V IN .
  • Both V R and V IN may be measured using the vector voltmeters 406.
  • the input impedance can be obtained from:
  • the WDP impedance ⁇ ( ⁇ ) is obtained from measuring ⁇ / ⁇ ( ⁇ ) with the impedance measurement system 304.
  • the fault monitor 300 may measure ⁇ ⁇ ( ⁇ ) periodically during drilling for at least two reasons. First, if the input impedance is unchanged and equal to that expected for WDPs 1 18, then the WDP system is functioning correctly. Accordingly, the values of ⁇ ⁇ ⁇ ) should be recorded over the telemetry bandwidth for future reference. Second, if the input impedance begins to significantly change, then the properties of the WDP system are being adversely affected by downhole conditions. Such change in impedance is an indication of a developing problem. If the telemetry signal becomes noisy, is intermittent, or fails altogether, then there is a fault somewhere in the WDPs 1 18.
  • the fault locator 306 collects the impedance measurements provided by the impedance measurement system 304, determines, based on the measurements and other indications of telemetry problems (e.g., discontinuation of communication with other repeater subs, etc.), whether a fault is present in the section of WDPs 118 adjacent to the fault monitor 300, and determines a location of the fault.
  • the fault locator 306 includes processor(s) 308 and storage 310.
  • the processor(s) 308 may include, for example, one or more general-purpose microprocessors, digital signal processors, microcontrollers, or other suitable instruction execution devices known in the art.
  • Processor architectures generally include execution units (e.g., fixed point, floating point, integer, etc.), storage (e.g., registers, memory, etc.), instruction decoding, peripherals (e.g., interrupt controllers, timers, direct memory access controllers, etc.), input/output systems (e.g., serial ports, parallel ports, etc.) and various other components and sub-systems.
  • execution units e.g., fixed point, floating point, integer, etc.
  • storage e.g., registers, memory, etc.
  • instruction decoding e.g., peripherals, interrupt controllers, timers, direct memory access controllers, etc.
  • input/output systems e.g., serial ports, parallel ports, etc.
  • the storage 310 is a non-transitory computer-readable storage device and includes volatile storage such as random access memory, non-volatile storage (e.g., a hard drive, an optical storage device (e.g., CD or DVD), FLASH storage, read-only- memory), or combinations thereof.
  • the storage 310 includes impedance measurements 314, propagation constant logic 312, and fault distance evaluation logic 316 and various data processed by and produced by the processor(s) 308.
  • the impedance measurements 314 include WDP impedance values generated by the impedance measurement system 304.
  • the propagation constant logic 312 includes instructions for determining a propagation constant value useable for determining the location of a fault in the WDPs 118.
  • the fault distance evaluation logic 316 includes instructions for determining a distance from the fault monitor 300 to a fault in the WDPs 118 based on the impedance measurements and the propagation constant. Processors execute software instructions. Software instructions alone are incapable of performing a function. Therefore, any reference herein to a function performed by software instructions, or to software instructions performing a function is simply a shorthand means for stating that the function is performed by a processor executing the instructions.
  • FIG. 5 shows a transmission line model of wired drill pipes 118 in accordance with principles disclosed herein.
  • a fault develops at a point 502 at distance L from a measurement point 504 (e.g., the location of fault monitor 300).
  • the fault can be represented as a terminating impedance, Z t , on the section of WDP 118 transmission line.
  • Z t terminating impedance
  • a tten 8.686 ⁇ , (4) and the imaginary part ⁇ ) is related to the phase velocity ⁇ ' f , (c ) and angular frequency by:
  • ⁇ is nearly a linear function of frequency, while a is relatively independent of frequency.
  • the propagation constant ⁇ can be determined in a variety of ways. For example, ⁇ may be calculated from the known physical properties of the cable 202, the contacts 204, and the insulators 208. Alternatively, ⁇ may be directly measured by transmitting a signal of known phase and amplitude at one end of a WDP 1 18 and measuring the phase and amplitude at the other end of the WDP 1 18. Such measurement may be performed at the surface using a network analyzer as is well known. A system and method for accurately measuring the propagation constant ⁇ while the WDP 1 18 is in the borehole 1 16 is described herein. The fault monitor 300 determines ⁇ ⁇ ) as a function of frequency.
  • the normalized input impedance measured by the fault monitor 300 at point 504 is defined as:
  • Some embodiments of the drilling system 100 determine the propagation constant ⁇ of the WDP 1 18 via a process that includes transmitting sinusoidal signals between two calibration subs coupled to the wired drill pipes 1 18.
  • the calibration subs may be included in the WDP repeater subs 132.
  • the calibration subs measure the phase and amplitude of the sinusoidal signals propagated in both directions, and, based on the measurements, provide amplitude and phase information from which attenuation, phase velocity, and group velocity of the WDP 1 18 may be computed.
  • the calibration subs 602 may be disposed at opposing ends of the drill string 108 (e.g., a sub at the surface and a sub at the BHA 134, rather than included in WDP repeater subs 132.
  • Figures 6A and 6B show block diagrams of a pair of repeaters subs 132 (132A, 32B) configured to determine the propagation constant of the WDP 1 18 disposed between the repeater subs 132. That is, the repeater subs 132A, 132B include calibration subs 602, the blocks of which are shown in Figures 6A and 6B.
  • repeater subs 132A, 132B may include similar circuitry.
  • repeater sub 132A transmits sinusoidal signal to repeater sub 132B via WDP(s) 1 18, consequently, only a portion of the circuitry of repeater sub 132A is shown.
  • Repeater sub 132B processes the received sinusoidal signal and produces information that can be used to determine channel parameters.
  • Each repeater sub 132A, 132B includes an oscillator 612, mixers 604 (604A, 604B), low pass filters 606 (606A, 606B), analog-to-digital converters 608 (608A, 608B), and a processor 610.
  • a single filter 606, digitizer 608, or other component may be shared by the two signal paths.
  • the processor 610 may be remote from a repeater sub 132A, 132B in some embodiments.
  • the processor 610 may be disposed at the surface, and WDP channel characterization information may be transmitted to processor 610 at the surface by the repeater subs 132A, 132B via WDP telemetry.
  • the processor 610 may be included in the processor(s) 308.
  • the oscillator 612 provides a stable frequency source that allows the repeater sub 132A, 132B to generate a sinusoidal signal at frequencies of interest over the WDP transmission channel.
  • the oscillator 612 may be a dual-mode quartz oscillator suitable for downhole operation. Such oscillators may be accurate to 0.1 parts-per-million (ppm) and have a resolution of 0.2 ppb, and be qualified to 185° Celsius. Some embodiments may apply software correction to achieve even higher oscillator accuracy (e.g. , 10 ppb to 40 ppb).
  • the imaginary part of ⁇ is related to the phase velocity V p via equation (6).
  • the group velocity is related to ⁇ ( ⁇ ) c)co
  • the group velocity can be determined by measuring ⁇ at adjacent angular ⁇
  • repeater sub 132A generates a signal V sin( y + (9, ) , where V is a known voltage.
  • V is a known voltage.
  • the repeater sub 132A can measure the voltage ⁇ .
  • the angular frequency ⁇ ⁇ of the oscillator 612 is also known to a given accuracy.
  • the repeater subs 132A, 132B may be sufficiently well matched to the WDP transmission line impedance that there are only negligible reflections.
  • the repeater sub 32B is configured to receive the signal transmitted by the sub 132A.
  • the frequency of the oscillator 612 of the sub 132B is set to an angular frequency ⁇ 2 .
  • ⁇ 2 - ⁇ ® Preferably, but there may be a small angular frequency difference
  • the repeater sub 132B splits the received signal into two equal signals ⁇ V ⁇ e ' aL sin( ⁇ 3 ⁇ 4> - ⁇ + ( ) and provides one of the two signals to each of the mixers
  • the osciiiator 612 of the sub 132B provides mixer 604A with a signal V sin(a) 2 t + ⁇ 2 ) , and provides mixer 604B with a signal V cos(a> 2 t + ⁇ 2 ) .
  • Mixer 604A mixes
  • the output of mixer 604A is provided to the low pass filter 606A.
  • the low pass filter 606A blocks the high frequency term ⁇ + ⁇ 2 and passes the low frequency term
  • Mixer 604 B mixes V ] e 'aL sm(c - ⁇ + 6> ) and F cos(.3 ⁇ 4 + ⁇ 2 ) producing:
  • the output of mixer 604B is provided to the low pass filter 606B.
  • the low pass filter 606B blocks the high frequency term ⁇ ⁇ + ⁇ 2 and passes the low frequency term
  • Signals p 2 (t) and ⁇ r 2 (i) are digitized by the A/D converters 608A and 608B, and the digitized signals are provided to the processor 610 for further processing.
  • characterization data is acquired using signal propagating in the opposite direction along the WDP 118 (e.g., downhole to upho!e).
  • repeater sub 132B is downhole from repeater sub 132A and the signals p 2 (t) and a 2 (t) described above have been acquired by propagating signal from repeater sub 132A downhole to 132B.
  • the oscillators 812 continue to operate at the same angular frequencies, ⁇ and co 2 and with the same phases, ⁇ ⁇ and ⁇ 2 .
  • the repeater sub 132B generates the signal V 2 sin( ⁇ y 2 t + 0 2 ) .
  • the voltage V 2 can be either set to a specific value or measured in the repeater sub 132B, and the voltage value digitally transmitted to the repeater sub 132A.
  • the upward propagating wave on the WDP transmission line at any location x and any time / is V 2 e a(x ⁇ L) sm( 2 t + ⁇ ( ⁇ - L) + 0 2 ) .
  • the signal received at the repeater sub 132A is V 2 e ⁇ aL ⁇ ( ⁇ 2 ⁇ - ⁇ + ⁇ 2 ) .
  • the repeater sub 132A splits the received signal into two equal signals
  • 604A mixes ⁇ V 2 e ' aL ⁇ ⁇ 2 ⁇ - ⁇ + ⁇ 2 ) and + producing:
  • Mixer 604 ⁇ mixes ⁇ V 2 e " L sm(a> 2 t ⁇ ⁇ + ⁇ 2 ) and Vcos((o i + 0 x ) producing;
  • the outputs of the mixers 604A, 604B are provided to the low pass filters 606A, 606B. From the mixer output data, the low pass filters 606A, 606B respectively produce t-, ( ) .. I V,e ⁇ aL sin ( ⁇ - ⁇ + ⁇ 2 - ⁇ ⁇ ) . (20) 4
  • Signals S 2 (t) and s 2 (t) are digitized by the A/D converters 608A and 608B, and the digitized signals are provided to the processor 610 for further processing.
  • the instantaneous values /3 ⁇ 4(/) , a 2 (t) , S 2 (t) and ⁇ 2 ( ⁇ ) are integrated using integration circuitry ahead of the A/D converters 608A and 608B or by the processor 610 using a measurement time series. If a first repeater sub 132A is transmitting sinusoidal signal to a second repeater sub 132B during time t ⁇ [ , 0] , and the second repeater sub 132B is transmitting sinusoidal signal to a first repeater sub 132A during time i e [0j] , then integration of each of p, (t) , ⁇ 2 ( ⁇ ) , S 2 ⁇ t) and ⁇ ,( ⁇ ) produces:
  • Embodiments may let , ⁇ ] - ⁇ 2 - ⁇ , and set the variable of integration to u ⁇ + ⁇ , resulting in: P 3
  • the ratio remains close to unity for small values of ACOT . Since the oscillators 612 are very close in frequency, ⁇ « ⁇ 1 can be achieved.
  • CF 3 is similarly integrated:
  • embodiments may let ⁇ 2 ⁇ ⁇ - ⁇ 2 + ⁇ , and set the variable of integration to u ⁇ 0) ⁇ + ⁇ , resulting in:
  • embodiments generate a (i.e., the 3al part of ⁇ ) by combining terms p 3 and ⁇ 3 .
  • embodiments may generate a by combining terms S ⁇ and
  • Both ⁇ 3 ⁇ 4 and 3 ⁇ 4 include the term ⁇ ] - ⁇ 2 + ⁇ + ⁇ 12 .
  • the signs of ⁇ and & ⁇ ⁇ 2 change with respect to the phase difference ( ⁇ - ⁇ 2 ).
  • embodiments can eliminate the phase difference by combining expressions for the two directions of signal propagation.
  • embodiments To determine the imaginary part ⁇ of the propagation constant ⁇ , embodiments form the ratios: -- 1 - tarsi
  • Figure 7 shows a flow diagram for a method 700 for determining the propagation constant for WDP 1 18 in accordance with various embodiments. Though depicted sequentially as a matter of convenience, at least some of the actions shown can be performed in a different order and/or performed in parallel. Additionally, some embodiments may perform only some of the actions shown.
  • the operations of the method 700 can be performed by the drilling system 100. In some embodiments, at least some of the operations of the method 700, as well as other operations described herein, can be performed by a processor executing instructions stored in a computer readable medium.
  • the drill string 108 comprising WDPs 118
  • the borehole 116 is disposed in the borehole 116.
  • Two or more calibration subs 602 are coupled to the drill string 108.
  • the calibration subs 602 cooperatively characterize the WDPs 1 18 to determine the propagation constant ⁇ .
  • the calibration subs 602 are included in the WDP repeater subs 132.
  • Other embodiments position the calibration subs 602 at various locations in the drill string 118.
  • the method 700 is described with reference to an embodiment of the WDP repeater sub 132 that includes the calibration sub 602.
  • two repeater subs 132A and 132B are configured to exchange sinusoidal signal transmissions via the WDP 118.
  • the frequencies and phases of the signals to be exchanged are set. Signal frequency and phase may, for example, be set via command from the surface or preprogrammed into the repeater subs 132.
  • the oscillators 612 of the repeater subs 32, which generate the set frequencies, may not generate precisely the same frequencies.
  • a first of two repeater subs 132A transmits sinusoidal signal to the second of the repeater subs 132B via the WDP 118.
  • the first of the repeater subs 132A may be, for example, uphole from the second repeater sub 132B.
  • the second repeater sub 132B receives the sinusoidal signal transmitted by the first repeater sub 132A and splits the received signal into two identical copies. One of the copies is provided to each of two mixers 604 of the second repeater sub 132B. Each mixer 604 mixes the received sinusoidal signal with one of two sinusoidal signals generated by the oscillator 612 of the second repeater sub 132B. The two sinusoidal signals provided by the oscillator 612 of the second repeater sub 132B (one to each mixer 604) are offset in phase by 90°. The mixers 604 produce output signals in accordance with equations (10) and (13).
  • the signals generated by the mixers 604 are filtered by the low pass filters 606.
  • the low pass filters 606 eliminate or reduce high frequency components of the mixer output signals to produce signal outputs in accordance with equations (11 ) and
  • the low pass filtered signals are integrated over time.
  • Embodiments may perform the integration before or after the filtered signals are digitized by the AID converters 608 in block 712.
  • Embodiments integrate the filtered signals in accordance with equations (21)-(24), (28), (32), (35), and (38).
  • the second repeater sub 132B may transmit the digitized integrated signal to the first repeater 132A or to a processor 610 disposed at the surface or in the drill string 108.
  • the two repeater subs 132 are reconfigured such that the second repeater sub 132B transmits sinusoidal signal to the first repeater sub 132A via the WDP 118.
  • the frequency and phase of the sinusoidal signal transmitted remains unchanged from the setting applied in block 702.
  • the first repeater sub 132A receives the sinusoidal signal transmitted by the second repeater sub 132B and splits the received signal into two identical copies. One of the copies is provided to each of two mixers 604 of the first repeater sub 132A. Each mixer 604 mixes the received sinusoidal signal with a signal generated by the oscillator 612 of the first repeater sub 132A. The two sinusoidal signals provided by the oscillator 612 of the first repeater sub 132A (one to each mixer 604) are offset in phase by 90°. The mixers 604 produce output signals in accordance with equations (16) and (18).
  • the signals generated by the mixers 604 are filtered by the low pass filters 606 of the first repeater sub 132A.
  • the low pass filters 606 of the first repeater sub 132A eliminate or reduce high frequency components of the mixer output signals to produce signal outputs in accordance with equations (19) and (20).
  • the low pass filtered signals are integrated over time.
  • Embodiments may perform the integration before or after the filtered signals are digitized by the A/D converters 608 of the first repeater sub 132A in block 722.
  • Embodiments integrate the filtered signals in accordance with equations (23), (24), (35), and (38).
  • the first repeater sub 132A may transmit the digitized integrated signal to the second repeater 132B or to a processor 610 disposed at the surface or in the drill string 108.
  • the low pass filtered signals are integrated over time.
  • Embodiments may perform the integration before or after the filtered signals are digitized by the A/D converters 608 in block 722.
  • the processor 610 computes the propagation constant of the WDP 1 18 based on the information provided by the first and second repeater subs 132.
  • the processor 610 computes the propagation constant in accordance with equations (40), (41), and (46A).
  • phase difference between the two oscillators 612 may be determined by adding equations (44) and (45):
  • phase difference can be set to 0 degrees by adjusting the phase of one or the other oscillator 612.
  • synchronizing the phases of two oscillators can be used to synchronize the frequencies of the two oscillators.
  • Two synchronized oscillators can then be used as clocks for measurements requiring accurate timing.
  • An example of a measurement requiring synchronized oscillators is measuring the arrival times of seismic signals at two physically separated locations.
  • the fault monitor 300 when the fault monitor 300 detects a fault in WDP 118, the nature of the fault (whether it is an open, a short, or some other in- between value) and the location of the fault are unknown.
  • the propagation constant ⁇ ) the WDP characteristic impedance ⁇ ) (from measurements before the fault occurs), and the input impedance Z IN ⁇ co) (from measurements after the fault has occurred) are known.
  • the normalized input impedance ⁇ ( ⁇ ) Z [N ( ⁇ ) I ⁇ ( ⁇ ) is also known. These known quantities are complex numbers, and they are functions of frequency, but the distance L f to the fault is a real number and is not a function of frequency. Additionally, if the fault is either an open or a short, then the reflection coefficient r is a real number and it is not a function of frequency.
  • Figure 8 shows a flow diagram for a method for determining the location of a fault in wired drill pipe in accordance with principles disclosed herein. Though depicted sequentially as a matter of convenience, at least some of the actions shown can be performed in a different order and/or performed in parallel. Additionally, some embodiments may perform only some of the actions shown.
  • the operations of the method 800 may be performed by the fault monitor 300. At least some of the operations of the method 800 can be performed by the processor 308 executing instructions read from a computer-readable medium (e.g., storage 310).
  • the drill string 08 is disposed in the borehole 1 16.
  • the drill string 08 includes a downhole communication network comprising WDPs 1 18 and one or more WDP fault monitors 300. Proper operation of the WDPs 1 18 is verified, for example, by validation of information packets transferred through the WDP or validation of an expected input impedance.
  • the fault monitor 300 determines a propagation constant for the WDPs 1 18. Some embodiments of the fault monitor 300 may compute the propagation constant as:
  • D is the length of a joint of the WDP 1 18, estimated to be the length of the cable 202 in the joint of WDP 8;
  • 0 is the known characteristic impedance of the cable 202
  • ⁇ 0 is the known propagation constant of the cable 202.
  • Z p , and z are impedances of the WDP 1 8 as shown in schematic diagram of Figure
  • the cable 202 is represented by the transmission line between points 902 and 904.
  • the pair of contacts 204 is represented by the circuit elements between points 904 and 906.
  • the pair of contacts 204 represents the box of one joint of WDP 1 18 and pin of another joint of WDP 118.
  • the values for L , R , C , and S may be obtained from measurements or may be calculated from the known geometry of the contacts 204 and insulators 208.
  • other methods may be used to estimate the propagation constant by analytical, numerical, or experimental methods.
  • the characteristic impedance z for the string of WDPs 1 18 may be calculated using the principle of transiational symmetry.
  • the input impedance z at point 902 must be the same as the input impedance to the next joint of WDP 1 18, also represented by z at point 906. Equating the impedances at points 902 and 906, and incorporating the cable 202 and circuit elements z s and Z p , produces a set of equations that can be solved to obtain the characteristic impedance Z in terms of known quantities. Once z has been obtained, the voltages, currents, and power levels, can be calculated as well as the propagation constant.
  • FIG. 9B An example of the characteristic impedance for a string of WDPs 118 is shown in Figure 9B.
  • WDP 1 18 is operating correctly. When ⁇ ⁇ ⁇ ) ⁇ ) , it indicates that a fault has occurred.
  • the impedance measurement system 304 measures the input impedance of the wired drill pipes 118 coupled to the fault monitor 300.
  • the impedance measurement system 304 measures the input impedance of the WDPs 1 18 for a plurality of angular frequencies ⁇ spanning the bandwidth of the WDPs 118. The measurement may be made at least once when a new joint of WDP 1 18 is added to the drill string 108.
  • the input impedance may be measured for section of WDPs 118 that is separated by fault monitors 300 (e.g., repeater subs 132 that include a fault monitor 300) so that all sections of WDP 1 18 are characterized.
  • the verification may include validating continued telemetry function (e.g., transmitting an information packet through the WDPs 118 and validating that the packet is received without error), and/or that the measured input impedance is within predetermined limits (e.g., limits based on the resolution or random noise of the WDP telemetry system). If the WDPs 118 are operating properly in block 610, then the impedance measurement is periodically repeated in block 606.
  • validating continued telemetry function e.g., transmitting an information packet through the WDPs 118 and validating that the packet is received without error
  • predetermined limits e.g., limits based on the resolution or random noise of the WDP telemetry system
  • fault distance evaluation logic 316 is applied to compute, as shown in equation (7), and record the normalized input impedance in block 812.
  • the measured impedance values may be stored in the sub (e.g., sub 132, 134) for retrieval when the drill string is extracted from the borehole 116.
  • the fault monitor 300 computes the location of the fault.
  • the fault monitor may apply one or a combination of techniques disclosed herein to compute the distance to the fault, where the distance from the fault monitor 300 to the fault identifies the location of the fault.
  • the location determination may be performed at the surface using impedance measurements stored in the sub (e.g., sub 132, 134), or retrieved from the sub that performed the location determination for WDPs 118 uphole of the sub, where a fault prevented transmission of information from the sub.
  • the fault monitor may transmit impedance measurements, and/or location determinations to the surface.
  • embodiments may employ fault location determinations from both uphole and downhole of the fault to improve location accuracy.
  • the fault monitor 300 has determined the location of the fault to within a few joints of WDP 118.
  • the drill string 108 is extracted from the borehole 1 16, and the WDP 118 at the determined fault location is removed from the drill string 1 16 and replaced.
  • FIG. 10 shows a flow diagram for a method 800 for determining the distance to a fault in wired drill pipes 1 18 in accordance with principles disclosed herein. Though depicted sequentially as a matter of convenience, at least some of the actions shown can be performed in a different order and/or performed in parallel. Additionally, some embodiments may perform only some of the actions shown. At least some of the operations of the method 1000 can be performed by the processor 308 executing instructions read from a computer-readable medium (e.g., storage 310). The method 1000 may be applied alone or in combination with other fault distance determination disclosed herein to compute the location of a fault in block 614 of the method 800. [0100] In block 1002, the fault monitor 300 has determined that a fault is present in the wired drill pipes 1 18. The fault location monitor 300 determines whether the fault is an open circuit or a short circuit by analyzing the imaginary part of the measured input impedance at low frequencies.
  • Figure 11 are based on equation (7) and typical values for characteristic impedance, phase velocity, and attenuation for WDP 1 8.
  • ⁇ ⁇ ) and ⁇ "( ⁇ ) vary with frequency, indicating that a fault has occurred. Because ⁇ " > o at low frequencies (e.g.,
  • FIGS 11-12 an open circuit and a short circuit have different characteristics versus frequency.
  • the sign of ⁇ " indicates whether the fault is a short " > 0 , or an open ⁇ " ⁇ 0 .
  • a short circuit looks like an inductive load jcoL at low frequencies, while an open circuit looks like a capacitive load -j /( oC) .
  • the fault monitor 300 computes the distance to the fault based on whether the fault is determined to be a short circuit or an open circuit. Equation (7) is inverted to find the apparent distance, ⁇ ( ⁇ ) , to the fault.
  • the propagation constant ⁇ ) ⁇ ( ⁇ ) + ; ⁇ ( ⁇ ) in equation (48) is assumed to be known from measurements or from modeling.
  • the normalized impedance ⁇ ) - ⁇ '( ⁇ ) + ⁇ " ⁇ ) is obtained using vector voltmeter 406.
  • r ⁇ 1 . Consequently, when the fault is a short, when the fault is an open,
  • the explicit frequency dependence is shown as a reminder that the estimated distance to the fault can be a function of frequency when measurement errors are present.
  • equation (50) (impedance) and ⁇ ( ⁇ ) (propagation constant) in equation (50) to compute the distance to the fault.
  • Figures 11 and 12 do not have any noise superimposed on the measurements and thus equations (49) and (50) give accurate results for the distances to the faults.
  • the fault monitor 300 analyzes the computed distance to the fault over frequency, and determines whether the computed distance to the fault remains relatively constant over the frequency range (e.g., the bandwidth of the WDP 1 18).
  • the fault monitor 300 im roves the estimate of the distance to the fault by computing an average of the distances computed over a selected frequency range
  • Such averaging may be applied to reduce the effects of random noise on the distance determination.
  • random noise with a standard deviation of 1 ohm is added to the input impedance ⁇ ⁇ ⁇ ) .
  • a short circuit is located 100 meters below the fault monitor 300.
  • the input impedance before the fault occurs is approximately 40 ohms.
  • the resulting normalized input impedance ⁇ ⁇ ) with the short is shown in Figure 13. Since " > 0 , one can deduce that the fault is a short circuit and therefore equation (49) applies.
  • Figure 14 shows the inverted distances to the fault versus frequency using equation (49) applied at each frequency. The estimated distances from individual frequencies are very noisy, but the average value for the distance is very close to 100 meters.
  • Figure 15 shows a flow diagram for an alternative method 1500 for determining the distance to a fault in wired drill pipes 1 18 in accordance with principles disclosed herein. Though depicted sequentially as a matter of convenience, at least some of the actions shown can be performed in a different order and/or performed in parallel. Additionally, some embodiments may perform only some of the actions shown. At least some of the operations of the method 1500 can be performed by the processor 308 executing instructions read from a computer-readable medium (e.g., storage 310). The method 500 may be applied alone or in combination with other fault distance determination disclosed herein to compute the location of a fault in block 614 of the method 800.
  • a computer-readable medium e.g., storage 310
  • the fauit monitor 300 has determined that a fault is present in the wired drill pipes 118.
  • the fault monitor 300 determines whether the fault is an open circuit or a short circuit by analyzing the imaginary part of the measured input impedance at low frequencies as explained herein with regard to block 002 of method 1000.
  • Figure 16 is an example of the normalized impedance ⁇ ( ⁇ ) where a short is located 500 meters from the fault monitor 300.
  • the fault monitor 300 identifies one or more zero crossings in the imaginary part, ⁇ "( ⁇ ) , of the normalized impedance of the wired dill pipes 118.
  • Some embodiments of the fault monitor 300 may least squares fit a line to ⁇ "(a>) about the zero crossing to identify the frequency of the zero crossing.
  • An example of a linear fit to data is shown in Figure 17. It is sufficient to measure the normalized impedance around such zero crossings to estimate the distance to a fault.
  • equation (54) can be solved for the distance to the fault L f . There are multiple solutions to equation (54) corresponding to zeros on the tangent function.
  • the fault monitor 300 applies the solutions to equation (54), in block 1506, to compute the estimated distance to the fault:
  • the fault monitor 300 averages a plurality of values of Z 7J to improve the estimate of the distance to the fault. Using the zero crossings of ⁇ ' ⁇ ) to determine the distance to a fault provides a very robust distance computation with the additional advantage of requiring data at only a few discrete data points at frequencies surrounding the zero crossing. If the fault monitor 300 determines that the fault is so close to the fault monitor 300 that there are no zero crossings in the bandwidth, then the method 800 may be applied to determine distance to the fault.
  • Figure 18 shows a flow diagram for another method 1800 for determining the distance to a fault in wired drill pipes 1 18 in accordance with principles disclosed herein. Though depicted sequentially as a matter of convenience, at least some of the actions shown can be performed in a different order and/or performed in parallel. Additionally, some embodiments may perform only some of the actions shown. At least some of the operations of the method 1800 can be performed by the processor 308 executing instructions read from a computer-readable medium (e.g., storage 310). The method 1800 may be applied alone or in combination with other fault distance determination disclosed herein to compute the location of a fault in block 614 of the method 800.
  • a computer-readable medium e.g., storage 310
  • the fault monitor 300 has determined that a fault is present in the wired drill pipes 1 18.
  • the fault location monitor 300 determines whether the fault is an open circuit or a short circuit by analyzing the imaginary part of the measured input impedance at low frequencies as explained herein with regard to block 802 of method 800.
  • the fault monitor 300 least squares fits the measured impedance measured for the WDPs 118 over a wide frequency range to impedance functions denoted by equations (56)-(57) below. Assuming that the reflection coefficient is a real number, i.e. »
  • the fault monitor 300 determines the distance to the fault.
  • Figure 19 is an example of the normalized impedance ⁇ ) where the fault is located 2000 meters from the fault monitor 300.

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Abstract

La présente invention concerne un appareil et un procédé permettant de localiser des défauts à l'intérieur d'une tige de forage câblée lors d'un forage. Selon un mode de réalisation, le système de localisation de défaut comprend une pluralité de sections supports de communication couplées de manière conductrice, des dispositifs électroniques de mesure d'impédance et un dispositif de localisation de défaut. Chaque section supports de communication comprend des coupleurs conducteurs sur des extrémités opposées de la section de support de communication, et des supports conducteurs connectés aux coupleurs conducteurs et couplant ceux-ci en communication. Les dispositifs électroniques de mesure d'impédance sont conçus pour mesurer une impédance d'entrée des sections supports de communication. Le dispositif de localisation de défaut est conçu pour déterminer une constante de propagation pour les sections supports de communication, et pour déterminer, en fonction de l'impédance d'entrée et de la constante de propagation, une localisation d'un défaut dans les sections supports de communication.
PCT/US2013/056965 2013-08-28 2013-11-05 Système et procédé de détermination de localisation de défaut WO2015030743A1 (fr)

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CN107075936A (zh) * 2014-12-31 2017-08-18 哈利伯顿能源服务公司 用于对高级三维井底钻具组件进行建模的方法和系统
CN114384376B (zh) * 2022-03-23 2022-06-24 浙江浙能能源服务有限公司 一种直流配电网故障分类定位方法

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US6798211B1 (en) * 1997-10-30 2004-09-28 Remote Monitoring Systems, Inc. Power line fault detector and analyzer
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WO2009151648A1 (fr) * 2008-06-13 2009-12-17 Cascade Microtech, Inc. Technique d’étalonnage

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US4820991A (en) * 1985-12-23 1989-04-11 Progressive Electronics, Inc. Apparatus for determination of the location of a fault in communications wires
US6798211B1 (en) * 1997-10-30 2004-09-28 Remote Monitoring Systems, Inc. Power line fault detector and analyzer
US6822457B2 (en) * 2003-03-27 2004-11-23 Marshall B. Borchert Method of precisely determining the location of a fault on an electrical transmission system
US20080158005A1 (en) * 2006-12-29 2008-07-03 David Santoso Method and apparatus for locating faults in wired drill pipe
WO2009151648A1 (fr) * 2008-06-13 2009-12-17 Cascade Microtech, Inc. Technique d’étalonnage

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