EP0565141A2 - Akustische Datenübertragung über ein Bohrgestänge - Google Patents

Akustische Datenübertragung über ein Bohrgestänge Download PDF

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Publication number
EP0565141A2
EP0565141A2 EP19930111079 EP93111079A EP0565141A2 EP 0565141 A2 EP0565141 A2 EP 0565141A2 EP 19930111079 EP19930111079 EP 19930111079 EP 93111079 A EP93111079 A EP 93111079A EP 0565141 A2 EP0565141 A2 EP 0565141A2
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EP
European Patent Office
Prior art keywords
drill string
signal
acoustical
receiver
transmitter
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP19930111079
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English (en)
French (fr)
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EP0565141A3 (de
Inventor
Douglas Schaeffer Drumheller
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National Technology and Engineering Solutions of Sandia LLC
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Sandia Corp
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Publication date
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Priority to EP19930111079 priority Critical patent/EP0565141A3/de
Publication of EP0565141A2 publication Critical patent/EP0565141A2/de
Publication of EP0565141A3 publication Critical patent/EP0565141A3/de
Withdrawn legal-status Critical Current

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    • E—FIXED CONSTRUCTIONS
    • E21—EARTH DRILLING; MINING
    • E21B—EARTH DRILLING, e.g. DEEP 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
    • E21B47/14—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 using acoustic waves
    • E21B47/16—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 using acoustic waves through the drill string or casing, e.g. by torsional acoustic waves

Definitions

  • This invention relates generally to a system for transmitting data along a drill string, and more particularly to a system for transmitting data through a drill string by modulation of intermediate-frequency acoustic carrier waves.
  • Deep wells of the type commonly used for petroleum or geothermal exploration are typically less than 30 cm (12 inches) in diameter and on the order of 2 km (1.5 miles) long. These wells are drilled using drill strings assembled from relatively light sections (either 30 or 45 feet long) of drill pipe that are connected end-to-end by tool joints, additional sections being added to the uphole end as the hole deepens.
  • the downhole end of the drill string typically includes a drill collar, a dead weight assembled from sections of relatively heavy lengths of uniform diameter collar pipe having an overall length on the order of 300 meters (1000 feet).
  • a drill bit is attached to the downhole end of the drill collar, the weight of the collar causing the bit to bite into the earth as the drill string is rotated from the surface.
  • Drilling mud or air is pumped from the surface to the drill bit through an axial hole in the drill string. This fluid removes the cuttings from the hole, provides a hydrostatic head which controls the formation gases, and sometimes provides cooling for the bit.
  • This invention is directed towards the acoustical transmission of data through the metal drill string.
  • the history of such efforts is recorded in columns 2 - 4 of U.S. Patent No. 4,293,936, issued Oct. 6, 1981, of Cox and Chaney.
  • the first efforts were in the late 1940's by Sun Oil Company, which organization concluded there was too much attenuation in the drill string for the technology at that time. Another company came to the same conclusion during this period.
  • the aforementioned Cox and Chaney patent concluded from their interpretation of the measured data obtained from a field test in a petroleum well that the Barnes model must be in error, because the center of the passbands measured by Cox and Chaney did not agree with the predicted passbands of Barnes et al.
  • the patent uses acoustic repeaters along the drill string to ensure transmission of a particular frequency for a particular length of drill pipe to the surface.
  • the present invention is based upon a more thorough consideration of the underlying theory of acoustical transmission through a drill string.
  • the work of Barnes et al. has been analyzed as a banded structure of the type discussed by L. Brillouin, Wave Propagation in Periodic Structures, McGraw-Hill Book Co., New York, 1946.
  • the theoretical results have also been correlated to extensive laboratory experiments on scale models of the drill string, and the original data tape obtained from Cox and Chaney's field-test has been reanalyzed. This analysis shows that Cox and Chaney's measurements contain data which is in excellent agreement with the theoretical predictions; that Sharp misinterpreted the cause of the fine structure; and that the ringing and the frequency limitations cited by Shawhan and Hixon are easily overcome by signal processing.
  • Figure 1 shows some of the results of the new analysis of the data recorded by Cox and Chancy. This figure is a plot of the power amplitude versus frequency of the transmitted signal. The theoretical boundaries between the passbands and the stopbands are shown by the vertical dotted lines. If this figure is compared to Figure 1 in Cox and Chaney's patent, significant and obvious differences can be noted. These are attributable to error in Cox and Chaney's analysis.
  • FIG 1 also shows the "fine structure" of Sharp et al. From the new analysis we now know that this fine structure is caused by echos bouncing between opposite ends of the drill string, the number of peaks being correlated to the number of sections of drill pipe. A theoretical calculation of this field test was used to produce Figure 2. All of the phenomena important to the transmission of data in the drill string is represented in this calculation. These theoretical results accurately predict the location of the passbands and the fine structure produced by the echo phenomena.
  • the present invention relates to a method for transmitting data on a continuous data carrier signal through a drill string, comprising the steps of acoustically generating said signal at a first location near a first end of the drill string and detecting said acoustically generated signal at a second location near a second end of the drill string.
  • a first object of the present invention is to improve said method
  • This object is achieved by suppressing that part of said acoustically generated signal which travels in the direction of said first end of the drill string.
  • a second object of the present invention is to provide an apparatus for carrying out said improved method.
  • the apparatus and method for transmitting data along a drill string preferably use a modulated continuous acoustical carrier wave (waves) which is (are) centred within one (several) of the passbands of the drill string.
  • waves modulated continuous acoustical carrier wave
  • Preferred embodiments provide a system for suppressing the transmission of noise within the transmission band or bands.
  • this invention involves the transmission of acoustical data along a drill string 10 which consists of a plurality of lengths of constant diameter drill pipe 15 fastened end-to-end at thicker diameter joint portions 18 by means of screw threads as is well known in this art.
  • Lower end 12 of drill string 10 may include a length of constant diameter drill collar to provide downward force to drill bit 22.
  • a constant diameter mud channel 24 extends axially through each component of drill string 10 to provide a path for drilling mud to be pumped from the surface at upper end 14 through holes in drill bit 22 as is well known in this art.
  • drill string 10 is terminated in conventional structure such as a derrick, rotary pinion, and kelly, represented by box 25, to permit additional lengths of drill pipe to be added to the string, and the string to be rotated for drilling. Details of this conventional string structure may be found in the aforementioned patent of E. Hixon.
  • Equation 1 Equation 1
  • each piece of drill pipe consists of a tube of length d 1 , mass density p i , cross-sectional area a 1 , speed of sound c 1 , and mass r 1 ; and a tool joint of length d 2 , mass density P2 , cross-sectional area a 2 , speed of sound c 2 , and mass r 2 .
  • a procedure demonstrated at page 180 of Brillouin has been used with the Floquet theorem to generate the following eigenvalue problem:
  • Equation 18 ⁇ /Z ⁇
  • f the frequency being transmitted.
  • Brillouin shows that frequencies which yield real solutions for k are banded and separated by frequency bands which yield complex solutions for k. He calls these two types of regions passbands and stopbands. The attenuation in the stopbands is generally quite large. Within each of the passbands the value of the phase velocity ⁇ /k depends upon the value of w.
  • the drill string functions as an acoustic comb filter, and frequencies which propagate in the passbands are dispersed. Thus, signals which have broad frequency spectra are severely distorted by passage through a drill string. However, signal processing techniques can be used to remove this distortion.
  • comb filter refers to the gross structure in the frequency spectrum which is produced by the stopbands and the passbands, where each tooth of the comb is an individual passband.
  • Sharp's reference to a comb refers to a fine structure which exists within each passband.
  • Figure 4 shows a plot of the characteristic determinate of Equation 2 using values for P. , a., c .' and d . representative of actual drill pipe parameters.
  • the straight dotted line represents the solution for a uniform drill string, e.g., one where the diameter of the joints is equal to the diameter of the pipe.
  • the velocity of propagation for a given frequency is represented by the phase velocity.
  • this ratio is constant and equal to the bar velocity of steel.
  • the gaps represent stopbands. This analysis predicts the same values for the boundaries between the stopbands and the passbands as that of Barnes et al.; however, it also shows the characteristics of wave propagation within each of the passbands. Barnes et al. did not predict the distortion resulting from the effects of the passbands .
  • Fig. 2 shows the third and fourth passbands of a fast Fourier transform of the waveform which results from a signal which represents, to a rough approximation, the hammer blow used in the Cox and Chaney field test. This signal has a relatively narrow frequency content which only stimulates the third and fourth passband of the drill string.
  • Ten sections of drill pipe were used in this field test, and the ends of the drill string produced nearly perfect reflection of the acoustic waves which resulted from the hammer blows.
  • This figure shows the "fine structure" of Sharp et al. to be caused by standing wave resonances within the drill string.
  • the number of spikes in each passband correlates with the number of sections of pipe in the drill string, as explained in greater detail in the Appendix.
  • the analysis suggests the following technique for processing data signals and compensating for the effects of the stopbands and dispersion.
  • First transmit information continuously (as opposed to a broadband pulse mode) and only within the passbands and away from the edges of the stopbands.
  • Second compensate for dispersion by multiplying each frequency component by exp(-ikL), where L is the transmission length in the drill pipe section 18 of the drill string.
  • L is the transmission length in the drill pipe section 18 of the drill string.
  • the foregoing analysis is based on the assumption that echos are suppressed at each end of the drill string. This is necessary to eliminate the spikes or fine structure within each of the passbands. It is common knowledge that signal processing is effective when echo strength is 20 dB below the the signal level. Each time the acoustic wave interacts with the intersection of the drill pipe and the drill collar 80, the signal weakens by 6 dB. Also, from the analysis of Cox and Chaney's field test, the signal attenuates about (2 dB/1000 feet).
  • an echo which is generated by a reflection of the data signal 2 dB/300 m at the top of the drill string 14 will lose 6 + 4 (L/300) dB (if L in meters) or 6 + 4 (L/1000) dB (if L in feets) as it travels back down the drill string to 80 and then returns to the receiver.
  • the drill pipe section has a length of 1065 m (3500 feet) or more, the echos from the receiving end of the string will be naturally attenuated to an acceptable level.
  • a terminating transducer For shorter drill strings, additional echo suppression will be required. This can be accomplished with a device called a terminating transducer. This device has an acoustical impedance which matches the acoustical impedance of the drill string and an acoustical loss factor which is sufficient to make up the required 20 dB of echo suppression.
  • the characteristic impedance of the drill string is the force F divided by velocity
  • This value is the eigenvalue part of Equation 2, a complex number with a real part called the viscous component and an imaginary part called the elastic component.
  • the terminating transducers must have a stiffness equal to the elastic component and a damping coefficient equal to the viscous component. Practically, the response need only make up the difference between 20 dB and the natural attenuation of the drill string.
  • the characteristic impedance is a function of frequency and position, the position dependence being periodic in accordance with the period of the drill string. Calculations show that tool joints are not a good location for a termination because the impedance is a sensitive function of position. For the fourth passband, a location 1/3 or 2/3 along the pipe is better.
  • termination transducers is a conventional problem to those of ordinary skill in that art provided with the impedance data from Equation 2.
  • This device could consist of a ring of polarized PZT ceramic elements and an electronic circuit whose reactive and resistive components are adjusted to tune the transducer to the characteristic impedance of the drill string and provide the necessary acoustic loss factor.
  • Echo suppression is a more critical problem at the downhole end of the drill string where echos travel freely up and down the drill collar section and confuse the transmission of data. At this location, it is useful to use noise cancellation techniques both to suppress echos and to prevent the noise of the drill bit or drilling mud from interfering with the desired data signal uphole.
  • a noise cancellation technique is disclosed hereinafter.
  • Fig. 5 shows a section 30 of drill collar 20 located relatively close to downhole end 12 of drill string 10 and containing apparatus for transmitting a data signal towards the other end of the drill string while suppressing the transmission of acoustical noise up the drill string.
  • this apparatus includes a transmitter 40 for transmitting data uphole, but not downhole, a sensor 50 for detecting acoustical noise from downhole and applying it to transmitter 40 to cancel the uphole transmission of the noise, and a sensor 60 for providing adaptive control to transmitter 40 and sensor 50 to minimize uphole transmission of noise.
  • Transmitter 40 includes a pair of spaced transducers 42, 44 for converting an electrical input signal into acoustical energy in drill collar 30.
  • Each transducer may be a magnetostrictive ring element with a winding of insulated conducting wire. These transducers are spaced apart a distance b equal to one quarter wavelength of the center frequency of the passband selected for transmission.
  • a data signal from source 28 is applied directly to uphole transducer 44, preferably through a summing circuit 46.
  • the data signal is also applied to transducer 42 through a delay circuit 47 and an inverting circuit 48.
  • Delay circuit 47 has a delay value equal to distance b divided by the speed of sound in drill collar 30 at transmitter 40.
  • transmitter 40 transmits an uphole signal having approximately twice the amplitude A of the applied signal, and no downhole signal.
  • Noise sensor 50 includes a pair of spaced sensors 52, 54 which operate in a similar manner to provide an indication of acoustic energy moving uphole, and no indication of energy moving downhole.
  • the output of sensor 52 which sensor may be an accelerometer or strain gauge, is an electrical signal that is summed in summing circuit 56 with the output of similar sensor 54, which output is delayed by delay circuit 57 and and inverted by inverting circuit 58. If the delay of circuit 57 is equal to the spacing b divided by the speed of sound c, downward moving energy is first detected by sensor 54 and delayed, and later detected by downhole sensor 52.
  • the inverted electrical signal from 54 arrives at summing circuit 56 at the same time as the output of sensor 52, providing a net output of zero for downward moving noise.
  • Upward moving noise of the form Asin",(t - x/c) yields an output from summing circuit 56 of: where f o is the center frequency of the passband.
  • adaptive control 70 a conventional control circuit that has an input from a second pair of sensors 62, 64. These sensors, identical to sensors 52, 54, also have corresponding delay circuit 67 and inverter 68 to provide an output indicative of an upward moving wave and no output in response to a downward moving wave.
  • the upward moving wave at control sensors 60 is a mixture of the noise and data that passed transmitter 40. Accordingly, by delaying the data signal in delay circuit 72 and adding the result to the output of sensors 60 with summing circuit 74, an error signal is produced which indicates the effectiveness of noise cancelation. This signal is fed into an adaptive control circuit 70 which controls conventional circuitry 75 to adjust voltage amplitudes or phases of the signals being applied to any of sensors 52 and 62 or transmitters 42, 44 to minimize the amount of noise being transmitted upward towards the surface.
  • the spacing b between sensors or transmitters in the third passband would be about 30 cm (78 inches) or about 21 cm (53 inches) in the fourth passband.
  • the operation of the invention is as follows:
  • the circuitry of Fig. 5 is mounted on a drill collar, including suitable circuitry 28 for generating data representative of a downhole parameter.
  • Power supplies such as batteries or mud-driven electrical generators, and other supportive circuitry known to those of ordinary skill in the art, would also be incorporated into drill collar 30.
  • the drill bit and mud create acoustic noise that travels in both directions through drill string 10. Downward noise is not sensed by the sensors; however, upward noise, including echos from the bottom of the drill collar, are sensed by sensor circuit 50 and applied to transmitter circuit 40, yielding a greatly reduced upward noise component. Primarily the data travels to the connection 80 (Fig.
  • the data from circuit 28 may be precompensated by multiplying each frequency component of the signal by exp(-ikL) to adjust for the distortion caused by the passbands of the drill string.
  • Such compensation may be accomplished by any manner known to those of ordinary skill in the art with a device such as an analog-to-digital signal processing circuit.
  • This invention recognizes and solves the problems noted by many previous workers in the field of transmitting data along a drill string.
  • quality transmission on continuous acoustic carrier waves without extensive downhole circuitry, and without the use of impractical repeater circuits and transducers along the drill string is possible at frequencies on the order of several hundred to several thousand Hertz. These frequencies are high in relation to the ambient drilling noise (about 1 to 10 Hz), and therefore allow transmission relatively free of this noise. Also the bandwidths of the passbands allow data rates far in excess of present mud pulse systems. Also it is recognized that this method will work in drilling situations where air is used instead of mud.
EP19930111079 1988-04-21 1989-04-21 Akustische Datenübertragung über ein Bohrgestänge Withdrawn EP0565141A3 (de)

Priority Applications (1)

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EP19930111079 EP0565141A3 (de) 1988-04-21 1989-04-21 Akustische Datenübertragung über ein Bohrgestänge

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US18432688A 1988-04-21 1988-04-21
US184326 1988-04-21
EP19930111079 EP0565141A3 (de) 1988-04-21 1989-04-21 Akustische Datenübertragung über ein Bohrgestänge

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EP19890905949 Division EP0408667B1 (de) 1988-04-21 1989-04-21 Akustische datenübertragung über ein bohrgestänge
EP89905949.7 Division 1989-04-21

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EP0565141A2 true EP0565141A2 (de) 1993-10-13
EP0565141A3 EP0565141A3 (de) 1993-10-20

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2361789A (en) * 1999-11-10 2001-10-31 Schlumberger Holdings Mud-pulse telemetry receiver
WO2003093872A1 (en) * 2002-04-30 2003-11-13 Baker Hughes Incorporated Method of detecting signals in acoustic drill string telemetry
WO2007107734A1 (en) * 2006-03-22 2007-09-27 Qinetiq Limited Acoustic telemetry
DE102010047568A1 (de) 2010-04-12 2011-12-15 Peter Jantz Einrichtung zur Übertragung von Informationen über Bohrgestänge
EP2971500A4 (de) * 2013-03-12 2016-11-23 Xact Downhole Telemetry Inc Akustischer empfänger zur verwendung bei einem bohrstrang

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4293936A (en) * 1976-12-30 1981-10-06 Sperry-Sun, Inc. Telemetry system
US4562559A (en) * 1981-01-19 1985-12-31 Nl Sperry Sun, Inc. Borehole acoustic telemetry system with phase shifted signal

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4293936A (en) * 1976-12-30 1981-10-06 Sperry-Sun, Inc. Telemetry system
US4562559A (en) * 1981-01-19 1985-12-31 Nl Sperry Sun, Inc. Borehole acoustic telemetry system with phase shifted signal

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2361789A (en) * 1999-11-10 2001-10-31 Schlumberger Holdings Mud-pulse telemetry receiver
GB2361789B (en) * 1999-11-10 2003-01-15 Schlumberger Holdings Mud pulse telemetry receiver
WO2003093872A1 (en) * 2002-04-30 2003-11-13 Baker Hughes Incorporated Method of detecting signals in acoustic drill string telemetry
GB2405012A (en) * 2002-04-30 2005-02-16 Baker Hughes Inc Method of detecting signals in acoustic drill string telemetry
GB2405012B (en) * 2002-04-30 2005-12-14 Baker Hughes Inc Method of detecting signals in acoustic drill string telemetry
US7911879B2 (en) 2002-04-30 2011-03-22 Baker Hughes Incorporated Method of detecting signals in acoustic drill string telemetry
WO2007107734A1 (en) * 2006-03-22 2007-09-27 Qinetiq Limited Acoustic telemetry
CN101405475B (zh) * 2006-03-22 2012-12-05 秦内蒂克有限公司 声学遥测
DE102010047568A1 (de) 2010-04-12 2011-12-15 Peter Jantz Einrichtung zur Übertragung von Informationen über Bohrgestänge
US9982529B2 (en) 2010-04-12 2018-05-29 Universitaet Siegen Communication system for transmitting information via drilling rods
EP2971500A4 (de) * 2013-03-12 2016-11-23 Xact Downhole Telemetry Inc Akustischer empfänger zur verwendung bei einem bohrstrang
US10408050B2 (en) 2013-03-12 2019-09-10 Baker Hughes Oilfield Operations Llc Acoustic receiver for use on a drill string

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