Assessing a solids deposit in an oilfield pipe

• US 20030185100A1
• Filed: 03/29/2002
• Published: 10/02/2003
• Est. Priority Date: 03/29/2002
• Status: Active Grant

• Current Assignee: Penn State Research Foundation (Pennsylvania State University), Schlumberger Technology Corporation (SLB)
• Original Assignee: Schlumberger Technology Corporation (SLB)
• Inventors: DʼAngelo, Ralph M., Mullins, Oliver C., Johnson, David L., Gustavson, Gale, Winkler, Kenneth W.
• Granted Patent: US 7,095,676 B2
• Time in Patent Office: Days
• US Class Current: 367/82
• CPC Class Codes: G01N 2291/012 Phase angle
• CPC Class Codes: G01N 2291/015 Attenuation, scattering
• CPC Class Codes: G01N 2291/0423 Surface waves, e.g. Rayleigh waves, Love waves
• CPC Class Codes: G01N 2291/057 Angular incidence, parallel to surface propagation
• CPC Class Codes: G01N 2291/106 one or more transducer arrays
• CPC Class Codes: G01N 2291/2634 cylindrical from outside
• CPC Class Codes: G01N 29/07 by measuring propagation velocity or propagation time of acoustic waves
• CPC Class Codes: G01N 29/222 Constructional or flow details for analysing fluids optoacoustic fluid cells G01N29/2425
• CPC Class Codes: G01N 29/46 by spectral analysis, e.g. Fourier analysis or wavelet analysis spectral signal processing per se G06F17/14
• CPC Class Codes: G01N 29/52 using inversion methods other that spectral analysis, e.g. conjugated gradient inversion

Abstract

Tube waves are used to locate and characterize a solids deposit inside a fluid-filled pipe. An acoustic tube wave pulse is transmitted along the pipe. On encountering a solids deposit, the tube wave pulse is perturbed and partially reflected by changes in the boundary conditions between the fluid and the pipe to produce two deposit-modified acoustic waves. One is a perturbed wave travelling in the same direction as the tube wave pulse. The other is a reflected wave travelling in the opposite direction. One of these deposit-modified acoustic waves is received to produce an acoustic signal. Accumulated acoustic signals are processed by Fast-Fourier Transform to produce frequency-based digital data. Phase data from the frequency-based digital data is inverted to produce slowness spectrum data. Power data from the frequency-based digital data is inverted to produce attenuation spectrum data. Spectrum data is used to locate a solids deposit in the pipe. Inversion model processing of the spectrum data is used to estimate solids deposit thickness and type.

Claims

1. A method for assessing a solids deposit inside a fluid-filled pipe, comprising:

transmitting a first acoustic tube wave along said pipe to produce two deposit-modified acoustic tube waves, including a perturbed wave and a reflected wave following encounter of said first acoustic wave with a solids deposit;

receiving a deposit-modified acoustic wave to produce at least one acoustic signal; and

determining the value of a selected characteristic of said at least one acoustic signal indicative of a solids deposit in said pipe.

2. A method according to claim 1, wherein receiving a deposit-modified acoustic wave includes receiving a perturbed tube wave at a pair of spaced-apart first and second receivers to produce first and second acoustic signals at said first and second receivers.

3. A method according to claim 2, wherein determining the value of a selected characteristic includes:

digitizing said first and second acoustic signals to produce time-based digital data;

performing FFT on said time-based digital data to produce frequency-based digital data;

subtracting phase associated with said second acoustic signal from phase associated with said first acoustic signal to produce a phase difference for each of a plurality of frequencies;

multiplying each phase difference by its associated frequency; and

dividing the result by the distance between said first and second receivers to produce slowness spectrum data.

4. A method according to claim 3, wherein determining the value of a selected characteristic further includes:

subtracting power associated with said second acoustic signal from power associated with said first acoustic signal to produce a power difference for each of a plurality of frequencies; and

dividing power difference by the distance between said first and second receivers to produce attenuation spectrum data.

5. A method according to claim 4, further comprising determining the thickness of said solids deposit using inversion model to process said slowness spectrum data, said power spectrum data, and material parameter data.

6. A method according to claim 5, wherein said material parameter data is derived from an engineering judgement determination of the most likely deposited material.

7. A method according to claim 5, further identifying the location of said solids deposit as being between said first and second receivers.

8. A method according to claim 1, wherein receiving a deposit-modified acoustic wave includes receiving a perturbed tube wave at the at least of one pair of spaced-apart first and second receivers to produce first and second acoustic signals;

and wherein determining the value of a selected characteristic includes using TKO processing to produce slowness spectrum data and attenuation spectrum data.

9. A method according to claim 1, wherein receiving a deposit-modified acoustic wave includes receiving a perturbed wave at spaced-apart first and second receivers to produce first and second acoustic signals;

and wherein determining the value of a selected characteristic includes subtracting time of arrival of said first acoustic signal from time of arrival of said second acoustic signal to determine slowness.

10. A method according to claim 1, further including moving a pair of receivers within the interior of said pipe to a succession of positions along said pipe.

11. A method according to claim 1, further including moving a logging tool, including one transmitter and a distant pair of spaced-apart receivers, within the interior of said pipe to a succession of positions along said pipe.

12. A method according to claim 1, wherein said deposit-modified acoustic wave is a perturbed wave, and wherein said selected characteristic is attenuation.

13. A method according to claim 1, further including moving one transmitter/receiver within the interior of the pipe to a succession of positions along said pipe.

14. A method according to claim 1, wherein said selected characteristic is slowness, the method further comprising:

determining an initial value of said selected characteristic during initial production;

determining a later value of said selected characteristic during production; and

subtracting said initial value from said later value to produce a difference value indicative of an increase in thickness of a solids deposit.

15. A method according to claim 14, further comprising:

using said difference value together with material parameter data of a selected deposited material to produce an estimate of thickness of said solids deposit;

wherein said elected deposited material is selected based on an engineering determination of most likely deposited material.

16. A method according to claim 1, wherein said deposit-modified acoustic wave is a reflected wave, and wherein said selected characteristic is power.

17. A method according to claim 16, further determining an average value of slowness over a length of pipe adjacent to a transmitter, and locating the solids deposit using the equation:

distance=(transit time)/(2*average slowness).

18. A permanent-sensor flow assurance measurement system for assessing a solids deposit inside a fluid-filled pipe, said system comprising:

an instrumented pipe including;

a pipe;

a transmitter attached to said pipe positioned to transmit a first acoustic wave along said pipe; and

an array of receivers, said array aligned with said pipe, said receivers attached to said pipe, said array spaced apart from said transmitter, each of said receivers adapted to receive a potentially perturbed tube wave propagating along said pipe and to produce from the received wave an acoustic signal; and

means for processing acoustic signals to determine the value of a selected characteristic of an acoustic wave indicative of a solids deposit in a fluid-filled pipe.

19. An instrumented pipe for use in a permanent-sensor flow assurance measurement system for assessing a solids deposit inside a fluid-filled pipe, said instrumented pipe comprising:

a pipe;

a transmitter attached to said pipe positioned to transmit a first acoustic tube wave along said pipe; and

an array of receivers, said array aligned with said pipe, said receivers attached to said pipe, said array spaced apart from said transmitter, each of said receivers positioned to receive a potentially perturbed tube wave propagating along said pipe and to produce from the received wave an acoustic signal.

20. A permanent-sensor flow assurance measurement system for assessing a solids deposit inside a fluid-filled pipe, said system comprising:

an instrumented pipe including;

a pipe and an array of transmitter/receivers, said array aligned with said pipe, each transmitter/receiver attached to said pipe, each transmitter/receiver having a transmitter function and a receiver function, each transmitter/receiver positioned to transmit a first acoustic wave along said pipe to produce a reflected wave when said first acoustic wave encounters a solids deposit in said fluid-filled pipe, each transmitter/receiver positioned to receive a reflected tube wave produced from its first acoustic tube wave, and adapted to produce therefrom an acoustic signal; and

means for processing acoustic signals to determine the value of a selected characteristic of an acoustic wave indicative of a solids deposit in a fluid-filled pipe.

21. An instrumented pipe for use in a permanent-sensor flow assurance measurement system for assessing a solids deposit inside a fluid-filled pipe, said instrumented pipe comprising:

a pipe; and

an array of transmitter/receivers, said array aligned with said pipe, each transmitter/receiver attached to said pipe, each transmitter/receiver having a transmitter function and a receiver function, each transmitter/receiver positioned to transmit a first acoustic tube wave along said pipe to produce a reflected wave when said first acoustic wave encounters a solids deposit in said fluid-filled pipe, each transmitter/receiver positioned to receive a reflected tube wave produced from its first acoustic tube wave, and adapted to produce therefrom an acoustic signal.

22. A flow assurance measurement system for assessing a solids deposit inside a fluid-filled pipe, said system comprising:

A logging tool including;

An elongated housing adapted for travel within said pipe;

a transmitter attached to said elongated housing positioned to transmit a first acoustic tube wave along said pipe; and

an array of receivers, said array aligned with said elongated housing, each of said receivers attached to said elongated housing and spaced apart from said transmitter, each of said receivers adapted to receive a potentially perturbed tube wave and to produce from the received wave an acoustic signal; and

means for processing acoustic signals to determine the value of a selected characteristic of an acoustic wave indicative of a solids deposit in a fluid-filled pipe.

23. A logging tool for assessing a solids deposit inside a fluid-filled pipe, said logging tool comprising:

an elongated housing adapted for travel within said pipe;

a transmitter attached to said elongated housing positioned to transmit a first acoustic tube wave along said pipe, and

an array of receivers, said array aligned with said elongated housing, each of said receivers attached to said elongated housing and spaced apart from said transmitter, each of said receivers adapted to receive a potentially perturbed tube wave and to produce from the received wave an acoustic signal.

24. A flow assurance measurement system for assessing a solids deposit inside a fluid-filled pipe, said system comprising:

a logging tool including;

an elongated housing adapted for travel within said pipe;

an array of transmitter/receivers, said array aligned with said elongated housing, each transmitter/receiver having a transmitter function and a receiver function, each transmitter/receiver attached to said housing and positioned to transmit a first acoustic tube wave along said pipe, each transmitter/receiver positioned to receive a reflected tube wave produced from its first acoustic tube wave, and adapted to produce therefrom an acoustic signal; and

means for determining the value of a selected characteristic of said acoustic signal indicative of a solids deposit in said pipe.

25. A logging tool for assessing a solids deposit inside a fluid-filled pipe, said logging tool comprising:

an elongated housing adapted for travel within said pipe; and

an array of transmitter/receivers, said array aligned with said elongated housing, each transmitter/receiver having a transmitter function and a receiver function, each transmitter/receiver attached to said housing and positioned to transmit a first acoustic tube wave along said pipe, each transmitter/receiver positioned to receive a reflected tube wave produced from its first acoustic tube wave, and adapted to produce therefrom an acoustic signal.