Method and apparatus for logging flow characteristics of a well

• US 3,908,454 A
• Filed: 01/09/1974
• Issued: 09/30/1975
• Est. Priority Date: 10/12/1972
• Status: Expired due to Term

• Current Assignee: Lynn D. Mullins, Willett F. Baldwin
• Original Assignee: Lynn D. Mullins, Willett F. Baldwin
• Inventors: Mullins, Lynn D., Baldwin, Willett F.
• Primary Examiner(s): Queisser, Richard C.
• Assistant Examiner(s): Rasco, Marcus S.
• Application Number:
  US05/432,129
• Time in Patent Office: 629 Days
• Field of Search: 73/155,194A,194B,71.5US,61R 181/102 340/18FM 310/8.1 166/250 175/50
• US Class Current: 340/855.7
• CPC Class Codes: E21B 47/107 using acoustic means
• CPC Class Codes: E21B 47/12 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
• CPC Class Codes: G01N 2291/014 Resonance or resonant frequency
• CPC Class Codes: G01N 2291/02408 Solids in gases, e.g. particle suspensions
• CPC Class Codes: G01N 2291/02416 Solids in liquids
• CPC Class Codes: G01N 2291/101 one transducer
• CPC Class Codes: G01N 29/032 by measuring attenuation of acoustic waves
• CPC Class Codes: G01N 29/036 by measuring frequency or resonance of acoustic waves
• CPC Class Codes: G01N 29/046 using the echo of particles imparting on a surface; using acoustic emission of particles investigating concentration of particle suspensions G01N15/06; devices for measuring flow of solids in suspension G01F1/74
• CPC Class Codes: G01N 29/28 providing acoustic coupling , e.g. water impedance matching G10K11/02
• CPC Class Codes: G01N 29/348 with frequency characteristics, e.g. single frequency signals, chirp signals measuring frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04; measuring frequency or analysing frequency spectra G01R23/00
• CPC Class Codes: G01N 29/42 by frequency filtering or by tuning to resonant frequency
• CPC Class Codes: G01N 29/4436 with a reference signal amplitude comparison G01N29/48
• CPC Class Codes: G01V 1/44 using generators and receivers in the same well G01V1/52 takes precedence

Abstract

A method and apparatus for logging the flow characteristics of a downhole interval in a well. The apparatus includes a tool which is lowered in the well to the downhole interval where flow, if any, into the wellbore (e.g., through perforations in the well casing) excites a transducer within the tool. The transducer generates a signal in response to flow having dominant ultrasonic frequency components which, when processed and analyzed, establish whether or not flow is actually occurring in said interval and whether or not said flow contains particulate material, e.g., sand. The tool further includes encoding circuitry for processing the downhole signal and for transmitting same to the surface where it is processed into a usable format by surface decoding circuitry.

Claims

1. A method of investigating the flow characteristics of a downhole interval in a well, said method comprising:

generating a signal at said downhole interval in response to flow into said interval, said signal having dominant ultrasonic frequency components; and

processing said generated signal to provide two processed signals, one of said processed signals having dominant ultrasonIc frequency components indicative of flow and the other of said processed signals having dominant ultrasonic frequency components indicative of flow which contains particulate material.

2. The method of claim 1 wherein said processing of said generated signal includes:

filtering said generated signal to pass dominant ultrasonic frequency components of 75 kilohertz and greater to provide said one of said processed signals; and

filtering said generated signal to pass a narrow band of frequency components centered around approximately 700 kilohertz to provide said other of said procssed signals.

3. A method of investigating the flow characteristics of a downhole wellbore interval in a well, said method comprising:

generating a signal at said downhole interval in response to flow into said wellbore interval, said signal having dominant ultrasonic frequency components;

processing said generated signal at said downhole interval to provide a first signal having dominant ultrasonic frequency components indicative of said flow and a second signal having dominant ultrasonic frequency components indicative of flow which contains particulate material;

transmitting said first and second signals to the surface of said well; and

processing said first and second signals into a usable format at the surface.

4. The method of claim 3 wherein said processing of said generated signal at said downhole interval includes:

filtering said generated signal to pass dominant ultrasonic frequency components of 75 kilohertz and greater to provide said first signal; and

filtering said generated signal to pass a narrow band of frequency components centered around approximately 700 kilohertz to provide said second signal.

5. The method of claim 3 where said transmitting said first and second signals includes:

mixing said first and second signals at said downhole interval to provide a single, mixed signal; and

transmitting said single, mixed signal to the surface.

6. The method of claim 5 wherein said well is cased throughout its depth and said interval to be investigated is an interval in which a perforation operation has been carried out.

7. A method of investigating the flow characteristics of a multiply completed cased well including a tubing string extending through an upper producing zone to produce from a lower production zone, said method comprising:

generating a signal within said tubing string adjacent said upper producing zone in response to flow from said upper producing zone onto said tubing string, said signal having dominant ultrasonic frequency components; and

processing said generated signal to produce a first signal having dominant ultrasonic frequency components indicative of flow and a second signal having dominant ultrasonic frequency components indicative of flow which contains particulate material.

8. The method of claim 7 wherein said processing of said generated signal includes:

filtering said generated signal to pass dominant ultrasonic frequency components of 75 kilohertz and greater to provide said one of said processed signals; and

filtering said generated signal to pass a narrow band of frequency components centered around approximately 700 kilohertz to provide said other of said processed signals.

9. Apparatus for investigating the flow characteristics of a downhole interval in a well, said apparatus comprising:

flow detection means adapted to be positioned in a well adjacent the downhole interval to be investigated;

transducer means within said flow detection means which when excited by flow will generate a signal indicative of same, said transducer having a first primary resonant frequency in the range of dominant ultrasonic frequencies normally generated by flow into said downhole interval and a second primary resonant frequency in the range of dominant ultrasonic frequencies normally generated by flow containing parTiculate material into said downhole interval; and

circuitry means for processing said generated signal to produce a first processed signal having only dominant frequency components beginning near the lowest response of said first primary resonant frequency and greater and a second processed signal having only dominant frequency components in a narrow band centered about said second primary resonant frequency; and

means for transmitting said first and second signals to the surface of the well.

10. The apparatus of claim 9 including:

means for tuning said signal generated by said transducer to said second primary resonant frequency of said transducer.

11. The apparatus of claim 9 including:

decoding circuitry means adapted to be positioned at the surface of the well to process said transmitted first and second signals into a usable format.

12. The apparatus of claim 9 wherein:

said first primary resonant frequency is approximately 100 kilohertz and said second primary resonant frequency is approximately 700 kilohertz.

13. The apparatus of claim 12 including:

means for tuning said signal generated by transducer to approximately 700 kilohertz.

14. The apparatus of claim 13 wherein said circuitry means includes:

encoding circuitry for processing said generated signal to produce a first processed signal having those dominant frequency components in said generated signal of 75 kilohertz and greater and a second processed signal having those dominant frequency components in said generated signal which lie in a narrow band centered about approximately 700 kilohertz.

15. The system of claim 14 wherein said encoding circuitry means includes:

modulator means for converting said first processed signal into a first AC signal proportionate to said first processed signal and for converting said second processed signal into a second AC signal proportionate to said second processed signal; and

means to add said first and second AC signals to produce a single, mixed signal for transmission to the surface

16. The apparatus of claim 15 including:

decoding circuitry means adapted to be positioned at the surface of the well, said decoding circuitry means comprising;

means to separate said single, mixed signal into said first and second AC signals; and

demodulator means to convert said first AC signal into a first signal representative of said first processed signal and to convert said second AC signal into a second signal representative of said second processed signal.

17. Apparatus for flow the flow characteristics of a downhole interval in a well, said apparatus comprising:

a body adapted to be positioned in a well adjacent the downhole interval to be investigated;

a housing mounted on said body;

transducer means suspended in said housing for maximum sensitivity to vibration to generate a signal in response to said vibration, said transducer means having a first primary resonant frequency in the range of dominant ultrasonic frequencies normally generated by flow into said downhole interval and a second primary resonant frequency in the range of dominant ultrasonic frequencies normally generated by flow containing particulate material into said downhole interval;

noncompressible liquid filling said housing to acoustically couple said transducer means to said housing;

encoding circuitry means in said body for processing said signal generated by said transducer means to produce a first processed signal having only dominant frequency components beginning near the lowest response of said first primary resonant frequency and greater and a second processed signal having only dominant frequency components in a narrow band centered about said second primary resonant frequency; and

means for transmitting said first and second processed signals to the surface of the well.

18. The apparatus of claim 17 wherein said first primary resonant frequency is approximately 100 kilohertz and the second primary resonant frequency is approximately 700 kilohertz.

19. The apparatus of claim 18 wherein said encoding circuitry means includes:

means for processing said generated signal to produce a first processed signal having only dominant frequency components of 75 kilohertz and greater and a second processed signal having only a narrow band of dominant frequency components centered about approximately 700 kilohertz.

20. The apparatus of claim 19 including:

decoding circuitry means adapted to be positioned at the surface of the well to receive and process said transmitted signal into a usable format.

21. The system of claim 20 wherein said encoding circuitry means includes:

modulator means for converting said first processed signal into a first AC signal proportionate to said first processed signal and for converting said second processed signal into a second AC signal proportionate to said second processed signal; and

means to add said first and second AC signals to produce a single, mixed signal for transmission to the surface; and

wherein said decoding circuitry means includes;

means to separate said single, mixed signal into said first and second AC signals;

demodulator means to convert said first AC signal into a first signal representative of said first processed signal and to convert said second AC signal into a second signal representative of said second processed signal.

22. The system of claim 21 wherein said decoding circuitry means further includes:

means for recording said first and second representative signals.