Downhole ultrasound image correction in oil based mud

Patent metadata

Field	Value
Publication number	US-11927712-B2
Application number	US-202217745599-A
Country	US
Kind code	B2
Filing date	May 16, 2022
Priority date	Oct 16, 2018
Publication date	Mar 12, 2024
Grant date	Mar 12, 2024

Abstract

Disclosed herein is a method for eccentricity correction. This method may dispose a downhole tool into a borehole. The downhole tool may comprise a measuring assembly that has at least one transducer, determining a beam pattern from the at least one transducer, determining a center of the measurement assembly in the borehole with the beam pattern, calculating a beam pattern factor with at least the beam pattern, calculating an angle factor with at least the beam pattern, calculating an eccentricity factor with at least the beam pattern factor and the angle factor, and creating an eccentricity corrected image with at least the eccentricity factor.

First claim

What is claimed is:

1. A method for eccentricity correction comprising:
disposing a downhole tool into a borehole, wherein the downhole tool comprises a measuring assembly having at least one transducer;
determining a beam pattern and a beam pattern factor from the at least one transducer;
determining a center of the measurement assembly in the borehole with the beam pattern;
calculating an angle factor with at least a radius of the borehole;
calculating an eccentricity factor with at least the beam pattern factor and the angle factor; and
creating an eccentricity corrected image based at least on the eccentricity factor.

2. The method of claim 1 , further comprising multiplying the beam pattern factor and the angle factor to calculate the eccentricity factor.

3. The method of claim 2 , further comprising determining an echo amplitude from the beam pattern.

4. The method of claim 3 , further comprising producing a raw image from the beam pattern and the echo amplitude.

5. The method of claim 4 , further comprising dividing an amplitude of the raw image at one or more azimuthal and depth locations with an inverse of the eccentricity factor.

6. The method of claim 5 , further comprising determining an attenuation correction factor.

7. The method of claim 6 , further comprising dividing the attenuation correction factor to obtain a corrected wave.

8. The method of claim 6 , further comprising:
identifying a time domain signal from the transducer;
converting the time domain signal to a frequency domain;
correcting a spectrum amplitude at one or more frequencies to form a corrected frequency domain signal;
converting the corrected frequency domain signal to a corrected time domain data; and
computing an attenuation factor.

9. The method of claim 8 , wherein the attenuation factor is an amplitude ration between the corrected time domain data and the time domain signal.

10. The method of claim 1 , wherein determining a center of the measurement assembly comprises calculating an incident angle, a normal direction, and a standoff.

11. A system comprising:
a downhole tool, wherein the downhole tool comprises:
a measuring assembly, wherein the measuring assembly comprises at least one transducer and wherein the at least one transducer is configured to emit a pressure pulse and record an echo; and
an information handling system configured to:
determine a beam pattern and a beam pattern factor from the echo;
determine a center of the measurement assembly in a borehole with the beam pattern;
calculate an angle factor with at least a radius of the borehole;
calculate an eccentricity factor with at least the angle factor and the beam pattern factor; and
create an eccentricity corrected image based at least on the eccentricity factor.

12. The system of claim 11 , wherein the information handling system is further configured to multiply the beam pattern factor and the angle factor to calculate the eccentricity factor.

13. The system of claim 12 , wherein the information handling system is further configured to determine an echo amplitude from the beam pattern.

14. The system of claim 13 , wherein the information handling system is further configured to produce a raw image from the beam pattern and the echo amplitude.

15. The system of claim 14 , wherein the information handling system is further configured to divide an amplitude of the raw image at one or more azimuthal and depth locations with an inverse of the eccentricity factor.

16. The system of claim 15 , wherein the information handling system is further configured to determine an attenuation correction factor.

17. The system of claim 16 , wherein the information handling system is further configured to divide the attenuation correction factor to obtain a corrected wave.

18. The system of claim 16 , wherein the information handling system is further configured to:
identify a time domain signal from the transducer;
convert the time domain signal to a frequency domain;
correct a spectrum amplitude at one or more frequencies to form a corrected frequency domain signal;
convert the corrected frequency domain signal to a corrected time domain data; and
compute an attenuation factor.

19. The system of claim 18 , wherein the attenuation factor is an amplitude ration between the corrected time domain data and the time domain signal.

20. The system of claim 11 , wherein determining a center of the measurement assembly comprises calculating an incident angle, a normal direction, and a standoff.

Assignees

• Halliburton Energy Services Inc

Inventors

• Weng Yu
• Li Peng
• Chang Chung
• Coates Richard
• Marlow Rodney Allen
• Wu Xiang
• Ge Yao
• Jin Jing

Classifications

• G01V1/50 Primary

  Analysing data · CPC title

• E21B47/0025

  generating an image of the borehole wall using down-hole measurements, e.g. acoustic or electric · CPC title

• E21B47/02

  Determining slope or direction · CPC title

• G01V1/305

  Travel times · CPC title

• G01V1/307

  for determining seismic attributes, e.g. amplitude, instantaneous phase or frequency, reflection strength or polarity · CPC title