Method and device to measure perforation tunnel dimensions

1. A method of logging a perforation tunnel and associated features of the perforation tunnel, comprising:

a) locating a logging device including an ultrasonic transducer into a well, the well having a casing, the ultrasonic transducer having a focal point that is a distance from the ultrasonic transducer so as to be behind the inner face of the casing;

b) projecting an ultrasonic signal from the ultrasonic transducer;

c) detecting a reflection of the ultrasonic signal from an internal portion of the perforation tunnel, the perforation tunnel extending through the casing and into formation;

d) measuring a transit time between transmission and reception of the ultrasonic signal;

e) determining a position of the ultrasonic transducer corresponding to the ultrasonic transmission and reception of the reflected signal;

f) repeating steps b)-e) multiple times and recording resultant data;

g) processing the resultant data with a computer and determining a dimension of the perforation tunnel; and

wherein the ultrasonic transducer is located a standoff distance from the wellbore casing at least one-third of a length of a minimum open tunnel length required to measure;

the standoff distance being so that reflections from the casing reverberate and substantially dissipate before a reflection from inside the perforation tunnel is received by the ultrasonic transducer.

2. A method of claim 1 , wherein the ultrasonic signal is within a range of 500 kHz to 5000 kHz.

3. A method of 1 , wherein the ultrasonic signal is within a range of 300 kHz to 3000 kHz.

4. A method of 1 , wherein the ultrasonic signal is approximately 1000 kHz.

5. A method of claim 1 , comprising processing the resultant data with a computer and determining a dimension of debris in the perforation tunnel.

6. A method to detect perforation tunnels and associated features of the perforation tunnels, comprising:

a) lowering an ultrasonic transducer into a wellbore, the wellbore having a casing lining the wellbore, a perforation tunnel extending through the casing and into the formation;

b) positioning the ultrasonic transducer adjacent to and facing into the perforation tunnel, the ultrasonic transducer being a standoff distance from the casing so that reflections from the casing reverberate and substantially dissipate before a reflection from inside the perforation tunnel is received by the ultrasonic transducer;

c) projecting an ultrasonic signal;

d) detecting a reflection of the ultrasonic signal reflected from an internal portion of the perforation tunnel;

e) detecting a reflection of the ultrasonic signal reflected from the inside surface of the casing;

f) measuring transit times and amplitudes of the reflection from the casing and of the reflection from inside the perforation tunnel;

repeating steps b)-f) and recording the resultant data;

processing the resultant data with a computer and determining a depth of the perforation tunnel and a dimension of debris in the perforation tunnel.

7. The method of claim 6 , comprising determining a position of the ultrasonic transducer corresponding to the ultrasonic transmission and reflection reception.

8. The method of claim 6 , wherein the standoff distance is at least one-third a length of a minimum open tunnel length required to measure.

9. The method of claim 7 , further comprising: configuring the signal diameter to be equal to or less than an expected width of an opening in the casing at the opening of the perforation tunnel.

10. A method of claim 6 , wherein the ultrasonic transducer is a focused ultrasonic transducer and is focused at a point behind an inside surface of the casing.

11. A method of claim 10 , wherein the signal diameter is determined by way of the following formula:

Signal Diameter(−6 dB)=(1.02* Fc )/ fD , wherein

F is the focal length of the transducer;

C is the sound speed in the wellbore fluid;

f is the frequency of the transducer;

D is the diameter of the transducer element in SI units.

12. A method of determining a depth of a perforation tunnel, comprising:

lowering a logging device into a wellbore, the wellbore having a casing that lines the wellbore;

a perforation comprising a tunnel that extends through the casing into formation;

the logging device comprising an ultrasonic transducer;

positioning the ultrasonic transducer adjacent to the perforation so as to overlap the perforation in a direction extending along a central longitudinal axis of the perforation;

emitting an ultrasonic signal from the ultrasonic transducer into the perforation;

receiving reflections of the ultrasonic signal from inside the perforation tunnel; and

determining the depth of the perforation tunnel and a dimension of debris in the perforation tunnel.

13. The method of claim 12 , comprising:

using a processor to determine the depth of the perforation tunnel based on the signal received from reflecting inside the perforation.

14. A method of claim 12 , comprising:

presenting the depth of the perforation tunnel on a digital visual display.

15. A method of claim 1 , wherein the perforation tunnel has a circular cross section.

16. The method of claim 6 , wherein the perforation tunnel has a circular cross section.

17. The method of claim 12 , wherein the perforation has a circular cross section.

18. The method of claim 1 , wherein the perforation tunnel has a tapered cylindrical shaped volume.

19. The method of claim 6 , wherein the perforation tunnel has a tapered cylindrical shaped volume.

20. The method of claim 12 , wherein the perforation has a tapered cylindrical shaped volume.

21. A method of logging a perforation tunnel and associated features of the perforation tunnel, comprising:

a) locating a logging device including an ultrasonic transducer into a well, the well having a casing, the ultrasonic transducer having a focal point that is a distance from the ultrasonic transducer so as to be behind the inner face of the casing;

b) projecting an ultrasonic signal from the ultrasonic transducer;

c) detecting a reflection of the ultrasonic signal from an internal portion of the perforation tunnel, the perforation tunnel extending through the casing and into formation;

d) measuring a transit time between transmission and reception of the ultrasonic signal;

e) determining a position of the ultrasonic transducer corresponding to the ultrasonic transmission and reception of the reflected signal;

f) repeating steps b)-e) multiple times and recording resultant data;

g) processing the resultant data with a computer and determining a dimension of the perforation tunnel and a dimension of debris in the perforation tunnel.

22. A method of claim 21 , wherein the ultrasonic transducer is located a standoff distance from the wellbore casing at least one-third of a length of a minimum open tunnel length required to measure.

23. A method of claim 22 , wherein the standoff distance being so that reflections from the casing reverberate and substantially dissipate before a reflection from inside the perforation tunnel is received by the ultrasonic transducer.

24. A method of claim 21 , wherein the ultrasonic signal is within a range of 500 kHz to 5000 kHz.

25. A method of 21 , wherein the ultrasonic signal is within a range of 300 kHz to 3000 kHz.

26. A method of 21 , wherein the ultrasonic signal is approximately 1000 kHz.