Placement of isolator and electronics in same collar section to reduce tool length

1 . A downhole sensing system, comprising:

a first collar configured to accept a receiver;

a second collar configured to accept a transmitter; and

an acoustic isolator disposed between the first collar and the second collar, the acoustic isolator comprising:

a tubular body having a generally smooth exterior surface and an interior surface with a plurality of circumferential grooves formed in the interior surface that modify the acoustic impedance of the tubular body thereby attenuating an acoustic signal passing through the tubular body; and

a sonde disposed within an interior space of the tubular body and configured to accept an electronics package associated with at least one of the transmitter and the receiver.

2 . The downhole sensing system of claim 1 , wherein a first groove of the plurality of circumferential grooves has a first width and a second groove of the plurality of circumferential grooves has a second width that is different from the first width.

3 . The downhole sensing system of claim 2 , wherein a difference between the first width and the second width is in the range of 5-15% of the first width.

4 . The downhole sensing system of claim 3 , wherein the plurality of circumferential grooves have a respective plurality of different widths that monotonically increase along the tubular body.

5 . The downhole sensing system of claim 1 , wherein adjacent pairs of the plurality of circumferential grooves are separated by a plurality of separation distances that monotonically increase along the tubular body.

6 . The downhole sensing system of claim 5 , wherein the separation distances are in the range of 150-400% of the first width.

7 . The downhole sensing system of claim 1 , further comprising a spacer ring disposed between the first and second collars, wherein:

at least one of the first and second collars is primarily composed of a first material having a first speed of sound; and

the spacer ring is primarily composed of a second material having a second speed of sound that is different from the first speed of sound, thereby attenuating an acoustic signal passing between the first and second collars through the spacer ring.

8 . The downhole sensing system of claim 7 , wherein the second speed of sound is at least 10% different from the first speed of sound.

9 . The downhole sensing system of claim 7 , wherein the second material is primarily composed of one of the group of a ceramic, a stainless steel, an Inconel™ alloy, Invar, a copper alloy comprising nickel and tin, a copper alloy comprising beryllium, a nickel alloy comprising chromium and molybdenum, a cobalt alloy comprising chromium and tungsten, a tungsten alloy, and a molybdenum alloy.

10 . An acoustic isolator comprising:

a tubular body having a generally smooth exterior surface and an interior surface with a plurality of circumferential grooves formed in the interior surface that modify the acoustic impedance of the tubular body thereby attenuating an acoustic signal passing through the tubular body;

a sonde disposed within an interior space of the tubular body and configured to accept an electronics package associated with at least one of a transmitter and a receiver.

11 . The acoustic isolator of claim 10 , wherein a first groove of the plurality of circumferential grooves has a first width and a second groove of the plurality of circumferential grooves has a second width that is different from the first width.

12 . The acoustic isolator of claim 11 , wherein a difference between the first width and the second width is in the range of 5-15% of the first width.

13 . The acoustic isolator of claim 11 , wherein the plurality of circumferential grooves have a respective plurality of widths that monotonically increase along the tubular body.

14 . The downhole sensing system of claim 10 , wherein adjacent pairs of the plurality of circumferential grooves are separated by a plurality of separation distances that monotonically increase along the tubular body.

15 . The downhole sensing system of claim 14 , wherein the separation distances are in the range of 150-400% of the first width.

16 . The acoustic isolator of claim 10 , wherein the acoustic isolator is integrated into one of a first collar comprising a transmitter and a second collar comprising a receiver.

17 . A downhole sensing system, comprising:

a first collar comprising a first recess configured to accept a receiver;

a second collar comprising a second recess configured to accept a transmitter;

a spacer ring disposed between the first and second collars; and

an acoustic isolator disposed between the first collar and the second collar, the acoustic isolator comprising:

a tubular body having a generally smooth exterior surface and an interior surface with a plurality of circumferential grooves formed in the interior surface that modify the acoustic impedance of the tubular body thereby attenuating an acoustic signal passing through the tubular body; and

a sonde disposed within an interior space of the tubular body and configured to accept an electronics package associated with at least one of the transmitter and the receiver;

wherein:

at least one of the first and second collars are primarily composed of a first material having a first speed of sound; and

the spacer ring is primarily composed of a second material having a second speed of sound that is different from the first speed of sound, thereby attenuating an acoustic signal passing between the first and second collars through the spacer ring.

18 . The downhole sensing system of claim 17 , wherein the second material is primarily composed of one of the group of a ceramic, a stainless steel, an Inconel™ alloy, Invar, a copper alloy comprising nickel and tin, a copper alloy comprising beryllium, a nickel alloy comprising chromium and molybdenum, a cobalt alloy comprising chromium and tungsten, a tungsten alloy, and a molybdenum alloy.