Method and apparatus for determining fluid flow characteristics

1. A measuring device, the device comprising:

a thermal insulating body having an exterior surface;

a thermal conductivity detector (TCD) recessed into the exterior surface of the thermal insulating body, comprising:

a thermally conductive pane sealed within an opening of the thermal insulating body such that no space exists between a circumference of the thermally conductive pane and the thermal insulating body, and oriented parallel to the exterior surface, said thermally conductive pane having a sensor face recessed below the exterior surface providing a cavity between the sensor face and the exterior surface, and

a single-component sensing element that converts electricity to heat and senses temperature, the single-component sensing element directly contacting the thermally conductive pane and embedded in and directly contacting the thermal insulating body.

2. The device of claim 1 , further comprising a strut partially covering the opening.

3. The device of claim 1 , wherein the sensing element is in direct connection with an interior surface of the pane opposite from the sensor face, the sensing element in connection with a sensing circuit.

4. The device of claim 3 , wherein the TCD is configured to measure thermal characteristics at the exterior surface.

5. The device of claim 1 , wherein:

the sensing element is in direct connection with an interior surface of the pane opposite from the sensor face, the sensing element in connection with a sensing circuit;

the thermal insulating body is mounted in a housing; and

the sensing circuit is disposed in the housing with a shock absorbing material.

6. The device of claim 5 , wherein the housing is loaded in a perforating gun.

7. The device of claim 1 , further comprising a pair of spaced apart TCDs mounted in the thermal insulating body, wherein each TCD of the pair of TCDs comprises a sensor face positioned substantially co-planar with the exterior surface.

8. The device of claim 7 , wherein the pair of spaced apart TCDs and the recessed TCD are mounted in a housing which is loaded into a perforating gun.

9. The device of claim 7 , wherein:

the pair of TCDs each comprise a sensing element, the sensing element of the pair of TCDs and the sensing element of the recessed TCD are in connection with a sensing circuit;

the thermal insulating body is mounted in a housing; and

the sensing circuit is disposed in the housing with a shock absorbing material.

10. The device of claim 9 , wherein the housing is loaded in a perforating gun.

11. A downhole tool, comprising:

a perforating gun comprising a plurality of shaped explosive charges; and

a measuring device configured in a shaped charge package and mounted in the perforating gun, the measuring device comprising:

a thermally conductive pane having a sensor face recessed and sealed within an opening in an exterior surface of a thermal insulating body, the sensor face being oriented parallel to the exterior surface of the thermal insulating body and providing a cavity between the sensor face and the exterior surface of the thermal insulating body such that no space exists between a circumference of the thermally conductive pane and the thermal insulating body, wherein the thermal insulating body directly contacts the measuring device to insulate the measuring device, and

a sensing element embedded in the thermal insulating body and in direct connection with an interior surface of the pane opposite from the sensor face, the sensing element in connection with a sensing circuit configured to measure a thermal characteristic of the fluid flowing across the exterior surface of the tool.

12. The downhole tool of claim 11 , comprising a reference measuring device located below the perforating gun.

13. The downhole tool of claim 11 , wherein the sensing circuit is configured to determine a velocity of a fluid flowing across the perforating gun and the measurement device.

14. The downhole tool of claim 13 , wherein the thermal insulating body is mounted in a housing; and the sensing circuit is disposed in the housing with a shock absorbing material.

15. The downhole tool of claim 11 , further comprising a thermal conductivity detector (TCD), the TCD comprising:

a pair of thermal conductivity detectors (TCD) spaced laterally apart in the thermal insulating body, each TCD of the pair of TCDs having a thermally conductive pane having a sensor face located substantially co-planar with the exterior surface of the thermal insulating material, and a sensing element in connection with an interior surface of the pane.

16. The downhole tool of claim 15 , further comprising a strut partially covering the opening.

17. A method, comprising:

disposing a downhole tool in a well, the downhole tool comprising a perforating gun comprising a plurality of shaped explosive charges and a measuring device configured in a shaped charge package and mounted in the perforating gun, the measuring device including a pair of recessed thermal conductivity detectors (TCD) spaced laterally apart and recessed and sealed within in a thermal insulating body such that no space exists between a circumference of the TCD and the thermal insulating body, wherein the thermal insulating body directly contacts the TCD to insulate the TCD, and the TCD including a thermal conductive pane having a sensor face recessed and sealed below an opening in an exterior surface of the thermal insulating body providing a cavity between the sensor face and the exterior surface, the TCD also including a sensor embedded in the thermal insulating body;

detonating the shaped explosive charges, thereby creating fluid communication with a subterranean formation through perforations; and

measuring a velocity of the fluid flowing in a direction from the perforations to a surface of the well utilizing the pair of TCDs.

18. The method of claim 17 , further comprising determining a thermal characteristic of the fluid flowing across the downhole tool utilizing the pair of recessed thermal conductivity detector (TCDs) located on the downhole tool.

19. The method of claim 17 , wherein fluid inside the cavity is in contact with the sensor face; and determining a thermal characteristic of the fluid flowing across the TCD.