Patent Number: 
Section: claims

1. An apparatus for detecting the location of an annulus spacer between concentric interior and exterior tubes when a temperature gradient is present between an interior surface of the interior tube and an exterior surface of the exterior tube, the apparatus comprising:a probe head assembly movable within the interior tube;at least one temperature sensor coupled to the probe head assembly and configured to detect a temperature of the interior surface of the interior tube;a drive assembly operable to move the probe head assembly relative to the interior tube; anda data acquisition system coupled to the at least one temperature sensor and configured to receive a plurality of temperature measurements in order to identify at least one position along the interior surface of the interior tube having a temperature abnormality in which the temperature of the interior surface of the interior tube is closer to a temperature of the exterior surface of the exterior tube with respect to other positions along the interior surface of the interior tube. 2. The apparatus of claim 1, wherein the probe head assembly includes a wheeled centering assembly. 3. The apparatus of claim 1, wherein the drive assembly includes at least one threaded rod configured to axially slide the probe head assembly through the interior tube when rotated. 4. The apparatus of claim 1, wherein the at least one temperature sensor includes a non-contact thermal imaging device. 5. The apparatus of claim 1, wherein the drive assembly includes a computer-controlled drive. 6. The apparatus of claim 5, wherein the drive assembly is configured to provide position data to the data acquisition system to be correlated with the temperature measurements to develop a temperature map of the interior surface of the interior tube. 7. The apparatus of claim 6, further comprising a display device configured to display the temperature map in real time. 8. The apparatus of claim 1, further comprising one of an active heating apparatus and an active cooling apparatus configured to establish or enhance a thermal gradient between the interior surface of the interior tube and the exterior surface of the exterior tube. 9. The apparatus of claim 8, wherein the active cooling device is coupled to the probe head assembly and configured to chill the interior surface of the interior tube. 10. The apparatus of claim 9, wherein the active cooling device is a liquid cooling jacket including a central support spool and a coil of tubing for conveying a chilled heat exchange fluid. 11. The apparatus of claim 9, wherein the active cooling device is a cold air generator. 12. The apparatus of claim 1, wherein the at least one temperature sensor includes a plurality of temperature probes positionable in contact with the interior surface of the interior tube when the probe head assembly is positioned inside the interior tube. 13. The apparatus of claim 12, wherein the plurality of temperature probes are arranged in an axial row. 14. The apparatus of claim 12, wherein the plurality of temperature probes are coupled to the probe head assembly to be biased in a radially outward direction. 15. The apparatus of claim 12, wherein the plurality of temperature probes are arranged in a circular array at a first axial location. 16. The apparatus of claim 15, further comprising a second plurality of temperature probes arranged in a circular array at a second axial location. 17. A method for detecting the location of at least one annulus spacer between concentric interior and exterior tubes having a temperature gradient therebetween between an interior surface of the interior tube and an exterior surface of the exterior tube, the method comprising:inserting a probe head assembly including at least one temperature sensor into the interior tube;detecting the temperature of an interior surface of the interior tube at a plurality of locations along the interior surface; andidentifying at least one position along the interior surface of the interior tube having a temperature abnormality corresponding to a reduced temperature gradient. 18. The method of claim 17, wherein detecting the temperature of an interior surface of the interior tube at a plurality of locations along the interior surface includes detecting the temperature with a non-contact thermal imaging device. 19. The method of claim 17, wherein a plurality of annulus spacers between the interior and exterior tubes are detected by identifying a plurality of positions along the interior surface of the interior tube, each having a temperature abnormality corresponding to a reduced temperature gradient. 20. The method of claim 17, further comprisingdriving the probe head assembly to a plurality of locations within the interior tube;collecting position data corresponding to the position of the at least one temperature sensor; andcorrelating temperature data and position data to develop a temperature map of the interior surface. 21. The method of claim 20, further comprising displaying the temperature map in real time. 22. The method of claim 17, further comprising establishing one of the interior and exterior tubes as a hot side and the other of the interior and exterior tubes as a cold side, and at least one of actively heating the hot side and active cooling the cold side to establish or enhance a thermal gradient between the interior and exterior tubes. 23. The method of claim 22, wherein the interior surface of the interior tube is actively cooled by blowing chilled air from a cold air generator on the interior surface. 24. The method of claim 22, wherein the interior surface of the interior tube is actively cooled by providing a liquid cooling jacket on the probe head assembly and flowing a chilled heat exchange fluid through the liquid cooling jacket. 25. The method of claim 17, wherein detecting the temperature of an interior surface of the interior tube at a plurality of locations along the interior surface includes providing a plurality of probes in contact with the interior surface. 26. The method of claim 25, wherein detecting the temperature of an interior surface of the interior tube at a plurality of locations along the interior surface includes detecting a plurality of temperatures at a first axial location along the interior surface with the plurality of probes, moving the plurality of probes to a second axial location along the interior surface with a drive assembly coupled to the probe head assembly, and detecting a plurality of temperatures at the second axial location. 27. The method of claim 25, wherein detecting the temperature of an interior surface of the interior tube at a plurality of locations along the interior surface includes detecting the temperature of the interior surface at a plurality of axially spaced positions with the probe head assembly at a first position. 28. The method of claim 27, further comprising moving the probe head assembly to a second position and detecting the temperature of the interior surface of the interior tube at a plurality of additional axially spaced positions.