Patent ID: 7565834

Claim:
A method comprising: (a) inserting a tubular into a wellbore of a formation, the tubular comprising a tubular section having an upper and a lower fluid injection port, the tubular having a thermally insulated fiber optic cable section positioned inside the tubular extending to the upper fluid injection port, and a non-insulated fiber optic cable section positioned outside of the tubular section and extending at least between the upper and lower fluid injection ports for better thermal contact with formation fluids; (b) positioning the tubular section having the upper and lower fluid injection ports near a suspected thief or pay zone section of a formation; (c) injecting a fluid through the upper fluid injection port; (d) determining a first differential temperature profile along the tubular between the upper and lower fluid injection ports using the fiber optic cable; (e) injecting a fluid through the lower fluid injection port; and (f) determining a second differential temperature profile along the tubular at least between the upper and lower fluid injection ports using the fiber optic cable.