SYSTEM AND METHOD FOR DOWNHOLE TIME-OF-FLIGHT SENSING, REMOTE NMR DETECTION OF FLUID FLOW IN ROCK FORMATIONS

摘要

A system and method for measuring fluid flow in a wellbore (15) in an earth formation using time-of-flight (TOF) sensing and remote detection nuclear magnetic resonance (NMR) techniques, by applying a magnetic field to the formation to polarize spins present in a portion of the formation, providing an encoding shell (110) in, the formation, selecting an encoding volume from the encoding shell, applying an encoding signal to excite the spins in the encoding volume, introducing a time delay to the encoding signal, providing a detection shell (100) in the formation, applying a detection signal to the detection shell, detecting an NMR signal generated by the migration of spins from the encoding shell to the, detection shell, and collecting TOF data corresponding to time elapsed from when a spin is encoded to when the spin reaches the detection shell.