The induction time, t(ind), of calcium carbonate precipitation in porous rocks was experimentally measured under dynamic conditions at temperatures from 25 to 120 ° C with the use of a radiotracer technique, where the gamma-emitting nuclide Ca-47 was used as a tracer in order to monitor the scale deposition at real time. Based upon nucleation theory and experimental observations, the following improved correlation is proposed: log t(ind) (min) = 3.2 - 3.1/SI - 959.8/T + 1849.9/SIT. This equation predicts satisfactorily the induction time of calcium carbonate scale formation under specific dynamic (flow) conditions in the near-well region (T is the absolute temperature in K, and SI is the saturation index, SI = log SR, where SR is the saturation ratio). © 2005 Elsevier Inc. All rights reserved.