Patent ID: 7475724

Claim:
A method of determining a fluid inflow profile along the length of a permeable inflow region of an underground wellbore, the method comprising the steps of: transferring heat into or from the permeable inflow region of the wellbore during a well shut in period such that at least a part of the inflow region has a temperature which is different from the temperature of the surrounding formation; starting production of hydrocarbon fluids via said permeable inflow region; measuring substantially simultaneously the temperature of the fluids at various points along at least part of the length of the inflow region; and determining at selected intervals of time after production start up a temperature profile along at least part of the length of the inflow region on the basis of the thus measured temperatures; wherein the method further comprises determining a fluid inflow profile along the length of said inflow region on the basis of a comparison of the determined temperature profiles at selected intervals after production start up, wherein during an initial period of time after starting production of hydrocarbons via said permeable inflow region said heat transfer into or from the permeable inflow region is continued and wherein during a subsequent period of time following said initial period said heat transfer is interrupted, and the temperature is measured both during said initial and subsequent periods of time and wherein differences between the temperature variation over time measured during said initial and subsequent period are used to determine a heat capacity of the inflowing fluid.