Patent ID: 6719049
Filing Date: 2004-04-13
Classification: E21B

Abstract:
A method of sampling the formation fluids in an earth formation surrounding a borehole, the region of the formation immediately surrounding the borehole being at least partially invaded by borehole fluids, said method comprising the steps of lowering a borehole tool with a sampling probe device into the borehole; urging the sampling probe device into contact with the borehole wall and withdrawing fluid samples from the formation, the sampling probe device comprising an inner probe and an outer probe surrounding the inner probe for withdrawing respective fluid samples from the formation, said method further comprising the step of selecting the ratio between the respective flow areas of the inner and outer probes so as to tend to reduce the time taken to obtain via the inner probe a sample of the formation fluids having a given level of contamination by borehole fluids.