FLUID SAMPLING METHODS AND APPARATUS FOR USE IN BOREHOLES

摘要

The invention concerns a method and apparatus for sampling formation fluids surrounding a borehole within a minimum of contamination by borehole fluids. A borehole tool is provided with a sampling probe to contact the borehole wall. The probe comprises an inner probe and an outer probe for withdrawing respective fluid samples for the formation. The ratio between the respective flow areas of the inner and outer probes is selected 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.