Patent ID: 7469746

Claim:
A downhole sampling tool positionable in a wellbore penetrating a subterranean formation, the subterranean formation having a formation fluid therein, the wellbore having a contaminated fluid therein extending into an invaded zone about the wellbore, comprising: a housing; a shaft extendable from the housing, the shaft positionable in a perforation penetrating the formation beyond the invaded zone about the wellbore; a flowline extending through the shaft and into the housing, the flowline having an inlet for receiving downhole fluids through the perforation; and a first fluid restrictor positioned at least in part outside of the perforation, the first fluid restrictor adapted to isolate the perforation from the wellbore fluids; wherein the first fluid restrictor comprises a fluid injected into the formation about the perforation, the fluid adapted to penetrate the formation and create a seal about at least a portion of the perforation.