US Patent 7841406 Formation fluid sampling apparatus and methods

A fluid sampling system retrieves a formation fluid sample from a formation surrounding a wellbore extending along a wellbore axis, wherein the formation has a virgin fluid and a contaminated fluid therein. The system includes a sample inlet, a first guard inlet positioned adjacent to the sample inlet and spaced from the sample inlet in a first direction along the wellbore axis, and a second guard inlet positioned adjacent to the sample inlet and spaced from the sample inlet in a second, opposite direction along the wellbore axis. At least one cleanup flowline is fluidly connected to the first and second guard inlets for passing contaminated fluid, and an evaluation flowline is fluidly connected to the sample inlet for collecting virgin fluid.