Importance

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Abstract

An apparatus for extracting a virgin fluid sample from a selected formation of subterranean well comprises an outer tubular housing disposed between two packing elements straddling the selected formation and having radial ports communicating with the annulus adjacent the selected formation. A hollow mandrel extends entirely through the length of the tubular housing, and the lower portions of such mandrel cooperate with the bore of the internal tubular housing to define a sample-collecting chamber. Fluid passage from the radial ports to the collecting chamber are blocked in the run-in position of the apparatus by an axially shiftable valve sleeve, which is shear pinned in a flow-blocking position during run-in of the tool. Fluid pressure is then applied to the bore of the hollow mandrel to shift the valve sleeve upwardly and remove the valve sleeve from its flow-blocking position, thereby permitting flow from the radial ports into the sampling chamber. After a sufficient sample has been collected, further upward movement of the valve sleeve produced by a higher fluid pressure in the mandrel bore shifts the valve sleeve to a second position wherein a second set of seals block the communication between the radial ports and the fluid-collecting chamber and effectively isolates the collecting chamber for withdrawal from the well.

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First Claim