Patent ID: 7036579
Filing Date: 2006-05-02
Classification: E21B

Abstract:
1. A downhole tool for evaluating a subterranean formation, comprising: a probe positionable adjacent the subterranean formation; a flowline having a first portion extending from the probe into the downhole tool, a second portion extending from the first portion to the wellbore and a third portion extending from the first portion through the downhole tool; a pretest chamber operatively connected to the first portion of the flow line between the probe and the second and third portions of the flowline, the pretest chamber having a pretest piston movably positioned therein for selectively withdrawing from and emitting fluid into the first portion of the flowline; a probe isolation valve disposed in the first portion of the flow line between the probe and the pretest chamber, the probe isolation valve adapted to selectively vary the pressure of fluid in the flowline; an equalization valve disposed in the second portion of the flow line, the equalization valve adapted to selectively permit fluid communication between the first portion of the flow line and the wellbore; a flow line isolation valve disposed in the third portion of the flow line, the flow line isolation valve adapted to selectively permit fluid communication between the first flowline and the remainder of the downhole tool; and at least one gauge operatively connected to one of the first portion, the second portion, the third portion and combinations thereof of the flowline whereby at least one parameter of the formation may be determined.