Patent ID: 9605530
Date: 2017-03-28
CPC Classifications: E21B

Claim:
1. An apparatus comprising: a probe drill collar configured for location in a borehole such that an outer surface of the probe drill collar is opposed to a cylindrical wall of the borehole; and a formation probe assembly located within the probe drill collar, the formation probe assembly comprising: a piston configured for reciprocal movement between a retracted position and an extended position in which an outer end of the piston projects beyond the outer surface of the probe drill collar, the piston extending along a piston axis transverse to a longitudinal axis of the borehole; a metal skirt at the free end of the piston, the metal skirt having, relative to the piston axis, an axially outer surface that is partially cylindrical and non-planar; and a seal pad mounted on the metal skirt and confirming to the axially outer surface of the metal skirt such that the seal pad defines, relative to the piston axis, an axially outer surface that is partially cylindrical, and that is shaped and configured for congruent sealing engagement with the cylindrical wall of the borehole when the piston is in the extended position.