05934374 is referenced by 88 patents and cites 76 patents.

This invention provides a formation evaluation tool for collecting a formation fluid in a chamber at a predetermined pressure and for maintaining the pressure of the collected fluid at a desired level during the retrieval of the chamber to the surface. The formation fluid is pumped into the chamber while a piston exposed to the hydrostatic pressure maintains the chamber pressure at the hydrostatic pressure. During retrieval of the chamber, the pressure in the chamber is maintained at a predetermined level by pumping wellbore fluid to the piston. A control unit at the surface is utilized for controlling the operation of the formation tool.

Title
Formation tester with improved sample collection system
Application Number
8/691125
Publication Number
5934374
Application Date
August 1, 1996
Publication Date
August 10, 1999
Inventor
Mark A Proett
Houston
TX, US
James M Moore
Houston
TX, US
Andrew A Hrametz
Rosenberg
TX, US
Agent
Eugene R Montalvo
Assignee
Halliburton Energy Services
TX, US
IPC
E21B 49/10
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