3664415 is referenced by 63 patents and cites 4 patents.

A method and apparatus for testing offshore wells where variations in well annulus pressure are utilized to control the valving operation of a testing tool and entrap a formation sample.A confined body of pressurized fluid positioned in a testing string is utilized to predetermine the annulus pressure changes which will effect said valving and sample entrapping operations.

Title
Method and apparatus for testing wells
Application Number
05/071,695
Publication Number
3664415
Application Date
September 14, 1970
Publication Date
May 23, 1972
Inventor
Petty George E
Wray Gary Q
Assignee
Halliburton Company
IPC
E21b 27/00
E21B 49/00
E21B 49/08
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