The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 23, 1987
Filed:
Feb. 28, 1986
Wayne V Vogen, Oakland, CA (US);
URS Corporation, San Mateo, CA (US);
Abstract
Method and apparatus for downhole seismic exploration employing vibration emanating from a point deep in a well. An elastic steel column has an upper end extending above the top of the well. A reaction mass is attached vertically thereabove through a vertically mounted compression spring system, in parallel with it a vertically mounted servo-controlled hydraulic cylinder-piston assembly. The displacement of a spear or bit on the lower end of the column relative to earth develops a displacement signal. The piston in the hydraulic cylinder is under reciprocated servo control to apply vertical vibration to the upper end of the column and thereby to the spear, while developing an electrical, pressure-differential signal corresponding to the pressure across the cylinder-piston assembly. The vertical vibration is adjusted by feedback through the servo control in accordance with the displacement signal and the pressure differential signal, to seek and find an appropriate resonant frequency for the column in the range of 5 Hz to 250 Hz. The frequency is maintained at resonance to generate and transmit a downhole signal, which is detected at a location at a known distance from the spear so that the time differential between transmission and detection of the signal.