Patent Number: 7,762,353

Title: Downhole valve mechanism

Abstract: In one aspect of the invention, a downhole tool string component comprises a fluid passageway formed between a first and second end. A valve mechanism is disposed within the fluid passageway adapted to substantially cyclically build-up and release pressure within the fluid passageway such that a pressure build-up results in radial expansion of at least a portion of the fluid passageway and wherein a pressure release results in a contraction of the portion of the fluid passageway. The valve mechanism disposed within the fluid passageway comprises a spring. Expansion and contraction of the portion of the fluid passageway varies a weight loaded to a drill bit disposed at a drilling end of the drill string.

Inventors: Hall; David R. (Provo, UT), Bailey; John (Spanish Fork, UT)

Assignee: Schlumberger Technology Corporation

International Classification: E21B 7/00 (20060101)

Expiration Date: 7/27/12018