BOTTOM-HOLE DRILL STRING ASSEMBLY Russian patent published in 1996 - IPC

FIELD: well drilling. SUBSTANCE: bottom-hole drill string assembly includes damper of longitudinal vibrations, drill collars and member with high hydraulic resistance, for instance, jet rolling cutter bit or downhole hydraulic motor. Damper is made in form of flexible cylindrical shell located between drill collars and the member with high hydraulic resistance. Under the action of internal excessive pressure required for functioning of member with high hydraulic resistance, the flexible cylindrical shell assumes bulged form, its longitudinal rigidity drops and damping capacity rises, and in subsequent dynamic action on shell from bottom, developed in the process of operation of rolling cutter bit, longitudinal cyclic deformation of shell occurs due to formation of waves in shell wall along its generating line. EFFECT: higher efficiency of damping, workability and reliability of protection of drilling string from vibration. 5 dwg