DRILLING OVERTREPAN SHOCK ABSORBER Russian patent published in 1995 - IPC

FIELD: drilling. SUBSTANCE: shock absorber has a body, stepped shaft located in its cavity. The shaft together with casing of its larger step form spline cavity. The smaller step of the shaft forms a cavity to locate elastic element and a chamber of hydraulic relief communicated with beyond tube space. Flexible wall is fastened on the shaft. The wall forms a chamber hydraulically connected to spline cavity. Trepan vibration does not affect tube column when drilling, since it is absorbed with elastic elements. Isolation of elastic element cavity from spline cavity provides eliminating pressure drop in elastic element cavity in nonuniform trepan feed. The chamber and wall are used as buffer reservoir with oil reserve, and pressure leveler in increased compressibility of the oil. EFFECT: increased reliability and durability. 3 dwg