SHUT-OFF DEVICE FOR WELL TESTING Russian patent published in 2002 - IPC

FIELD: oil and gas producing industry, particularly, devices for well investigation by pipe formation tester with remote recording of bottom-hole pressure and with logging accompaniment. SUBSTANCE: device includes remote downhole instruments lowered into tested zone on cable and consisting of valve mechanism and shutoff unit connected with string. Hollow body of valve mechanism accommodates, for autonomous motion, upper and lower rod-pistons, operating one for compression, and the other for tension at same differential pressures. Shut-off unit is made in form of sealing bushing with radial channels, thicker part for ball retainers, flow-through ribbed stop at end and protects remote instrument from impact loads. EFFECT: higher operate reliability of device. 2 cl, 4 dwg