DEVICE FOR HYDRAULIC SANDBLAST PERFORATION OF A WELL Russian patent published in 1995 - IPC

FIELD: well production. SUBSTANCE: device has upper, medium, and lower sections. A rod sealed with rings in its face part and lubricated in additional circumferential turning is installed in upper section. At the top the rod is connected to pump/compressor pipes, and is provided with face limiter in its bottom. Extension pieces for hydraulic perforation are installed in the medium section. Spring- loaded two-step piston is located above the pieces. Lateral openings suitable for overlapping by the piston, when it is in limiting lower position, are made in the medium section. Two step piston and the rod are in contact through the spring. Spring-loaded two=step sleeve with a seat for a ball is installed in the lower section. Radial holes for spring- loaded dies are made just opposite intermediate turning. As a result ring cavity is hydraulically connected to overpiston space of the dies. EFFECT: wider technological opportunities, particularly, emptying pump/compressor pipes from mud in the process of device lifting, as well as increased life and enhanced operating reliability of the device with casing fixed about perforated casing string, that in turn, accelerates forming point-like perforating passage. 2 dwg