METHOD FOR WELL CONSERVATION Russian patent published in 1995 - IPC

FIELD: oil producing industry. SUBSTANCE: before lowering of casing string into well, layer of rare-earth matter and electrodes are placed on casing string. After lowering the casing string, pulse exciting voltage is applied to electrodes. Pulse exciting voltage ensures excitation of elastic vibrations in rock mass with frequency of 10-1500 Hz. Simultaneously on the ground surface, round well, elastic vibrations are registered. These elastic vibrations are used to determine hollows and fissures in rock mass round well. Then, cementing mortar with rare-earth matter is injected into casing string-wellbore annulus. Elastic vibrations are excited for a time during which strength of cementing mortar reaches half of its rated strength. Then, elastic vibrations are excited, in mass section adjacent to detected hollows and fissures. Injected additionally to these hollows and fissures is cementing mortar. Besides, after lowering of casing string, applied to electrodes is alternating pulse excitation voltage. EFFECT: higher efficiency of well conservation. 2 cl, 1 dwg