METHOD OF PERFORATION OF PRODUCING FORMATIONS IN OIL AND GAS WELLS UNDER DRAWDOWN Russian patent published in 2001 - IPC

FIELD: oil producing industry; applicable in increase of oil recovery. SUBSTANCE: method is realized by means of hollow-carrier jet-type perforators of large diameter with use of logging cable and at reduced formation back pressure. Prior to lowering into well, perforator is placed into sluice chamber. Chamber is lifted on cable and secured by flange joint on well head above blowout preventing gate valve. Sluice chamber inner diameter equals diameter of perforated string. Length of sluice chamber exceeds that of perforator by 1.0-1.5 m. Blowout preventing gate valve is opened and perforator is lowered into perforation interval. After perforation, process of perforator entering into sluice chamber is controlled with help of system of audible signaling and electrical interlocking for automatic stopping of lowering and-lifting unit. Upon perforator entering into sluice chamber, the latter is shutoff, blowout preventing gate valve is closed, pressure is sluice chamber is released and perforator is withdrawn. EFFECT: higher efficiency of perforation by series- produced hollow-carrier jet-type perforators. 2 dwg