METHOD FOR PERFORATION OF CASING STRINGS IN GAS-PETROLEUM HOLES Russian patent published in 1996 - IPC

FIELD: gas-petroleum geology. SUBSTANCE: used for checking intervals of geological record of holes in zones of interfluidic contacts and ensures reduction of volumetric deformation of casing tubes, also minimizes untightness of threaded joints of sleeves and tubes and degree of cracking cement stone beyond casing string during perforation of casing string intervals such as in zone of interfluidic contacts. First, perforator is selected, density of casing string column and perforation interval are determined according to geological record. Then perforator is equipped and lowered down into hole. Perforating operation is performed and actual position of perforation interval in casing string is determined. Prior to that, position of sleeves on casing tubes in hole within perforation interval is found with the help of sleeve locator. Exposed band-type shaped-charge perforator in the form of sections is used. Its length is equal to extension of casing string perforation interval. Charges are adapted to selective electric firing and location with clearance in casing string relative to frontal part of container. Idle sections between charges are of length equal to sum of sleeve length and two double spacings between charges. During lowering-down of perforator each section of it with charges is positioned symmetrically relative to sleeves. Perforations is performed in two salvos. First salvo induces two charges symmetrically neared toward center of section and located in each section with charges. Second salvo fires all remaining charges. EFFECT: high efficiency. 2 dwg