WELL BLOWOUT PREVENTER Russian patent published in 1997 - IPC

FIELD: mining industry; applicable in construction and operation of wells. SUBSTANCE: blowout preventer includes body accommodating seat and holder reciprocating relative to body. Holder upper part has posts and axial recess on its external side. Installed in holder on trunnions is shutoff member with central axial channel and unit restricting its turning in form of pins interacting with posts. Shutoff member is made in form of ball in which two side ball segments are cutoff. These side surfaces are parallel and equidistant from central axis of shutoff member channel. Shutoff member has radial channels to receive trunnions and pins. Trunnions are installed in radial channels which are located closer to centers of side surfaces than radial channels receiving pins. Axes of radial channels are found in diametrical plane which makes angle of 45 deg with diametrical plane running through central axis of shutoff member channel and square to its side planes. Installed under holder in body is nozzle with shaped recess on its external surface. Recesses of nozzle and holder may be partially or fully aligned when holder is turned round its axis. Spring-loaded ring is installed between holder and seat and interacted with post upper ends. Prior to running into well, the device is adjusted to calculated critical flow rate of fluid or gas. For this purpose, degree of alignment of axial recesses of nozzle and holder is regulated. Upon reaching the critical flow rate, shutoff member turns in holder and lowers onto seat to seal tubular channel. To open the shutoff member, it is enough to equalize pressure above and under the shutoff member. In this case, energy of compressed spring prevents shutoff member from sticking on seat. EFFECT: higher efficiency. 3 cl, 3 dwg