SUBSURFACE SAFETY VALVE Russian patent published in 1995 - IPC

FIELD: oil field equipment. SUBSTANCE: subsurface safety valve has body 1 in which movable rod is installed. Movable rod 2 is engageable with compression string 3. Axial channel 4 of rod 2 accommodates main seat 5 made in form of spring split ring engageable with balls 7, and additional seat 9 engageable with balls 11. Balls 7 are engageable with inner surface of body 1 and main seat 5, and balls 11 are engageable with inner surface of body 1, and additional seat 9 that is responsible for formation of, either, gap which provides for expansion of seats 5 and 9 between balls 7 and 11 and seats 5 and 9, respectively, or they prevent seats 5 and 9 from expanding. Seats 5 and 9 have flexible seal 13 which protects spaces of grooves 6 and 10 of holes 8 from formation fluid. Installed in bore 4 is spring-loaded stepped bushing 15 whose outer diameter of lower step 17 is larger than outer diameter of upper step 18. Located in central channel 19 of bushing 15 is seat 20 similar in design with seats 5 and 9. To change over the safety valve to the CLOSED position, shutoff member 33 is dropped to build up pressure above it. Shutoff member 33 is made in form of ball and is alternately engageable with seats 20, 5 and 9. To open the safety valve, shutoff member-ball 33 is forced through seat 9 to drop into accumulator. EFFECT: higher operate reliability, extended operation capabilities and reduced maintenance costs. 4 dwg