CIRCULATION VALVE Russian patent published in 2002 - IPC

FIELD: down-hole equipment. SUBSTANCE: invention can be used for development, plugging and washing of vertical, inclined and horizontal oil and gas wells. Circulation valve has case with overflow and circulation holes. Stepped bushing is mounted uniaxially for axial movement and shutting off circulation holes of case. High-pressure chamber is formed by stepped bushing and case. Seals are installed in grooves of case. Spring-loaded bushing is put uniaxially on stepped bushing. Ring chamber is made in mobile bushing. At least one spring-loaded beveled pin is placed in case and fixes stepped bushing after its axial movement. Stepped bushing is positioned inside case. High-pressure chamber communicates hydraulically with hole and interpipe clearances. Spring-loaded bushing is mounted for axial movement and shutting off hydraulic coupling of ring chamber with interpipe clearance. Surfaces of lower part of spring-loaded bushing match edges of ring chamber. EFFECT: enhanced operational reliability, widened functional capabilities. 4 cl, 9 dwg