| 摘要 |
FIELD: drilling wells; check valves for casing strings; lowering casing strings in well without addition of washing solution and for closing it upon completion of pumping-in and injection of plugging-back solution. ^ SUBSTANCE: proposed check valve has cylindrical body with axial passage, spring-loaded shut-off member secured to body from below, bush with throttling orifice fitted in axial passage of body and secured by means of shear members and control go-devil plug. Bush is provided with radial throttling orifices which are open for filling casing string with well fluid in lowering them into well. Axial passage of bush is closed from below with shut-off member. ^ EFFECT: enhanced operational reliability; simplified construction of valve. ^ 3 cl, 1 dwg |
