ANTI-SIPHON SEALING DEVICE Russian patent published in 2015 - IPC E21B33/08 

FIELD: oil and gas industry.

SUBSTANCE: method of sealing of pipe string and annular space at repair during tripping operations at gas, oil and water inflow with a controlled condition of a well is offered which is characterized by that the process includes the installation of preventer with blind and/or pipe rams, installation on the top flange of preventer of wellhead equipment with the sealant sealing directly along the outer diameter the fixed or moving column inside it, pipes and control of flow of the borehole medium in annular space. Besides, the installation on the flange of the flushing coil of the wedge tubing hanger or the spider holding a pipe string, the installation on the spider crescent of the anti-siphon sealing device providing overlapping and control of flow of borehole liquid in the pipe string are performed. The anti-siphon sealing device comprises the housing containing the telescopic chamber a large size of the axial stroke consisting of several interconnected cylindrical parts installed one into another. The housing contains a threaded hole with the manometer installed in it for monitoring of pressure in the chamber and, at least, one hole with a by-pass branch pipe for liquid drainage. In the by-pass branch pipes for liquid drainage the ball valves with high pressure hoses are mounted the second ends of which are routed to collector tanks, the discharge line is installed from the annular valve to collector tanks. In case of first signs of gas, oil and water shows the pipe string is put on wedges of the tubing hanger or the spider so that to place the pipe connecting coupling between the top sealing assembly at static position of the anti-siphon device and the hydraulic key. The pipe rams of the lower sealing assembly are closed below the coupling on the pipe body which is located in the well, the middle and the top sealing assemblies are lifted manually against the stopper or to a certain interval, having matched the stopper of one of cylinders of the telescopic chamber with the horizontal blind cut of another cylinder in the same plane so that to locate the middle sealing assembly above the pipe connecting coupling, and to fix by rotation around its axis of the middle sealing assembly so that the stopper interacting with a figured groove has moved from the vertical cut into horizontal one and fixed in the seat. The blind dies of the middle sealing assembly are closed above the pipe connecting coupling located in the well. The monitoring of pressure in the chamber is executed using the manometer, and the annular space above the preventer seals the wellhead equipment with the sealant and discharge of annular space is performed through the annular valve down the discharge line to the collector tanks. Meanwhile the monitoring of pressure in annular space is performed using the manometer installed in the wellhead equipment. A plug, or a ball valve, or a swivel with a branch pipe is installed into the cavity between the top and the middle sealing assemblies upstream the blind dies of the middle sealing assembly. The pipe rams of the top sealing assembly are closed, being placed on the swivel branch pipe body, the blind dies of the middle sealing assembly are spaced, and discharge of the cavity of pipes is performed inside the chamber between the lower and the top sealing assemblies, downstream through by-pass branch pipes by the high pressure hoses to the collector tanks and through the swivel downstream to the high pressure hose to the collector tanks. The top and the middle sealing assemblies together with the swivel are lowered down to the place of installation of nipple part of the threaded connection of the branch pipe of the swivel into the connecting coupling of the pipe. Manually minimum five-six turns are screwed-in, making sure that the fixing is reliable, screwing-in is performed with the booster or the hydraulic key. After that the pipe rams of the top and the lower sealing assemblies are spaced, the middle and the top sealing assemblies are lowered to the starting position, the elevator is engaged with the connecting coupling of the swivel or the pipe, the pipe string is released from wedges of the tubing hanger or the spider and lifted from the well. The pipe string is placed on wedges of the spider or the tubing hanger, the pipe rams of the lower sealing assembly are mounted below the coupling on the pipe body located in the well, the hydraulic key is put, the fixing on the connecting coupling of the pipe is installed, the lifted pipe is screwed-out for two-three turns, the middle and the top sealing assemblies are lifted and pipe rams of the top sealing assembly are closed above the coupling on the body of the lifted pipe. The lifted pipe together with a pipe is screwed out, the rotation of the top sealing assembly occurs independently from the middle one, the hydraulic key is put, after that the pipe for disjoining is lifted together with the top and the middle sealing assemblies due to tightly pressed pipe rams to the body of the lifted pipe and large size of the axial stroke of the telescopic chamber. After that the blind dies of the middle sealing assembly are closed above the connecting coupling of the pipe which is located in the well, thus shutting the top sealing assembly and the lifted pipe. And the residue of borehole liquid in the lifted pipe and in the high pressure hose are drained through holes of interconnected cylindrical rings, downstream through by-pass swivel branch pipe by the high pressure hose to the collector tanks. Pipe rams of the top sealing assembly are spaced, and the lifted pipe is lowered on the catwalk. When lowering the pipe string all actions are performed in reverse sequence, in case of necessity in pack-off into the pipe string a ball valve is screwed-in, the coupling is lowered below the preventer dies, the preventer is closed, the pipe rams are installed on the body of the remote branch pipe of the ball valve, the ball valve is closed, then annular valves are closed then the excessive pressure is measured.

EFFECT: ensuring reliable sealing of cavity of pipes at their joining before tightening and at disjoining after loosening during tripping operations at gas, oil and water inflow in tubes.

7 cl, 8 dwg