SEALING METHOD OF CAVITY OF PIPES AND ANNULAR SPACE OF WELL; PGU-2 ANTI-SYPHONAGE SEALING DEVICE; PK-1 WASHING COIL Russian patent published in 2015 - IPC E21B33/08 

FIELD: oil and gas industry.

SUBSTANCE: group of inventions relates to a sealing procedure and technology of cavity of pipes and annular space of the well during performance of lowering-and-lifting operations at gas, oil and water inflows. The invention proposes a sealing method of cavity of pipes and annular space of the well during performance of lowering-and-lifting operations at gas, oil and water inflows with the controlled state of the well, which is characterised by the fact that it involves installation of a preventer with pipe rams, installation to a side outlet of a swivel of a high pressure hose; after that, during lowering or lifting of pipes, at occurrence of the first signs of gas, oil and water inflows, the pipe is put on spider wedges so that a connection coupling of the pipe can be located between the upper sealing assembly, at static position of an anti-syphonage device, and hydraulic tongs; pipe rams the lower sealing assembly are closed below the coupling on the pipe body located in the well; middle and upper sealing assemblies are elevated manually, or by means of an auxiliary winch, or by means of pneumatic or hydraulic or mechanical cylinders, or an articulated-lever drive, or an articulated-lever drive with a "rack-gear" gear unit, which are installed between lower and middle sealing assemblies. Blind rams of the middle sealing assembly are closed above the connection coupling of the pipe located in the well; with that, discharging of the pipe cavity takes place inside the chamber between lower and middle sealing assemblies and then through an outlet branch pipe via a high pressure hose to collecting tanks. Control of pressure inside the chamber is performed due to a pressure gauge installed on it, and annular space above the preventer is sealed by the washing coil, and discharging of the annular space occurs through a pipe gate valve further via a discharge line to the collecting tanks; with that, control of pressure in annular space is performed due to a pressure gauge installed in the washing coil. A swivel with a branch pipe, on the end of which a coupling with a threaded nipple connection is installed, is installed into the cavity between upper and middle sealing assemblies to blind rams of the middle sealing assembly; with that, outside diameter of the swivel branch pipe corresponds to outside diameter of pipes located in the well and to bore size of pipe rams of the upper sealing assembly. Pipe rams of the upper sealing assembly are closed by being installed on the body of the branch pipe of the swivel; blind rams of the middle sealing assembly are spread; at this time, discharging of the pipe cavity takes place inside the chamber between the lower and the upper sealing assemblies and through the swivel; the upper and the middle sealing assemblies together with the swivel are lowered till installation of the nipple part of the threaded connection of the swivel branch pipe into the connection coupling of the pipe; at least five or six turns are screwed on after one is sure that engagement is correct. Screwing is performed with a booster or a hydraulic wrench; besides, discharging of the pipe cavity occurs through the swivel via a high pressure hose to collecting tanks. After that, pipe rams of the upper and the lower sealing assemblies are spread; the middle and the upper sealing assemblies are lowered to initial position; an elevator is fastened to the connection coupling of the swivel or the pipe; a pipe string is removed from spider wedges, and the pipe is lifted out of the well; the pipe string is put on the spider wedges; the hydraulic wrench is set up; a catch is installed behind the connection coupling of the pipe; the elevated pipe is backed off two or three turns; after one is sure that the coupling is not backed off together with the pipe, pipe rams of the lower sealing assembly are installed below the coupling on the body of the pipe located in the well. Then, the middle and the upper sealing assemblies are elevated, and pipe rams of the upper sealing assembly are installed above the coupling on the body of the elevated pipe. The elevated pipe is backed off; along with the above, rotation of the upper sealing assembly is performed irrespective of the middle one; the hydraulic wrench is removed; after that, a pipe for detachment is elevated together with the upper and the middle sealing assemblies due to the pipe rams tightly pressed to the body of the elevated pipe and a high value of axial working stroke of the chamber; at this time, discharging of the pipe cavity takes place inside the chamber between the lower and the upper sealing assemblies and through the swivel. After that, blind rams of the middle sealing assembly are closed above the connection coupling of the pipe located in the well, thus cutting off the upper sealing assembly and the elevated pipe; at this time, discharging of the pipe cavity takes place inside the chamber between the lower and the middle sealing assemblies. Pipe rams of the upper sealing assembly are spread, and the elevated pipe is lowered. The swivel is backed off and installed with its branch pipe into a cavity between the upper and the middle sealing assemblies to blind rams of the middle sealing assembly. Pipe rams of the upper sealing assembly are closed thus being installed on the body of the swivel branch pipe; blind rams of the middle sealing assembly are spread; at this time, discharging of the pipe cavity takes place inside the chamber between the lower and the upper sealing assemblies and through the swivel. The upper and the middle sealing assemblies together with the swivel are lowered till installation of the nipple part of the threaded connection of the branch pipe of the swivel to the connection coupling of the pipe located in the well, and they are screwed up manually by means of at least five or six turns after one is sure that engagement is correct. Screwing-up is performed with the booster or the hydraulic wrench; at this time, discharging of the pipe cavity through the swivel takes place; after that, pipe rams of the upper and the lower sealing assemblies are spread; upper and lower sealing assemblies are lowered to initial position; a pipe string is removed from the spider wedges and the next pipe is lifted out of the well. When sealing of the well is required, a ball valve is screwed on the pipe, a coupling for preventer rams is lowered, the preventer is closed thus installing pipe rams on the body of the remote branch pipe of the ball valve, the ball valve is closed, then, casing valves are closed, after that, excess pressure is measured.

EFFECT: reliable protection of environment against a well; preservation of collecting properties of the bed and reduction of time and material costs for performance of well repair.

5 cl, 9 dwg