RU2280754C1 - Well repair method - Google Patents

Abstract

FIELD: oil industry, particularly cutting or destroying pipes, packers, plugs, or wire lines, located in boreholes or wells, for instance, cutting of damaged pipes, of windows.

SUBSTANCE: method involves detecting well section to be repaired; lowering flexible integral coiled tubing plant pipe in well; injecting process liquid in the pipe; lifting the flexible integral coiled tubing plant pipe from well and executing time lag; bringing the well in operation; installing explosive packer below well section to be repaired; lowering elongated flexible integral coiled tubing plant pipe in well through lubricator; sealing well head; injecting cement grout used as process liquid via the elongated flexible integral coiled tubing plant pipe, wherein the cement grout has viscosity of up to 80 cP and production string pressure of 6-10 MPa; forcing cement grout through well section to be repaired to well casing annulus; removing elongated flexible integral coiled tubing plant pipe from well without pressure reduction; exercising technological time-delay for not less than 48 hours to provide cement grout hardening under well pressure of 6-10 MPa; drilling cement bridge to reach explosive packer; determining well air-tightness and drilling explosive packer.

EFFECT: increased efficiency and reliability of well repair.

1 ex

Description

The invention relates to the oil industry and may find application in the repair of wells.

A known method of liquidation, conservation of wells in conditions of abnormally low reservoir pressure, including the installation of an insulating bridge, waiting for cement to harden, testing the bridge and the final work on liquidation, conservation of the well. Long without clutching tubing into the well, the long, sleeveless flexible pipes of the coiled tubing unit are lowered, in the interval of artificial slaughter — the production packer is installed an insulating bridge under the equilibrium of the bottomhole and reservoir pressure, the cement is hardened and the bridge is tested, and then the tubing is disconnected compressor pipes from the production packer, remove them to the surface and carry out the final work on liquidation, well conservation (application for zobretenie RF №2001128133, publ. 2004.02.20).

The known method involves the placement of long clutchless flexible pipes coiled tubing installation inside the tubing string, which imposes restrictions on the possibilities of the method.

Closest to the invention in technical essence is a method of repairing a well equipped with a tubing string and a packer under conditions of abnormally low reservoir pressure, including determining the interval of insulation work, installing an insulation bridge, waiting for cement to harden, and putting the well into operation. After determining the interval of insulation work, the tubing string is perforated with special holes above the roof of the insulation bridge, flexible couplingless long pipes of the coiled tubing unit are lowered into the well without preliminary killing, and a viscous fluid is pumped into the bottomhole when the well is closed, the volume of the waterproofing solution is determined by the volume of viscous fluid when she reaches the special holes, they purge the well until the viscous fluid is completely removed, and then pump it with a waterproofing creates carried installation insulating bridge at spetsotversty, raised from the well flexible tubes, waiting is carried hardening grout in the borehole and run work (application for invention RF №2001133624 / 03, published 2003.08.20 -. prototype).

The placement of long clutchless flexible pipes of the coiled tubing unit outside the tubing string expands the possibilities of the method, however, this method does not allow well repair to be carried out with sufficient efficiency and reliability.

The proposed invention solves the problem of increasing the efficiency and reliability of well repair.

The problem is solved in that in a method of repairing a well, including locating a repair site, lowering a flexible sleeveless long pipe of a coiled tubing installation, pumping process fluid through it, lifting a flexible couplingless long pipe of a coiled tubing from a well, holding the process, and putting the well into operation, according to the invention an explosion packer is installed below the repair site, a flexible sleeveless long pipe of a coiled tubing installation is lowered into the well through a lubricator, the wellhead They analyze that, as a process fluid, a cement mortar with a viscosity of up to 80 cPs is pumped under pressure to a production string of 6-10 MPa through a flexible collarless long pipe of a coiled tubing installation and the cement slurry is pumped through the repair site into the annulus of the borehole, without reducing pressure, the flexible couplingless is removed from the borehole a long pipe of a coiled tubing installation, carry out technological exposure to wait for the cement to harden for at least 48 hours under pressure in the well 6-10 MPa, cement is drilled tn bridge to the blast packer, determine the tightness of the well and drill blast packer.

SUMMARY OF THE INVENTION

During repair work in the well, a very laborious and expensive operation is the descent and lifting of the tubing string. The use of a flexible sleeveless long pipe of a coiled tubing unit allows to simplify this operation. This saves time and money. However, the existing methods for processing the bottom-hole zone of the well using flexible sleeveless long pipes of the coiled tubing installation are far from perfect and do not lead to a significant increase in the efficiency and reliability of well repair. The proposed method solves the problem of increasing the efficiency and reliability of well repair. The problem is solved as follows.

During the repair, a repair location is detected, i.e. discontinuities in the casing of the well, for example, by stepping up the tubing string with a removable packer and testing the well for leaks, stepping the packer on the cable or using geophysical methods. After detecting the casing discontinuity, the tubing string with a removable packer is lifted from the well and an explosion packer is installed below the repair site that covers the well space. The blast packer is made of aluminum, i.e. from easily drilled material. A flexible, sleeveless, long pipe of coiled tubing installation is lowered through the lubricator into the well to an explosive packer. The wellhead is sealed. A cement slurry with a viscosity of up to 80 cps is pumped through a flexible sleeveless long pipe of a coiled tubing installation. The injection pressure is set so that in the annular space (the space between the flexible sleeveless long pipe of the coiled tubing unit and the production string), the pressure is 6-10 MPa. The injection is carried out with the sale of cement mortar through the repair site in the annulus of the well. Without reducing pressure, a flexible sleeveless long pipe of a coiled tubing installation is removed from the well. Carry out technological exposure to wait for the hardening of cement for at least 48 hours under pressure in the well 6-10 MPa. Drill a cement bridge to the blast packer. The tightness of the well is determined. With sufficient tightness, an explosive packer is drilled. If the well is leaking, the cement grouting operations are repeated. Launch the well into operation.

The flexible sleeveless long pipe of the coiled tubing installation can be removed from the well while maintaining pressure. It is possible to maintain pressure while waiting for cement to harden. The use of cement slurry with a viscosity of up to 80 cps promotes better penetration into casing discontinuities, more complete filling of the defect site. Due to this, the efficiency and reliability of well repair is increased. Also, due to the low viscosity of the cement slurry, high hydraulic resistances in the long pipes of the coiled tubing installation are avoided. Due to the easy drilling of the blast packer, the commissioning of the well is facilitated. Practice shows that well tightness is achieved immediately without repeating cement grout injection operations.

An example of a specific implementation of the method.

Repair work is being carried out in an oil producing well with a depth of 1180 m. The diameter of the casing string is 146 mm. The repair location is detected, i.e. well casing discontinuities by geophysical method. It is determined that the defective place is located at a depth of 965 m. An aluminum explosive pack of the VP-118 brand is installed 25 meters below the repair site, which covers the borehole space. A flexible, sleeveless, long pipe of a coiled tubing installation with a diameter of 40 mm is lowered into the well through the lubricator into the blast packer. The wellhead is sealed. A cement slurry with a viscosity of 75 cPs under a pressure of 8 MPa in a volume of 6 m ^{3 is} pumped through a flexible sleeveless long pipe of a coiled tubing installation with the cement grout being pumped through the repair site into the annulus of the borehole and forming a “cement glass” in the borehole. Without reducing pressure, a flexible sleeveless long pipe of a coiled tubing installation is removed from the well. Carry out technological exposure to wait for the hardening of cement for 48 hours under pressure in the well 6 MPa. Drill a cement bridge to the blast packer. The tightness of the well is determined. The well is tight. Drill an explosive packer. Launch the well into operation.

The application of the proposed method will improve the efficiency and reliability of well repair.

Claims (1)

A method of repairing a well, including locating a repair site, running a flexible sleeveless long pipe of a coiled tubing installation, pumping process fluid through it, lifting a flexible sleeveless pipe of a coiled tubing installation from a well, holding a process shutter and putting the well into operation, characterized in that the repair location is set below an explosive packer, a flexible sleeveless long pipe of a coiled tubing installation is lowered into the well through a lubricator, the wellhead is sealed, as a techno of logical fluid through a flexible sleeveless long pipe of a coiled tubing installation pump cement slurry with a viscosity of up to 80 cP under pressure to a production casing of 6-10 MPa with a flow of cement mortar through a repair site into the annulus of the well, without reducing the pressure, and remove a flexible sleeveless long pipe of coiled tubing from a well without pressure they carry out technological exposure to wait for the cement to harden for at least 48 hours under pressure in the well 6-10 MPa, drill a cement bridge to an explosion packer, op edelyayut wells and drilled out vzryvpaker tightness.