RU2199658C2 - Technique of completion of oil well - Google Patents

Abstract

FIELD: oil production, secondary opening of productive pools under condition of depression. SUBSTANCE: technique includes running of casing string with filter into well, cementation of well, destruction of hollow end-caps, cleaning of bottom hole zone of pool with the help of tubing string, sinking of well pump and putting well into operation. Filter is fitted with hollow end-caps protruding beyond body and filled with viscoplastic substance. End-caps are destroyed by sinking of cutting cone included in mix of one part of device that forms depression in pool. Device has packer, body, ball valve, perforated branch pipe. It is lowered on tubing string and is employed to clean bottom zone of pool. Device is sunk to bottom of well after cutting cone destroys hollow end-caps. The productive pool is isolated from above-lying part of well. Depression in pool is formed by communication of well zone opposite to productive pool with internal space of tubing string found under atmospheric pressure. On completion of this above- mentioned part of device forming depression in pool that includes packer, body, ball valve and perforated branch pipe with cutting cone are left in well. Another part of device forming depression in pool that includes rod, spring and bushing is raised to surface and well pump is sunk. EFFECT: preservation of collector properties of productive pool, reduced time and usage of materials for completion of oil well. 1 dwg

Description

 The invention relates to the oil industry and can be used for the secondary opening of reservoirs in a depressed mode.

 A known method of developing an oil well, including creating perforation channels in the casing and cement ring in the zone of the reservoir, depressurizing it and putting the well into operation (1).

 The disadvantage of this method is that between the operations of depressurization of the reservoir and the launch of the well into operation, there is a temporary gap that ranges from several days to several months. This leads to the fact that while waiting for launch, the reservoir absorbs the wellbore fluid, sharply worsening its filtration properties, which ultimately reduces its productivity.

 The closest in technical essence to the proposed one is a method of developing an oil well, including lowering a casing string into the well with a filter equipped with hollow plugs with a viscoplastic substance, protruding beyond the filter housing, cementing the well, lowering the tubing with a cutting funnel , the destruction of the ends of the hollow plugs and the descent of the deep pump (2).

 In the known method, the time gap between the depressurization operations of the formation and the launch of the well into operation is reduced, but it still exists. In addition, if the pump fails, it must be raised to the surface and the other pump lowered. During these tripping operations, water hammering occurs, which leads to intensive penetration into the reservoir of both the wellbore fluid and all kinds of contaminants in it, which impairs its reservoir properties and, in fact, necessitates repeated operations to clean the formation. And this leads to additional borrowing a significant amount of time and the expenditure of material resources.

 The objective of the invention is to provide a method that ensures the safety of the reservoir properties of the reservoir with minimal time and material costs during the secondary opening and development of an oil well.

 This problem is solved by the proposed method, including a casing string descent into the well with a filter equipped with hollow plugs with a viscoplastic substance protruding from the filter housing, well cementing, a tubing run into the well with a shear funnel, a hollow plug plug destruction by a funnel, and a submersible pump descent.

 New is that on the tubing together with a cutting funnel, a device for creating depression on the formation is lowered into the well, including a packer element installed above the cutting funnel, and after cutting the last ends of the hollow plugs, the device for creating depression is lowered to the bottom of the well and the reservoir is turned off from the overlying part of the well, and then create a depression on the formation by communicating the zone of the well opposite the reservoir with the internal space of the tubing under atmospheric pressure by water, after which the device, in addition to the packer element, is raised to the surface, the deep pump is lowered and the well is put into operation.

 The drawing shows a longitudinal section of a device for creating depression on the formation used in the implementation of the proposed method.

 The device consists of a rod 1, inside of which at the top there is a blind transverse partition 2, above and below which there are radial channels 3. In the lower part of the rod there is a vertically horizontal guide groove 4. A sleeve 5 s is installed on the outside of the rod in the zone of radial channels cylindrical sampling 6 inside. At one end, the sleeve abuts the spring 7, and it, in turn, abuts the annular protrusion 8, and the other, into the expanding cone 9. The latter contacts the sealing element 10 of the packer, the housing 11 of which is connected to the rod 1 with a shear element 12, which protects against unauthorized rotation of them relative to each other, and is equipped with a partition 13 with longitudinal channels 14. The packer body 11 is stepped and connected to the perforated pipe 15, on the ledge of the connection 16 of which there is a ball valve 17. At the other end of the perforated cartridge a cutting funnel 18 with a comb 19 is installed; the expanding cone 9 is connected to the stem 1 with a cutting element 20. The mating surfaces of the device are equipped with sealing elements 21. Locking screws 22 (at least two) are screwed into the packer housing 11, the free ends of which are located in the horizontal part of the guides grooves 4. Locking screws 22 are made strong enough, they experience significant axial loads and are not destroyed during operation.

 The lengths of the perforated pipe 15 and the packer body 11 are taken from the calculation so that when the device is installed in the well, the holes of the perforated pipe are lower and the packer is higher than the reservoir.

 The casing string is lowered into the well so that the filter 23 with the hollow plugs 24 installed in it, filled with a visco-plastic substance 25 (for example, paraffin, tar, etc.), is opposite the reservoir. Cementing is carried out using conventional technology.

 After setting the cement slurry, the opening and development of the reservoir is as follows.

 The assembled device on the FCT is lowered into the well until it stops at the bottom, while the funnel 18 cuts off the heads of the hollow plugs 24, and the tubing string with the rod is turned clockwise. The sheared element 12 is destroyed, and the locking screw 22 from the horizontal part of the groove 4 falls into the vertical part. The rod 1, the expanding cone 9 and the sleeve 5 are moved down, the packer is locked, and then the sheared element 20 is destroyed and the rod 1 is further lowered relative to the sleeve 5. In this case, the upper and lower radial channels 3 are connected to each other in a cylindrical sample 6 and thereby there is a message of the zone opposite the productive part of the reservoir with the internal space of the tubing, which is under atmospheric pressure.

 Due to the significant pressure difference, instant depression occurs, the cement stone (its thickness is 4-5 mm) opposite the holes where the plugs were installed, collapses, there is a sharp discharge of fluid and with it clogged the pores of the formation substances. In this case, a deep depression is achieved on the reservoir and a high level of cleaning the bottom-hole zone of the formation, since the magnitude of the depression can be created almost any way, and only the strength characteristics of the casing string, cement ring and skeleton of the rock of the reservoir can be a limitation here.

 Depression on the formation can be controlled by topping up the estimated volume of fluid in the tubing.

 After the operation to clean the formation, one part of the device is raised to the surface, namely: rod 1, spring 7 and sleeve 5. The latter then returns to its original position, i.e. overlaps the upper row of radial channels 3 and prevents the flow into the well of fluid and sludge from the tubing. Another part of the device, including the packer 9 and 10, the housing 11, the perforated pipe 15 with a cutting funnel 18 and a ball valve 17, remains in the well. In the process of lifting the PCT into the well, fluid is added.

 After rising into the well, the downhole pump is lowered and put into operation.

 The application of the proposed method will save the reservoir properties of the reservoir from the negative effects of the borehole fluid and contaminants in the wellbore when lifting the device to the surface, when lowering and raising pumps, etc. Eliminates the need for repeated operations to clean the bottom-hole zone of the well. All this will lead to significant material savings and ensure high productivity of the well.

Information used
1. The analogue. A.S. 1754885, MKI E 21 V 43/11, 1992.

 2. The prototype. RF patent 2108447, MKI 6 E 21 V 43/00, 43/11, 1998.

Claims (1)

 A method for developing an oil well, including lowering a casing string with a filter equipped with hollow plugs with a viscoplastic substance protruding behind the filter body, cementing the well, destroying the hollow plugs by lowering a cutting funnel, cleaning the bottom-hole formation zone using tubing (tubing), launching the deep pump and putting the well into operation, characterized in that a funnel is used to cut the plugs, which is part of one of the parts of the device to create depression on a formation including a packer, a housing, a ball valve, a perforated nozzle, which is lowered onto the tubing and used to clean the bottom-hole zone of the formation, for which, after breaking the ends of the hollow plugs with a shearing funnel, they are lowered to the bottom of the well, then the producing formation is disconnected from the overlying part of the well, create depression on the formation by communicating the zone of the well opposite the productive formation with the internal space of the tubing under atmospheric pressure, after which the said part of the device for creating epressii on a layer comprising a packer body, a ball valve with perforated pipe cutoff funnel was left in the wellbore, and another part of the device to create a depression in the reservoir, comprising a stem, a spring and sleeve lifted to the surface and proceed to descend downhole pump.