RU2155862C1 - Device for stimulation of well bottom-hole zone by differential pressure pulse - Google Patents

Abstract

FIELD: oil producing industry; devices for increase of production rate of wells operating by means of deep-well sucker-rod pumping plants. SUBSTANCE: device has cylindrical body with side holes and plug in lower end part. Located in body for reciprocation is plunger with valve. Installed on tubing string is branch pipe carrying sealing member. Device body is telescopically installed on tubing string branch pipe for axial motion and engagement with sealing member through movable stop. Sealing member is in form of hollow cylindrical flexible collar with holes made in its middle part. EFFECT: higher efficiency of bottom-hole formation zone due to effect of multiple pulses of differential pressure and creation of cyclic sign- varying pressure gradients in zone of drainage with simultaneous pumping out of fluid from well. 2 dwg

Description

 The invention relates to the oil industry, in particular to devices for impacting the bottom-hole zone with a depression pulse in order to increase the productivity of wells operated by rod-type deep-well pumping units.

 A device for creating instantaneous depressions on the reservoir, including a tubing string with start-up holes and a movable column assembly above the packer and a perforated liner [1].

 A disadvantage of the known device is the use of special equipment (lift, compressor) at low productivity and the complexity of the operations to create pulses of instantaneous depressions on the reservoir.

 Closest to the proposed invention in technical essence is a device for creating depression on the formation, including a tubing string provided with a bursting diaphragm in the lower part and a sealing element installed between the upper movable and lower fixed stops. The sealing element is made in the form of a hollow cylindrical elastic cuff with holes in the upper part and is provided with a cylindrical spring on the inside and which at the moment of diaphragm rupture blocks the annulus of the well [2].

 This device does not provide the creation of multiple pulses of depression for high-quality cleaning of the bottomhole formation zone without additional multiple tripping operations. A sharp hydraulic shock at the time of creating a deep one-time depression can lead to the destruction of the bottom-hole zone and the collapse of the production casing of the well. In addition, in the process of exposure, the creation of cyclic alternating pressure gradients is not ensured, which determine vibrational-wave movements of fluids in the drainage zone, which favorably affect the process of cleaning the bottom-hole formation zone from clogging particles.

 The aim of the invention is to increase the efficiency of cleaning the bottom-hole zone of the reservoir by providing multiple pulses of depression and the creation of cyclic alternating pressure gradients in the drainage zone while pumping fluid from the well.

 This goal is achieved in that the device for influencing the bottom hole of the well with a depression pulse is equipped with a cylindrical body with side openings and with a plug in the lower end part, in which the plunger with valve is arranged for reciprocating movement. A telescopic cylindrical housing is installed on the pipe nozzle of the tubing string with the possibility of axial movement and interaction through a movable stop with a sealing element, also mounted on the pipe. The opening of the cuff of the sealing element is made in its middle part.

 In FIG. 1 shows the proposed device installed in the well; figure 2 - shows the node of the sealing element at the time of creation of the pulse of depression.

 The device consists of a cylindrical housing 1 with a plug 2 with side holes 3, hydrodynamically connecting the internal cavity of the housing 1 with the annulus of the well 4 and the reservoir 5. The plunger 6 with a discharge valve 7 located in the housing 1 is connected to the machine using a rod string 8 a rocking chair (not shown in FIG.). The housing 1 with its upper end through a sub 9 is rigidly connected to a movable stop 10 telescopically mounted on a pipe 11, which is mounted on a tubing string 12. A sealing element in the form of an elastic hollow cylindrical sleeve 13 with radial holes 14 and a coil spring 15 coaxially placed in it, installed on the pipe 11 between the stops 16 and 10, which have centralizers 17 and 18.

 The device operates as follows.

 A device without a plunger 6 is lowered onto the string of tubing 12 into the well 4. During the descent of the device into the well, the movable stop is in its lowest position and is fixed with shear pins (not shown in Figs. 1, 2) on the stop of the nozzle 11. The cuff 13 due to the spring 15 is in a stretched state with an outer diameter smaller than the inner diameter of the production casing 4.

 During the descent of the device, the pressure inside the cuff 13 is aligned with the pressure in the well due to the flow of fluid through the radial holes 14, and the centralizers 17 and 18 protect it from rubbing against the walls of the well 4.

 The device is installed in the well 4 in such a way that the housing 1 is opposite the treated formation 5, and the cuff 13 is above its roof. Next, the plunger 6 descends on the rod string 8 and is installed in the housing 1. In this case, the stroke length of the plunger 6 is selected so that the side holes 3 are opened at the topmost position and closed at the lowest position of the plunger 6.

 The working volume in the housing 1, the stroke length of the plunger 6, the location and diameter of the holes 3 are selected based on the parameters of a particular well and the treated formation.

 During the course of the column string 8 and the associated plunger 6 down, the valve 7 opens, the openings 3 of the housing 1 are closed and the fluid is pumped into the space above the valve 7. At the beginning of the upward movement of the plunger 6, the valve 7 closes and a vacuum is created under it in the housing 1 . Moreover, the higher the movement of the plunger, the lower the pressure in the rarefaction cavity of the housing 1. In this case, due to the difference in pressure in the vacuum cavity and the bottomhole pressure in the well 4, a vertical buoyant force is created that acts on the plug 2 of the housing 1. Under the action of this force, the housing 1 and the movable stop 10 rigidly connected to it, destroying the shear pins, moves up. The emphasis 10, overcoming the elastic force of the spring 15, presses the cuff 13 and expands it diametrically. The radial holes 14 at the moment of contact with the wall of the well 4 are covered, and the liquid located in the inner cavity of the cuff 13 causes a uniform distribution of the compression pressure in it. Upon reaching the supporting surface of the sub 9 of the lower end of the limiter of the pipe 11, the annular space is reliably closed by the cuff 13.

 Plunger 6 continues to move upward and by the time of opening of hole 3, the maximum rarefaction occurs in housing 1. Fluid from under the cuff and borehole zones rushes into housing 1. At the same time, a deep depression pulse occurs under cuff 13 in the bottom of the borehole 4, causing accelerated fluid movement in bottomhole zone, and propagating in accordance with the piezoconductivity of the reservoir 5. After equalizing the fluid pressure in the housing 1 with the current bottomhole pressure, the housing 1 with a movable stop 10 due to its own weight and elastic compressive force Ia spring 15 moves downward. In this case, the cuff 13, diametrically decreasing, depressurizes the annulus of the well. The hydrostatic pressure of the liquid column above the sealing element is instantly transmitted to the bottom of the well and creates a pressure impulse, which also propagates in the bottomhole zone of the well.

 As a result, first a depression impulse is created in the bottomhole zone, and then a pressure impulse, which is again replaced by a depression impulse, etc. Thus, the creation of time-varying depression pulses and pressure pulses causes the appearance of alternating (tensile and compressive) pressure gradients in the bottom-hole zone of the well. This leads to the formation of microcracks in the rocks and high-quality cleaning from contamination of the first space of the bottomhole zone of the well.

 After exposure to the bottom-hole zone of the formation with simultaneous pumping of fluid from the well for 2-3 days, the device is removed and the deep-well pump is launched by the design parameters for well operation.

 The combination of the claimed essential features of the technical solution allows to obtain a new technological result, namely, by providing multiple pulses of depressions with the simultaneous creation of cyclic alternating pressure gradients in the drainage zone, a more effective effect on the bottom-hole formation zone is achieved.

 The proposed device allows you to combine intensive drainage of the bottom-hole zone with other methods of stimulating the work of the well, for example, with the injection of process fluid (ASPO solvents, surfactant solutions, etc.) to process the bottom-hole zone of the formation without raising the bottom-hole equipment.

Sources of information
1. Abdullin F.S. Improving the productivity of wells.- M .: Nedra, 1975, p.178.

 2. Patent PU 2014443 C1, publ. 06/15/1994.

Claims (1)

 A device for influencing the bottomhole zone of a well with a depression pulse, including a tubing string installed between the stops, one of which is a movable, sealing element made in the form of a hollow cylindrical elastic cuff with holes, provided with a cylindrical spring on the inside that stretches it into axial direction, characterized in that a pipe is fixed to the tubing string and a cylindrical body is connected to it with side holes and a plug in the bottom of the end part, the sealing element is located on the nozzle, a plunger with a valve is arranged for reciprocating movement in the cylindrical body, while the cylindrical body is telescopically mounted on the nozzle with the possibility of axial movement and interaction through the movable stop with the sealing element cyclically overlapping the annulus, and the holes in the cuff are made in its middle part.

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