RU2373378C2 - Method for well cleaning from proppant plug - Google Patents

Abstract

FIELD: oil and gas production.

SUBSTANCE: invention is related to oil and gas production industry and is intended for treatment of wells in case there is a tight sand and clay plug. Device comprises vessel connected to lift column via adapter by means of hydraulic cylinder to a connection nozzle with ring piston pulled through axial channel of adapter, spring-loaded circular piston with a hollow stem, which is installed inside hydraulic cylinder and is connected to a body of breaking mechanism, in axial channel of which the following components are serially installed - throttle orifice with throttling axial channel, seat with longitudinal slots on external surface and pusher that is pressed by spring to end of throttle orifice, end valve that covers lower end of pusher and rests on seat, being connected to tube, which in its turn is connected to internal crown and adjustment nut with calibrated holes. Hollow stem and body are arranged accordingly with a circular bore on external and internal sides, in which split spring ring is installed. In axial channel of lift pipe string there is a control mechanism in the form of partition with throttle and axial channels, equipped with a check valve in the form of seat, ball and cage. Pusher of breaking mechanism is arranged as hollow and is equipped with a check valve in the form of seat, ball and cage installed with clearance in axial channel of throttle orifice. Area of cross section of throttle channel of partition exceeds area of cross section of throttle channel of orifice. Total area of calibrated holes of adjustment nut and axial opening of internal crown exceeds total area of partition throttling channel and throttling channel of throttle orifice.

EFFECT: improved efficiency of breaking and plug removal.

2 cl, 6 dwg

Description

The invention relates to the oil and gas industry and is intended for the treatment of wells, in the presence of dense sand-clay plugs in the tubing string and borehole in the perforation interval.

Known flushing device (see AS No. 1.043.289. Ml. E21B 21/00. Publ. 23.09.83. Bull. No. 35). The device consists of a ground and underground downhole chamber.

The well is equipped with two rows of pipes, the outer - outer pipe string is connected to a cross-piece - a tee, with the formation of an outer chamber, for backwashing, and for raising sand-containing liquid during direct flushing.

In the case of direct flushing, the inner tube is equipped with cuffs and a valve for switching from direct flushing to reverse.

The operation of the device.

With direct flushing, flushing fluid is fed into the annulus and through the valve enters the flushing tubes and then rises to the surface. By switching the taps at the wellhead, the flow of flushing fluid is controlled.

The device allows for continuous direct, reverse or combined washing of sand plugs in oil and gas wells.

The lack of device design:

- the need to build two pipe columns to ensure flushing and destruction of a dense sand and clay cork of high power;

- the difficulty of installing the inner pipe string, equipped with valves inside the outer one;

- the destruction of a dense sandy-clay or proppant plug is carried out only by using the kinetic energy of the jet of working fluid.

A device is known for cleaning a well from sand plugs (see Pat. RF No. 2.242.585. Ml. E21B 37/00; 21/00, publ. 20.12.2004).

The device consists of an adapter with which it is connected to the lower end of the flexible pipe string. A sleeve, a detachable body and a casing are connected to the lower end of the adapter.

The lower part of the body is equipped with end teeth. The casing is equipped with an annular groove with a split spring ring. Coaxially in the sleeve, a destruction mechanism is installed, in the form of a detachable hollow rod, equipped with an annular piston and a crown. The split hollow rod forms an expansion chamber with the split hollow body and rests on the return spring. The upper end surface of the detachable hollow rod is made in the form of a truncated cone and forms an end valve with the seat. The crown is equipped with a hydraulic nozzle and has an axial throttle bore. The annular chamber is connected by radial holes with a common axial hydraulic channel. The cross-sectional area of the annular chamber is equal to the cross-sectional area of the common hydraulic channel.

The operation of the device.

The device through the adapter is connected to the lower end of the flexible pipe string and lowered into the well to the depth of the formation of sand-clay cork. Under overpressure, the flushing fluid is supplied to the device, with the exit of the jet from the throttle hole and the tangential channels of the crown nozzle, with the action of the jet on the surface of the sand-clay plug.

The total flow rate of the working fluid through the throttle aperture and the tangential channels of the device is less than the flow rate supplied to the flexible pipe string from the surface, which leads to a smooth increase in pressure in the axial channel.

With the calculated pressure difference on the annular piston, an axial force arises, which is perceived by the split spring ring, which is deformed in the radial direction, the detachable hollow stem is detached from the seat, and the working fluid enters the expansion chamber, with the overpressure affecting the area of the annular piston. This leads to a sharp movement of the fracture mechanism relative to the liner and mechanical impact of the teeth of the crown on the sand-clay plug. The working fluid from the expansion chamber through the circulation holes in the detachable body is discharged into the annulus, which leads to a release of pressure in the axial channel of the flexible pipe string and the fracture mechanism returns to its original position by the pre-compressed spring. The supply of working fluid to the expansion chamber is stopped, pressure builds up again, and the cycle repeats.

From the practice of carrying out work related to the destruction and removal of dense sand-clay plugs from the axial channel of the pipe lift string and the wellbore, using a coiled tubing installation, the throughput of the flexible pipe string has flow limitations. In this regard, the speed of the upward flow of the working fluid in the annulus is insufficient to ensure the removal of mechanical particles to the surface, especially when working in the wellbore, where the cross-sectional area is large enough.

In addition, the design of the device does not allow it to be used in wells with low reservoir pressure, while ensuring the effective removal of mechanical particles through the tubing string, during backwashing.

Development of the design of a larger-diameter device according to this structural scheme may prove to be ineffective if it is used as part of an elevator pipe string to flush a wellbore in the perforation interval. This is due to the fact that the throughput of an elevator pipe string of a conventional design far exceeds the throughput of a flexible pipe string and has less hydraulic resistance. In this regard, to relieve pressure in the axial channel of the pipe tubing string to ensure that the fracture mechanism returns to its original position becomes problematic.

Known hydropercussion device for the destruction of dense sand-clay plugs, taken by the authors as a prototype (see "Problems of overhaul of wells and operation of underground gas storage facilities", Stavropol, 2001, issue No. 34. The causes of the destruction of unstable reservoirs and methods for removing sand plugs from the well ").

The hydropercussion device consists of a housing connected through an adapter with a compensator. Inside the detachable body, a hollow rod with an annular piston is mounted, relying on a spring. An adapter is attached to the lower end of the hollow rod, which, in turn, is connected with an extension extending into the fracture mechanism. A saddle is installed in the axial channel of the extension, a pusher is passed into the axial channel, resting on the seat in the saddle and passing through the landing sleeve. An extension cord is connected through an adapter to a crown equipped with teeth on the end part facing the surface of the sand cork.

A spring-loaded valve is installed in the axial channel of the adapter, connected with a hollow rod passing through the crown body and equipped with an internal crown with a throttle aperture. The hollow stem is equipped with an end valve, which it rests on the seat, with the possibility of covering the lower end of the pusher. The axial channel of the adapter is hydraulically connected by calibrated holes in the body of the saddle to the internal cavity of the extension.

Calibrated channels are also made in the external crown, hydraulically connecting the internal cavity of the extension with its external side. An annular groove is made in the body of the body, equipped with a split spring ring covering the hollow rod and entering the groove on its body. The axial channel of the flexible pipe string is constantly hydraulically connected to the axial channel of the hydraulic hammer device.

The operation of the hydraulic shock device.

On a flexible pipe string, the device is lowered into the well, to the level of the sand-clay cork, with the teeth of the outer crown resting on it. The size of the throttle holes in the seat body is determined based on the possibility of missing part of the flow rate of the working fluid supplied from the surface.

With a given flow rate, the working fluid passes through calibrated holes in the body of the external crown and acts on the surface of a dense sand-clay plug. In this case, a gradual increase in pressure occurs in the axial channel of the hollow rod of the hydraulic shock device, perceived by the annular piston, which is perceived through the groove on the body of the hollow rod as a split spring ring. At a certain pressure drop, the split spring ring is deformed in the radial direction, and the fracture mechanism moves sharply downward, with the teeth of the external crown acting on the surface of the sand-clay plug. In this position, an even greater set of pressure occurs, which affects the cross-sectional area of the pusher in the axial channel of the device, and is communicated to the end valve. The end valve is detached from the surface of the seat and the overpressure of the working fluid moves sharply downward, with the teeth of the inner crown on the sandy clay plug. At the same time, the hydraulic connection of the axial channel of the extension cord with the axial channel of the hollow rod opens, which leads to a sharp release of pressure inside the body of the hydraulic shock device and the force of the compressed spring of the hollow rod of the percussion mechanism and the hollow rod with the end valve to the initial position, with the repetition of the process.

The disadvantages of the hydropercussion device include:

- the complexity of setting up the design for sequential operation for operation with an external crown, and then internal, for which it is necessary to choose the stiffness of the split spring ring and return springs;

- due to the small estimated throughput of the calibrated channels in the body of the external crown, there is no possibility of performing backwashing, which is necessary when equipping the pipe tubing with this device and supplying mechanical particles with an upward flow of the working fluid to the surface;

- the operability of the hydropercussion device directly depends on the possibility of a sharp pressure relief in the pipe lift string, with increased flow through the device, with direct supply of working fluid.

The need for direct and reverse flushing arises in the case of work in the well with an abnormally low reservoir pressure and the presence of absorption of the working fluid, which does not allow for the effective lifting of mechanical particles along the annulus due to the insufficient flow rate of the working fluid.

The transition to backwashing can significantly increase the speed of the upward flow with a corresponding increase in the removal efficiency of mechanical particles.

The technical result that can be obtained by implementing the invention is reduced to the following:

- improving the efficiency of the destruction and removal of dense sandy-clay and proppant plugs in the axial channel of the wellbore during the API;

- the possibility of backwashing the well through a hydropercussion device, with the provision of effective supply of mechanical particles by the flow of the working fluid through the pipe tubing to the surface;

- the ability to provide reciprocating movement of the destruction mechanism of the hydropercussion device when using an elevated pipe string of increased size.

The technical result is achieved using the present invention - a device for cleaning a well from a sand plug, consisting of a housing connected via a hydraulic cylinder with a compensator, a fracture mechanism including a detachable housing, in the axial channel of which a throttle washer with a throttle channel, a saddle with an axial channel and longitudinal grooves on the outside, a pusher with an end valve in the axial channel, mounted to interact with the end face of the saddle from the bottom and equipped with a tube with internal crown with axial bore. The split housing is equipped with an external crown and an adjusting nut with calibrated holes, a split spring ring in the annular groove. The internal cavity of the detachable body forms an annular chamber with a face valve and a hollow tube hydraulically connected by calibrated holes to the well cavity, the hydraulic channel of the hydraulic hammer device is constantly connected with the cavity of the pipe tubing string, the control mechanism is made in the form of a partition with a throttle channel and a check valve in the axial channel, the pusher is hollow and is equipped with a check valve installed in the axial channel of the throttle washer, and the cross-sectional area of the throttle channel eregorodki adopted more than the total cross-sectional area of the throttle duct orifice and the total area of the calibrated holes in the adjusting nut and the axial bore of the inner crown adopted greater cross-sectional area of the throttle channel partition management mechanism.

The analysis of the inventive step, carried out on patent and scientific literature, showed the following:

- we have not identified technical solutions that are based on features that match the distinctive features of the claimed technical solution, namely, the design features of the pusher included in the fracture mechanism.

To ensure the reciprocating movement of the fracture mechanism in the case of using the device as part of tubing, the axial channel of the pipe lift string is equipped with a baffle with a throttle channel, since the hydraulic resistance of the axial channel of the pipe lift string is much less than the hydraulic resistance of the axial channel of the flexible pipeless pipe string. To ensure the passage of the working fluid through the hydraulic device and through the baffle in the axial channel of the pipe riser during backwash, the pusher and the baffle are equipped with check valves to ensure free passage of the working fluid with mechanical particles through the pipe riser to the surface.

Thus, the achieved technical result is due to the unknown properties of the parts of the device in question and the relationships between them. The invention does not explicitly follow from the prior art, i.e. meets the condition of inventive step.

The design of the device for cleaning wells from sand plugs is illustrated by drawings, where:

In Fig.1 shows the design of the hydropercussion device in the initial position in the context,

- figure 2 - the design of the hydropercussion device as part of the tubing string with throttle washer,

- figure 3 - the design of the hydropercussion device in the actuation position of the fracture mechanism - impact with an external crown with direct supply of working fluid.

- figure 4 - the relative position of the parts of the hydropercussion device when triggered by the impact of the inner crown with a direct supply of working fluid,

figure 5, 6 - the relative position of the structural elements of the hydraulic shock device and the throttle washer during backwashing of the well.

A device for cleaning a well from sand plugs consists of a hydropercussion device at the lower end of the pipe string and a control mechanism in the form of a partition in the axial channel installed at a calculated distance.

The hydropercussion device consists of a housing 1 connected through a hydraulic cylinder 2 with a connecting pipe 3 with an annular piston 4, which is passed into the axial channel of the adapter 5 and forms a telescopic connection with it. Inside the hydraulic cylinder 2, an annular piston 6 is installed, equipped with a hollow rod 7, which forms a movable connection with the housing 1 and rests on the spring 8.

An annular groove 9 is made on the outer side of the hollow rod 7, and an annular groove 10 in which a split spring ring 11 is installed in the body of the housing 1.

The lower end of the connecting pipe 3 is passed through the axial channel of the housing 1 and is connected with the detachable housing 12 of the destruction mechanism.

In the axial channel of the detachable housing 12, a throttle washer 13 is installed in series with the axial channel 14, which is blocked in the initial position by the pusher head 15, pressed by the spring 16. In the middle part of the detachable housing 12, a seat 17 is installed, the end valve 19 is pressed against the end of the spring 18, connected by a tube 20 to the inner crown 21.

The lower end of the pusher 15 extends beyond the seat 17 and is covered by the body of the mechanical valve 19.

To adjust the pressure force of the mechanical valve 19 to the seat 17 by the spring 18, an adjusting nut 22 is installed in the detachable housing 12, and it is equipped with an external crown 23. A check valve is installed in the axial channel 24 of the pusher 15, which consists of a seat 25, a ball 26 and a cage 27, which installed with a gap in the axial channel 14 of the throttle washer 13.

The axial channel 28 of the hollow rod 7 is constantly hydraulically connected by the throttle channel 29 in the body of the washer of the throttle 13 with the annular chamber 30 formed by the inner surface of the detachable housing 12, the outer pusher 15 and the seat 17, which, in turn, is hydraulically connected through the longitudinal grooves 31 in the body saddles 17 with an annular chamber 32, between the inner surface of the detachable body 12, the outer surface of the tube 20 and the adjusting nut 22, in which calibrated holes 33 are made connecting the annular chamber 3 with the cavity of the well. The axial channel 24 of the pusher 15 is constantly hydraulically connected with the axial channel 34 of the tube 20 and the axial hole 35 in the inner crown 21. In the body of the hydraulic cylinder 2, a radial hole 36 is made in the lower part, connecting the annular chamber 37 under the annular piston 6 with the borehole.

On the end surfaces of the inner 21 and outer 23 crowns teeth are made for effective impact on the surface of the sand cork. The adapter 5 is equipped with a shank 38 for connection with the pipe tubing 39. The control mechanism is installed in the axial channel of the pipe tubing 39 (see figure 2) and is made in the form of a partition 40, in the axial channel of which there is a check valve including a seat 41, a ball 42 and cage 43. In the body of the partition 40, a hydraulic throttle channel 44 is made that connects the axial channel of the pipe tubing above it with the axial channel above the device.

To ensure the operation of the device for cleaning the well from proppant plugs (hereinafter referred to as the device), the hydraulic throttle channel 44 in the partition 40 has a cross-sectional area greater than the cross-sectional area of the throttle channel 29 in the body of the throttle washer 13.

The cross-sectional area of the calibrated holes 33 in the body of the adjusting nut 22 is adopted less than the cross-sectional area of the throttle channel 29.

At the same time, the total area of the calibrated holes 35 in the body of the inner crown 21 is taken to be larger than the cross-sectional area of the hydraulic throttling channel 44.

The operation of the device for cleaning wells from sand and clay corks is carried out by lowering it on an elevator pipe string 39, to the level of location of the sand and clay cork. Above the installation location of the device, in the axial channel of the pipe pipe riser, a partition 40 is installed.

Connect the pump unit to the intake manifold of the pipe pipe string 39 and supply the working fluid with the specified process parameters for flow rate and discharge pressure.

The working fluid is supplied through the throttle channel 44 to the axial channel of the pipe tubing string 39 above the device and through the axial channel of the hollow rod 3 and hollow rod 8 is supplied to the throttle channel 29, from where it is supplied to the annular chamber 30 and through the longitudinal grooves 31 in the body of the saddle 17 into the annular the chamber 32 and then through the calibrated holes 33 in the adjusting nut 22 is fed into the well, with the impact on the surface of the sand plug. Since the total cross-sectional area of the calibrated holes 33 is assumed to be less than the cross-sectional area of the throttle channel 44, pressure increases in the axial channel of the pipe tubing 39 below the installation of the baffle 40 and in the axial channel 28 of the device.

The excess pressure of the working fluid is perceived by the cross-sectional area of the annular piston 6 inside the hydraulic cylinder 2 and through the hollow stem 7 is closed on a split spring ring 11, which, with a certain axial force, is radially deformed inside the annular bore 10.

This leads to a sharp movement of the annular piston 6, connected through the hollow rod 7 with the destruction mechanism, providing compression of the spring 8 and the impact of the teeth of the external crown 23 on the surface of the sand cork.

With a further increase in pressure by a value of the order of ΔР = 0.2-0.5 MPa, the latter is perceived by the pusher 15, which leads to its separation from the end of the throttle washer 13 and entry into the end contact with the end valve 19, which leaves the interaction with the seat 17, with the formation of an annular gap into which a working fluid is supplied under excessive pressure, acting on the cross-sectional area of the end valve 19 of the pusher 15, which moves sharply downward, with the teeth of the inner crown 21 acting on the surface of the sand plug and compressing spring 18 m.

When the working fluid is supplied to the axial channel 34 of the tube 20, the latter acts on the surface of the sand plug, and since the total flow rate of the working fluid through the axial hole 35 and the calibrated holes 33 exceeds the flow rate of the working fluid through the throttle channel 44, a pressure drop occurs inside the axial channel of the pipe lift string 39 under the partition 40 and in the device. This leads to the return of the fracture mechanism to its original position, with the introduction of the split spring ring 11 into the annular groove 9 on the body of the hollow stem 7. By the force of the compressed spring 18, the end valve 19 sits on the surface of the seat 17 with the flow of the working fluid through the axial channel 34 of the tube 20. The pusher 15 by the force of the compressed spring 16 is introduced into the end contact with the throttle washer 13. The operation is repeated in accordance with the previously described. With direct supply of working fluid, the check valves on the baffle 40 and the pusher 15 are in the closed state.

The use of a device of the claimed design will improve the process of destruction of dense sand-clay plugs due to the hydraulic effect of a pulsed jet of a working fluid of variable flow rate by direct washing by destruction and removal of mechanical particles by backwashing, in the presence of ANPD. The design of the hydraulic shock device of the UG-100 brand for working with a tubing Du = 73 mm was developed.

In the absence of removal of mechanical particles to the surface along the annular space of the well, which is possible with low reservoir pressure and partial absorption of the working fluid, they switch to backwashing.

In this case, the pump unit is switched to supply the working fluid to the annular space of the well, returning to the surface through a hydraulic hammer device and a control mechanism along the pipe lift string.

The flow of the working fluid with mechanical particles passes sequentially through the axial hole 35 of the inner crown 21, the axial channel 34 of the tube 20 of the mechanical valve 15, the axial channel 24 of the pusher 15, with the ball 26 rising above the seat 25 and reaching the axial channel 28 of the hollow rod 7. Next, the working the fluid enters the axial channel of the pipe tubing string 39 below the baffle 40, tears off the ball 42 from the seat 41 in the baffle plate 40 and then rises to the surface along the pipe tubing 39.

When the device is used to clean the well from sand plugs at the time of descent into the well, there is a possibility of hard contact between the teeth of the inner 21 and outer 23 crowns with its surface. To mitigate the interaction of the device during descent and support on the surface of the sand plug, a compensation spring is provided covering the hollow rod 3, which, when the hydraulic cylinder 2 and the housing 1 are moved upward, is compressed and dampens shock loads.

Claims (2)

1. A device for cleaning a well from a sand plug, containing a housing connected to the tubing string through an adapter through a hydraulic cylinder with a connecting pipe with an annular piston passed into the axial channel of the adapter, a spring-loaded annular piston with a hollow rod mounted inside the hydraulic cylinder and connected to the mechanism body destruction, in the axial channel of which a throttle washer with a throttle axial channel, a saddle with longitudinal grooves on the outer surface and a pusher, crushed by a spring to the end of the throttle washer, an end valve covering the lower end of the pusher and resting on the seat, which is connected to a tube connected in turn with the internal crown of the fracture mechanism, the body of which is equipped with an external crown and an adjusting nut with calibrated holes, and the hollow stem and the housing is respectively made with an annular groove on the outer and inner sides, in which a split spring ring is installed, characterized in that it is equipped with a control mechanism in the axial channel of the elevator a new pipe string in the form of a partition with a throttle and axial channels, equipped with a check valve in the form of a saddle, a ball and a cage, the pusher of the fracture mechanism is hollow and equipped with a check valve in the form of a saddle, a ball and a cage installed with a gap in the axial channel of the throttle washer, when this cross-sectional area of the throttle channel of the septum exceeds the cross-sectional area of the throttle channel of the washer, and the total area of the calibrated holes of the adjusting nut and the axial hole of the inner crown exceeds the total cross-sectional area of the throttle channel of the septum and the throttle channel of the throttle washer. 2. The device according to claim 1, characterized in that the diameter of the mechanical valve along the line of contact with the seat is larger than the diameter of the tube.

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