RU2331005C1 - Device for sealing flexible drawbar - Google Patents

Abstract

FIELD: mechanics.

SUBSTANCE: invention relates to sealing movable devices in processes involving using cable containers and can be used to seal a moving cable at wellheads on lifting liquid there from by means of swabs. The said device incorporates a casing with an attachment unit, a main and additional sealers furnished with retrievable sealing elements, a main and additional hydraulic mechanisms tightening sealing elements to the drawbar, the said mechanisms being connected to the appropriate main and additional speeders. The casing space with a drain channel is arranged between sealers. The main and additional speeders are controlled by pressure fed from outside. The casing outside accommodates a vessel to gather and remove liquid, the vessel communicating, via a drain valve, with the casing space and wellhead via the valve opening on pulling the cable down into the well. The vessel volume should be no less than that of the liquid leaking into the casing space on lifting the cable from the well. An air valve can be arranged above the vessel valve to prevent and ingress of air into the well.

EFFECT: reliable isolation of movable flexible means with a complicated outer surface being isolated, minimum possible wear out of sealing elements.

2 cl, 2 dwg

Description

The proposal relates to a sealing technique, in particular, to sealing movable elements using cable-container technologies and can be used to seal a moving rope at the wellhead when lifting swab fluid from them.

It is known "Device for sealing movable and stationary elements of piston and plunger pumps" (see AS USSR No. 227024, F16J 15/14, F15J 15/40, publ. BI No. 29 of 09.16.1968), containing a seal , the annular chamber of which is filled with compressed gas, while in order to automatically maintain the pressure of the compressed gas in the annular chamber close to the pressure of the working fluid in the pump cylinder, the annular chamber is connected to a pulsation damper filled with compressed gas and installed at the cylinder exit.

The disadvantages of this design are the low reliability and manufacturing complexity due to the use of compressed gas, the impossibility of high-quality sealing at low pressures of the sealing medium, while in the process there is no way to control the process of wear of the sealing elements, and there is also no possibility of collecting and removing the transmitted fluid.

Also known is the “Stuffing box for sealing the pump stem” (see AS USSR No. 142529, F16J 15/40, publ. BI No. 21 of 1961), consisting of a body and hemp salted packing, with the aim of sealing ability, the gland is equipped with a rubber sleeve, sealed with its ends in the body and crimped together with the packing around the stem by the action of a fluid supplied from the pump cylinder into the annular chambers from the outside of the sleeve.

The disadvantages of this design are the low reliability when sealing movable elements with a complex shape of the outer surface, especially at low pressures of the medium to be sealed, the difficulty of changing worn sealing elements - seals, while in the process there is no way to control the process of wear of the sealing elements, and there is no possibility of collecting and removing leaking fluid.

Also known is “Shaft Seal” (see AS USSR No. 723282, F16J 15/48, publ. BI No. 11 of 03/25/1980), in the bore of which there is a sealing element covering the shaft, and an inflatable elastic ring element covering the sealing element, in order to increase reliability and service life in the bore from the side of the cavity being sealed, a thrust ring is installed that interacts with the end face with the inflatable elastic element, and through holes can be made in the thrust ring connecting the pressure cavity with the end of the inflatable elastic th element.

The disadvantages of this design are the low reliability when sealing movable elements with a complex shape of the outer surface, especially at low pressure values of the medium to be sealed, the difficulty of changing worn sealing elements, while in the process there is no way to control the wear of the sealing elements, and there is no possibility of collecting and removing the leakage liquids.

It is also known "Waterproof cable sealing for objects operating at shallow and deep depths" (see AS USSR No. 153740, Е21С 23/07, published in BI No. 7, 1963), made in the form of a gland with elastic a shell filled with grease, which is under the influence of outboard pressure, in order to ensure the reliability of the seal during small immersions of the object, a multiplier is used, equipped with a spring and connected by a tube to the internal cavity of the seal.

The disadvantages of this design are the difficulty of replacing worn sealing elements, low reliability and durability due to the inability to change the degree of increase in pressing pressure as the seal wears, which in the known device is rigidly set initially by the ratio of the diameters of the piston stages of the multiplier and remains unchanged during operation of the device, while in the process there is no way to control the process of wear of the sealing elements, there is also no possibility of collection and removing leaking fluid.

The closest in technical essence and the achieved result to the proposed one is “A device for sealing a rope” (patent RU No. 229049, F16J 15/46, publ. Bull. No. 14 dated 05/20/2004), containing a housing with a mounting unit, a sealant with elastic sheath, a multiplier connected by a tube to the inner cavity of the elastic sheath, while the device for providing sealing of the movable rope is equipped with an additional multiplier and an additional sealant with an additional elastic sheath connected by a tube with additional m multiplier, while the seals are equipped with replaceable sealing elements that cover the movable rope with the inner surface and interact with the corresponding elastic shells of the seals from the outside, the multiplier under the influence of borehole pressure equipped with an amplifier consisting of a cylinder with a piston, with an additional multiplier and the multiplier amplifier is under the influence of an external control pressure, and the working volumes of each multiplier, which are communicate with the corresponding elastic shells of the seals, do not exceed the corresponding initial volume of the replaceable sealing element, each multiplier is equipped with a wear indicator of the interacting replaceable sealing element made in the form of an indicator of the position of the multiplier piston, and a cavity with a drainage channel for collection and fluid removal. The number of additional seals with additional elastic shells with replaceable sealing elements and the corresponding additional multipliers may be more than one each.

The disadvantages of this design are:

firstly, the communication of one of the multipliers directly with the wellhead, where the pressure is not constant, which can lead to increased wear of the sealing elements or to poor-quality sealing of the rope;

secondly, the need for constant drainage of fluid from the cavity between the seals, which requires the construction of a discharge pipe or placement of a collection tank, which requires additional material costs.

The technical task of the proposed design is to reduce material costs by draining the fluid directly into the well and increasing the life of the sealing elements, as well as improving the quality of the sealing of the rope by adjusting the force of its coverage by external pressure sources.

The stated technical problem is solved by a device for sealing flexible traction, comprising a housing with a mounting unit, main and additional seals equipped with interchangeable sealing elements and the main and additional, pressing the sealing elements to the flexible traction, hydraulic mechanisms that are connected to the corresponding main and additional multipliers, case a cavity with a drainage channel located between the seals, and an additional multiplier is made with the possibility external pressure control.

New is that the main multiplier is made with the ability to control external adjusting pressure, and outside the casing there is a container for collecting and removing fluid, which communicates through the drainage channel with the casing cavity and with the wellhead through a valve that opens when the rope is lowered into the borehole, while capacity not less than the volume of leaking fluid into the body cavity when lifting the rope from the well.

Also new is the fact that an air valve is located above the valve of the tank, which does not allow air to pass from the tank to the well.

Figure 1 shows a diagram of a device for sealing a movable rope with hydraulic mechanisms in the form of elastic shells.

Figure 2 shows a diagram of a device for sealing a movable rope with hydraulic mechanisms in the form of piston pairs.

The device for sealing flexible traction was made in two versions:

- with hydraulic mechanisms in the form of elastic shells (see Figure 1);

- with hydraulic mechanisms in the form of piston pairs (see Figure 2).

First option.

A device for sealing a flexible rod 1 (see FIG. 1), for example, in the form of a rope, comprises a housing 2 with a fastener 3, a main seal 4 with an elastic shell 5, a main multiplier 6 connected by a tube 7 to the internal cavity 8 of the elastic shell 5 The sealing device also includes an additional multiplier 9 and an additional seal 10, comprising an additional elastic shell 11 with an internal cavity 12, which is connected by a tube 13 with an additional multiplier 9. The seals 4 and 10 are equipped with interchangeable seals lnymi elements 14 and 15 which cover the inner surface 16 of the movable rope 1, and the outside cooperate with respective elastic membranes 5 and 11, seals 4 and 10.

Option Two.

A device for sealing a flexible rod 1 (see FIG. 2), for example, in the form of a rope, comprises a housing 2 with a mounting unit 3, a main seal 4 with a piston 5, a main multiplier 6 connected by a tube 7 to an internal cavity 8 located under the piston 5. The sealing device also includes an additional multiplier 9 and an additional seal 10, comprising an additional piston 11 with an internal cavity 12 located below, which is connected by a tube 13 to an additional multiplier 9. The seals 4 and 10 are equipped with interchangeable and sealing elements 14 and 15, which inner surface 16 enclose the movable rope 1, and from the bottom interact with the corresponding pistons 5 and 11 of the seals 4 and 10.

The remaining symptoms in the first and second options are common.

The main multiplier 6 (see Figs. 1 and 2), which is under the influence of the external adjusting pressure P _p , is equipped with an amplifier 17 consisting of a cylinder 18 with a piston 19, while the additional multiplier 9 and the amplifier 17 of the multiplier 6 are also influenced by an external adjusting pressure pressure P _p '. The working volumes V and V _{d of} each multiplier 6 and 9, which communicate with the corresponding internal cavities 8 and 12 of the hydraulic mechanisms 5 and 11, do not exceed the corresponding initial volume V _c1 and V _{c2 of} replaceable sealing elements 14 and 15. Each multiplier 6 and 9 can be equipped with a wear indicator for the interchangeable sealing element 14 and 15 interacting with it, made in the form of a position indicator 20 or 21 of the pistons 22 and 23, respectively, or the piston 24 of the multiplier 6 or 9. A housing cavity is located between the seals 4 and 10 25, which through a drainage channel 26 communicates with a container 27 (shown schematically) for collecting and removing fluid, placed outside of the housing 2. A container 27, the volume of which is not less than the volume of leaking fluid into the housing cavity when lifting the rope 1 from a well (not shown), through the valve 28, passing during the descent of the rope 1 into the well, communicated with the wellhead under pressure P _c . O-rings 29, 30, 31, 32, 33 and 34 prevent unauthorized fluid flows in the device. To prevent the intake of air from the reservoir 27 into the well above the valve 28 of the reservoir, an air valve 35 can be located that does not allow air from the reservoir to the well and is made , for example, in the form of a float that blocks the flow of air through the valve 28 with the complete discharge of fluid from the tank 27 into the well.

The device operates as follows.

In the initial state, the device is fixed by the mounting unit 3 (see Figs. 1 and 2), consisting of guides 36, 37, 38 and pins 39, which fix the replaceable sealing elements 14 and 15 in the housing 2. Pistons 19, 22, 23 and 24 set in the initial position (extreme lower position in figures 1 and 2). The internal cavities 8 and 12 of the hydraulic mechanisms 5 and 11 of the seals 4 and 10, the tubes 7 and 13, as well as the working volumes V and V _{d of the} multipliers 6 and 9 and the channels 40 and 41 for supplying the control pressures P _p and P _p ′ are filled with a working fluid , which is practically incompressible and not freezing over the entire temperature range of operation (for example, transformer oil, liquid for hydraulic systems such as AMG, etc.). The device is assembled installed in the upper part of the lubricator 42. The necessary downhole equipment 43 (for example, cargo, swab) is connected to the cable 1 and introduced into the lubricator 42. The lubricator 42 is hermetically mounted on the buffer shutoff element of the wellhead reinforcement. Open the buffer locking body, communicating the cavity of the lubricator 42 with the well. Dip 1 swab 43 is lowered into the well and the process of lifting fluid from the well is carried out by periodic immersion of swab 43 below the fluid level, followed by lifting the fluid column with swab 43. To ensure tightness and cleaning of the rope from the well fluid from a variable pressure source (pump), it is supplied through channels 40 and 41 working fluid, respectively, into an additional multiplier 9 and an amplifier 17 under pressure P _p and the main multiplier 6 under pressure P _p , which are minimally necessary and sufficient for tight compression the relative elements 14 and 15 of the rope 1. When the reciprocating movement of the rope 1, it wears its surface against the sealing elements 14 and 15. The volume of the sealing elements 14 and 15 decreases by the amount of wear. The working fluid from the working volumes V and V _d under the pressure of the pistons 22 and 23 into the internal cavities 8 and 12 of the hydraulic mechanisms 5 and 11, which, swelling (see Figure 1) or moving upward (see Figure 2), deform worn-out sealing elements 14 (see Figs. 1 and 2) and 15, tightly pressing them with their inner surface 16 to the rope 1. As the sealing element 15 is worn out, a leak of the sealed well fluid appears, which collects in the body cavity 25 between the sealing elements 14 and 15 and is discharged through the drainage channel 26 into the container 27, located laid outside the housing 2. If the leakage exceeds the permissible value (exceeding the volume of the container 27) or when the medium to be sealed into the atmosphere through the sealing element 14, the control pressures P _p and P _p ′ from the alternating pressure sources are increased by the minimum value necessary to restore the tightness.

When the rope 1 with the downhole equipment 43 is moved down, the downhole pressure P _c decreases, this is especially characteristic of downhole equipment 43 with an outer diameter that is close in size to the inner diameter of the well, for example, swabs. In this case, the liquid from the tank 27 through the valve 28, configured to pass when a certain pressure differential is exceeded, flows back into the well. As a result, the disposal and removal of this fluid from the well is not required. At the same time, the magnitude of the adjusting pressures P _r and P _r ′ is reduced to exclude increased wear of the sealing elements 14 and 15.

Constant monitoring of the state of the sealing elements 14 and 15 (degree of wear) during operation of the device is carried out visually by the output of the corresponding piston position indicators 20 and 21 from the multipliers 6 and 9. The possibility of constant monitoring of the state of the sealing elements 14 and 15 ensures high reliability of the device, since allows timely measures to be taken to replace worn-out sealing elements 14 and 15, avoiding unexpected depressurization of the wellhead. If necessary, the replacement of replaceable sealing elements 14, 15 and 22 is carried out as follows. Downhole equipment 43 is introduced into the lubricator 42. The buffer shutoff member (not shown) is closed, the pressure in the cavity of the lubricator 42 is aligned with atmospheric pressure by reducing the pressures P _p and P _p ′ of the respective multipliers 6 and 9. The pins 39 are removed from the housing 2, after which carry out the movement of the rope 1 up to the exit from the housing 2 (not shown) together with the rope 1 of replaceable sealing elements 14 (see Figure 1) and 15 with guides 36, 37 and a guide 38, which rests against the swab 43 or replaceable sealing elements 14 (see Figure 2) and 15 with a guide 36, 37, guide 38, which abuts swab 43, together with hydraulic mechanisms 5 and 11. The assembly of the device after replacement of sealing elements 14 (see FIG. 1 and 2) and 15 is performed in reverse order and the device is ready for subsequent operation.

Using the proposed device design makes it possible to reliably isolate flexible flexible carriers with a complex insulated surface (for example, a rope) with the minimum possible wear of the sealing elements due to the use of external variable pressure multipliers for all seals and cost savings by draining the leaking fluid directly into the well.

Claims (2)

1. A device for sealing flexible traction, comprising a housing with a mounting unit, a primary and secondary seal, equipped with interchangeable sealing elements and a primary and secondary pressing sealing elements to the flexible rod hydraulic mechanisms that are connected to the respective primary and secondary multipliers, the housing cavity with a drainage channel located between the seals, with an additional multiplier configured to control an external adjusting pressure em, characterized in that the main multiplier is made with the ability to control external adjusting pressure, and a container for collecting and removing fluid is placed outside the casing, communicating through the drainage channel with the casing cavity and with the wellhead through a valve that opens when the rope is lowered into the well, the volume of the tank is not less than the volume of leaking fluid into the body cavity when lifting the rope from the well. 2. The device according to claim 1, characterized in that an air valve is located above the valve of the tank, which does not allow air from the tank to the well.

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