RU2186946C2 - Device for removal of fluid from bottom hole of gas well - Google Patents

Abstract

FIELD: gas producing industry; applicable in removal of formation fluid from bottom holes of gas and gas-condensate wells. SUBSTANCE: installed in hollow cylindrical body with axial channel is lower supporting surface which has limiter, hollow rod loaded by spring relative to limiter to form circular gap between them. Installed in axial channel of hollow rod is ball check valve which consists of seat and ball. Rigidly secured to hollow rod is surface valve resting on limiter. Diffuser is installed on lower end of hollow rod, above lower supporting surface, to form gap between them. Diffuser has conical axial channel and tangential channels in lower part. Diffuser upper part has perforated partition. Diffuser together with device body forms circular chamber hydraulically communicated by perforation holes with axial channel. Tangential channels hydraulically communicate circular channel with conical axial channel. Upper supporting surface is spring-loaded with respect to device body. Installed into tubing string of operating well through lubricator is rated number of devices. They are installed in joints. EFFECT: higher efficiency of operation. 4 dwg

Description

 The invention relates to the gas industry, in particular to devices for removing formation fluid from the bottom of gas and gas condensate wells.

Analysis of the existing level showed the following:
A device is known for removing liquid from the bottom of a gas well, described in copyright certificate 1391201 "Method for removing liquid from the bottom of a gas well" (see AS 1391201 from 06/18/86 according to class E 21 B 43/00, publ. OB 11 (Part II), 1999), consisting of a string of tubing with a lower supporting surface installed in the axial channel, including a limiter (support ring) and a check ball valve, consisting of a ball and a seat. The diffuser function is a saddle in the form of a short venturi nozzle. The upper supporting surface is made in the form of a spherical cross.

 A disadvantage of the known device is the inefficiency.

This is due to several reasons:
- the impossibility of conducting research at the bottom of the well if there are devices in the axial channel of the tubing string, for the removal of which the lifting of the tubing string is necessary;
- the need to pre-configure each device to one specific technological mode by a limiter when changing the technological mode of operation of a gas well, for example, the formation of a sand plug in the filter zone, the release of hydrates at the mouth, wear of the seat of the saddle and ball, etc., the operating mode also changes devices for the worse, which requires reconfiguration to a new mode with the corresponding rise of the device and tubing string;
- the inability to automatically maintain the calculated pressure drop across the device and the absence of a siphon effect.

 As a prototype taken device for removing fluid from the bottom of a gas well, described in A.S. 302468 "Device for removing water from the bottomhole zone of the well" (see AS 302468 of 04/19/67, class E 21 B 43/00, published in OB 15, 1971), consisting of a housing (couplings ), a lower supporting surface containing a limiter made in the axial channel of the housing, a ball check valve, consisting of a seat and a ball. Diffuser (spool), spring-loaded at the bottom. The upper supporting surface is made in the form of a pin rigidly connected to the diffuser.

A disadvantage of the known device is the inefficiency due to several reasons:
- the impossibility of equipping the well without killing it;
- the impossibility of conducting research in the zone of the reservoir, since the axial channel of the tubing string is occupied by a device, the removal of which requires tubing string lifting;
- the lack of the possibility of active influence on the gas-liquid flow in order to increase the efficiency of crushing drops of formation fluid and transporting the latter to the surface;
- the inability to automatically maintain the calculated pressure drop across the device and the absence of a siphon effect;
- with a sufficiently large column of liquid in the tubing string above the device, for example, 20-30 m, which corresponds to a pressure of 2-3 atm, it is possible to move the diffuser (spool) with the ball down and opening the hydraulic connection between the tubing string cavity and the well cavity, which leads to liquid entering the face.

The technical result is to increase work efficiency due to the following reasons:
- the possibility of conducting research work without stopping the well and raising the tubing string to the day surface due to the autonomous launching and lifting of the device;
- providing a siphon effect, actively influencing the gas-liquid flow and crushing the droplets of the formation fluid to the fog structure, automatically maintaining the calculated pressure drop across the device with excitation of pressure and flow waves in the gas-liquid flow due to the occurrence of hydraulic connections and ball vibrations in the transverse and axial directions.

 The technical result is achieved using a known device comprising a housing, a lower supporting surface including a limiter and a ball check valve, a diffuser installed in the axial channel of the housing, and an upper supporting surface in which the lower supporting surface is configured to form a gap with the lower surface of the diffuser and further comprises a spring-loaded hollow rod forming an annular gap with a limiter, and a mechanical valve rigidly fixed to the outside of the hollow rod, based on the limiter, and the ball check valve is installed in the axial channel of the hollow rod, and the diffuser additionally contains a perforated baffle and is made in the form of a sleeve with a conical axial channel and tangential channels in the lower part, and forms an annular chamber hydraulically connected with the axial channels of the housing and the diffuser and the upper abutment surface further comprises a perforated partition with a conical abutment protrusion included in the axial channel of the diffuser, spring-loaded relative to the housing and installed with the possibility of axial movement.

 An analysis of the inventive step showed the following: a device is known for removing liquid from the bottom of a gas well, in which there is a similar embodiment of tangential channels in the form of slots placed tangentially to the longitudinal axis of the dispersant.

 A device for removing liquid from gas and gas condensate wells is known, in which an annular chamber is formed which is hydraulically connected to the axial channel (see p. 2058476 of 06.22.93 according to class E 21 V 43/00, published in OB 11, 1996 .). Known hydraulic ball vibrator with an upper support ledge, seat, ball and conical axial channel (see p. 2148148 from 11/17/97 according to class E 21 V 28/00, publ. In OB 12, 2000). Moreover, a device is known for influencing the bottom-hole zone with a conical axial channel, a spring-loaded hollow rod (piston) with a seat and a ball mounted in the housing with the possibility of forming an annular chamber (see AS 1535971 from 09.24.87, class. E 21 B 43/00, published in OB 2, 1990). Thus, the set of structural elements of the distinguishing part of the claims giving the above technical result is not revealed by sources of fame, i.e. possesses an inventive step.

The design of the claimed device is illustrated by the following features:
- figure 1 shows the device in section, in a static position;
- figure 2 presents the device in the context, in the position of gas production;
- in FIG. 3 shows the device in a section, with increasing pressure drop in the axial channel of the diffuser above the calculated;
- figure 4 shows a diagram of the equipment of the tubing string device.

 The inventive device has a hollow cylindrical body 1 with an axial channel 2, in which a lower supporting surface is installed. The lower supporting surface includes a stop 3, a hollow stem 4, spring loaded with a spring 5 relative to the stop 3, with the formation of an annular gap between them 6. In the axial channel 7 of the hollow stem 4 there is a ball check valve consisting of a seat 8 and a ball 9. On the outside of the hollow rod 4, a mechanical valve 10 is fixed that is supported by a stop 3. An adjusting nut 11 is fixed at the lower end of the hollow rod 4. A diffuser 12 is mounted above the lower supporting surface with the possibility of creating a gap between them 13. Diff the gap 12 is made in the form of a sleeve with a conical axial channel 14 and tangential channels 15 in the lower part. In the upper part, the diffuser 12 is provided with a perforated partition 16 connecting the diffuser 12 with the housing 1. The diffuser 12 forms an annular chamber 17 hydraulically connected with the perforation holes 18 made in the perforated partition 16 with the housing 1 and the axial channel 2 of the housing 1. The tangential channels 15 are hydraulically connect the annular chamber 17 with the conical axial channel 14 of the diffuser 12. Above the diffuser 12 is installed the upper abutment surface, which consists of a perforated partition 19 with perforations 20 and cal supporting protrusion 21 entering into the tapered axial passage 14 of the diffuser 12. The upper bearing surface is spring-loaded by a spring 22 relative to the housing 1.

The device for the tubing string with a diameter of 114 mm has the following dimensions:
outer diameter mm - 96
the diameter of the axial channel of the hollow rod, mm - 30
length, mm - 270
weight, kg - 11
Device operation
At the wellhead, before the device is lowered into the axial channel of the tubing string, it is adjusted to the technological mode (Fig. 1). The device is installed on the lower end of the packing device and lowered through the lubricator into an existing well with installation at a given depth. The device is fixed at the junction of the pipe coupling with the overlap of the annular gap with a sealant. When the gate valve is opened at the wellhead (Fig. 2), the gas-liquid flow enters the axial channel of the hollow rod 4 and pushes the ball 9 upward until it contacts the tapered abutment protrusion 21 of the upper abutment surface. In this case, an annular gap is formed between the ball 9 and the seat 8, along which the gas-liquid mixture enters the conical axial channel 14 of the diffuser 12, flowing around the ball 9. Due to the unstable position of the ball 9 in the conical axial channel 14 of the diffuser 12, the latter performs transverse vibrations with a high frequency. When the pressure drop across the ball 9 exceeds the compression force of the spring 22, the upper abutment surface rises upward relative to the diffuser 12, which leads to the rise of the ball 9 to a new level relative to the seat 8 of the lower abutment surface and the diffuser 12 with a corresponding increase in the annular gap between its wall and the ball 9. This leads to an increase in the flow rate of the gas-liquid mixture through the device, a decrease in the pressure drop across the ball 9, and a change or decrease in the oscillation frequency. When the pressure decreases, the ball 9 can automatically lower by some amount down, with the repetition of the process of lifting-moving. The force of the spring 22 is selected in such a way that the pressure drop across the ball 9 can be changed in a small range of the order of 0.1-0.15 atm. The gas-liquid mixture passes through the conical axial channel 14 of the diffuser 12, then through the perforations 20 in the perforated baffle 19 it is fed into the axial channel 2 of the housing 1 and then along the tubing string to the wellhead. Oscillations of the ball 9 in the conical axial channel 14 of the diffuser 12 in the transverse and axial directions lead to the imposition of pulsating fluctuations in flow and pressure on the gas-liquid flow and the crushing of formation fluid droplets to a fog structure. As the gas-liquid flow rises along the tubing string, the smallest droplets of the formation fluid coarsen and condense on the tubing wall to form a film. Practice shows that the film fluid gradually flows down the pipe wall to the installation site of the device and through the perforations 20 in the partition 19, the perforations 18 in the perforated partition 16 of the diffuser 12 accumulate in the annular chamber 17. From the annular chamber 17 along the tangential channels 15 of the diffuser 12, the liquid due to the action of the siphon effect, it is sucked into the conical axial channel 14 and again carried away by the flow into the tubing column.

 If the pressure drop across the ball 9 exceeds the permissible value determined by the operating conditions of the well (Fig. 3), for example, the gas pressure in the field reservoir, the influence of a neighboring well, etc., which will ultimately lead to a halt in the production process, under the action of the increased pressure drop, the lower supporting surface moves upward relative to the limiter 3 with the mechanical valve 10 being separated from it, compressing the spring 22 and supplying the gas-liquid mixture through the annular gap 6 into the annular chamber 17 with an increased flow rate. The flow of the gas-liquid mixture is also maintained through the diffuser 12 while maintaining the process of droplet crushing and removal of the tubing string into the axial channel.

 When the pressure drop decreases to the calculated force of the spring 22, the lower supporting surface returns to its original position with the mechanical valve 10 landing on the stop 3 and the hydraulic connection of the annular gap 6 with the annular chamber 17 is stopped.

 When the gas production process is stopped, the ball 9 sits on the saddle 8, blocking the connection between the tubing string cavity and the reservoir. The formation fluid located in the form of a film on the wall of the tubing string gradually flows down and accumulates above the ball 9, thereby eliminating its entry into the zone of the productive formation, with its corresponding killing at low reservoir pressure and a high column of liquid.

 The number of devices installed in the well is calculated on the basis of specific operating conditions, the design of the well, the flow rate of gas and liquid (see AS 1391201 dated 06/18/86 according to class E 21 B 43/00, published in OB 11 ( Part II), 1999). When the well stops, the total volume of fluid available in the tubing string is divided into the volumes of fluid that accumulate above each device. When the well is restarted, gas sparges through the liquid above each device with a gradual aeration of the liquid column and its removal to the surface.

 The inventive device has passed bench tests and is widely applicable, because changing the dimensions of the device, it can be used when working in a tubing string of various diameters.

Claims (1)

 A device for removing liquid from the bottom of a gas well, comprising a housing, a lower supporting surface including a limiter and a ball check valve, a diffuser installed in the axial channel of the housing, and an upper supporting surface, characterized in that the lower supporting surface is configured to form a gap with the lower surface of the diffuser and further comprises a spring-loaded hollow rod forming an annular gap with a limiter, and a mechanical valve rigidly mounted on the outside of the hollow rod a, based on the limiter, and the ball check valve installed in the axial channel of the hollow rod, and the diffuser further comprises a perforated baffle and made in the form of a sleeve with a conical axial channel and tangential channels in the lower part and forms an annular chamber hydraulically connected with the axial channels of the housing and the diffuser, and the upper abutment surface further comprises a perforated partition with a conical abutment protrusion included in the axial channel of the diffuser, spring-loaded relative to the housing, and installed with the possibility of axial movement.

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