RU2067164C1 - Well gas-lift unit - Google Patents

Abstract

FIELD: oil and gas producing industry, particular, methods for oil recovery; applicable in starting and operation of wells by gas-lift method. SUBSTANCE: to increase reliability and efficiency of gas lift, the radial channels of nipple are inclined and, in height of tubing from bottom upward, diameter of each next axial channel nipple is larger than that of the previous one, and distance between next two nipples is larger than the distance between previous two nipples. Lower end of starting and working valves is rigidly connected with landing unit made with through axial channel whose lower end has opposite additional valve. Device has damper in form of hollow cylindrical stepped guide located in the body hollow and bellows for formation in the initial position of gap between body and guide, with gap reduction in the working position when stepped guide moves in body. Installed on valve bodies are cases with seals disconnecting hydraulic communication between internal and external hollows of valves. Valves have additional bellows installed in body. In this case, bellows form airtight neutral chamber together with body. Efficient diameter of additional bellows is less than diameter of gate which is determined by the following relation dPf/dPg = 1-(Db/Dgt)Dgt)², where dPf is range of variation of fluid flow pressure, MPa; dPg is range of variation of injected gas pressure, MPa; Db is effective diameter of bellows, m; Dgt is gate diameter, m. Chamber between bellows is neutral and airtight. Diameter of gate equals that of lower bellows and is larger than diameter of upper bellows, which is determined from the following relation dPf/dPg=(Db/Dgt)Dgt)², where Db is effective diameter of bellows, m. Landing units are made with through slots which accommodate thrust lugs of stop collet which is connected with lower ends of landing units by means of shear pins (screws) or resting on spiral spring. Collet is installed in lower part of ring with lugs upward and internal beads resting from above on shear ring. Stop collet is rigidly connected with lower end of landing unit. EFFECT: higher efficiency. 9 cl, 13 dwg

Description

 The invention relates to the oil and gas industry, in particular to the technique of oil production and can be used when starting and operating wells by a gas lift method.

 Known gas lift valve (Aut. St. USSR N 1717796, M. CL E 21 B 34/06, 1992), comprising a hollow body with passage channels, upper and lower uncoupling elements in the form of a bellows or piston, each of which forms with the body a chamber partially filled with a damping fluid and compressed gas, a charging unit, a saddle and a shutter.

 Known gas lift well installation (Mirzadzhanzade A.Kh. Technology and technique for oil production, M. Nedra, 1986 p.118, 129, 130), including a pipe string with a shoe check valve, nipples with non-axial, radial and axial passage channels for installation and fixation of starting and working valves made in the form of a hollow body with a seat and an outer diameter for the diameter of the axial channel of the nipple installed in the cavity of the bellows body, rigidly connected with the valve stem installed with the possibility of landing in the body seat. In this installation, the change of all valves in the well with one wireline tool is not possible, and it also has a low probability of starting the well with a gas outlet through the lower working valve. Also, the gas lift valves themselves, if necessary, cannot be used as a blind plug for crimping a pipe string. In addition, in all cases, they require charging the bellows chamber with compressed gas, which reduces their reliability when the charging unit is leaking, requires a special stand and additional labor costs for calibration. Also, when the bellows chamber is filled with damping fluid, an air ineffective space is created between the guide and the bellows wall. The same valves have a small cross-section with a limited outer diameter.

 The purpose of the invention is to increase the reliability and efficiency of a gas lift installation. The positive effect is expressed in an increase in oil production and an increase in the service life of the installation.

The goal is achieved through the following solutions:
the radial channels of the nipple are made oblique, and the diameter of each subsequent axial channel of the nipple is larger than the diameter of the previous one along the height of the pipe string from bottom to top, and the distance between the next two nipples is greater than the previous one. This allows for a consistent change of valves from the nipple and to ensure reliable start of the well;
the lower end of the starting and working (gas-lift) valves is rigidly connected to the landing unit made with a through axial channel, at the lower end of which an additional valve is installed opposite, which increases its throughput section;
the valve is equipped with a damper made in the form of a hollow cylindrical step guide located in the housing of the housing and the bellows with the possibility in the initial position of the formation of a gap between the body and the guide with a decrease in the gap in the working position when moving the step guide in the body;
casings with seals are installed on the bodies of gas-lift valves, disconnecting the hydraulic connections between the internal and external cavities of the gas-lift valves, which allows pressure testing of tubing strings with installation for tightness;
the valves are equipped with an additional bellows installed in the housing, while the bellows form a sealed neutral chamber with the body, and the effective diameter of the additional bellows is less than the diameter of the shutter, which is determined from the following ratio:
dPp / dPg 1 (Dc / Dз) ²
dPp range of variation of fluid flow pressure, MPa;
dPg range of pressure changes of the injected gas, MPa;
Dc is the effective diameter of the bellows, m;
Dz is the diameter of the shutter.

This feature excludes valve charging and ensures its operation from the difference in forces acting from above and from below;
the chamber between the bellows of the gas lift valve is neutral and sealed, while the diameter of the shutter is equal to the effective diameter of the lower bellows, and in turn, is larger than the diameter of the upper bellows, which is determined from the following ratio:
dPp / dPg (Dвc / Dз) ²
where Dвс is the effective diameter of the bellows, m.

This feature also eliminates the charging of the valve with compressed gas and ensures its operation from the difference in forces acting from below on the valve and from above on the effective area of the upper bellows;
the landing nodes are made with through slots in which the thrust lobes of the locking collet are mounted, which connects to the lower ends of the landing nodes with shear pins (screws) or resting on a spiral spring;
the collet is installed in the lower part of the ring and placed with its petals upward with inner collars resting on top of the shear ring;
a collet-shaped latch is rigidly connected to the lower end of the landing unit, which eliminates the use of shear pins for small valve stall forces;
a latch in the form of a retaining spring ring can be installed on the housing of the landing unit with a radial clearance;
the latch can be made in the form of a ring-mounted spring assembly spring-loaded along the axis of the housing, having locking balls or cams in radial channels.

 The figure 1 shows a General view of a gas lift installation; in FIG. 2 - nipple with gas lift valve; in FIG. 3, section AA in FIG. 2; in FIG. 4 - gas lift valve with one bellows; in FIG. 5 gas lift valve with two bellows; in FIG. 6 10 latches; in FIG. 11 node consisting of two valves; in FIG. 12 bellows chamber with a damper in the initial position; in FIG. 13 two-way bellows valve with damper (damper in working position).

 The installation includes tubing string 1 with nipples 2, gas lift valves 3 and check valve 4 (Fig. 1). The nipples 2 for gas-lift valves 3 have non-axial 5 and non-associated radial inclined through channels 6 (Fig. 2), the inner diameter of the axial passage channel of each subsequent lower nipple 2 being smaller than the previous one, and accordingly the outer axial channels of the nipples 2 are made outer the diameters of the landing nodes 7 of the gas lift valves 3. When lowering the tubing into the well, the distance between the nipples 2 in the direction from top to bottom is reduced to ensure the transition of the gas injection point to the underlying valve with limited pressure and injected gas for reliable start of the well.

 Gas-lift (starting and working) valves 3 consist of a hollow body 8 with radial 9 and axial 10 channels, a bellows 11, rigidly connected to the stem 12 and installed in the upper part of the housing 8, forming a sealed chamber 13. The stem 12 is rigidly connected to shutter 14 over the saddle 15 (Fig. 2).

 The landing unit 7 with the latch 16 has a seal separating the channels 6 of the nipple 2. The radial 17 and axial 18 channels of the landing unit 7 are hydraulically connected by the channel 10 of the valve 3 and the channels 6 of the nipple 2.

 Cases 19 with seals 20 can be installed on the bodies of gas-lift valves 3, separating hydraulic connections between the internal cavity of the bodies 8 of the gas-lift valves 3 and the internal cavity of the tubing 1 for pressure testing the tightness of the pipe string in the well (Fig. 2). In the valves 3 can be installed nodes 21 to fill the chambers 13 with gas under high pressure.

The bellows 11 of the gas lift valve can form a sealed neutral chamber 22 with the body 8 (in this case, the charging unit 21 is excluded), while its effective diameter (Dc) is smaller than the diameter of the shutter 14 (Dз), which
determined from the equation of the balance of forces (Fig. 4):
Pg.max • (Sz-Sc) Fg.max (1)
Pg.min • (Sz-Sc) Fg.min (2)
Pp.max • Sz Fp.max (3)
Ppmin • Sz Fpmin (4)
From equality (1) (4) we obtain
dFg Fg.max Fg.min dFp Fp.max Fpmin (5)
dPg • (Sz-Sc) dPp • Sz (6)
From here
dPp / dPg 1 (Dc / Dз) ² (7)
where dPp Pp.max Pp.min range of pressure change of the fluid flow;
dРг Рг.max Пг.min range of pressure change of the injected gas;
Sc 0.785 • Dc ² effective transverse area of the bellows;
Sz 0.785 • Dz ² transverse shutter area.

 If the force from the rigidity of the bellows is not enough, then a spiral compression spring can be installed on the shutter 14 to squeeze the shutter.

The chamber 21 (Fig. 5) between the bellows 22 and 23 of the housing 8 of the gas lift valve 3 can be made neutral and tight, while the diameter of the shutter 14 is equal to the effective diameter of the lower bellows 23 (Dns) and, in turn, is larger than the diameter of the upper bellows 22 ( Dвс), which is under the influence of gas pressure. This ratio is also determined from the equation of the balance of forces acting on the operating state of valve 3:
Pg.max • Sv.s Fg.max (8)
Pg.min • Sv.s Fg.min (9)
Pp.max • Sz Fp.max (10)
Ppmin • Sz Fpmin (11)
From equality (8) (11) we obtain
dPg • Sv.s dPp • Sz (12)
From here
dPp / dPg (Dвс / Dз) ² (13)
where Sv.s with 0.785 • Dvs ^{2 is the} effective area of the upper bellows.

 The housing 24 of the landing unit 7 can be made with through slots 25, in which the thrust lobes of the locking collet 26 (latch 16) are mounted, connected to the tip by means of a shear pin (screw) 27 or supported by a spiral spring 28 (Fig. 5).

 The latch 16 in the form of a collet 29 can be installed at the bottom of the shear ring 30 and placed with its petals up with inner collars resting on top of the shear ring 30 (Fig. 6).

 The latch 16 in the form of a collet 29 can be rigidly connected with the housing 24 of the landing unit 7, having a gap between the petals of the collet 29, which eliminates the use of shear pins 27 with small efforts to stall the valve (Fig. 7).

 The latch 16, in the form of a snap spring ring 31, can be installed on the housing 24 of the landing unit 7 with a radial clearance (Fig. 9).

 The latch 16 can be made in the form of a spring-loaded on the axis of the housing 24 of the landing unit 7, a ring 32 having locking balls or cams 33 in the radial channels (Fig. 10).

 The housing of the landing unit (Fig. 11) can be made with a through axial channel 34, and at its lower end an additional (second) gas lift valve is installed opposite to increase its gas throughput section.

 The damper (Fig. 12) can be made in the form of a hollow cylindrical stepped guide 35, which enters the housing 36 of the bellows 11, and in the initial state between the housing 36 of the bellows 11 and the guide 35 there is a gap 37 for free flow of damping fluid, and in the working state of the bellows 11 (Fig. 13) a step with a large diameter 38, the guide 35 enters the housing 36 of the bellows, reducing the gap, creates a damping effect, which eliminates the appearance of an air cushion in the bellows chamber, since there is an air outlet through the gap 37 when filling the cam ery liquid.

 The bellows 11 can be rigidly connected in the middle part with the housing 7 (for example, pins 39). The bellows 11 can be fixed at the top and bottom with shutters 40 and 41, supported by the seats 42 and 43. In this case, the seats 42 and 43 can be rigidly connected to the housing 7 with pins 44.

 The valve (Fig. 4) works from the difference in forces arising from the action of gas pressure on the shutter 14 from above and from the pressure of the liquid flow from below on it. Due to the difference in area under the influence of liquid and gas pressures, the shutter 14 opens despite the fact that the gas pressure is greater than the pressure of the liquid flow. In this case, gas passing through the valve channels enters the pipe.

 The valve (Fig. 5) operates from the difference in forces arising from the action of gas pressure on the bellows 22 and from the pressure of the liquid flow from below to the valve 14. Due to the difference in the areas under the influence of the pressure of the liquid and gas, the valve 14 opens.

 The valves shown in FIG. 3 and 4, can provide different pressures for their opening and closing from the fluid flow at different wellhead gas pressures without removing the valves from the well. That is, when the gas pressure at the wellhead is changed with the help of a regulator, this pressure on the valve level acts from above on the shutter 14 (Fig. 4) or on the bellows 22 (Fig. 5). While changing the magnitude of the resistance force to move the shutter 14 upward, the opening or closing pressure of the valves changes from the pressure of the fluid flow. This, in turn, allows you to expand the range of regulation of the bottomhole pressure of the well.

 The latch during installation and removal of the valves operates as follows.

 On the housing 24 of the landing unit 7, when the valve is lowered, the collet petals 26 are recessed into the inside of the housing 24 due to contact with the inner surface of the nipple 2. When the valve 3 is fully installed in the nipple 2, the collet 26 petals return to their original position and prevent valve 3 from moving upward when gas moves and fluid in the well. When removing the valve 3 from the nipple 2, the petals of the collet 26 abut against the nipple (for example, the lower end) and the pin 27 is cut off or the spring 28 is compressed (Fig. 5).

 The retainer in the form of a collet 29 when the valve 3 is seated moves up and drowns behind the shoulder of the housing 24. When the valve 3 is fully installed in the nipple 2, the collet 29 returns to its original position and rests on the shear ring 30. When the valve 3 is removed from the nipple 2, the collet 29 rests against the internal the collar of the petals on the stall ring 30 and the pin 27 is cut off (Fig. 7).

 The latch in the form of a collet 29 (Fig. 8) or a spring ring 31 (Fig. 9) when landing valve 3 is pressed by the walls of the nipple 2 and is recessed into the gap. When the valve 3 is fully installed in the nipple 2, the collet 29 or the spring ring 31 returns to its original position and abuts against the end of the nipple 2 by the outer collars.

 When the valve 3 is removed from the nipple 2, the collet 29 or ring 31 abuts against the chamfer at the end of the nipple 2 with the outer shoulder and is pressed inward into the gap (Fig. 8).

 When installing the valve 3 (Fig. 10) in the nipple, the balls 33 of the ring 32 abut against the upper end of the nipple 2, while the spiral spring is pressed and the ring 32 is displaced upward and the balls 33 slide off the shoulder of the housing 24 and go inside the ring 32. After landing the valve the spring pushes the ring 32 onto the shoulder of the housing 24 and the balls 33 fix the valve in the nipple 2. When the valve 3 is removed from the nipple 2, the balls 33 abut against the end of the nipple 2 and the pin 27 breaks. Next, the ring 32 extends downward over the shoulder of the housing and the balls 33 go down by releasing the valve (Fig. 9).

 Gas lift installation operates as follows.

 Gas lift valves are open under static fluid pressure and overpressure at the wellhead. High pressure gas enters from the wellhead into the tubing string 1, reduces the liquid level and reaches the first valve 3 (Fig. 1). When this gas, passing through the channels 18 and 17 of the valve 3 and the channels 6 of the nipple 2 (Fig. 2), enters the space between the pipes (for example, "2" and "4" tubing) of the well and reduces the fluid pressure at the level of the first valve, which means it reduces the pressure on the bottom of the well. When the bottomhole pressure decreases to the required value, the gas passes through the channel 17 of the landing unit 7 and the channels 5, 6 of the nipple 2 and reaches the second valve 3, then enters through it into the space between the pipes. Thus, the liquid level between the pipes decreases and, accordingly, the pressure at the bottom of the well decreases, which ensures gas injection through the lower working valve. At the same time, the upper starting valves are closed by reducing the pressure of the liquid and gas flow. YYY2 YYY4 YYY6 YYY8 YYY10 YYY12

Claims (9)

 1. Gas lift well installation, including a pipe string with a shoe check valve, nipples with non-axial, radial and axial passage channels for installing and fixing the start and operating valves, made in the form of a hollow body with a seat and an outer diameter under the diameter of the axial channel of the nipple installed in the cavity of the bellows body, rigidly connected to the valve stem, mounted with a possibility of landing in the saddle of the body, characterized in that the radial channels of the nipple are made inclined, and along the height of the pipe string From bottom to top, the diameter of each subsequent axial channel of the nipple is larger than the diameter of the previous one, and the distance between the next two nipples is greater than the previous ones.  2. Installation according to claim 1, characterized in that the lower end of the starting and operating valves is rigidly connected with the landing unit made with a through axial channel, at the lower end of which an additional valve is installed opposite.  3. Installation according to paragraphs. 1 and 2, characterized in that it is equipped with a damper made in the form of a hollow cylindrical stepped guide placed in the cavity of the housing and the bellows with the possibility in the initial position of the formation of a gap between the housing and the guide with a decrease in clearance in the working position when moving the stepped guide in the housing.  4. Installation according to paragraphs. 1 and 3, characterized in that on the valve bodies there are housings with seals that disconnect the hydraulic connections between the internal and external valve cavities. 5. Installation according to paragraphs. 1, 3 and 4, characterized in that the valves are equipped with an additional bellows installed in the housing, while the bellows form a sealed neutral chamber with the housing, and the effective diameter of the additional bellows is less than the diameter of the shutter, which is determined from the following ratio:
d _Pp / d _Pg 1 (D _s / D _s ) ² ,
where d _Pп range of pressure changes in the fluid flow, MPa;
d _Pg range of pressure changes of the injected gas, MPa;
D _{with the} effective diameter of the bellows, m;
D _s shutter diameter, m. 6. Installation according to paragraphs. 1, 3 and 4, characterized in that the chamber between the bellows of the valve is made neutral and sealed, while the diameter of the shutter is equal to the effective diameter of the lower bellows and larger than the diameter of the upper bellows, which is determined from the following ratio:
d _Pp / d _Pg (D _sun / D _s ) ² ,
_Sun D where the effective diameter of the bellows, m.  7. Installation according to paragraphs. 1 to 6, characterized in that the landing nodes are made with through slots, in which are placed the thrust petals of the locking collet, connected to the lower ends of the landing nodes with shear pins (screws) or supported by a spiral spring.  8. Installation according to paragraphs. 1 to 6, characterized in that it is equipped with a shear ring, the collet is installed in the lower part of the ring and the petals up with inner collars resting on top of the shear ring.  9. Installation according to paragraphs. 1 to 6, characterized in that the retaining scurvy is rigidly connected with the lower end of the landing node.

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