US3559671A

US3559671A - Gas lift valve

Info

Publication number: US3559671A
Application number: US755364A
Authority: US
Inventors: Bobby L Douglas
Original assignee: Dresser Industries Inc
Current assignee: Dresser Industries Inc
Priority date: 1968-08-26
Filing date: 1968-08-26
Publication date: 1971-02-02
Anticipated expiration: 1988-02-02

Abstract

A gas lift valve that is connected in a tubing string and disposed in a cased well bore. The gas lift valve provides communication between the casing and tubing whereby gas in the annular space therebetween can be injected into the tubing to aid in producing oil from the well. The gas lift valve includes a valve member that is responsive to pressure within the tubing for movement between open and closed positions to control the flow of gas into the tubing.

Description

United States Patent [56] References Cited UNITED STATES PATENTS 3,016,844 1/1962 Vincent 137/155X 3,214,134 10/1965 Noakes 251/282 3,375,846 4/1968 Canalizo [37/155 3,417,774 12/1968 Douglas et a1. 137/155 Primary Examiner-Alan Cohan Attorney- Robert W. Mayer. Daniel Rubin, Peter J.

Murphy, Frank S. Troidl, Roy L. Van Winkle and William E. Johnson, Jr.

ABSTRACT: A gas lift valve that is connected in a tubing string and disposed in a cased well bore. The gas lift valve provides communication between the casing and tubing whereby gas in the annular space therebetween can be injected into the tubing to aid in producing oil from the well. The gas lift valve includes a valve member that is responsive to pressure within the tubing for movement between open and closed positions to control the flow of gas into the tubing.

PATENTED FEB 2 l97l FIG; 2A FIG. 25

, FIG. I

INVENTOR BOBBY L. DOUGLAS fMW-J ATTORNEY GAS ur'r VALVE BACKGROUND OF THE INVENTION This invention relates generally to improved gas lift valves for use in well bores. More particularly. but not by way of limitation. this invention relates to an improved gas lift valve for use in a tubing disposed in a cased well bore wherein the gas lift valve is moved between open and closed positions in response to change in the pressure within the tubing.

Gas lift valves utilized in the oil and gas industry in situations wherein the formation pressure alone is not sufficient to lift the oil to the surface of the well. The gas lift valves provide controlled communication between the annulus (the annular space that is between the casing and tubing exterior) and the interior of the tubing to permit gas in the annulus to be injected into the tubing to aid in lifting oil from the formation to the fur surface through the tubing.

Gas lift valves may be divided into two categories, that is. into valves are controlled by the gas pressure within the annulus and into valves controlled by the pressure of fluid, generally oil, that is in the tubing. U.S. Reissue Pat. No. 24,0l5 issued to R0. Walton on May 31, I955 illustrates a gas lift valve of the type that is controlled by gas pressure in the annulus. US. Pat. No. 2,982,226 issued to CM. Peters et al. on May 2, I96] illustrates a gas lift valve that is controlled by pressure within the tubing.

Tubing pressure controlled gas life valves may be further classified in two groups. One group, as illustrated by the valve in Peterspatent, involves the use of a sliding seal located between the valve stem and the valve body to prevent communication between the pressure in the tubing, which is always imposed on the bellows of Peters valve, and the pressure in the annulus. The sliding seal serves to balance the valve member with respect to gas pressure in the annulus whereby movement of the valve member is the result of change in the tubing pressure alone. The second group of tubing pressure controlled valves does not have the sliding seal in the vale, but necessarily includes a device known as a crosshead" in the lower end thereof. The crosshead"performs the function of imposing the tubing pressure on the valve member so that it is controlled thereby, but this type has a very circuitous flow path for gas passing through the valve. The circuitous flow path results in considerable erosion in the valve as the gas. which frequently has sand entrained therein. flows through the valve.

SUMMARY OF THE INVENTION This invention provides an improved gas lift valve for use in a well bore, the valve comprising: a hollow valve body having an outlet passageway and having an inlet port that is of smaller cross-sectional area than the outlet passageway; and annular valve seat located in the body between the inlet port and the outlet passageway, the valve seat having a flow area larger than the cross-sectional area of the inlet port; a valve member in the body movable between a closed position, wherein the valve member engages the seat, and an open position, wherein the valve member is out of engagement with the seat; and, pressure responsive means in the body connected with the valve member biasing the valve member toward the seat, the pressure responsive means being exposed to fluid pressure through the inlet port when the valve member is in the closed position and exposed to fluid pressure in the outlet passageway when the valve member is in the open position.

One object of this invention is to provide an improved gas lift valve that eliminates the need for a sliding seal to isolate the tubing and easing pressures.

Another object of the invention is to provide an improved gas lift valve that is controlled by tubing pressure and has a substantially direct flow passageway therethrough reducing erosion in the valve to the minimum.

Another object of the invention is to provide an improved tubing pressure controlled valve that is relatively simple in construction and requires little or no maintenance during its operating life;

The foregoing and additional objects and advantages of the invention will become more apparent as the following detailed description is read in conjunction with the accompanying drawings wherein like reference characters denote like parts in all views.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a cross-sectional view illustrating a portion of a casing disposed in a well bore, a section of tubing located therein, and a gas lift valve constructed in accordance with the invention disposed in a side pocket in the tubing.

FIG. 2A is an enlarg'ed view of the upper portion of the gas lift valve, partially in elevation and partially in cross section, taken substantially along the lines 2A-2A of FIG. 1.

FIG. 2B is an enlarged view of the lower portion of the gas lift valve, partially in elevation and partially in cross section taken substantially along the lines 28-25 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawing and to FIG. 1 in particular, shown therein and generally designated by the reference character 10 is a well casing disposed in a well bore 12. A tubing string 14 extends into the casing and includes a plurality of identical sections that are threadedly connected as is well known in the art.

The tubing string 14 also includes one or more sections 16 having a side projection 18 thereon. Each of the side projections 18 has a tubular pocket 20 formed therein for receiving a gas lift valve assembly 22. As clearly shown in FIG. I, the tubular pocket 20 has open upper and open

lower ends

24 and 26, respectively; spaced upper and

lower sealing surfaces

28 and 30, respectively; and, a plurality of ports 32 extending through the wall of the side projection 18. The ports 32 are located between the

sealing surfaces

28 and 30. A latch lug 34 extends inwardly from the interior of the projection 18 for purposes that will be described hereinafter.

The enlarged views of FIGS. 2A and 2B illustrate the structure of the gas lift valve assembly 22 in more detail. A valve cap and guide nose 36 is located at the upper end of the valve assembly 22. The valve cap 36 covers a valve (not shown) that is provided to permit filling a chamber 38 formed in valve body 40 with a compressible gas. such as nitrogen. The lower end of the chamber 38 is in communication with a flexible pressure responsive bellows 42 that has its upper end connected to a bellows support member 41. The bellows support member 41 is suitably connected to and forms a portion of the valve body 40.

Encircling the upper end of the body 40 of the valve assembly 22 is a helical spring 44. The helical spring 44 is disposed between a shoulder 46 and a latch ring 48. The lath latch ring 48 is movable upwardly against the spring 44 and to some extent laterally with respect to the body 40 to permit the valve assembly 22 to move past the latch lug 34 on the projection 18 (see FIG. -l) so that the valve assembly 22 is securely latched in the tubular pocket 20 when located therein.

Encircling the body 40 below the spring 44 is an upper seal 50 that is arranged to sealingly engage the sealing surface 28 in the tubular pocket 20 as shown in FIG. 1. The upper seal 50 is shown schematically and may be constructed in any desired manner, such as from a,plurality of alternating resilient mate metallic members A medial portion 52 of the body 40 extends downwardly and is threadedly connected at its lower end with a lower body section 54. Near the lower end of the medial portion 52 is a plurality of inlet ports 56 of relatively small diameter for purposes which will be explained more fully hereinafter. The ports 56 extend at an angle downwardly and inwardly to provide a direct flow path into the body 40 to rediice erosion in the body 40 to the minimum and to increase valve efficiency by reducing the resistance to fluid flow therethrough.

The medial portion 52 and the lower portion 54 of the the body 40 cooperate to support an annular valve seat 58. The annular valve seat 58 has a flow passageway 60 extending therethrough which. in the preferred arrangement, has an area equal to the effective area of the bellows 42 and which is large as compared to the area of the parts 56. The areas may .deviate somewhat from being precisely equal without affecting the operating characteristics of the valve assembly 22. Also, it is preferred that the ports 56 have a total flow area no more than 75 percent of the area of the flow passageway 60.

A lower seal 62 encircles the exterior of the lower portion 54 of the body 40 and is arranged to sealingly engage the sealing surface 30 within the pocket 20 (see F IG. 1). The seal 62 may also be constructed in any suitable configuration.

Connected with the lower body portion 54 is a surge valve assembly 64. The surge valve assembly includes an annular valve seat 66, a valve member 68 and a spring 70 that biases the valve member 68 towards the seat 66. All of the foregoing are located within a surge valve body 72. The lower end of the surge valve body 72 has a plurality of outlet passageways 74 extending therethrough to permit fluid communication from the interior of the gas lift valve assembly 22 into the interior of the tubing string 14. It will be noted that the valve member 68 is positioned so that it does not engage the valve seat 66 thus permittinga low unit volume flow thereby or pressure from the tubing string 14 to be applied therethrough. However, if a sudden surge or high volume flow enters the passageways 74 passing upwardly the surge valve assembly 64, the valve member 68 moves into engagement with the seat 66 preventing flow therethrough in an upwardly direction.

A main valve member 76 is connected at its upper end with the lower end of the bellows 42. A spherical closure member 78 mounted on the lower end of the valve member 76 sealingly engages the annular valve seat 58 when in the closed position of the valve assembly 22.

The upper end of the valve member 76 is also connected with a bellows protector member 80 that extends upwardly through the bellows 42 and into the lower end of the chamber 38. The upper end of the protective member 80 has an upwardly facing shoulder 82 formed thereon that is engageable with the bellows support member 41 to limit the upward movement or collapsing of the bellows 42. Also, the bellows protective member 82 carries one or more limit rings 84 that are positioned above the bellows support member 41 and are engageable with the support member 41 to limit the downward movement or extension of the bellows 42. Thus, the protective member 80 controls the travel of the main valve member 76 and the collapsing and extension of the bellows 42 during operation of the gas lift valve assembly 22.

OPERATION 1n the form of gas valve assembly 22 illustrated, the tubing string 14 is first disposed in the well casing and the gas lift valve assembly 22 is lowered therein on a special running-in tool (not shown) that is well known in the art. The running-in tool is arranged to deposit the gas lift valve assembly 22 in the appropriate tubular pocket in the tubing string 14. It should be pointed out that valve assembly 22 may be constructed for pennanent installation on a tubing string as illustrated in the aforementioned Peters et al. Patent.

After the valve assembly 22 is or a plurality of assemblies 22 have been deposited in the tubing string 14, gas is introduced into the annulus between the casing 10 and the tubing string 14. The pressurized gas, and initially some liquid, passes through the ports 32 in the projection 18 entering the space within the tubular pocket 20 defined by the upper and

lower seals

50 and 62, respectively.

After entering the space between the

seals

50 and 62, the gas passes through the inlet ports 56 into the body 40. Since the area of annular valve seat 58 is substantially the same as the effective area of the bellows 42, the pressure of the gas passing through the inlet ports 56 has little or no effect on the main valve member 76. Stated in another way, the main valve member is substantially balanced with respect to the gas pressure.

Oil in the tubing string .14 enters the lower end 26 of the tubular pocket 20 passing upwardly through the passageways 74 and the surge valve assembly 64. Since the pressure of the oil is relatively stabilized. the pressure passes the valve member 68 and is imposed upon the spherical closure member 78 through the flow passageway 60 in the annular valve seat 58.

When the force on the main valve member 76 developed by the pressure of the oil in the flow passageway 60 becomes sufficient to overcome the force exerted by the nitrogen in the chamber 38, the main valve member 76 rises off the valve seat 58. When this occurs, communication between the gas in the body 40, which has entered through the inlet ports 56 and the oil in the flow passageway 60 occurs.

As previously mentioned, the total area of the flow ports 56 is not more than 75 percent of the area of the flow passageway Thus, the gas entering through the ports 56 will be choked and subjected to a pressure drop as it flows into the valve body 40. in practice, the ports 56 and flow passageway 60 are sized so that the pressure existing in the area around the main valve member 76 and exterior of the bellows 42 will be the pressure of the oil in the tubing string 14 at the location of the valve assembly 22.

After the valve member 76 has moved to the open position, the gas flows through the flow passageway 60, past the surge valve member 68, downwardly through the ports 74 and the open lower end of 26 of the tubular pocket 20 into the tubing string 14. The gas then mixes with the oil in the tubing string 14 flowing upwardly therethrough toward the surface of the well and reducing the fluid head until the formation pressure is sufficient to produce the oil and gas mixture at the surface of the well. i

As production of the oil occurs through the tubing string 14, the decrease in pressure, resulting from the oil and gas mixing, is reflected as a decrease of pressure in the valve assembly 22. When the pressure is reduced to a predetermined value, the nitrogen in the bellows 42 extends the bellows until the spherical closure member 78 engages the annular valve seat 58 closing the flow passageway 60 and preventing the entrance of gas into the tubing string 14 through the valve assembly 22. When the gas entrained in the column of oil reaches the surface, the density and thus the weight and pressure of the column again increases and is reflected in the gas lift valve assembly 22 as an increase in pressure on the main valve member 76 moving the valve member 76 off the seat 58 to initiate a repetition of the foregoing procedure.

Frequently, there will be sand or other abrasive materials entrained in the and liquid which can cause considerable damage in the gas life valve. The valve assembly 22 reduces the possibility of erosion to the minimum since the inlet ports 56 are directed relatively downwardly whereby the flow of gas and liquid with sand entrained therein is directed, without change of direction, into the outlet or flow passageway 60 in the annular valve seat 58. Thus, and since no change in direction is necessary the greatest cause of erosion is eliminated.

Also, and as can be appreciated from the foregoing detailed description, the valve is of relatively simple construction and due to the balancing of the bellows effective area with the area of the main valve seat, the need for a sliding seal on the valve member has been eliminated. The elimination of the sliding seal avoids not only the danger of leakage across the seal as it wears during operation, but also the chance of trapping sand and other particles above the seal in the vicinity of the bellows which may interfere with proper operation of the gas 18f lift valve.

It will be understood that the foregoing has been presented by way of example only and that many changes and modifications can be made thereof without departing from the spirit and scope of the invention.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1 claim:

1. A gas lift valve for use in a well bore, said valve comprisa hollow valve body having an outlet passageway and having an inlet port of smaller cross-sectional area than said outlet passageway;

an annular valve seat located in said body between said inlet port and outlet passageway, said valve seat having a flow larger area larger than the cross-sectional area of said inlet port;

a valve member in said body movable between a closed position, wherein said member engages said seat, and an open position, wherein said member is out of engagement with said seat; and A pressure responsive means in said body connected with said valve member biasing said valve member toward said seat, said pressure responsive means being exposed to fluid pressure through said inlet port when said valve member is in the closed position and exposed to the fluid' pressure in said outlet passageway when said valve member is in the open position, and said pressure responsive means having a cross-sectional area exposed to fluid pressure substantially equal to the cross-sectional .area of said valve seat, whereby the pressure acting through said inlet port has no substantial effect on said valve member or pressure responsive means.

2. A gas lift valve for use in a cased well bore having tubing disposed therein, said vale comprising:

a hollow valve body adapted for connection with the tubing,

said body having an outlet passageway arranged to communicate with the tubing and having an inlet port of smaller cross-sectional area than said outlet passageway providing communication with the casing;

an annular valve seat located in said body between said inlet port and outlet passageway said seat having a flow area larger than the cross-sectional area of said inlet port;

a valve member in said body move movable between a closed position, wherein said member engages said seat, and an open position, wherein said member is out of engagement with said seat; and 7 pressure responsive means in said body connected with said valve member biasing said valve member toward said seat, said pressure responsive means being exposed to pressure in the casing through said inlet port when said valve member is in the closed position and exposed to pressure in the tubing when said valve member is in the open position, whereby the movement of said valve member between said positions is controlled by the pressure in the tuning tubing acting through said outlet passageway; and said pressure responsive means having a cross-sectional area exposed to fluid pressure substantially equal to the cross-sectional area of said valve seat, whereby the pressure acting through said inlet port has no substantial effect on said valve member or pressure responsive means.

3 The gas lift valve of claims 1 and 2 wherein said pressure responsive means extends across said hollow valve body form ing a chamber therein and wherein said valve also includes a compressible gas in said chamber for biasing said pressure responsive means and connected valve member toward said valve seat.

4. A gas lift valve for use in a cased well bore having tubing disposed therein, said valve comprising:

an elongated tubular body adapted for connection with the tubing, said body having a closed upper end.

a lower end including an outlet passageway proving providing communication with the tubing passageway, and

an inlet port intermediate said ends providing communication with the casing;

an annular valve seat encircling said outlet passageway and having a cross-sectional flow area larger than the crosssectional area of said inlet port;

A valve member movable between a closed position,

' wherein said valve member is in engagement with said seat, and an open position, wherein said valve member is not in engagement with said seat; an expansi le and contractible bellows in said body connected with said valve member and forming a chamber with said upper end;

A compressible gas in said chamber biasing said valve member relatively toward said valve seat; and toward said valve seat; and

said bellows being located between said closed end and side inlet port and exposed to fluid pressure from the casing through said inlet port when said valve member is in the closed position and exposed to fluid pressure from the tubing through said outlet passageway when said valve member is in the open position, and said bellows having a cross-sectional area exposed to fluid pressure substantially equal to the cross-sectional area of said valve seat, whereby the casing pressure acting through said inlet port has no substantial effect on said valve member or bellows.

5. The gas lift valve of claims 1, 2, or 4 wherein the crosssectional area of said inlet port is at least 25 percent smaller than the cross-sectional area of said valve seat.

6 The gas lift valve of claims 1. 2, or 4 and also including surge valve means located in said outlet passageway said surge valve means including:

a surge valve encircling said outlet passageway between said valve seat and surge valve member;

a surge valve member in said outlet passageway;

resilient means biasing said surge valve member toward, but not into engagement with said surge valve seat, whereby fluid pressure in said outlet is exerted through said outlet passageway and fluid flow thereby toward said valve member is substantially prohibited.

Claims

1. A gas lift valve for use in a well bore, said valve comprising: a hollow valve body having an outlet passageway and having an inlet port of smaller cross-sectional area than said outlet passageway; an annular valve seat located in said body between said inlet port and outlet passageway, said valve seat having a flow larger area larger than the cross-sectional area of said inlet port; a valve member in said body movable between a closed position, wherein said member engages said seat, and an open position, wherein said member is out of engagement with said seat; and pressure responsive means in said body connected with said valve member biasing said valve member toward said seat, said pressure responsive means being exposed to fluid pressure through said inlet port when said valve member is in the closed position and exposed to the fluid pressure in said outlet passageway when said valve member is in the open position, and said pressure responsive means having a cross-sectional area exposed to fluid pressure substantially equal to the crosssectional area of said valve seat, whereby the pressure acting through said inlet port has no substantial effect on said valve member or pressure responsive means.

2. A gas lift valve for use in a cased well bore having tubing disposed therein, said vale comprising: a hollow valve body adapted for connection with the tubing, said body having an outlet passageway arranged to communicate with the tubing and having an inlet port of smaller cross-sectional area than said outlet passageway providing communication with the casing; an annular valve seat located in said body between said inlet port and outlet passageway said seat having a flow area larger than the cross-sectional area of said inlet port; a valve member in said body move movable between a closed position, wherein said member engages said seat, and an open position, wherein said member is out of engagement with said seat; and pressure responsive means in said body connected with said valve member biasing said valve member toward said seat, said pressure responsive means being exposed to pressure in the casing through said inlet port when said valve member is in the closed position and exposed to pressure in the tubing when said valve member is in the open position, whereby the movement of said valve member between said positions is controlled by the pressure in tHe tuning tubing acting through said outlet passageway; and said pressure responsive means having a cross-sectional area exposed to fluid pressure substantially equal to the cross-sectional area of said valve seat, whereby the pressure acting through said inlet port has no substantial effect on said valve member or pressure responsive means. 3 The gas lift valve of claims 1 and 2 wherein said pressure responsive means extends across said hollow valve body forming a chamber therein and wherein said valve also includes a compressible gas in said chamber for biasing said pressure responsive means and connected valve member toward said valve seat.

4. A gas lift valve for use in a cased well bore having tubing disposed therein, said valve comprising: an elongated tubular body adapted for connection with the tubing, said body having a closed upper end, a lower end including an outlet passageway proving providing communication with the tubing passageway, and an inlet port intermediate said ends providing communication with the casing; an annular valve seat encircling said outlet passageway and having a cross-sectional flow area larger than the cross-sectional area of said inlet port; A valve member movable between a closed position, wherein said valve member is in engagement with said seat, and an open position, wherein said valve member is not in engagement with said seat; an expansible and contractible bellows in said body connected with said valve member and forming a chamber with said upper end; A compressible gas in said chamber biasing said valve member relatively toward said valve seat; and toward said valve seat; and said bellows being located between said closed end and side inlet port and exposed to fluid pressure from the casing through said inlet port when said valve member is in the closed position and exposed to fluid pressure from the tubing through said outlet passageway when said valve member is in the open position, and said bellows having a cross-sectional area exposed to fluid pressure substantially equal to the cross-sectional area of said valve seat, whereby the casing pressure acting through said inlet port has no substantial effect on said valve member or bellows.

5. The gas lift valve of claims 1, 2, or 4 wherein the cross-sectional area of said inlet port is at least 25 percent smaller than the cross-sectional area of said valve seat. 6 The gas lift valve of claims 1, 2, or 4 and also including surge valve means located in said outlet passageway said surge valve means including: a surge valve encircling said outlet passageway between said valve seat and surge valve member; a surge valve member in said outlet passageway; resilient means biasing said surge valve member toward, but not into engagement with said surge valve seat, whereby fluid pressure in said outlet is exerted through said outlet passageway and fluid flow thereby toward said valve member is substantially prohibited.