EP0204823B1

EP0204823B1 - Side pocket mandrel

Info

Publication number: EP0204823B1
Application number: EP86900445A
Authority: EP
Inventors: Douglass W. Crawford; William B. Crawford; Robert W. Dinning
Original assignee: DINNING Robert W
Current assignee: DINNING Robert W
Priority date: 1984-12-07
Filing date: 1985-12-04
Publication date: 1990-08-29
Also published as: DE3579457D1; AU5206086A; EP0351884A1; EP0345830A2; AU585298B2; WO1986003544A2; AU3955189A; EP0204823A1; WO1986003544A3; EP0345830A3; AU3955389A

Abstract

In accordance with illustrative embodiments of the present invention, a side pocket mandrel (10, 410) having a side pocket laterally offset from the open bore (425) has an opening (29, 430) at the upper end adapted to receive a gas lift valve (21). The axis (428) of the opening is inclined in a downward and inward direction toward the axis (429) of the open bore. The opening can be formed in a short-length seating section (412) that is welded to one end of a central body section (413). A kickover (20) tool for replacing and removing valves includes an orienting section (60) having angularly spaced dogs (26, 92) that are cooperable with a sleeve in the mandrel to cause orientation of the tool and to trigger longitudinal movement of a control rod (94). Rod movement actuates guides on a pivot arm (24) that cooperates with ramps (450) or the like in the mandrel to cause the valve to be inserted through the opening to a position extending upwardly into the annulus with a packing sub thereon engaging the opening.

Description

Side Pocket Mandrel

The present invention relates generally to side pocket mandrels for well flow control devices, such as gas lift valves.
Wells having a production string of tubing that includes vertically spaced side pocket mandrels arranged for placing, retrieving and manipulating flow control devices such as gas lift valves, are used extensively in gas and oil well production operations. Each of the mandrels generally includes an open-topped side pocket that is laterally offset to the side of the mandrel bore. A placement and removal tool known as a "kick- over" tool is lowered through the tubing to the level of the mandrel to effect placement or removal of a valve assembly in the side pocket. As mentioned, the device can be a gas lift valve, and which is held in the pocket by a latch assembly that engages a shoulder above the top of the pocket. Prior side pocket mandrels generally have been constructed with a main bore that is aligned with the bore ofthe well tubing and a side pocket that is laterally offset from the main bore. Examples of such devices are shown in United States Patent Nos. 2,824,525,3,268,006, and 3,741,299. The main bore of the mandrel allows various wire line tools to pass therethrough for the performance of well operations belowthe mandrel while a flow control device is positioned in the side pocket. The side pocket typically has polish bores at the upper and lower ends thereof that are engaged by spaced packing rings in the flow control devices, and a plurality of ports through the wall thereof to communicate gas from the well annulus to a valve element that controls the injection of the gas into the tubing string. In many instances in the prior art, the mandrel assembly is made as a weldment of swage nipples to the ends of a round or oval pipe section, which is a construction that is inherently weak and subject to corrosion at the weld points. Moreover, a weldment is more difficult to protect through use of an internal plastic coating.
By way of example US-A-3,268,006 discloses a side pocket mandrel comprising a tubular body having a hollow interior that defines a main bore on one side thereof and another bore on the other side thereof including a valve seating bore having an axis which is spaced laterally with the axis of the main bore and is inclined at a small angle of between 1° and 3° with respect to said main bore; said valve seating bore including an opening which extends to the exterior of said tubular body, a polish section to be engaged by a gas lift valve member and a latch shoulder adjacent the seating section.
Prior art mandrels also have been provided with deflector means for protecting flow control devices positioned in the side pocket, and guide means for preventing tools moving through the well tubing from catching and hanging in the mandrel. Examples of such devices are disclosed in U.S. Patent Nos. 3,741,299,3,802,503,4,106,503 and 4,106,564.
The side pocket of the typical prior art mandrel generally is enclosed within the mandrel body, and thus the condition of the bore of the side pocket cannot be observed prior to running. A worn-out or corroded bore in the side pocket may result in having to pull the entire string of well tubing - a very costly and time-consuming operation. Furthermore, the machining of these mandrels has not allowed for precision work in connection with the maintenance of close tolerances, or visual inspection which invariably results in excessive manufacturing costs.
Additionally, in mandrels having an internal side pocket, the flow control devices that are seated therein are in contact with noxious well fluids and subject to varying temperatures which require that the devices be designed to meet these conditions. This results in the use of expensive materials for construction of the flow control devices and the performance of tedious calculations for temperature corrections.
It is a common occurrence for the flow control devices to be difficult or even impossible to remove. The usual flow control device seats within a side pocket that is aligned parallel to the longitudinal axis of the main bore of the mandrel. As mentioned above, two sets of packing are used to seal the flow control device within the pocket, one near the top of the device and one near the bottom. Due to the parallel alignment of the flow control device relative to the main bore, and to the use of the two sets of packing, a removal tool has to make a long straight pull on the flow control device upwardly through the side pocket in order to remove the device from its seat. The conventional removal tools inherently pull on the valve latch at an angle which places the latch and the flow control device in a bind, thereby causing, in many instances, bent or broken flow control devices and latches. Such damage may result in a costly pulling job, and oftentimes may require the replacement of equipment.
The presence of two sets of packing may also cause a great amount of friction when removing the valve from the side pocket seats. This is due to the fact that the annular area between the device and the pocket wall above the lower packing element can become filled with sand and debris through which the packing must be pulled in order to remove the device from the side pocket. This increase in pulling force, and the inclination thereof with respect to vertical as discussed above, provides a further basis for damaging the rather slender and delicate valves and latches when removal becomes necessary.
It has been typical practice to machine the polish bores that are engaged by the two sets of packing on the flow control device on the same diameter so that the device is balanced with respect to fluid pressures. However, with a balanced design, the operator cannot determine if the flow control device is properly set in the first instance. If the flow control device is not properly set, it may hold in one direction and not the other, and this condition may not become apparent until the wire line crew has left the well site and the proper equipment to correct the situation have been moved off location.
A further disadvantage of prior structures is that the side pocket mandrels have required that retrievable-type flow control devices be utilized, negating the use of conventional type flow control devices within this type of equipment.
Starting from US-A-3,268,006, the present invention is characterised in that the mandrel is formed by an upper tubular body, by a short length seating section below said tubular body and by a main body portion below said seating section, in that said short length seating section has a diameter greater than that of the upper tubular body, said seating section having upper and lower faces, with said main bore extending fully from the upper face to the lower face of said seating section, in that said upper tubular body is welded to said upper face fully to surround said main bore, in that said valve seating bore extends fully from the upper face to the lower face of said seating section and is provided with a single polish bore of which opens directly into the upper face, beside said upper tubular body, to enable a gas lift valve member to project through said polish bore to the exterior of the mandrel and in that said main body portion is of the same diameter as said seating section and is welded to the lower face thereof.
In one embodiment, a lower end portion of the side pocket mandrel of the present invention can be provided with generally longitudinally extending guide means on interior walls thereof which cooperate with instrumentalities on the kick-over tool to guide the flow control device into the cylindrical opening during upward movement of the kick-over tool within the mandrel. Such instrumentalities are normally retracted as the kick-over tool is being run into the well, and are released to project outwardly and engage the guide means in response to manipulation of the kick-over tool as will be subsequently described. The mandrel has in its upper end section an orienting sleeve having oppositely disposed helical lower surfaces that lead to a longitudinally extending groove.
The unique construction of the side pocket mandrel of the present invention obviated numerous disadvantages of the prior art structures. The use of one packing and one seal or polish bore provides a simplified construction which is much easier to release when it is desired to remove the valve. The flow control device protrudes into the annulus, as opposed to being confined within the mandrel body, which enables the side pocket mandrel to be constructed with a significantly shorter length, with consequent savings in material and manufacturing costs. The inclination of the cylindrical opening with respect to central bore of the mandrel facilitates removal and placement of flow control devices because the direction of placement and removal forces is substantially aligned with the axis of the opening. Thus, the instances of bent or otherwise damaged latches and valve bodies is substantially reduced. The oversizing of the cylindrical opening relative to the o.d. of the valve body enables the valve to pivot to some extent during placement and removal so that it is not put in a bind as in the case of a valve having two sets of packing located near its opposite ends. It also is possible to use conventional gas lift valves with the seal sub of the present invention, rather than being confined to the use of retrievable-type valves. The use of guide means in the mandrel insures precise alignment of the valve with the cylindrical opening, and the provision of an inwardly biased pivot arm on the kick-over tool provides a construction that is considerably less likely to hang up in the tubing in which it is being run and retrieved, as compared to prior art devices of this general type.
The present invention has other objects, features, and advantages which will become more clearly apparent in connection with the following detailed description of one or more embodiments, taken in conjunction with the appended drawings in which.

Figures 1A and 1B are longitudinal sectional views of a side pocket mandrel that is constructed in accordance with this invention;
Figure 2 is a three-dimensional view of the valve seating section of Figure 1A;
Figure 3 is a cross-section taken on line 3-3 of Figure 1; and
Figures 4 and 5 show modifications of the mandrel of the present invention.

Referring now to Figures 1A and, 1B a side pocket mandrel assembly indicated generally at 410 includes an upper tubular member 411 having internal threads 399 for connecting the same to a string of production tubing (not shown). The tubular member 411 is secured by a transverse weld 455 to a seating section 412 of relatively short length, and the section 412 is secured by a transverse weld 456 to a main body section 413. The main body section 413 preferably is circular in cross-section, and one side 414 of the hollow interior thereof is axially aligned with the bore of the tubular member 411. The other side 415 of the hollow interior provides an elongated space for operation of the kickover arm of a gas lift valve setting or retrieving tool, such arm being typically a segmented subassembly that can be pivoted outward in order to align a valve attached to the end thereof for insertion into a valve seat or pocket in the mandrel. The lower end of the main body section 413 is secured by a transverse weld 457 to a swage nipple 416 that has internal threads 417 for connection to the tubing.
As shown in Figure 1A, the tubular member411 can have an orienting sleeve 420 fixed within the bore thereof. The sleeve 420 has a pair of helical lower surfaces 421 that lead upward to an elongated vertical slot 422. The slot 422 is arranged to receive a key on a setting tool as it is moved upward therethrough, in order to rotationally orient the tool in a manner such that the kickover arm and valve are generally aligned within the region 415 of the body section 413. Such orientation is achieved by the fact that the key will first encounter one of the inclined surfaces 421 and be guided thereby into the slot 422. A second key that initially is vertically misaligned with the first- mentioned key will then encounter one of the surfaces 421 during continued upward movement, and the camming action as the keys are forced into vertical alignment achieves proper orientating and causes the kickover tool to trigger the release of guide rollers or wings on the arm assembly. The wings then cause the inwardly biased arm assembly to be pivoted outward during continued upward movement.
The seating section 412 of the present invention is shown in detail in Figures 2 and 3. The section 412 is generally tubular, and has a main bore 425 machined to one side thereof. The upper end of the bore 425 opens through an annular lip 426 which is chamfered to facilitate welding to the lower end of the tubular member 411. Another bore 427 is formed on the opposite side of the section 412, and has its central axis 428 slightly inclined downward and inward with respect to the axis 429 of the main bore 425. The angle of inclination may be, for example, from 1-1/2° to 3°. The upper end portion 430 of the bore 427 has a reduced diameter (for example 28.57mm (1.125 inches), and is machined as a polish bore that receives an annular packing assembly of a gas lift valve or other flow control device shown in phantom lines in Figure 24. The bore 430 opens to the outside of the mandrel at its upper end as shown, and is joined by an annular inclined surface 431 to a larger diameter bore 432 which receives the latch element (for example collet) of a typical latch assembly which releasably connect the gas lift valve, or other flow control device, in place. The latch element has shoulder surfaces that engage an inclined shoulder 433 at the lower end of the enlarged bore 432, and the shoulder 433 forms the upper side of an inwardly directed flange 434 that has another inclined annular shoulder 435 at its lower side. The shoulder 435 is at the upper end of another enlarged diameter bore 436 that opens through the lower end surfaces 440 of the section 412. The lower end of the section 412 is bevelled at 437, again to facilitate welding to the upper end of the main body section 413.
A generally frusto-conical surface 440 is machined in the lower portion of the section 412 as shown, and a vertical slot 441 is milled out in the wall that separates the bores 430 and 425 in order to provide for the inward flow of lift gas. The slot 441 extends upward to a point 442 adjacent the "no go" shoulder431, and preferably has a width such that the latch shoulder 433 extends circumferentially through an angle of about 290° (145° to either side of a radial line that intersects the respective centerlines of the bores 428 and 429) to provide ample stop surface area for the latch element. The slot 441 also functions as a guide for proper rotational orientation of the body of the gas lift valve to radially align a port in the neck of the valve such that the lift gas is injected into the bore 425 where it is admixed and entrained in the upward flow of production fluids.
If desired, the central bore 42 have a transverse dimension of, for example, 69.85mm (2.750 inches) up to an inclined surface 443 where the diameter is reduced to 62mm (2.441 inches), which is the same dimension as the inner diameter of the orienting sleeve 420. Of course, these dimensions are applicable to a typical size side pocket mandrel, for example a mandrel sized to be connected in a 73.02mm (2-7/8") o.d. tubing string.
The swage nipple 415 shown in Figure 1B has fixed therein a ramp member 450 that is generally semi-circular in section and has inclined surfaces 451 and 452 on opposite sides thereof. The upper and lower ends of the member 450 can be oppositely inclined, as shown, so that no transverse shoulders are formed which could cause other tools to hang up on the member. If desired, a pair of oppositely disposed, elongated rails 451 are mounted inside the main body section 413 between the bore 414 and the region 415, in positions such that outwardly facing surfaces 452 thereof are generally vertically aligned with the innermost surface of the seating bore 430. The lower end of each rail 451 may be inclined at 453 to present a continuous ramp surface, and the upper end of each rail can terminate at approximately the upper end of the body section 413.
As shown in the drawings, the tubular member 411 is joined to the upper end of the receptacle section 412 by the transverse weld 455, and the lower end of the receptacle section 412 is joined to the upper end of the body section 413 by the transverse weld 456. The lower end of the body 413 is joined to the swage nipple by a transverse weld 457. It will be noted that there is a total absence of any vertical weld seams, or any partial transverse seams, which is a feature that greatly simplifies the manufacture of the mandrel, and provides a structure that compact and has high strength.
In a modification of the present invention as show in Figure 27, a guard lug 460 may be fixed to the outside of the tubular member 411 at a distance from the upper end of the section 412 such that it is closely adjacent the nose of the gas lift valve when the valve is latched in place. Thus arranged, the lug prevents the valve from being damaged in the event the tubing is moved upward in the casing while the valve is in place.
In a further modification of the present invention shown in Figure 28, the guard lug 460' may have a polish bore 462 formed therein on a diameter that is slightly less than the diameter of the bore 430, for example 1.000 inch. A gas flow port 463 communicates the polish bore 462 with the interior bore of the tubular member 412. This feature enables a more conventional gas lift valve to be used having spaced apart packing rings that engage the respective bores 430 and 461, and a gas outlet port through the end of the nose thereof which is packed off in the bore 462.
Having disclosed the principle components of the present invention, it will be apparent to those skilled in this art that these components could be rearranged from that shown in the drawing without departing from the concepts of the present invention. For example, the member 412 which houses an orienting sleeve 420 could be attached to a swage nipple and body section as previously described, except inverted, or turned upside- down. With this configuration of parts, the seating section 413 would be inverted also and would be located near the lower end of the mandrel, whereby the polish bore 430 would open downward. Of course the tubular member to which the section 413 is welded, in this configuration, would not have an orienting sleeve therein.
In another configuration, the entire assembly as shown in Figures 24A and 24B could be inverted, and the position of the orienting sleeve 420 reversed so that the guide surfaces would still lead in the upward direction to the slot. In any of these configurations, the guard lug, with or without polish bore and gas port, could be used.

Claims

1. A side pocket mandrel (410) comprising a tubular body (412, 413) having a hollow interior that defines a main bore (425, 414) on one side thereof and another bore (415, 530) on the other side thereof including a valve seating bore (427) having an axis which is spaced laterally with the axis of the main bore and is inclined at a small angle of between 1° and 3° with respect to said main bore; said valve seating bore including an opening which extends to the exterior of said tubular body, a polish section (430) to be engaged by a gas lift valve member and a latch shoulder (433) adjacent the seating section, characterised in that the mandrel (410) is formed by an upper tubular body (411), by a short length seating section (412) below said tubular body (411) and by a main body portion (413) below said seating section (412), in that said short length seating section (412) has a diameter greater than that of the upper tubular body (411), said seating section (412) having upper and lower faces, with said main bore (425) extending fully from the upper face to the lower face of said seating section, in that said upper tubular body is welded to said upper face fully to surround said main bore, in that said valve seating bore extends fully from the upper face to the lower face of said seating section and is provided with a single polish bore (430) which opens directly into the upper face, beside said upper tubular body, to enable a gas lift valve member to project through said polish bore to the exterior of the mandrel and in that said main body portion (413) is of the same diameter as said seating section (412) and is welded to the lower face thereof.

2. A mandrel according to claim 1 characterised in that said seating section (412) has a longitudinally extending opening (441) between said seating bore (427) and main bore (425), said longitudinally extending opening (441) serving for the passage of gas.

3. A mandrel according to claim 1 or 2, characterised in that said latch shoulder (433) has a generally angular shape and extends through an angle of approximately 145° to either side of a radial line that intersects the axis (428) of said main bores (414, 425) and the axis (429) of said seating bore (427).

4. A mandrel according to claim 1, 2 or 3, characterised in that said mandrel (410) further includes an orienting sleeve (420) and in that said orienting sleeve (420) is provided with a guide slot (422) including a helical surface (421) to engage and rotationally orient a key on the kick over tool.

5. A mandrel according to any preceding claim, characterised in that swage nipple means (416) are welded (at 457) to the lower end of said body section (412), in that a thread (417) is provided at the lower end of said swage nipple means (416), and in that said tubular member (411) has a thread (399) at its upper end, said threads (411 and 399) connecting said mandrel in a tubing string.

6. A mandrel according to claim 5, characterised in that ramps (450) are fixed within said swage nipple means (416) and have inclined surfaces (452) on opposite sides thereof and in that further guides (451) extend longitudinally along the inner wall surfaces of said body section (413) from said inclined surfaces (452) to a location adjacent the lower end of said seating section.

7. A mandrel according to claim 6, characterised in that said ramps (450) comprise a member that is generally semi-circular in transverse cross section, and has inwardly inclined surfaces (452) at the opposite ends thereof, said guides (451) including a pair of rails attached to said inner walls at a location between said main bore (414) and said other bore (415).

8. A mandrel according to claim 1, characterised in that the mandrel (410) further includes guard means (460) on the exterior of said tubular member (411) spaced a selected distance above and aligned with the upwardly facing opening of said polish section (430).

9. A mandrel according to claim 8, characterised in that said guard means (460) has another polish bore (462) formed in the interior thereof, and a gas flow port (463) communicates said other polish bore (462) with the interior of said tubular body.

10. A mandrel according to any preceding claim characterised in that an outwardly extending lip (426) is provided on the upper end of said seating section (412) and surrounds the opening of said main bore (414), said lip (426) having a chamfer on its outer surface.