Ball Injector

Abstract

An apparatus for loading and dispensing balls into a flow stream. The apparatus has an outer housing with a smooth cylindrical inner surface, and an inner housing, removably mounted within the outer housing. The inner housing has a hollow cylindrical body extending longitudinally between a lower guide plate and an upper guide band. A plurality of longitudinal slots are located in and extend the length of the cylindrical body and through the lower guide plate. The width of the slots is greater than the diameter of the balls. The apparatus also has a shaft with a smooth cylindrical outer surface, coaxially, rotatably, and removably mounted in the inner housing. The distance between the outer surface of the shaft and the inner surface of the outer housing is greater than the diameter of the balls.

Description

This application claims priority to provisional application 61/122,495, filed Dec. 15, 2008.

FIELD OF THE INVENTION

The present invention relates in general to an apparatus for dispensing objects and, in particular, to an apparatus for injecting spherical sealer balls into an oil well.

BACKGROUND OF THE INVENTION

When an oil or gas well is completed, it is common practice to cement the well casing into the well. The casing is then perforated to allow fluid from the producing formations to flow into the well bore.

In order to increase the productivity of oil and gas wells, producing formations are sometimes treated by hydraulic fracturing and acidizing. Hydraulic treating fluid is pumped into the well bore and exits through the perforations in the casing into the formation.

If some of the perforations are blocked by sediment, or if part of a formation has a lower permeability, part of the formation may not be treated. To insure that this does not happen, perforation sealer balls are introduced into the treating fluid. The sealer balls seal the open perforations, thus forcing the treating fluid to flow through the other perforations. Thus, ball injectors have been used in the well service industry as a means of selectively diverting acidizing or fracturing fluid to all of a well's perforations.

Several different types of devices have been devised for injecting such balls into a well. These devices must be capable of withstanding the high pressures of the well bore. The devices must also be able to easily and accurately count the number of balls inserted into the well. Sometimes several hundred balls are used, so at times it is very difficult to keep track of the number of balls that have been inserted. It is important that an exact count of balls be accurate at all times.

SUMMARY OF THE INVENTION

The apparatus of the invention is for dispensing spherical sealing balls. The apparatus includes an outer housing, having a smooth cylindrical inner surface. An inner housing is removably mounted within the outer housing, the inner housing has a hollow cylindrical body extending longitudinally between a lower guide plate and an upper guide band. A plurality of longitudinal slots are located in and extend the length of the cylindrical body and through the lower guide plate. The width of the slots is greater than the diameter of the balls.

A shaft has a smooth cylindrical outer surface and is coaxially, rotatably, and removably mounted in the inner housing. The distance between the outer surface of the shaft and the inner surface of the outer housing is greater than the diameter of the balls. A helical rib is mounted on the outer surface of the shaft. The distance between the rib and the inner surface of the outer housing is less than the diameter of the balls, so that the balls cannot fall between the rib and the inner surface of the outer housing. The distance between the outer surface of the shaft and the inner surface of the inner housing is less than the diameter of the balls, so that the balls cannot roll down the rib.

A device for rotating the shaft and the rib about the longitudinal axis of the shaft while the inner housing and the outer housing stay stationary, to move the balls through the inner housing and the outer housing. The inner housing, and the shaft and the rib are mounted independently from one another such that the shaft can be pulled upwardly from the inner housing, and the inner housing can be pulled upwardly from the outer housing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a ball injector of the invention;

FIG. 2 is a perspective view of the interior housing assembly and shaft of the ball injector of the invention;

FIG. 3 is a sectional view of the ball injector of the invention as seen along the line 3-3 in FIG. 1;

FIG. 4 is a sectional view of the ball injector of the invention as seen along the line 4-4 in FIG. 1;

FIG. 5 is a sectional view of the ball injector of the invention as seen along the line 5-5 in FIG. 1;

FIG. 6 is a side view of a portion of the shaft of the ball injector of the invention of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Although the following detailed description contains many specific details for purposes of illustration, anyone of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the exemplary embodiment of the invention described below is set forth without any loss of generality to, and without imposing limitations thereon, the claimed invention.

FIG. 1 shows a ball injector constructed according to the apparatus of the invention. The ball injector 11 has a cylindrical outer housing 13. The outer housing 13 is a hollow cylinder, having a smooth, cylindrical inner surface 15. The upper end of the outer housing 13 has external threads 17. The upper end of the outer housing 13 is closed by a cap 19, which has internal threads 21 to engage the threads 17 on the outer housing 13. An O-ring seal 23 seals between the cap 19 and the outer housing 13, and two set screws 25 hold the cap 19 against unthreading from the outer housing 13. A pair of lugs 27 are provided to facilitate the threading and unthreading of the cap 19. One of the lugs 27 shown in FIG. 1 is shown ninety degrees out of its true position.

A cylindrical inner housing 29 (FIG. 2) is mounted coaxially within the outer housing 13, so that the outer housing 13 and the inner housing 29 have the same longitudinal axis 31. The inner housing 29 is a hollow cylinder, having a smooth, cylindrical inner surface, with a number of straight longitudinal slots 33 extending the entire length of the inner housing 29. As shown in FIG. 2, the slots 33 are equally spaced around the diameter of the inner housing 29. The width 35 of the slots 33 is slightly larger than the diameter 37 of the balls 38 (FIG. 5).

The lower ends of the inner housing 29 are welded to a lower guide plate 39, shown in FIG. 2. The lower guide plate 39 is a cross shaped plate with four holes 40 evenly spaced and machined around the diameter of the guide plate 37 as shown in FIG. 3. The lower ends of the inner housing 29 are welded to the lower guide plate 39 along the outer diameter of the plate 39. A hole 41 is contained within and extends through the center of the lower guide plate 37 for accepting a shaft 43 (FIGS. 1, 2, and 3).

A circular upper guide band 45 is welded to the upper ends of the interior housing 29, as shown in FIGS. 2 and 4. The upper guide band 45 abuts against the upper ends of the outer housing 13. In the particular embodiment, a number of pins 47 pass vertically through the upper guide band 45 and extend into holes in the outer housing 13. Pins 47 act to secure the inner housing 29 against rotation relative to the outer housing 13. Alternatively, a single pin could be used to secure the inner housing 29 against rotation relative to the outer housing 13. The inner housing 29 can be pulled upward from the outer housing 13.

Shaft 43 is mounted coaxially within the inner housing 29, so that the inner housing 29 and the shaft 43 have the same longitudinal axis 31. The shaft 43 has a smooth, cylindrical outer surface 49, and the lower end of the shaft 43 fits within the circular hole 41 in the lower guide plate 37 of the inner housing 29. As best shown in FIG. 5, the distance 51 between the inner surface 15 of the outer housing 13 and the outer surface 49 of the shaft 43 is greater than the diameter 37 of the balls 38 as shown in FIG. 1, so the balls 38 can fit between the shaft 43 and the outer housing 13.

Shaft 43 extends upward. The upper end of shaft 43 has a small extension 53 (FIG. 6) that extends axially from the shaft 43 and allows for a drive stem 55 to be attached to the shaft 43. The drive stem 55 connects to the shaft 43 and extends upwards through the cap 19. Packing 59 seals between the drive stem 55 and the cap 19, and a bearing 61 allows the drive stem 55 and shaft 43 to rotate relative to the inner housing 29 and outer housing 13.

The drive stem 55 also extends upwardly through a bushing 63, which is threaded onto the cap 19. The bushing 63 has external threads (not shown), which engage internal threads (not shown) on the cap 19. A seal 65 seals between the drive stem 55 and the bushing 63.

A crank 67 is attached to the upper end of the drive stem 55. A handle 69 is provided on the end of the crank 67 to facilitate the manual rotating of the crank 67 and the drive stem 55 and shaft 43.

A counter 71 is mounted on the crank 67 in order to automatically count the number of balls 38 which are dispensed from the ball injector 11. Four roll pins 73 are mounted on the top of the cap 19, equally spaced around the bushing 63. As the crank 67 is turned, a swing arm (not shown) on the counter 71 contacts the roll pins 73 in turn. The counter 71 counts one ball 38 each time the swing arm (not shown) contacts a roll pin 73.

A helical rib 75 is integrally formed on the outer surface 49 of the shaft 43. The rib 75 spirals downwards to the right, so that when the crank 67 is rotated counterclockwise, the rib 75 will -move the balls 38 downward. The distance 77 between the outer edge of rib 75 and the inner surface 15 of the outer housing 13, as shown in FIG. 5, is smaller than the diameter 37 of the balls 38 as shown in FIG. 1. This keeps the balls 38 from falling between the rib 75 and the outer housing 13. As shown in FIG. 6, the pitch 79 of the rib 75 is slightly larger than the diameter 37 of the balls 38 (FIG. 1), so that the balls 38 fit within the rib 75. Referring to FIG. 5, the distance 81 between the inner sides of the inner housing 29 and the outer surface 49 of the shaft 43 is smaller than the diameter 37 of the balls 38 (FIG. 1). Thus, the inner housing 29 keeps the balls 38 from rolling around the shaft 43 and down the rib 75.

When the ball injector 11 is being used to insert balls 38 into the flow line (not shown), the outer housing 13 is placed directly onto a base 83. The base 83 has a flow passage with external threads 85 on one end for connection to the flow line (not shown). At the other end, the base 83 has an outwardly extending lip 87. Three ring sections 89 fit around the end of the base 83, within the outwardly extending lip 87. These ring sections 89 also have an outwardly extending lip 91 on the end. A retainer ring 93 is located near the other end of the ring sections 89.

A lug nut 95 connects the base 83 to the flow line (not shown). The nut 95 has an inwardly extending shoulder 97, which contacts the outwardly extending lip 91 on the ring sections 89. The nut 95 also has threads 99 which engage the threads on the flow line (not shown). The base 83 can be removed from the flow line (not shown) by unthreading the nut 95. A lug 101 on the nut 95 facilitates the threading and unthreading of the nut 95. Connectors other than lug nuts may be employed, such as clamps (not shown).

In this embodiment, the outer housing 13 has an enlarged section 103 at the lower end, which has a larger outside diameter than the remainder of the outer housing 13, thus forming an upwardly facing shoulder 105. This lower section 103 also has a seal groove 107, in which as seal 108 is located.

The base 83 has a circular opening 109, which is smaller than the diameter of the lower section 103 of the outer housing 13. Concentric with that opening 109 is a larger opening 111, with a diameter slightly larger than the diameter of the lower section 103 of the outer housing 13. The outer housing 13 can thus be inserted into the larger opening 111 and rest upon the shoulder 113 formed above the other opening 109. The seal 108 in the seal groove 107 seals between the lower section 103 of the outer housing 13 and the base 83.

The outer housing 13 is secured to the base 83 by a flange 113. The flange 113 encircles the outer housing 13 and has a downward facing shoulder 115, which engages the upward facing shoulder 105 on the outer housing 13. The flange 113 is locked onto the base 83 by ten socket head cap screws (not shown).

The balls 38 are contained in the inner housing 29 in four vertical columns, one column being against each section of the inner housing 29. The balls in each column are separated by the threads of the rib 75.

As the crank 67 is turned counterclockwise, the rib 75 rotates, and pushes the balls 38 downward. As each ball reaches the lower guide plate 39, the ball 38 falls through one of the holes 40 in the lower guide plate 39, into the base 83, and into the bore of the flow line (not shown). Each time a ball 38 is released, the swing arm on the counter 71 contacts a roll pin 73 and counts the ball 38.

To load the ball injector 11, first the crank 67 is removed from drive stem 55. Then, the set screws 25 are loosened, and the cap 19 is unthreaded from the outer housing 13, and removed. The crank 67 is replaced on the drive stem 55 and the balls 38 are manually loaded into the ball injector 11. The balls 38 are placed between the sections of the inner housing 29 and the shaft 43 is rotated by rotation of crank 67, which is connected to drive stem 55. The balls 38 move downward in columns as the shaft 43 is rotated. This process is repeated until the inner housing 29 and shaft 43 are fully loaded with four columns of balls 38. The crank 67 is removed and cap 19 is replaced on the outer housing 29. The set screws 25 are tightened, and the crank 67 is replaced on the drive stem 55. The apparatus is now ready to inject the balls 38.

The ball injector 11 of the invention has several advantages over the prior art. One advantage is that the shaft 43 can be easily removed from the inner housing 29. For example, if any damage is done to shaft 43, it can simply be removed from the ball injector 11 without replacing the entire assembly as in the prior art.

Another advantage is that the welded shaft assembly cage of the prior art is replaced with a single piece, inner housing 29, machined from a cylindrical tube. The addition of inner housing 29 limits problematic welding of the welded shaft assembly cage.

Still another advantage is the removable drive stem 55. Prior art devices often fail in the area of the drive stem 55 due to torsion and require replacement of the entire shaft. The ball injector 11 of the invention allows the drive stem 55 to be removed for repair without replacing shaft 43.

Although the present invention and its advantages has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereupon without departing from the principle and scope of the invention. Accordingly, the scope of the present invention should be determined by the following claims and their appropriate legal equivalents.

Claims

1. An apparatus for loading and dispensing balls, comprising:

an outer housing, having a smooth cylindrical inner surface;

an inner housing, removably mounted within the outer housing, the inner housing having a hollow cylindrical body extending longitudinally between a lower guide plate and an upper guide band, a plurality of longitudinal slots located in and extending the length of the cylindrical body and the lower guide plate, wherein the width of the slots is greater than the diameter of the balls;

a shaft, having a smooth cylindrical outer surface, coaxially, rotatably, and removably mounted in the inner housing, wherein the distance between the outer surface of the shaft and the inner surface of the outer housing is greater than the diameter of the balls;

a helical rib, mounted on the outer surface of the shaft, wherein the distance between the rib and the inner surface of the outer housing is less than the diameter of the balls, so that the balls cannot fall between the rib and the inner surface of the outer housing, and wherein the distance between the outer surface of the shaft and the inner surface of the inner housing is less than the diameter of the balls, so that the balls cannot roll down the rib;

a device for rotating the shaft and the rib about the longitudinal axis of the shaft while the inner housing and the outer housing stay stationary, to move the balls through the inner housing and the outer housing; and

the inner housing, and the shaft and the rib being mounted independently from one another such that the shaft can be pulled upwardly from the inner housing, and the inner housing can be pulled upwardly from the outer housing.

2. The apparatus of claim 1, wherein the device for rotating the shaft and the rib about the longitudinal axis of the shaft comprises a hand crank.

3. The apparatus of claim 1, further comprising:

a drive member detachably connected between an upper end of the shaft and the device for rotating the shaft and the rib, such that the drive member can be removed without removing the shaft.

4. The apparatus of claim 1, wherein the upper guide band comprises a circular band with an inner diameter greater than the outer diameter of the inner housing and portions of an inner surface of the band are connected to the outer peripheries of the cylindrical body, the circular band has an outer diameter greater than the inner diameter of the outer housing such that portions of the band are in abutting contact with the upper end of the outer housing when mounted therein.

5. The apparatus of claim 4, further comprising:

a locking device connected between the circular band and the outer housing to prevent rotation of the circular band and outer housing relative to one another.

6. The apparatus of claim 5, wherein the locking device comprises a plurality of pins.

7. An apparatus for loading and dispensing balls, comprising:

an inner housing, adapted to be removably mounted within an outer housing, the inner housing having a hollow cylindrical body extending longitudinally between a lower guide plate and an upper guide band, a plurality of longitudinal slots located in and extending the length of the cylindrical body and the lower guide plate, wherein the width of the slots is greater than the diameter of the balls;

a shaft, having a smooth cylindrical outer surface, coaxially, rotatably, and removably mounted in the inner housing, wherein the distance between the outer surface of the shaft and the inner surface of the outer housing is greater than the diameter of the balls when the inner housing is mounted within the outer housing;

a helical rib, mounted on the outer surface of the shaft, wherein the distance between the rib and the inner surface of the outer housing is less than the diameter of the balls when the inner housing is mounted within the outer housing, so that the balls cannot fall between the rib and the inner surface of the outer housing, and wherein the distance between the outer surface of the shaft and the inner surface of the inner housing is less than the diameter of the balls, so that the balls cannot roll down the rib;

a device for rotating the shaft and the rib about the longitudinal axis of the shaft while the inner housing stays stationary, to move the balls through the inner housing;

a drive member detachably connected between an upper end of the shaft and the device for rotating the shaft and the rib, such that the drive member can be removed without removing the shaft; and

the inner housing, and the shaft and the rib being mounted independently from one another such that the shaft can be pulled upwardly from the inner housing.

8. The apparatus of claim 7, wherein the upper guide band comprises a circular band with an inner diameter greater than the outer diameter of the inner housing and portions of an inner surface of the band are connected to the outer peripheries of the cylindrical body.

9. The apparatus of claim 7, further comprising:

a plurality of pins extending downwards from the circular band and adapted to be connected to an outer housing to prevent rotation of the circular band relative to the outer housing when the inner housing is removably mounted within the outer housing.

10. The apparatus of claim 7, wherein the device for rotating the shaft and the rib about the longitudinal axis of the shaft comprises a hand crank.

11. A method of loading balls into an apparatus for dispensing the balls, the method comprising the steps of:

(a) providing the apparatus with an outer housing, a cylindrical hollow bodied inner housing having a plurality of longitudinal slots located in and extending along the length of the inner housing, the inner housing being removably mounted within the outer housing, a shaft with a helical rib mounted thereon removably mounted within the inner housing, the shaft being rotatable relative to the inner housing;

(b) inserting a ball into the upper end of the inner housing; and

(c) rotating the shaft relative to the inner housing, to thereby move the ball downward relative to the inner housing and the outer housing while being captured in one of the plurality of longitudinal slot.

12. The method of claim 11, wherein step (a) further comprises:

providing a device for rotating the shaft and the rib about to move the balls through the inner housing, and a drive member detachably connected between an upper end of the shaft and the device for rotating the shaft and the rib, such that the drive member can be removed without removing the shaft; and wherein step (c) further comprises simultaneously rotating the drive member with the device to thereby rotate the shaft and the rib.

13. The method of claim 11, wherein step (a) further comprises:

providing a locking device; and the method further comprising after step (a), but before step (b):

locking the inner housing to the outer housing with the locking device to prevent rotation of the inner housing relative to the outer housing.