Title:
Split ball valve
Kind Code:
A1


Abstract:
A split ball valve that may be positioned in a production string of line pipe, casing, or tubing. The split ball valve comprises a lower valve assembly and an upper valve assembly. Each of two valve doors in the lower valve assembly is connected to a pinion gear that intermeshes with racks on the upper valve assembly. The upper valve assembly can be vertically displaced relative to the lower valve assembly. A spring keeps the upper valve assembly extended away from the lower valve assembly and thus keeps the valve doors closed. When a downward force is applied to the upper valve assembly, the upper valve assembly is downwardly displaced causing the pinion gears to rotate, which opens the valve doors. The valve doors recede into cavities in the valve body. When open, the split ball valve is fully ported.



Inventors:
Hughes, William James (Bixby, OK, US)
Eilertsen, Bjorn Arvid (Hundvaag, NO)
Application Number:
10/844172
Publication Date:
11/17/2005
Filing Date:
05/12/2004
Primary Class:
International Classes:
E21B34/12; E21B34/14; (IPC1-7): E21B34/14
View Patent Images:
Related US Applications:



Primary Examiner:
NEUDER, WILLIAM P
Attorney, Agent or Firm:
DUKE W. YEE (MCKINNEY, TX, US)
Claims:
1. A valve assembly comprising: an upper valve assembly; a lower valve assembly located adjacent to the upper valve assembly; a plurality of valve doors located in the lower valve assembly; and wherein the valve doors are rotated by exerting a compressive force on the valve assembly.

2. The valve assembly of claim 1 wherein the rotation opens the valve doors.

3. The valve assembly of claim 1 wherein the rotation closes the valve doors.

4. The valve assembly of claim 1 wherein the flow of a fluid through the valve assembly is stopped when the valve doors are closed.

5. The valve assembly of claim 1 wherein the valve assembly is fully ported when the valve doors are open.

6. The valve assembly of claim 1 wherein the upper valve assembly comprises: an upper housing; an upper collar located adjacent to the upper housing; a longitudinal support located adjacent to the upper collar; and a lower collar located adjacent to the longitudinal support.

7. The valve assembly of claim 6 wherein the longitudinal support comprises a rack; and wherein the rack intermeshes with a pinion gear to rotate the valve doors.

8. The valve assembly of claim 1 wherein the lower valve assembly comprises: a lower housing; a valve body located adjacent to the lower housing; and a pinion gear passing through the valve body.

9. The valve assembly of claim 8 wherein the valve body comprises a plurality of cavities; and wherein the valve doors recede into the cavities when the valve doors are opened.

10. The valve assembly of claim 8 wherein the pinion gear intermeshes with a rack to rotate the valve doors.

11. The valve assembly of claim 8 wherein the valve body comprises a valve upper body and a valve lower body.

12. The valve assembly of claim 8 wherein a key prevents slippage between the valve doors and the pinion gear.

13. The valve assembly of claim 1 wherein the valve doors comprise an aperture; and wherein the aperture allows the valve assembly to function when a string of drill pipe, casing, tubing, or rods passes through the valve assembly.

14. The valve assembly of claim 1 wherein a spring creates a separating force between the upper valve assembly and the lower valve assembly.

15. The valve assembly of claim 1 wherein the valve assembly is located down hole.

16. The valve assembly of claim 1 further comprising: a string of line pipe, casing, or tubing; and wherein the valve assembly is positioned inline with the string of line pipe, casing, or tubing.

17. The valve assembly of claim 16 further comprising: a drilling apparatus connected to the string of line pipe, casing, or tubing.

18. The valve assembly of claim 16 further comprising: a production apparatus connected to the string of line pipe, casing, or tubing.

19. A valve comprising: a valve assembly; a plurality of valve doors located in the valve assembly; an aperture located in the valve doors; and wherein the aperture allows the valve assembly to function when a string of drill pipe, casing, tubing, or rods passes through the valve assembly.

20. The valve of claim 19 wherein the valve doors are rotated by exerting a compressive force on the valve assembly.

21. The valve of claim 20 wherein the rotation opens the valve doors.

22. The valve of claim 20 wherein the rotation closes the valve doors.

23. The valve of claim 19 wherein the flow of a fluid through the valve assembly is stopped when the valve doors are closed.

24. The valve of claim 19 wherein the valve assembly is fully ported when the valve doors are open.

25. The valve of claim 19 valve wherein the valve assembly comprises: an upper housing; an upper collar located adjacent to the upper housing; a longitudinal support located adjacent to the upper collar; and a lower collar located adjacent to the longitudinal support.

26. The valve of claim 25 wherein the longitudinal support comprises a rack; and wherein the rack intermeshes with a pinion gear to rotate the valve doors.

27. The valve of claim 19 wherein the valve assembly comprises: a lower housing; a valve body located adjacent to the lower housing; and a pinion gear passing through the valve body.

28. The valve of claim 27 wherein the valve body comprises a plurality of cavities; and wherein the valve doors recede into the cavities when the valve doors are opened.

29. The valve of claim 27 wherein the pinion gear intermeshes with a rack to rotate the valve doors.

30. The valve of claim 27 wherein the valve body comprises a valve upper body and a valve lower body.

31. The valve of claim 27 wherein a key prevents slippage between the valve doors and the pinion gear.

32. The valve of claim 19 wherein a spring creates a separating force between an upper valve assembly and a lower valve assembly.

33. The valve of claim 19 wherein the valve assembly is located down hole.

34. The valve of claim 19 further comprising: a string of line pipe, casing, or tubing; and wherein the valve assembly is positioned inline with the string of line pipe, casing, or tubing.

35. The valve of claim 34 further comprising: a drilling apparatus connected to the string of line pipe, casing, or tubing.

36. The valve of claim 34 further comprising: a production apparatus connected to the string of line pipe, casing, or tubing.

37. An apparatus for stopping the flow of a fluid in a string of line pipe, casing, or tubing, the apparatus comprising: an upper valve assembly comprising: an upper housing; an upper collar located adjacent to the upper housing; a longitudinal support located adjacent to the upper collar; and a lower collar located adjacent to the longitudinal support; a lower valve assembly located adjacent to the upper valve assembly, the lower valve assembly comprising: a lower housing; a valve body located adjacent to the lower housing; a pinion gear passing through the valve body; and a plurality of valve doors located in the valve body; wherein the longitudinal support comprises a rack; and wherein the rack intermeshes with the pinion gear to rotate the valve doors.

38. The apparatus of claim 37 wherein the valve doors are rotated by exerting a compressive force on the upper valve assembly.

39. The apparatus of claim 38 wherein the rotation opens the valve doors.

40. The apparatus of claim 38 wherein the rotation closes the valve doors.

41. The apparatus of claim 37 wherein the flow of a fluid through the valve assembly is stopped when the valve doors are closed.

42. The apparatus of claim 37 wherein the apparatus is fully ported when the valve doors are open.

43. The apparatus of claim 37 wherein the valve body comprises a plurality of cavities; and wherein the valve doors recede into the cavities when the valve doors are opened.

44. The apparatus of claim 37 wherein the valve body comprises a valve upper body and a valve lower body.

45. The apparatus of claim 37 wherein a key prevents slippage between the valve doors and the pinion gear.

46. The apparatus of claim 37 wherein the valve doors comprise an aperture; and wherein the aperture allows the valve assembly to function when a string of drill pipe, casing, tubing, or rods passes through the valve assembly.

47. The apparatus of claim 37 wherein a spring creates a separating force between the upper valve assembly and the lower valve assembly.

48. The apparatus of claim 37 wherein the valve assembly is located down hole.

49. The apparatus of claim 37 wherein the valve assembly is positioned inline with the string of line pipe, casing, or tubing.

50. The apparatus of claim 37 further comprising: a drilling apparatus connected to the string of line pipe, casing, or tubing.

51. The apparatus of claim 37 further comprising: a production apparatus connected to the string of line pipe, casing, or tubing.

Description:

FIELD OF THE INVENTION

The present invention relates generally to piping valves and specifically to a down hole ball valve operated by vertical displacement of an independent string of casing or tubing.

BACKGROUND OF THE INVENTION

When drilling or producing a subterranean well, it is often desirable to stop the flow of drilling or production fluid within the production line pipe, casing, or tubing. For example, a drilling engineer may want to stop the flow of drilling or production fluid within the line pipe, casing, or tubing in order to stop the flow of drilling or production fluid into a concentric string of casing or tubing. A drilling engineer may also want to stop the flow of drilling or production fluid within the line pipe, casing, or tubing in order to stop the circulation of drilling or production fluid within a section of the well bore. The most efficient method for stopping the flow of drilling or production fluid within the line pipe, casing, or tubing is to install a valve in the circulation path of the drilling or production fluid.

The location of the valve within the circulation path of the drilling or production fluid can be a critical component in controlling the drilling or production operations. One of the options is to place the valve at the surface in the line pipe. Placing the valve at the surface in the line pipe is advantageous because the valve can be easily actuated. However, placing the valve at the surface limits the control of the drilling or production fluid operations to the well bore as a whole. In other words, when the valve is located at the surface, the drilling engineer cannot independently control the drilling or production fluid at different depths within the well bore. Instead, the drilling engineer must control all the drilling or production fluid in the well bore using the valve at the surface. Allowing a drilling engineer to control the flow of drilling or production fluid at different depths within the well bore is an important feature in well control. Thus, it is preferable to locate the valve down hole (i.e. within the well bore) so that the drilling engineer may independently control different sections of the well bore. Therefore, a need exists for a valve that can be located down hole in the production string.

When a valve is located in a production string of casing or tubing, the valve encounters conditions unique to drilling and production operations. For example, when drilling or producing a well, the casing or tubing string is subjected to high levels of compressive and tensile stress. The valve must be able to withstand these high stress levels without failing. Additionally, when drilling a well using a casing or tubing string, the drill string rotates with a high rate of speed within the string of casing or tubing. When drilling a well using this configuration, the drill string frequently contacts the casing or tubing string, imparting rotational stress onto the casing or tubing string. Because it is not preferable to have a valve accidentally actuated by the rotating drill string, the valve must not be operated by rotational movement. In other words, the down hole valve must be operated only by tension or compression of the string of casing or tubing. Therefore, a need exists for a down hole valve that is operated by tension or compression of the string of casing or tubing.

In addition to being located within the string of casing or tubing, the open valve must not impede the flow of drilling or production fluid through the string of casing or tubing. The drilling or production fluid pressure is a critical factor when maintaining control of the well. If the drilling or production fluid pressure drops below the reservoir pressure, then the formation can blowout into the well bore and create a hazardous condition. Several types of valves, such as globe valves (See FIG. 1A), angle valves (See FIG. 1B), diaphragm valves (See FIG. 1C), and butterfly valves (See FIG. 1D), create an unacceptable pressure drop across the valve because the valve redirects the fluid around structures within the valve. Valves that do not redirect the flow of fluid around structures within the valve when the valve is fully open, such as gate valves (See FIG. 1E) and ball valves (See FIG. 1F), are more suitable for use in a production string in a well bore because the valve is fully ported. Fully ported means that the drilling or production fluid is not directed around any structures within the valve when the valve is fully open. Therefore, a need exists for a down hole valve that is fully ported when the valve is open.

The prior art has previously addressed the need to place a ball valve in the circulation path of the drilling or production fluid. For example, U.S. Pat. No. 3,589,667 (the '667 patent) entitled “Combination Well Blowout Preventer” discloses a ball valve located in the drilling or production fluid circulation path. The ball valve in the '667 patent is located in the control head assembly at the surface. U.S. Pat. No. 4,703,807 (the '807 patent) entitled “Rotatable Ball Valve Apparatus and Method” discloses a similar ball valve located in the control head assembly. While the '667 patent and the '807 patent disclose a ball valve that can be installed in the circulation path of the drilling or production fluid, the '667 patent and the '807 patent do not disclose a ball valve that can be placed down hole. Therefore, a need exists for a ball valve that can be installed down hole in the circulation path of the drilling or production fluid.

Consequently, a need exists for a down hole valve installed in the circulation path of the drilling or production fluid. The need extends a down hole valve that is able to withstand high levels of compressive and tensile stress and is operable only by compression or tension. Finally, a need exists for a down hole valve that is fully ported when the valve is open.

SUMMARY OF THE INVENTION

The present invention, which meets the needs identified above, is a split ball valve positioned down hole (i.e. in a production string in a well bore). The split ball valve comprises an upper valve assembly and a lower valve assembly. The upper valve assembly comprises an upper housing, an upper collar, a plurality of longitudinal supports, and a lower collar. The lower valve assembly comprises a lower housing, a valve body comprising a valve lower body and a valve upper body, two pinion gears, and two valve doors. The two valve doors are located within the valve body. Each of the valve doors are connected to a pinion gear that extends out of the valve body. The pinion gears intermesh with racks on the plurality of longitudinal supports. The longitudinal supports are affixed to a lower collar, an upper collar, and an upper housing. The upper valve assembly can be vertically displaced relative to the lower valve assembly. A spring is positioned between the lower collar and a lower housing collar. The spring keeps the upper valve assembly extended away from the lower valve assembly and thus keeps the valve doors closed.

When a downward force is applied to the upper valve assembly, the upper housing, upper collar, longitudinal supports, and lower collar are displaced downward relative to the lower valve assembly. The downward displacement compresses the spring. The downward displacement also causes the pinion gears to intermesh with the racks on the longitudinal supports. The intermeshing of the pinion gears and racks causes the pinion gears to rotate, which opens the valve doors. The valve doors recede into cavities in the valve body. When the valve doors are open, the split ball valve is fully ported and does not redirect the flow of drilling or production fluid around structures within the valve assembly. Releasing the downward pressure on the upper valve assembly causes the valve doors to close.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:

FIGS. 1A, 1B, 1C, 1D, 1E, and 1F are illustrations of cross-sectional views of prior art valves;

FIG. 2 is an illustration of an elevation view of the split ball valve of the present invention;

FIG. 3 is an illustration of a cross-sectional view of the split ball valve of the present invention taken along line 3-3 in FIG. 2;

FIG. 4 is an illustration of a cross-sectional view of the split ball valve of the present invention taken along line 4-4 in FIG. 3;

FIG. 5 is an illustration of a cross-sectional view of the split ball valve of the present invention taken along line 5-5 in FIG. 4;

FIG. 6 is an illustration of a perspective view of the valve body of the present invention;

FIG. 7 is an illustration of an elevation view of the actuation of the split ball valve of the present invention;

FIG. 8 is an illustration of a cross-sectional view of the actuation of the split ball valve of the present invention taken along line 8-8 in FIG. 7;

FIG. 9 is an illustration of a cross-sectional view of the actuation of the split ball valve of the present invention taken along line 9-9 in FIG. 8;

FIG. 10 is an illustration of a cross-section view of the actuation of the split ball valve of the present invention taken along line 10-10 in FIG. 9;

FIG. 11 is an illustration of an alternative embodiment of the valve body of the present invention; and

FIGS. 12A and 12B are exploded perspective views of the split ball valve of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As used herein, the term “casing” shall mean a plurality of connected cylindrical members that are permanently affixed in the well bore and are used in drilling and production operations.

As used herein, the term “drill pipe” shall mean a plurality of connected cylindrical members that are connected to a drill bit and are rotated to drill the well bore.

As used herein, the term “line pipe” shall mean a plurality of connected cylindrical members that are positioned on the surface and are used to transport drilling and production fluid to/from the well bore.

As used herein, the term “tubing” shall mean a plurality of connected cylindrical members that are removably positioned within the well bore and are used in production operations.

FIG. 2 is an illustration of an elevation view of split ball valve 100. Split ball valve 100 is shown inside a concentric string of casing 124, which is cutaway in FIG. 2 to show the exterior of split ball valve 100. For the purposes of the present invention, casing 124 may be line pipe, casing, or tubing or may be the side of the well bore. The production string or line pipe attaches to split ball valve 100 by threaded connection to the upper end of upper housing 102 and the lower end of lower housing 104. Persons of ordinary skill in the art are aware of other methods for attaching split ball valve 100 to a production string or line pipe.

One of the components of split ball valve 100 is the lower valve assembly. The lower valve assembly is cylindrical in shape and comprises lower housing 104, the valve body, pinion gears 116, and valve doors (not shown in FIG. 2). The valve body comprises valve lower body 110 and valve upper body 112. The lower portion of lower housing 104 screws onto the production string or line pipe (not shown). The upper portion of lower housing 104 screws onto valve lower body 110. The exterior of the upper portion of lower housing 104 is sized for sliding engagement with lower collar 108. Spring 106 is located around the exterior of lower housing 104 and is seated against lower collar 108. Lower housing 104 also contains a lower housing collar that seats spring 106.

Another component of split ball valve 100 is upper valve assembly. Upper valve assembly is cylindrical in shape and comprises upper housing 102, upper collar 120, longitudinal supports 114, and lower collar 108. The upper portion of upper housing 102 screws onto the production string or line pipe (not shown). The lower portion of upper housing 102 screws onto upper collar 120. The interior of the upper valve assembly is sized for sliding engagement with the exterior of the lower valve assembly.

Upper housing 102 and lower housing 104 connect together via upper collar 120, longitudinal supports 114, and lower collar 108. Upper collar 120 is affixed to upper housing 102. Extending downwardly from upper collar 120 are a plurality of longitudinal supports 114. Two of longitudinal supports 114 on opposite sides of split ball valve 100 contain a rack that intermeshes with pinion gear 116. Longitudinal supports 114 are affixed to lower collar 108, which is free to slide along the upper portion of lower housing 104. Spring 106 keeps lower collar 108, and thus longitudinal supports 114, upper collar 120, and upper housing 102 extended away from lower housing 104 in the absence of downward force from the surface exceeding the spring constant of spring 106. Persons of ordinary skill in the art are aware of how to choose an appropriate spring for a particular purpose based on the spring constant of the spring.

FIG. 3 is an illustration of a cross-sectional view of the split ball valve 100 taken along line 3-3 in FIG. 2. As seen in FIG. 3, two pinion gears 116 extend outwardly from valve lower body 110 and valve upper body 112. Pinion gears 116 rotate freely between valve lower body 110 and valve upper body 112. Pinion gears 116 connect to valve doors 118 on the inside of split ball valve 100. Key 126 prevents slipping between pinion gears 116 and valve doors 118. Pinion gears 116 are located on opposite sides of valve lower body 110. Two of longitudinal supports 114 that are on opposite sides of split ball valve 100 contain a rack. Each pinion gear 116 meshes with one of the racks located on longitudinal supports 114. Pinion gears 116 and the racks on longitudinal supports 114 are arranged such that pinion gears 116 rotate in opposite directions when split ball valve 100 is operated. FIG. 3 also details the connection between upper housing 102 and valve upper body 112 and the connection between upper collar 120, longitudinal supports 114, lower collar 108, spring 106, and lower housing 104.

FIG. 4 is an illustration of a cross-sectional view of the split ball valve 100 taken along line 4-4 in FIG. 3. The connection between pinion gear 116 and valve doors 118 is illustrated in FIG. 4. Pinion gear 116 in FIG. 4 is connected to only one of valve doors 118; pinion gear 116 (not shown) on the opposite side of split ball valve 100 is connected to the other valve door 118. As can be seen in FIG. 4, the shape of valve upper body 112 and valve lower body 110 are configured such that valve doors 118 can rotate with pinion gear 116 into recessed cavities within valve upper body 112 and valve lower body 110.

FIG. 5 is an illustration of a cross-sectional view of the split ball valve 100 taken along line 5-5 in FIG. 4. FIG. 5 depicts the two valve doors 118 in the closed position. When valve doors 118 are in the closed position, valve doors 118 and valve upper body 112 completely stop the passage of drilling or production fluid through split ball valve 100. FIG. 5 also illustrates the orientation of pinion gear 116 and longitudinal supports 114. The uppermost pinion gear 116 shown in FIG. 5 intermeshes with the rack on the upper rightmost longitudinal support 114 shown in FIG. 5. The upper leftmost longitudinal support 114 shown in FIG. 5 does not have a rack and thus does not contact uppermost pinion gear 116 shown in FIG. 5. Similarly, the lowermost pinion gear 116 shown in FIG. 5 intermeshes with the rack on the lower leftmost longitudinal support 114 shown in FIG. 5. The lower rightmost longitudinal support 114 shown in FIG. 5 does not have a rack and thus does not contact lowermost pinion gear 116 shown in FIG. 5. Valve upper body 112 and longitudinal supports 114 are configured such that the outside diameter of split ball valve 100 is sufficiently round and sized to be slightly smaller than the inside diameter of casing 124. Persons of ordinary skill in the art will appreciate that split ball valve 100 can be sized differently from the configuration depicted in FIG. 5.

FIG. 6 is an illustration of a perspective view of the valve body of the present invention. The valve body comprises valve lower body 110 and valve upper body 112. FIG. 6 depicts valve doors 118 in the closed position. One of pinion gears 116 extending outwardly from valve lower body 110 is also depicted in FIG. 6. Although not shown in FIG. 6, a similar pinion gear 116 extends out of valve lower body 110 opposite of pinion gear 116 shown in FIG. 6. Persons of ordinary skill in the art will also appreciate that the present invention can be configured with a single pinion gear 116 if valve doors 118 are configured with intermeshing gears on the side of valve doors 118 opposite of pinion gear 116. In such a case, the actuation of one valve door 118 rotates the other valve door 118.

FIG. 7 is an illustration of an elevation view of the actuation of the split ball valve 100. FIG. 7 is a view of split ball valve 100 similar to FIG. 2, but after a compressive force has been exerted on split ball valve 100. A drilling or production apparatus (not shown) exerts a compressive force from the surface via the production string or line pipe (not shown). Typically, the compressive force is exerted on the production string or line pipe using a hydraulic press or similar apparatus. Persons of ordinary skill in the art are aware of how to assert a compressive force on a down hole tool as evidenced by U.S. patent application Ser. No. 09/971,308 entitled “Concentric Casing Jack,” incorporated herein by reference. The downward force on split ball valve 100 moves upper housing 102 downward with respect to valve upper body 112. The downward force is transferred through upper housing 102, upper collar 120, and longitudinal supports 114 to lower collar 108. Lower collar 108 compresses spring 106 between lower collar 108 and the lower housing collar. When upper housing 102 is moved downward, lower housing 104 remains stationary because the production string below split ball valve 100 either contacts the bottom of the well bore or the production string is affixed to the well bore using a packer or similar device (not shown). Because lower housing 104 remains stationary, valve lower body 110, and valve upper body 112 remain stationary as well. The relative motion between longitudinal support 114 and pinion gear 116 causes pinion gear 116 to rotate against the rack of longitudinal support 114.

FIG. 8 is an illustration of a cross-sectional view of the actuation of the split ball valve 100 taken along line 8-8 in FIG. 7. FIG. 8 is a view of split ball valve 100 similar to FIG. 3, but after a compressive force has been exerted on split ball valve 100. As seen in FIG. 8, upper housing 102 has moved downward relative to valve upper body 112. The downward displacement of upper housing 102 has been transferred through upper collar 120 to longitudinal supports 114. The corresponding lack of vertical displacement by valve lower body 110, valve upper body 112, and pinion gear 116 causes pinion gear 116 to rotate and intermesh with the rack of longitudinal support 114. The rotation of pinion gear 116 causes a similar rotation of valve doors 118 into the cavities of valve upper body 112 and valve lower body 110. When upper housing 102 contacts upper body 112, the compression of split ball valve 100 is complete and valve doors 118 are fully open.

FIG. 9 is an illustration of a cross-sectional view of the actuation of the split ball valve 100 taken along line 9-9 in FIG. 8. FIG. 9 is a view of split ball valve 100 similar to FIG. 4, but after a compressive force has been exerted on split ball valve 100. FIG. 9 further details the vertical displacement of upper housing 102 relative to valve upper body 112. As stated previously in FIGS. 7 and 8, the vertical displacement of upper housing 102 causes pinion gear 116 to rotate, which rotates valve doors 118 into the open position. In FIG. 9, valve doors 118 are shown in the open position and are recessed into the cavities of valve lower body 110 and valve upper body 112. In the open position, valve doors 118 do not redirect the flow of drilling or production fluid around structures within split ball vale 100. In other words, split ball valve 100 is fully ported.

FIG. 10 is an illustration of a cross-sectional view of the actuation of the split ball valve 100 taken along line 10-10 in FIG. 9. FIG. 10 is a view of split ball valve 100 similar to FIG. 5, but after a compressive force has been exerted on split ball valve 100. FIG. 10 depicts the two valve doors 118 in the open position. When valve doors 118 are in the open position, valve doors 118 recess into the cavities of valve lower body 110 and valve upper body 112 (not shown). Thus, valve doors 118 do not redirect the flow of drilling or production fluid around structures within split ball valve 100. FIG. 10 also illustrates the orientation of pinion gear 116 and longitudinal supports 114. The uppermost pinion gear 116 shown in FIG. 10 intermeshes with the rack on the upper rightmost longitudinal support 114 shown in FIG. 10. The upper leftmost longitudinal support 114 shown in FIG. 10 does not have a rack and thus does not contact uppermost pinion gear 116 shown in FIG. 10. Similarly, the lowermost pinion gear 116 shown in FIG. 10 intermeshes with the rack on the lower leftmost longitudinal support 114 shown in FIG. 10. The lower rightmost longitudinal support 114 shown in FIG. 10 does not have a rack and thus does not contact lowermost pinion gear 116 shown in FIG. 10.

Persons of ordinary skill in the art will appreciate that the present invention can be configured to be operated by either compressive or tensile force. Similarly, persons of ordinary skill in the art will appreciate that the present invention may be configured to be initially open or closed. Persons of ordinary skill in the art will also appreciate that a plurality of the present inventions may be employed in a single production string. When a plurality of the present inventions are located in a single production string, one method for making a plurality of the present inventions independently operable is to change the spring constant of spring 106 in each of the present inventions. If the spring constants are different in a plurality of split ball valves 100 in a single production string, different amounts of compressive or tensile force will operate specific split ball valves 100 within the production string. Thus, by changing the spring constant a person of ordinary skill in the art can operate each of the present inventions independently.

Persons of ordinary skill in the art will also appreciate that one or more of split ball valves 100 can be configured with a catch mechanism to keep the split ball valve open or closed in the absence of an actuating force. Generally, such catch mechanisms require an initial actuating force to open split ball valve 100. When sufficient force is applied to split ball valve 100, the catch engages and split ball vale 100 will remain open when the force on split ball valve 100 is released. A subsequent force, slightly larger than the actuating force required to set the catch, is required to release the catch and return valve doors 118 to the original closed position.

In some situations, a drilling engineer will find it necessary to run a second, concentric production string or a drill string inside of the existing production string. This procedure is well known in the art. A drilling engineer may also need to run a sucker rod down the center of the production string. In either case, a cylindrical string of drill pipe, casing, tubing, or rods is positioned in the center of the existing production string. The positioning of the second string of drill pipe, casing, tubing, or rods renders prior art valves, particularly prior art ball valves, inoperable. A second string of drill pipe, casing, tubing, or rods renders prior art ball valves inoperable because the second string of drill pipe, casing, tubing, or rods does not allow the ball to rotate from the open position into the closed position.

FIG. 11 is an illustration of another alternative embodiment of the valve body of the present invention. The alternative embodiment of the present invention creates circular aperture 122 centered in the valve doors 118. FIG. 11 illustrates aperture 122 in the valve doors 118. FIG. 11 is similar to FIG. 6 with the exception of aperture 122. Aperture 122 is sized according to the second string of drill pipe, casing, tubing, or rods. When split ball valve 100 is configured with the valve body illustrated in FIG. 6, the positioning of a second string of drill pipe, casing, tubing, or rods within the original production string does not stop the rotation of valve doors 118. In other words, even with a second string of drill pipe, casing, tubing, or rods in the center of the production string, valve doors 118 can rotate to the open and closed positions. Persons of ordinary skill in the art will appreciate that the alternate embodiment illustrated in FIG. 11 can be combined in a single production string with the embodiment illustrated in FIGS. 2 through 10 to create a production string with split ball valves 100 that are operable with or without an inner string of drill pipe, casing, tubing, or rods.

FIGS. 12A and 12B are exploded perspective views of the split ball valve of the present invention. FIG. 12A depicts most of the parts of the upper valve assembly: upper housing 102, upper collar 120, and longitudinal supports 114. FIG. 12A also depicts some parts of the lower valve assembly: valve upper body 112 and valve doors 118. FIG. 12B depicts the remaining part of upper valve assembly: lower collar 108. FIG. 12B also depicts the remaining parts of the lower valve assembly: lower housing 104, valve lower body 110, and pinion gears 116. A person of ordinary skill in the art would be able to manufacture, assemble, and utilize the present invention from FIGS. 12A and 12B.

With respect to the above description, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function, manner of operation, assembly, and use are deemed readily apparent and obvious to one of ordinary skill in the art. The present invention encompasses all equivalent relationships to those illustrated in the drawings and described in the specification. The novel spirit of the present invention is still embodied by reordering or deleting some of the steps contained in this disclosure. The spirit of the invention is not meant to be limited in any way except by proper construction of the following claims.