BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates in general to drop balls, plugs, or darts used to operate well tool functions and, in particular, to a drop ball, plug, or dart launcher with a status indicator.
2. Brief Description of Related Art
Standard dart or ball launchers have a member that defines a central bore that may be coupled inline with a drill or tubing string. The launchers also include an angular bore that intersects the central bore at a shallow angle between the angular bore and the central bore. A dart or ball is dropped into the angular bore, and after opening a series of valves, the ball or dart is introduced into the central bore for further movement of the dart or ball down the borehole. There, the dart or ball will land at a predetermined location to block the borehole and allow hydraulic tool operations. In order to minimize the potential that the ball will snag or hang up as it moves from the angular bore to the central bore, the angle of the intersection between the two axes is as close to zero degrees as possible. This necessitates that the launcher must be very tall to smooth out the transition between the angular bore and the central bore. The height can make the launcher very difficult to access and operate.
Other devices couple inline with the drill or tubing string and use a series of valves to launch the ball or dart. The dart or ball may become stuck or snagged at the valve openings, preventing successful release of the dart or drop ball. In addition, these types of devices require bypass passages within the valves so that fluids may flow around the darts and valves prior to launching the dart or ball. These passages restrict fluid flow through the running string and may become clogged. Clogging of these passages will, in turn, require stoppage of drilling operations in order to remove and reset the launcher for operation. Even when not blocked, these passages may restrict the flow of fluid downhole, causing further complications in drilling operations.
Still other devices may couple inline with the drill or tubing string and use a series of balls to launch darts or plugs contained within the device. These devices rely on complex landing and sliding sleeve devices, to bypass the fluids around the landed balls and darts, again restricting fluid flow through the string. These devices also do not provide an indication that the proper dart or plug has been launched following landing of the ball.
Generally, following launch of a ball, dart, or plug, operators wait for an increase in pressure within the tubing string to indicate that the ball, dart, or plug has properly released into the drill string and landed at the ball, dart, or plug seat. Operators may then proceed with operations such as cementing or running tool actuation. However, in some wells, particularly in deep subsea wells, the distances between the operating platform and the landing location are large enough that it may take over an hour for the dart to land at the seat. As a result, operators may proceed with operations following release of the ball, dart, or plug but before they have received any indication that the ball, dart, or plug has landed. In the event that the ball, dart, or plug becomes hung up or snagged in the launcher and does not release into the tubing string, the well may be significantly damaged, necessitating expensive and time consuming repair operations. Some launchers include an electrical system for indicating that the dart, ball, or plug has released, however these systems require complex components that are prone to failure and difficult to adapt to changing types and sizes of balls, darts, and plugs. Thus, there is a need for a launcher that launches the dart or ball from an inline coupling without restricting fluid flow through the central bore of the tubing and that may provide an indication of a successful launch of the ball, dart, or plug.
SUMMARY OF THE INVENTION
These and other problems are generally solved or circumvented, and technical advantages are generally achieved, by preferred embodiments of the present invention that provide a modular dart launcher with a status indicator and a method for using the same.
In accordance with an embodiment of the present invention, a wellbore drop member launcher is disclosed. The launcher includes a launcher body defining a central bore having a central bore axis, the launcher body having a lower end configured to attach to a string of pipe extending into a wellbore. The launcher body also defines a launcher bore having a launcher bore axis at an angle to the central bore axis, the launcher bore in fluid communication with the central bore. A release assembly is coupled to the launcher body and has a release rod protruding into the launcher bore to prevent movement of a drop member positioned within the launcher bore in a drop member hold position. The release assembly is configured to move the release rod to a drop member release position to selectively release the drop member positioned within the launcher bore. A visual indicator assembly is, coupled to the launcher body and is configured to provide a mechanically produced visual indication that the drop member has moved from the launcher bore to the central bore.
In accordance with another embodiment of the present invention, a wellbore drop member launcher is disclosed. The launcher includes a launcher body defining a central bore having a central bore axis, the launcher body having a lower end configured to attach to a tubing string extending into a wellbore. The launcher body also defines a launcher bore having a launcher bore axis at an angle to the central bore axis. The launcher bore is in fluid communication with the central bore. A release assembly is coupled to the launcher body and has a release rod protruding into the launcher bore to prevent movement of a drop member positioned within the launcher bore into the tubing string. The release assembly is configured to move the release rod with a piston assembly from a drop member hold position to a drop member release position to selectively release the drop member. The piston assembly also biases the release rod to the drop member hold position. A pressure passage is defined by the release rod and is configured to equalize pressure between a compressible portion of the piston assembly and the launcher body, preventing premature drop member release. The pressure passage extends from an end of the release rod disposed within the launcher bore through a center of the release rod to an annular chamber within the piston assembly. An indicator housing is coupled to the launcher body proximate to an indicator bore that is defined by the launcher body and extends from an exterior of the launcher body to the launcher bore. An indicator rod extends through the indicator housing into the indicator bore. The indicator rod has a flapper formed near an end of the indicator rod and an arm secured to an opposite end of the indicator rod. The flapper and the arm are perpendicular to the indicator rod and parallel to each other. The flapper extends from the indicator bore into the launcher bore and the arm is visible to an operator. As the drop member passes the flapper it will rotate the flapper, indicator rod, and arm to indicate release of the drop member.
In accordance with yet another embodiment of the present invention, a method for launching a drop member into a wellbore tubing string is disclosed. The method provides a launcher body having a central bore with a central bore axis and a launcher bore with a launcher bore axis at an angle to the central bore axis and in fluid communication with the central bore. The method places a drop member in the launcher bore and resting the drop member on a release rod of a release assembly coupled to the launcher body. The method couples a visual indicator assembly to the launcher body so that the visual indicator assembly is in communication with the launcher bore at a location downstream from the release assembly. The method couples the launcher body in line with the tubing string so that the central bore of the launcher body aligns with a body passage through the tubing string. The method then actuates the release assembly to allow the drop member to flow from the launcher body into the central bore where the drop member may move down the tubing string. The method actuates the visual indicator assembly with the drop member as the drop member moves from the launcher bore into the central bore.
An advantage of a preferred embodiment is that it provides a dart launcher that may be used in high fluid pressures situations. In addition, the disclosed embodiments provide an apparatus and method to easily launch a ball, dart, or plug with minimal human intervention. Still further, the disclosed embodiments provide a modular apparatus that allows for variation in the size of the ball, dart, or plug launched. Sill further, the disclosed embodiment provides a visual indicator for an operator to confirm the successful launch of the ball, dart, or plug that does not rely on complicated electronics systems that may be prone to failure in harsh operating environments.
BRIEF DESCRIPTION OF THE DRAWINGS
So that the manner in which the features, advantages and objects of the invention, as well as others which will become apparent, are attained, and can be understood in more detail, more particular description of the invention briefly summarized above may be had by reference to the embodiments thereof which are illustrated in the appended drawings that form a part of this specification. It is to be noted, however, that the drawings illustrate only a preferred embodiment of the invention and are therefore not to be considered limiting of its scope as the invention may admit to other equally effective embodiments.
FIG. 1 is a perspective view of a dart launcher in accordance with an embodiment of the present invention.
FIG. 2 is a sectional view of the dart launcher taken along ling 2-2 of FIG. 1.
FIG. 3 is a sectional view of a release assembly of the dart launcher taken along line 3-3 of FIG. 1.
FIG. 4 is an enlarged view of a portion of the dart launcher indicated at FIG. 2.
FIG. 4A is an enlarged view of a surface of the release assembly taken along line 4A of FIG. 3.
FIG. 5 is an enlarged view of the portion of the dart launcher indicated at FIG. 2 following release of a dart.
FIG. 5A is an enlarged view of the surface of the release assembly taken along line 5A of FIG. 5.
FIG. 6 is a perspective view of a visual indicator assembly of the dart launcher.
FIG. 6A is a front view of the visual indicator assembly of FIG. 6.
FIG. 7 is a sectional view of the visual indicator assembly taken along line 7-7 of FIG. 2.
FIG. 8 is a sectional view of a portion of a spring plunger of the visual indicator assembly in pre-release position taken along line 8-8 of FIG. 6.
FIG. 9 is a perspective view of the visual indicator assembly following release of the dart.
FIG. 9A is a front view of the visual indicator assembly of FIG. 9.
FIG. 9B is a sectional view of a portion of a spring plunger of the visual indicator assembly in a post-release position taken along line 9B-9B of FIG. 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The present invention will now be described more fully hereinafter with reference to the accompanying drawings which illustrate embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and the prime notation, if used, indicates similar elements in alternative embodiments or positions.
In the following discussion, numerous specific details are set forth to provide a thorough understanding of the present invention. However, it will be obvious to those skilled in the art that the present invention may be practiced without such specific details. Additionally, for the most part, details concerning drilling rig operation, well tool manufacture, well tool operation, well tool uses, and the like have been omitted inasmuch as such details are not considered necessary to obtain a complete understanding of the present invention, and are considered to be within the skills of persons skilled in the relevant art.
Referring to FIG. 1, a dart launcher 11 is shown. Dart launcher 11 includes an upper tubular member or top pup 13 adapted to connect to a tubular member of a tubing or drill string. Fluid, such as drilling fluid, may circulate through dart launcher 11 from an external source coupled to top pup 13. Dart launcher 11 also includes a lower tubular member or bottom pup 15 adapted to connect to a tubular member of a tubing or drill string. The tubing string may continue into a well to transport the fluid to a. subsurface location. A person skilled in the art will recognize that top pup 13 and bottom pup 15 have ends adapted to connect dart launcher 11 in line in a tubing string. In the illustrated embodiment, the ends of top pup 13 and bottom pup 15 comprise threaded connectors. In other exemplary embodiments, the ends of top pup 13 and bottom pup 15 may be any suitable connector type such that dart launcher 11 may couple inline to a tubing string.
Dart launcher 11 also includes a launcher body 17, a dart release assembly 19, and a visual indicator assembly 21. Top pup 13 and bottom pup 15 may secure to or couple to launcher body 17 on opposite ends of launcher body 17 so that top pup 13 and bottom pup 15 are coaxial with an axis 23 of a central bore 25 of launcher body 17 (FIG. 2). In an exemplary embodiment, top pup 13 and bottom pup 15 secure to launcher body 17 through threaded connections. A person skilled in the art will understand that other connection types may be used.
Referring to FIG. 2, a sectional view of launcher body 17 is shown. Launcher body 17 defines central bore 25 and a launcher bore 27 that intersects central bore 25, allowing for fluid communication between central bore 25 and launcher bore 27. Launcher bore 27 intersects central bore 25 at opening 35. Opening 35 will be of a size and shape to allow a ball, plug, or dart 33 to pass from launcher bore 27 into central bore 25. Launcher bore 27 has an axis 29. Axis 29 my intersect axis 23 at an angle 31. Angle 31 may comprise any suitable angle such that a drop member or dart 33 may pass from launcher bore 27 into central bore 25 for travel through a coupled tubing string. In the illustrated embodiment, central bore 25 and launcher bore 27 are formed from a single launcher body 17. In other exemplary embodiments, central bore 25 and launcher bore 27 may be defined by separate bodies coupled or secured together. Dart release assembly 19 couples to launcher body 17 proximate to launcher bore 27 such that dart release assembly 19 may selectively allow passage of dart 33 from launcher bore 27 into central bore 25 through opening 35. Visual indicator assembly 21 will couple or secure to launcher body 17 proximate to opening 35 such that as dart 33 passes from launcher bore 27 into central bore 25, described in more detail below, visual indicator assembly 21 will indicate such passage. For illustrative purposes, visual indicator assembly 21 has been shown in the sectional view of FIG. 2 to aid in the illustration of the relationship between visual indicator assembly 21 and dart release assembly 19.
Referring to FIG. 3, a side sectional view of dart release assembly 19 is shown. Dart release assembly 19 includes a release housing 37 and a pressure chamber 39. Pressure chamber 39 may be a hydraulic pressure chamber, pneumatic pressure chamber, or the like. Pressure chamber 39 is coupled to an end of release housing 37 by any suitable means. In an exemplary embodiment, pressure chamber 39 is bolted to release housing 37. Pressure chamber 39 includes a piston 41 extending from an interior of pressure chamber 39 into an actuator bore 43 of release housing 37. Piston 41 has a piston head 45 that seals to the interior surfaces of pressure chamber 39 to divide pressure chamber 39 into two sections. Each section of pressure chamber 39 is in communication with a pressure source through ports 47, 49. The pressure source may be a hydraulic pressure source that supplies hydraulic pressure through ports 47, 49. In other embodiments, the pressure source may be a pneumatic pressure source that supplies pneumatic pressure through ports 47, 49. In the exemplary embodiment, port 47 comprises a dart release port, and port 49 comprises a vent. Pressure may be supplied to port 47 to assert a force on piston head 45 to move piston 41 from a dart hold position, where dart 33 (FIG. 2) is prevented from moving into central bore 25, to a dart release position, where dart 33 (FIG. 5) is allowed to move into central bore 25. Pressure within pressure chamber 39 will vent through port 49 when pressure is supplied through port 47 to move piston 41 from the dart hold to the dart release position. In other embodiments, pressure may be supplied to port 49 to assert a force on piston head 45 to move piston 41 from the dart release position to the dart hold position, shown in FIG. 3.
A shaft of piston 41 passes through a spring 51 disposed within actuator bore 43. An end of the shaft of piston 41 will couple to a spring perch 53 disposed within actuator bore 43 opposite pressure chamber 39 in the dart hold position. Spring perch 53 may move through actuator bore 43 with piston 41 in response to application of pressure to pressure chamber 39. Spring 51 will be positioned to bias spring perch 51 to the dart hold position of FIG. 3. Actuator bore 43 will include an indicator window 55 extending a portion of a length of actuator bore 43. An indicator screw 57 will pass through indicator window 55 and couple to spring perch 53 such that a head of indicator screw 57 will remain disposed within indicator window 55. As spring perch 53 moves through actuator bore 43 indicator screw 57 will move from an end of window 55 to an opposite end of window 55. In an exemplary embodiment, indicator screw moves from an area spaced from pressure chamber 39 to an area proximate to pressure chamber 39.
Release housing 37 defines actuator bore 43 and a rod bore 59. Rod bore 59 and actuator bore 43 are separated by a chamber wall 61 having a port for communication between actuator bore 43 and rod bore 59. Spring perch 53 may include a protrusion extending into the port of chamber wall 61 such that a release rod 63 may couple to spring perch 53. As shown in FIG. 4, a seal 60 may be positioned within chamber wall 61 to seal to release rod 63. Referring to FIG. 3, a surface of spring perch 53 may contact chamber wall 61 in the dart hold position, limiting movement of spring perch 53 away from pressure chamber 39. Release rod 63 extends from rod bore 59 to an exterior of release housing 37. Release rod 63 couples to spring perch 53 such that as spring perch 53 moves with piston 61, release rod 63 will move in response. Release rod 63 includes a flange portion 65 that seals with a seal 66 (FIG. 4) to rod bore 59. Flange portion 65 may be spaced from an end of release rod 63 coupled to spring perch 53 to define an annular passage 69 between flange portion 65 and chamber wall 61 in the dart hold position of FIGS. 3 and 4. Release rod 63 will include a pressure passage 67 extending through a length of release rod 63 and in fluid communication with annular passage 69. Launcher bore 27 will be in fluid communication with annular passage 69 through pressure passage 67 such that a hydraulic pressure of launcher bore 27 will be substantially equivalent to the hydraulic pressure within annular passage 69. Release housing 37 further includes a flange 71 formed on an end of release housing 37 opposite pressure chamber 39. Flange 71 provides a mating contact to couple dart release assembly 19 to launcher body 17. In the illustrated embodiment, flange 71 is bolted to launcher body 17.
Referring to FIG. 4, dart release assembly 19 is shown coupled to launcher body 17 and in the dart hold position of FIG. 3. As shown, an end of release rod 63 will extend from an end of releasing housing 37 and pass through a release rod bore 73 formed in a wall of launcher body 17. Release rod 63 will seal to release rod bore 73 with a seal 74 positioned within release rod bore 73. Release rod 63 will extend a sufficient distance into launcher bore 27 to prevent passage of dart 33 from launcher bore 27 into central bore 25. A person skilled in the art will recognize that release rod 63 extends into launcher bore 27 a sufficient length to allow for variation in the size of dart 33. Thus, dart launcher 11 may be used in various types of operations to release or launch multiple types of darts 33.
As shown in FIG. 4A, indicator screw 57 will be positioned in an end of window 55 proximate to launcher body 17. Referring to FIG. 5, pressure has been supplied to port 47, causing piston 41 to move to the dart release position. In response, spring perch 53 has moved toward pressure chamber 39, compressing spring 51. Release rod 63 will be pulled into rod bore 59 until flange portion 65 contacts chamber wall 61 opposite actuator bore 43. This will pull release rod 63 completely from launcher bore 27, allowing dart 33 to move freely from launcher bore 27 into central bore 25 for further movement through a tubing string coupled to bottom pup 15 (FIG. 1). As shown in FIG. 5A, when spring perch 53 moves from the dart hold position to the dart release position, indicator screw 57 will move through indicator window 55 from a position proximate to launcher body 17 (FIG. 4A) to a position proximate to pressure chamber 39 (FIG. 5A).
Referring to FIG. 6, visual indicator assembly 21 is shown. Visual indicator assembly 21 includes an indicator housing 75, and an indicator rod 77. Indicator rod 77 has an interior end 76 and an exterior end 78. Indicator rod 77 will pass through an indicator housing bore 79 (FIG. 7) extending through indicator housing 75. Indicator housing 75 will define a flange 81 adapted to secure visual indicator assembly 21 to launcher body 17. In the illustrated embodiment, flange 81 defines a plurality of bores through which a plurality of bolts are passed to thread into corresponding threaded bores of launcher body 17. A flapper 83 is formed near interior end 76 of indicator rod 77. Flapper 83 will be orthogonal to indicator rod 77. Indicator rod 77 will have a length greater than a length of indicator housing 75 such that, when indicator rod 77 is passed through indicator housing 75, interior end 76 having flapper 83 will protrude from indicator housing 75 into launcher body 17 as shown in FIG. 7. Exterior end 78 of indicator rod 77 will protrude from an opposite side of indicator housing 75. An arm 85 will be secured to indicator rod 77 on exterior end 78. In the illustrated embodiment, arm 85 is orthogonal to indicator rod 77 and extends from indicator rod 77 parallel to flapper 83.
Referring to FIG. 7, indicator rod 77 also includes an indicator flange 87 formed between interior end 76 and exterior end 78. Indicator flange 87 will define an outward facing shoulder 89 adapted to contact an inwardly facing shoulder 91 formed on an interior end of indicator housing 75. Contact between outward facing shoulder 89 and inwardly facing shoulder 91 will limit movement of indicator rod 77 in an outward direction. A seal 90 will be positioned in indicator housing bore 79 to seal indicator rod 77 to indicator housing bore 79 between outward facing shoulder 89 of indicator flange 87 and exterior end 78 of indicator rod 77.
Indicator housing 75 will secure to launcher body 17 so that indicator rod 77 will extend into an indicator bore 93. A seal 94 will be positioned within indicator housing 75 to seal an outer diameter of indicator housing 75 to indicator bore 93. Indicator bore 93 extends from an exterior surface of launcher body 17 to launcher bore 27. A keyhole 95 may be formed in an interior end of indicator bore 93. Interior end 76 of indicator rod 77 inserts into keyhole 95 so that indicator rod 77 may rotate on an axis 97. Flapper 83 will be spaced along axis 97 from interior end 76 so that interior end 76 may fully seat within keyhole 95. When indicator rod 77 is positioned within indicator bore 93 and seated within keyhole 95, flapper 83 will extend into launcher bore 27. In the illustrated embodiment, flapper 83 will extend from indicator rod 77 such that axis 29 of launcher bore 27 may pass through an outer end of flapper 83. In other embodiments, the outer end of flapper 83 may be proximate to axis 29 of launcher bore 27, but axis 29 may not pass through the outer end of flapper 83.
As shown in FIG. 6, visual indicator assembly 21 also includes a spring plunger 99 positioned within a spring plunger bore 101 formed in indicator housing 75. Referring to FIG. 8, spring plunger bore 101 extends from an exterior of indicator housing 75 to indicator housing bore 79. Spring plunger 99 will be disposed within spring plunger bore 101. Spring plunger 99 includes a plunger housing 103, a plunger 105, and a spring member 107. Plunger housing 103 secures within spring plunger bore 101 against a downward facing shoulder 109. Plunger housing 103 has an open end proximate to indicator housing bore 79 into which plunger 105 inserts. Spring member 107 will be disposed between an internal shoulder 111 of indicator housing 103 and an end 113 of plunger 105 proximate to an exterior of indicator housing 75. Plunger 105 includes an end 115 opposite end 113 and proximate to indicator housing bore 79. Plunger 105 includes a flange 117 between end 113 and exterior end 115. Flange 117 defines a shoulder 119 facing indicator housing bore 79. Exterior end 115 protrudes from flange 117 toward indicator housing bore 79. During operation of visual indicator assembly 21, spring member 107 will bias plunger 105 to the position illustrated in FIG. 8, where shoulder 119 will contact an oppositely facing shoulder 121 to limit movement of plunger 105. As shown, exterior end 115 may seat within a pre-launch detent 123 formed on an exterior surface of indicator rod 77. When exterior end 115 seats within pre-launch detent 123 rotation of indicator rod 77 will be stopped. When not in the position shown in FIG. 8, exterior end 115 may be in contact with an exterior surface of indicator rod 77, but shoulder 119 will be spaced from oppositely facing shoulder 121, allowing for exterior end 115 to move into pre-launch detent 123 when indicator rod 77 is rotated.
As shown in FIG. 9B, indicator rod 77 includes a post-launch detent 123′. Pre-launch detent 123 will be circumferentially spaced from post-launch detent 123′. When flapper 83 extends into launcher bore 27 as shown in FIGS. 2, 6, and 7, exterior end 115 of plunger 105 will extend into pre-launch detent 123 as shown in FIG. 8. In this manner, spring plunger 99 will prevent rotation of indicator rod 77 prior to launch of dart 33 so that visual indicator assembly 21 will not incorrectly indicate a launch of dart 33. When dart 33 is launched, dart 33 will overcome the spring force of spring member 107, allowing for rotation of indicator rod 77 and moving flapper 83 to the position of FIG. 9. Exterior end 115 of plunger 105 will then extend into post-launch detent 123′ (FIG. 9B), which is circumferentially spaced from pre-launch detent 123, to prevent additional rotation of indicator rod 77.
During operation of dart launcher 11, dart release assembly 19 will be in the position shown in FIGS. 2, 3, 4, and 4A; visual indicator assembly 21 will be in the position illustrated in FIGS. 2, 6, 6A, and 7. Referring to FIG. 2, dart 33 will be placed into launcher bore 27 and an end of dart 33 will rest on release rod 63 (FIG. 4). As shown in FIG. 2, a plug 125 will be placed within launcher bore 27 behind dart 33 to limit entry of undesired objects into launcher bore 27 and prevent release of fluid from launcher bore 27. As shown in FIGS. 2, 6, 6A, and 7, flapper 83 will extend into launcher bore 27 perpendicular to axis 29 of launcher bore 27 so that a flat portion of flapper 83 may contact an object moving through launcher bore 27. Similarly, arm 85 will be perpendicular to launcher bore 27. Pressure passage 67 will equalize pressure between annular passage 69 and launcher bore 27 to prevent hydraulic pressure in launcher bore 27 from acting on release rod 63 to cause premature release. Plunger 115 of FIG. 8 will be positioned within pre-launch detent 123.
When release of dart 33 is desired, pressure will be supplied to port 47 to act on piston head 45. This will result in movement of piston 41 from the position shown in FIG. 3 to a position where piston head 45 is proximate to port 49. As shown in FIG. 5, this will result in movement of release rod 63 from launcher bore 27 to allow dart 33 to move from launcher bore 27 into central bore 25. Indicator screw 57 will move from the position proximate to launcher body 17 as shown in FIG. 4A to the position spaced further from launcher body 17 as shown in FIG. 5A.
As dart 33 moves through launcher bore 27, it will contact flapper 83 as shown in FIG. 7. Flapper 83 will minimally resist movement of dart 33; thus, dart 33 will cause flapper 83, and consequently indicator rod 77 to rotate as dart 33 moves past visual indicator assembly 21. As indicator rod 77 rotates, plunger 105 will release from pre-launch detent 123 and bring post-launch detent 123′ proximate to plunger 105, allowing exterior end 115 of plunger 105 to move into post-launch detent 123′ as shown in FIG. 9B. This will arrest rotation of indicator rod 77 in the position shown in FIGS. 9 and 9A. As shown, arm 85 will undergo a ninety degree rotation so that arm 83 will be generally parallel to launcher bore 27 as shown in FIG. 5. This ninety degree rotation will indicate to an operator that dart 33 has successfully moved from launcher bore 27 into central bore 25 for further movement down a coupled drill string.
Accordingly, the disclosed embodiments provide numerous advantages. For example, the disclosed embodiments provide a dart launcher capable of launching darts, balls, or plugs of different sizes. In addition, the disclosed embodiments provide a pressure balancing system to prevent premature release of the dart that may be caused by hydraulic pressure within the launcher bore. The disclosed embodiments also allow for maintenance of circulation pressure within the coupled tubing string while dropping the dart. Still further, the disclosed embodiments provide a visual indicator of a successful dart launch, that requires no external energy source, can be seen from a distance, and is easy to assemble.
It is understood that the present invention may take many forms and embodiments. Accordingly, several variations may be made in the foregoing without departing from the spirit or scope of the invention. Having thus described the present invention by reference to certain of its preferred embodiments, it is noted that the embodiments disclosed are illustrative rather than limiting in nature and that a wide range of variations, modifications, changes, and substitutions are contemplated in the foregoing disclosure and, in some instances, some features of the present invention may be employed without a corresponding use of the other features. Many such variations and modifications may be considered obvious and desirable by those skilled in the art based upon a review of the foregoing description of preferred embodiments. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.
Patent Application
20130161005
