Modular dart launcher with status indicator

Abstract

A dart launcher launches a dart by placing the dart within a launcher bore formed within a launcher body. The launcher body also defines a central bore coupled inline with a tubing string and in fluid communication with the launcher bore. The launcher bore is formed at an angle to the central bore. A release assembly is coupled to the launcher body and includes a release rod protruding into the launcher bore to selectively release the dart. A visual indicator assembly is coupled to the launcher body downstream from the release assembly and includes a flapper protruding into the launcher bore. The release assembly is actuated by the dart rotating the flapper to rotate an arm from a non-released position to a released position.

What is claimed is: 
     
         1 . A wellbore drop member launcher comprising:
 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 defining 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 coupled to the launcher body and having 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;   wherein 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; and   a visual indicator assembly coupled to the launcher body and configured to provide a mechanically produced visual indication that the drop member has moved from the launcher bore to the central bore.   
     
     
         2 . The wellbore drop member launcher of  claim 1 , wherein the release assembly comprises:
 a piston assembly coupled to the release rod and configured to move the release rod between the drop member hold position and the drop member release position; and   wherein the piston assembly biases the release rod to the drop member hold position.   
     
     
         3 . The wellbore drop member launcher of  claim 2 , further comprising:
 a release body housing interposed between the piston assembly and the launcher body, the release rod at least partially disposed within the release body housing when in the drop member hold position and a portion of the piston assembly coupling to the release rod within the release body housing;   a window having a length formed in a portion of a release body housing;   an indicator screw threaded into the portion of the piston assembly so that an end of the screw is visible through the window; and   wherein the indicator screw moves from a first end of the window to a second end of the window when the piston assembly operates to move the release rod between the drop member hold and the drop member release positions, providing a visual indication of release assembly actuation.   
     
     
         4 . The wellbore drop member launcher of  claim 3 , wherein:
 the release rod defines a pressure passage extending 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 release body housing; and   wherein the pressure passage is configured to equalize pressure between the release body housing and the launcher bore to prevent premature dart member release.   
     
     
         5 . The wellbore drop member launcher of  claim 2 , wherein the piston assembly is a hydraulically actuated piston assembly. 
     
     
         6 . The wellbore drop member launcher of  claim 2 , wherein the piston assembly is a pneumatically actuated piston assembly. 
     
     
         7 . The wellbore drop member launcher of  claim 1 , wherein the visual indicator assembly comprises:
 an indicator bore defined by the launcher body extending from an exterior of the launcher body to the launcher bore;   an indicator housing coupled to the launcher body proximate to the indicator bore;   an indicator rod extending through the indicator housing into the indicator bore;   a flapper on an end portion of the indicator rod;   wherein the flapper is perpendicular to the indicator rod and extends from the indicator bore into the launcher bore;   an arm secured to an end of the indicator rod that protrudes from the indicator housing and located so as to be visible to an operator;   wherein the arm extends from the indicator rod perpendicular to the indicator rod and parallel to the flapper; and   wherein as the drop member passes the flapper it rotates the flapper, indicator rod, and arm to indicate release of the drop member.   
     
     
         8 . The wellbore drop member launcher of  claim 7 , further comprising:
 a pre-release detent formed in a surface of the indicator rod;   a post-release detent formed in a surface of the indicator rod axially aligned with the pre-release detent and circumferentially spaced from the pre-release detent; and   a spring plunger disposed within the indicator housing and adapted to insert into the pre-release detent to limit rotation of the indicator rod prior to passage of the drop member; and   the spring plunger further adapted to release from the pre-release detent to allow rotation of the indicator, rod as the drop member passes and insert into the post-release detent to prevent further rotation of the indicator rod following passage of the drop member.   
     
     
         9 . The wellbore drop member launcher of  claim 7 , wherein the flapper, indicator rod, and arm rotate ninety degrees. 
     
     
         10 . A wellbore drop member launcher comprising:
 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 defining 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 coupled to the launcher body and having a release rod protruding into the launcher bore to prevent movement of a drop member positioned within the launcher bore into the tubing string;   wherein 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;   wherein the piston assembly biases the release rod to the drop member hold position;   a pressure passage defined by the release rod and configured to equalize pressure between a compressible portion of the piston assembly and the launcher body to prevent premature drop member release, the pressure passage extending 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 coupled to the launcher body proximate to an indicator bore defined by the launcher body and extending from an exterior of the launcher body to the launcher bore;   an indicator rod extending through the indicator housing into the indicator bore, the indicator rod having a flapper on an end portion of the indicator rod and an arm secured to an opposite end of the indicator rod;   wherein the flapper and the arm are perpendicular to the indicator rod and parallel to each other;   wherein the flapper extends from the indicator bore into the launcher bore and the arm is located so as to be visible to an operator;   wherein as the drop member passes the flapper it will rotate the flapper, indicator rod, and arm to indicate release of the drop member.   
     
     
         11 . The wellbore drop member launcher of  claim 10 , further comprising:
 a release body housing coupling the piston assembly to the launcher bore, the release rod partially disposed within the release body housing;   a window having a length formed in a portion of a release body housing;   an indicator screw threaded into a portion of the piston assembly so that an end of the screw is visible through the window; and   wherein the indicator screw moves from a first end of the window to a second end of the window when the piston assembly operates to move the release rod, providing a visual indication of release assembly actuation.   
     
     
         12 . The wellbore drop member launcher of  claim 10 , wherein the piston assembly is a hydraulically actuated piston assembly. 
     
     
         13 . The wellbore drop member launcher of  claim 10 , wherein the piston assembly is a pneumatically actuated piston assembly. 
     
     
         14 . The wellbore drop member launcher of  claim 10 , further comprising:
 a pre-release detent formed in a surface of the indicator rod;   a post-release detent formed in a surface of the indicator rod axially aligned with the pre-release detent and circumferentially spaced from the pre-release detent; and   a spring plunger disposed within the indicator housing and adapted to insert into the pre-release detent to limit rotation of the indicator rod prior to passage of the drop member; and   the spring plunger further adapted to release from the pre-release detent to allow rotation of the indicator rod as the drop member passes and insert into the post release detent to prevent further rotation of the indicator rod following passage of the drop member.   
     
     
         15 . The wellbore drop member launcher of  claim 10 , wherein the flapper, indicator rod, and arm rotate ninety degrees. 
     
     
         16 . A method for launching a drop member into a wellbore tubing string, comprising:
 (a) providing 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;   (b) placing 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;   (c) coupling 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;   (d) coupling 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;   (e) actuating the release assembly to allow the drop member to move from the launcher body into the central bore where the drop member may move down the tubing string; and   (f) actuating the visual indicator assembly with the drop member as the drop member moves from the launcher bore into the central bore.   
     
     
         17 . The method of  claim 16 , wherein step (e) comprises applying hydraulic pressure to a piston assembly of the release assembly to move the release rod from the launcher bore. 
     
     
         18 . The method of  claim 16 , wherein step (e) comprises applying pneumatic pressure to a piston assembly of the release assembly to move the release rod from the launcher bore. 
     
     
         19 . The method of  claim 16 , wherein step (f) comprises:
 moving a flapper of the visual indicator assembly with the drop member to rotate an indicator rod and an arm coupled to the indicator rod; and   signaling to an operator that the drop member has moved into the central bore with rotation of the arm.   
     
     
         20 . The method of  claim 19 , wherein further comprising:
 securing a spring plunger within a housing of the visual indicator assembly adapted to insert into a pair of circumferentially spaced detents; and   limiting rotation of the indicator rod by inserting a plunger of the spring plunger into the detents.