Time-Controlled-PRV Cable-Head Cutter For Line Conveyed Tools

Abstract

A cable head line cutter tool comprising an internal mandrel anchored to a line and releasably held in an initial position by a pressure relief valve which may act in coordination with a locking mechanism disposed within an outer housing of the cable head cutter tool. When a tensile load is applied to the line sufficient to overcome an opening pressure of the pressure relief valve and a mechanical resistance acting upon the locking mechanism, and maintained for a duration sufficient to overcome a hydraulic resistance acting upon the locking mechanism, the internal mandrel may become released to travel within the outer housing. If the tensile load applied to the line is sufficient to open the pressure relief valve, release the mandrel from the locking mechanism, and maintained for sufficient duration, the mandrel may cause a line cutter device of the cable head line cutter tool to cut the line.

What is claimed is: 
     
         1 . A system comprising:
 a cable head cutter tool comprising an outer housing, an outer housing connector, an internal mandrel, and a combination of mechanical and hydraulic devices disposed within the outer housing which act upon the mandrel;   a tool string connected to the outer housing connector;   a line connected to the internal mandrel;   wherein at least one of the hydraulic devices comprises at least one pressure relief valve;   wherein the internal mandrel is held biased into a first position within the outer housing by a resistance provided by the combination of mechanical and hydraulic devices;   wherein the internal mandrel is released from the first position by applying tension on the line which exceeds a release tension and then maintaining an applied tension for a duration which exceeds a release duration, until the internal mandrel is by the combination of mechanical and hydraulic devices thereby allowing the internal mandrel to travel unrestricted within the outer housing; and   wherein upon being -freed the internal mandrel travels toward a second position at which the internal mandrel contacts a line cutting mechanism disposed within the outer housing, causing the line cutting mechanism to cut the line.   
     
     
         2 . The system of  claim 1 , wherein the line is a slickline, a braided line, an electromechanical line, a flexible rod, or a coiled tubing. 
     
     
         3 . The system of  claim 1 , wherein the line has a working tension limit and wherein the outer housing connector has a tensile strength limit greater than the working tension limit of the line. 
     
     
         4 . The system of  claim 1 , wherein the line cutting mechanism comprises a mechanical blade-based cutter, a ballistic cutter, or a chemical cutter. 
     
     
         5 . The system of  claim 1 , wherein the line cutting mechanism is coupled to the internal mandrel, wherein upon being released the internal mandrel travels toward a second position at which the line cutting mechanism contacts an inner profile of the outer housing, causing the line cutting mechanism to cut the line. 
     
     
         6 . The system of  claim 1 , wherein while applying the applied tension on the line and before the line cutting mechanism cuts the line, the mandrel is caused to be biased to the first position by reducing the applied tension. 
     
     
         7 . A method of releasing a line from a tool string, comprising: connecting a line to a cable head cutter tool with an anchoring method;
 supporting a tool string in a well with the line;   applying tension to the line;   holding the applied tension for a duration;   releasing a mandrel of the cable head cutter tool from a first position when an applied tension exceeds a preset release tension and the duration of the applied tension exceeds a selected release duration,
 wherein the preset release tension and selected release duration are based upon a resistance provided by a combination of mechanical and hydraulic devices disposed within the cable head cutter tool, 
 wherein at least one of the hydraulic devices comprises a pressure relief valve; 
   freeing the mandrel from being coupled to a housing of the cable head cutter tool after the releasing, thereby freeing the mandrel to travel unrestricted within the housing which results in a line cutting mechanism cutting the line; and   optionally reducing the applied tension below the preset release tension before the selected release duration is exceeded, thereby allowing the mandrel to be biased toward the first position.   
     
     
         8 . The method of  claim 7 , wherein external clamp-on subs or tools are mounted on a deployment line section above a fishing neck of the cable head cutter tool. 
     
     
         9 . A cable head cutter tool for raising and lowering a tool string within a well with a line, comprising:
 an outer housing comprising a connector adapted for connection to the tool string and an internal mandrel adapted for connection to the line;   one or more locking mechanisms in communication with the outer housing and the internal mandrel, each locking mechanism comprising a locked configuration, a released configuration, and a freed configuration,
 wherein in the freed configuration the internal mandrel is freed to travel unrestricted within the outer housing independent of the locking mechanism, and wherein in the locked configuration and the released configuration, each of the one or more locking mechanisms communicates with the outer housing through a system of mechanical devices, a system of hydraulic devices comprising at least one pressure relief valve, or a system of mechanical devices and hydraulic devices comprising at least one pressure relief valve, thereby providing each of the one or more locking mechanisms with a release tension and a release duration; 
   a line cutting mechanism disposed within the outer housing which cuts the line upon the internal mandrel communicating with the line cutting mechanism after the internal mandrel is freed by all of the one or more locking mechanisms;   wherein each of the one or more locking mechanisms is caused to be shifted from the locked configuration to the released configuration based upon a tension applied to the line causing activation of the pressure relief valve and exceeding a preset release tension of the locking mechanism, and being held for a duration exceeding a selected release duration of the locking mechanism.   
     
     
         10 . The apparatus of  claim 9 , wherein the line cutting mechanism is coupled to the internal mandrel, wherein upon being released the mandrel travels toward a second position causing the line cutting mechanism to cut the line. 
     
     
         11 . The apparatus of  claim 9 , wherein a cutter of the line cutting mechanism is driven by a compression force applied to the line cutting mechanism after the mandrel is released. 
     
     
         12 . The apparatus of  claim 9 , wherein a cutter of the line cutting mechanism comprises a ballistic cutter or a chemical cutter. 
     
     
         13 . The apparatus of  claim 9 , wherein one or more hollow tools are disposed between a fishing neck and a proximal end of the outer housing.