Mechanical Release Tool
Many tools and tubular are intended to be felt down hole in many types of wells. The most common of these would be casing strings. When running a string of production casing, it is more economical to run the casing the bottom of the well (bottom of the intermediate casing) and hang/seal it at this position. This eliminates running the entire string of casing to surface, within a previously cased hole.
The required amount of casing is assembled and then run into the well to a determined depth, using drill pipe above the casing. At the change over area (casing to drill pipe), there is usually a seal type casing hanger and some type of release mechanism. Once the seal or casing hanger is activated and set, the release mechanism is activated, separating the drill pipe from the hanger, allowing the drill pipe to be removed from the well, leaving the production casing in place down hole. The release mechanism can be activated mechanically or hydraulically. Mechanical release refers to any mechanical means used like pulling (tensile loads), pushing (compressive loads), or rotating (axial loads), to activate a mechanical device of releasing. Hydraulic release refers to any hydraulic means used like fluid flows or pressures to activate a mechanical device of releasing. Depending on the well and its circumstances, either a mechanical or hydraulic release type release tool will be chosen.
This Mechanical Release Tool (MRT) will release using rotation. The MRT is designed to grip the inside diameter of the tubular it will be releasing. The MRT does not use gripping dies to hold the tubular it will release, like most conventional mechanical release tools. The MRT relies on dogs that extent into a machined I.D. groove on the tubular to be released. The top of the tubular will also contain torque slots where torque blocks on the MRT would reside. These two features allow right hand rotation and up/down movements to the casing and drill pipe. To release the MRT, left hand rotation shears pins and allows further left hand rotation which retracts the dogs from the I.D. machined ring groove of the tubular, disengaging the MRT from the tubing by removing the drill pipe from the well. Unlike most mechanical releasing tools, this MRT can re-attach to the released tubular. Simply run the MRT to the top of the released tubular down hole and rotate until the torque blocks fit back into the torque slots. Continue rotating to the right to engage the dogs back into the I.D. machined groove of the tubular. Re-attachment is complete and the tubular can be removed if required.