Hydraulic unloading and circulating device

Claim 1

A hydraulic unloading and circulating device adapted to be inserted in a threaded joint of a well tool connected to sucker rods and including a pumping tube surrounding said tool and supported on the end of a pipe string through which said sucker rods extend, for passing fluid between the exterior of the tool and interior of the pumping tube to the interior of the tool so as to be placed in communication with the well annulus and thereby relieve the difference of hydrostatic pressure between fluid in the well annulus and fluid in the interior of the pumping tube and pipe string, said device comprising, in combination: a. a housing having lower threads for threaded connection to the lower threads of said joint; b. a mandrel having a lower end portion telescopically received in the upper portion of said housing, the upper end of said mandrel being coupled to the upper threads of said joint, said mandrel having a straight through central passage including a lateral port eclipsed by said housing when said mandrel is telescoped within said housing to a first given position, and exposed above said housing when said mandrel is pulled upwardly from said housing to a second telescoped position; c. a sleeve in the lower portion of said housing having cut-out wall portions defining vertical guide channels of given circumferential width, the lower end of said mandrel being received in said sleeve and having radially extending lugs of given circumferential extent receivable in said channels so that upward and downward telescoping movement of said mandrel between said first and second telescoped positions is guided by said guide channels, the lower ends of said sleeve between said channels being spaced above the lower end of said mandrel when in said first telescoped position so that rotation of said mandrel through a given number of degrees positions said lugs beneath said lower ends of the sleeve to thereby lock the mandrel against pulling movement when in its rotated position; and d. a torque spring connected between said mandrel and said housing to exert a circumferentially directed biasing force on said mandrel in a rotational direction to position said lugs beneath said lower ends of the sleeve, whereby intentional rotation of the sucker rods from the surface of the well through said given number of degrees in a rotational direction opposite to the bias of said torque spring positions through the upper threaded coupling of the mandrel said lugs in said channels, and subsequent upward pulling on said sucker rods from the surface of said well move said mandrel to said second telescoped position thereby exposing said port and placing fluid in said pump tube and pipe string in communication with fluid in the annulus of the well to thereby equalize the hydrostatic pressure of the fluid, subsequent urging of said mandrel to its first telescoped position eclipsing said port and permitting rotation of the mandrel by said spring to its rotated position to lock the mandrel against telescoping movement relative to said housing.