Tubing unloader apparatus and method

A tubing unloader for draining liquid from a production tubing comprising:

• an outer mandrel body comprising a first, hollow cylindrical body having a lower end, an upper end, and side port means in a sidewall of said cylindrical body, said side port means comprising a drain for draining said liquid from said outer mandrel body, said lower end comprising a first bottom sub means for coupling said lower end of said outer mandrel body to said production tubing, said outer mandrel body including a first internal diameter adjacent said lower end and a milled section having a second internal diameter adjacent said upper end, said second internal diameter being incrementally larger than said first internal diameter,
• an inner mandrel telescopically receivable inside said outer mandrel body, said inner mandrel comprising a first end and a second end, said first end comprising an anvil means for coupling said inner mandrel to said production tubing, said second end comprising a sliding valve means for selectively opening and closing said side port means;
• interlock means for slidably interlocking said inner mandrel inside said outer mandrel body, said interlock means comprising a J-sleeve telescopically received in said milled section and a top sub threadedly engaged to said upper end of said outer mandrel body to secure said J-sleeve in said milled section, said J-sleeve having a third internal diameter corresponding to said first internal diameter of said outer mandrel body, said J-sleeve comprising a pair of diametrally opposed J-slots, said J-slots comprising a leg having an open end adjacent said upper end and a closed arm spaced from and parallel to said leg with a transverse section interconnecting said closed arm with said leg, said inner mandrel comprising a pair of J-lugs, each J-lug configured as a raised boss extending outwardly on opposite sides of said inner mandrel, said J-lugs being configured to be slidingly engaged in said J-slots when said inner mandrel is telescopically received in said outer mandrel body said J-slots limiting movement of said inner mandrel relative to said outer mandrel body, said sliding valve means being held in a closed position over said side port means when said J-lugs are in said arms of said J-slots, said leg of said J-slot comprising a limited free travel between said inner mandrel and said outer mandrel body, said limited free travel comprising a down jar means for imparting a down jar on said outer mandrel body whereby a first predetermined force of overpull is exerted on said production tubing and released to produce said down jar on said outer mandrel body.

A tubing unloader for selectively draining liquid from a production tubing into which said tubing unloader is incorporated comprising:

• an upper knocker sub for coupling a top end of said tubing unloader into a production tubing;
• an inner mandrel coupled at a first end to said knocker sub, said inner mandrel having a J-lug means protruding outwardly from an external surface of said inner mandrel;
• an outer mandrel body for telescopically receiving said inner mandrel in a slide-fit relationship, said outer mandrel body including side port means for draining said liquid, said outer mandrel body including J-slot means guiding said J-lug means of said inner mandrel;
• a top anvil releasably mounted to said outer mandrel body, said top anvil securing said inner mandrel inside said outer mandrel body;
• a sliding valve means on said inner mandrel, said sliding valve means selectively closing said side ports in a first position of said J-lugs in said J-slots and selectively opening said side ports in a second position of said J-lugs in said J-slots;
• a scale scraper means on said sliding valve means for scraping scale from said outer mandrel body;
• and
• a lower tubing coupling means for coupling a lower end of said outer mandrel body to said production tubing.

A method of draining liquid from a production tubing comprising the steps of:

• obtaining an outer mandrel body as a hollow cylindrical body having side ports in a sidewall of said hollow cylindrical body, said side ports comprising a drain;
• preparing a hollow inner mandrel to be telescopically received in said outer mandrel body in sliding relationship;
• mounting a sliding valve means on one end of said inner mandrel for selectively occluding said side ports in said outer mandrel body as a function of the relative position of said inner mandrel in said outer mandrel body;
• forming a J-lug means on an external surface of said inner mandrel;
• configuring a J-slot means on an internal surface of said outer mandrel body;
• providing a free stroke in said tubing unloader by forming an elongated leg in said J-slot means, said elongated leg being closed by said top anvil;
• interlocking said J-lug means in said J-slot means in sliding relationship thereby controlling the relative positional relationship between said inner mandrel and said outer mandrel body;
• locking said inner mandrel in said outer mandrel body by mounting a top anvil to said outer mandrel body thereby forming a tubing unloader;
• coupling said tubing unloader in a production tubing with a knocker sub;
• imparting a down jar on said outer mandrel body by overpulling said production tubing and dropping said production tubing thereby causing said J-lug means to traverse said elongated leg and imparting said down jar on said outer mandrel body;
• and
• draining said production tubing by moving said sliding valve means away from said side ports by manipulating said inner mandrel relative to said outer mandrel body by selectively moving said J-lug means in said J-slot means.