Downhole swivel

Abstract

A method and apparatus is disclosed which reduces or removes axial loads on the drive string of a rotary downhole pump, i.e. tensile loads due to the hydrostatic load of the pumped liquid on the pump rotor, and/or at least part of the weight of the drive string, or thrust loads caused during pressurized fluid injection operations by backpressure of injected fluid on the pump rotor. This substantially prevents drive string/production tubing friction, wear and/or buckle in downhole rotary pumping arrangements operated in straight or curved well bores. When used in connection with fluid production pumping arrangements, the apparatus reduces the friction between the drive string and the production tubing of a downhole rotary pump for the pumping of well fluids which pump has a pump rotor connected to the drive string and is operated in a well bore. When used in connection with fluid injection pumping arrangements, the apparatus prevents drive string buckle, especially in curved well bore situations. The apparatus includes a support for rotatably supporting the drive string in the production tubing at a location above the pump, and a fluid passage for permitting the pumped fluid to flow from the pump to a wellhead of the well. The support includes an axial load bearing structure for supporting, from the production tubing, at least part of an axial load on the drive string either generated by the hydrostatic load of a pumped liquid on the pump rotor or backpressure of injected fluid on the pump rotor. The fluid passage is shaped and constructed such that the pumped fluid can flow from the pump past the axial load bearing means to the wellhead. In fluid pumping applications, the apparatus can also be used to support at least part of the weight of the drive string to reduce the axial load on the drivehead.