Continuous Well String Injector Using Multi-Piston Cylinder Blocks for Application of Skate Pressure

摘要

A continuous well string injector features a frame carrying a pair of endless chain conveyors on opposite sides of a pathway. Each chain carries gripper dies for engaging the continuous well string when received in the pathway. A respective skate and cylinder block reside in the closed loop path of each chain. Each cylinder block features a plurality of blind bores having open ends facing toward the respective skate, and a respective piston is slidably disposed within each bore. Hydraulic extension and retraction ports open into the cylinder bores on opposite sides of the piston, whereby back and forth displacement of the pistons forces the skates toward and away from one another to grip and release the continuous well string. A front wall of the frame has an open horizontal gap aligned with the pathway to enable lateral entrance and exit of the continuous string to and from the pathway.

主权项

1. An apparatus for injecting or withdrawing a continuous string into and from a wellbore, the apparatus comprising:
a frame; a pair of endless drive conveyors positioned on different respective sides of a pathway in which a length of the continuous string is receivable, each endless drive conveyor comprising an endless chain and a plurality of gripper dies coupled to the endless chain, each gripping die having a gripping face that faces outwardly from the endless chain and is shaped to engage a periphery of the continuous string and a base surface that faces inwardly from the endless chain, the endless chains entrained about respective set of sprockets that are rotatably mounted on the framework for driven movement around respective closed-loop paths on the different sides of the pathway such that the gripper dies of each endless chain are conveyed in a same direction along the pathway at the respective side thereof during a portion of the respective closed-loop path; a pair of skates respectively residing on the different respective sides of the pathway with the closed-loop path of each endless chain closing around a respective one of the skates; and a pair of cylinder blocks respectively residing within the closed loop paths of the endless chains, each cylinder block featuring a plurality of blind bores having open ends facing toward the one of the skates located within the closed-loop path of the same endless chain, and closed ends lying opposite to said open ends; a respective piston disposed within each bore and slidable back and forth in an axial direction of the bore; a respective connection between each piston and the one of the skates located within the closed-loop path of the same endless chain, whereby back forth displacement of the pistons within each cylinder block causes back and forth displacement of the one of the skates located within the closed-loop path of the same endless chain, thereby moving the skate toward and away from the cylinder block; and hydraulic extension ports opening into the cylinder bores of each cylinder block between the pistons and the closed ends of the cylinder bores for extension of said skate away from the cylinder block under pressurized introduction of hydraulic fluid into the cylinder bores through said hydraulic extension ports.