Concepts of continuous-rod pumping

The concept of continuous-rod pumping is nearly as old as pumping rods themselves, but only until recently has it been achieved. The problems overcome include: the manufacture, heat treating, welding together for specific lengths, and finally the handling during transportation. The rod is called corod and is constructed of solid steel, the same basic material of conventional sucker rods. The rods are produced in coils of 600 to 1,200 ft in length, depending on the diameter (weight), and are transported on 18-ft ID reels. During field installation, the corod is placed in the well with a chain-driven gripper mechanism, with a lifting capacity of 40,000 lb. Special pump connectors are required for the corod. Advantages include reduced well failure by approx. 65 to 85%. Tapered rod strings may be achieved by 1/16-in. increments, instead of the 1/8-in. graduations of conventional rods. Paraffin accumulation is reduced. Less wear occurs in the crooked hole situations. Slim-hole completions are more easily made. Limitations are needed for particular equipment is necessary to pull, handle, and install the rods.