What's new in artificial lift: Part 1—twenty new systems are described for sucker rod and progressing-cavity pumping, plunger lift and gas lift

World Oil, April, 2006 by James F. Lea, Herald W. Winkler, Robert E. Snyder

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Its 72-in. adjustable stroke, allows for slow speeds at higher flows than conventional units. It is recommended for use with 5/8-in. rods. Following past DynaPump operation techniques, this unit has a variable speed up and down, and an automatic pump-off controller. The cylinder seals are field serviceable. It is powered by a 480V, three-phase motor; or 220V/480V single phase as an option. The unit complies with API 500 code.

Low-profile pump unit, Another contribution from DynaPump is the DynaLow, a low profile unit with the same capacity and specifications as the DynaSave unit. It has a fixed height of less than 10 ft and a maximum stroke of 40 in., Fig. 5. This unit has been designed to work under farmland irrigation systems. Total weight is less than 1,400 lb. It is stated to have design features making it a safely operated unit.

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Pump intake pressure from downhole card. Pump-off controllers have evolved to become full-time dynamometers. Today, wellsite computers accurately measure load and position, along with pressures, temperatures, production rates, etc. This sophistication requires accurate measurement of surface load as a function of position. The SAM Well Manager from Lufkin Automation, Houston, not only calculates an accurate downhole pump card for every stroke of the pumping unit, but it also calculates pump intake pressure. This is important in managing flow regimes and pressure support initiatives. Getting this information daily, as opposed to whenever manual fluid levels can be recorded and analyzed, allows continual improvement.

Pump intake pressure can be calculated using the downhole pump card, Fig. 6. Input data from the card includes fluid load, gross stroke, net stroke and tubing movement, if applicable. Fluid load, the most important item, is the difference between upper and lower load lines, selected and drawn on the card. This load should not include friction and fluid inertia effects. Ideally, the lower load line should fall below zero load by the same amount as buoyancy; accuracy of the buoyancy calculation depends on good load measurements, rod design information and a known tubing fluid gradient. With all input data, a pump intake pressure can be computed. During this process, other items of interest are indicated, as in the example card.

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Replacing sucker rods with cable. A new oil well pumping system using cable instead of rods is being developed and tested by Vann Pumping Systems, Inc., Tyler, Texas. This system employs steel cable instead of sucker rods, and a surface Tower Lift unit that replaces the pump jack, Fig. 7. The pumping lift system connected to the cable is computer controlled. New patented tools have been developed and tested to reduce gas locking and pump off. The patented Vent Tools are run at the bottom of the pump barrel to allow fluid dumping from the tubing when desired. A couple of functions of these newly developed tools are for ease of unseating from hold-down and chemical spotting.