New Concepts in Sucker-Rod Pump Design

Abstract

New streamlined sucker-rod pumps improve production performance of viscous crude wells in Venezuela. The simple two-stage version further improves the volumetric and power efficiency and minimizes pounding, gaslock and rod fall problems. pounding, gaslock and rod fall problems. IntroductionAbout half a million sucker-rod pumps are installed in oil wells in the U. S. alone. In Venezuela, too, the system is widely used; some 5,000, or 90 percent, of Cia. Shell de Venezuela's wells produce a total of 400,000 BOPD by this method. Most of the crude pumped is viscous, gassy and contains relatively pumped is viscous, gassy and contains relatively small amounts of free water. API gravities vary from 9 degrees to 16 degrees; dead oil viscosities vary from 10 to 10,000 cp at the pump; and GOR's range from 100 to 2,000 cu ft/bbl. Pumps are set at depths ranging from a few hundred to 6,000 ft; the average setting depth is about 2,500 ft.From the literature, it appears that although recent years have seen significant progress toward understanding the rod pumping system as a whole, relatively little attention has been paid to those key items, the sucker-rod pump and the subsurface gas separator or gas anchor. Perhaps because of proration in the U. S., pump manufacturers have proration in the U. S., pump manufacturers have seemingly concerned themselves more with the durability of their product, achieved mainly through robust design and metallurgical know-how, than with its working efficiency.In 1963, CSV commenced a major rehabilitation and expansion of its heavy oil fields along the Bolivar Coast. The advent of the more efficient gravel-packed completion and of large-scale thermal recovery (mainly steam soak) operations resulted in well potentials greater than pump capacities. Hence, an urgent need arose to improve over-all pump efficiencies and to attack those special problems related to the production of both the extremely viscous and the hot, production of both the extremely viscous and the hot, steam-laden crudes that formed an increasing proportion of the total stream. There followed a detailed investigation and testing program, carried out in close cooperation with a major pump manufacturer. This culminated in the introduction to the oil industry of a new line of sucker-rod pumps.