Downhole Fluid Conditioning System for Electric Submersible Pumps

摘要

Argentinian oil production comes from five basins: the Noroeste basin in northern Argentina, the Cuyana and Neuquina basins in west-central Argentina, and two southern basins, the Golfo San Jorge at the center of Patagonia and the Austral, south of Patagonia. The Golfo San Jorge Basin is amongst the most prolific, with 39% of total oil production. The two most commonly used artificial lift (AL) methods are electric submersible pumps (ESPs) for 4% of total production and rod pumps (RPs) for 27.5% of total production. Most of the wells in these five producing basins are low-volume producers. Of the total wells, 80% produce less than 252 bpd (40 m3/d) and 13% produce between 252 bpd (40 m3/d) and 629 (100 m3/d). Because of these low production rates, RP systems account for the biggest percentage of AL installations in Argentina. Because of environmental considerations, the water injection process to support reservoir pressure is under evaluation in the Golfo San Jorge basin. Well productivity in the region has decreased because water injection flow rates have been reduced. To overcome this reduction in the productivity, ESPs are being installed deeper in the wells (at or below perforation depths) allowing an increase in the drawdown of the wells that corresponds to an increase in production rate. However, setting the ESP system adjacent to or below the perforations may adversely affect the cooling efficiency of the ESP motor. In a field trial in this basin, a recirculation system—the downhole fluid conditioning system for ESPs— was installed as a solution to the adverse motor cooling issues that typically result when ESPs are installed in front of the perforations. This recirculation system maintains or even increases the production rate by installing the ESP system deeper in the well. The system in this field study was installed in October 2007 and has a run life of more than 3 years.