Heavy sandy fluids production is one of the biggest challenges for an artificial lift system. Progressing cavity pumping (PCP) has always been the preferred method, but as sand cuts get higher a PCP by itself is not enough: this is when charge pumps come into the picture.
This system consists of a main pump, which has high lift and low volumetric capacity; a charge pump which has low lift and three times the capacity of the main pump and a perforated nipple between them. This arrangement provides higher suction velocities reducing the deposition of solids in the rathole and the recirculation between both pumps helps keeping the perforations clean.
This study is based on the first experience in Argentina using charge pumps. The field is "Cerro Huanul Sur" and is located in the Neuquen Basin. This system was installed in seven wells and this study covers the benefits and limitations of each case.
The design of the bottomhole assembly was tailored to the specific needs of each well. This included the analysis of fluid properties, well configuration and production history. The installations were carefully supervised and the performance tracked using data logging and surveillance.
The completion of this type of wells is costly and time consuming since the sand cut has to be reduced to acceptable values. Once in production, the typical problems are blocked suction, formation of sand bridges in the annular space between casing and tubing, bridges in the tubing itself and sanded pump. In the conclusion this study will show how these issues were all overcome; reducing completion time, the interventions of the well with a flush-by unit or a pulling rig and downtime, and increasing pump run life.