Progressing Cavity Pump Stainless Steel Impact in High Corrosive Environments Maximizing Economic Benefits in West Africa - Gabon

Abstract

The combination of well conditions such as high levels of carbon dioxide (CO₂, an average of 15%), 85% water cuts (WC), sand production, and heavy viscous oil is one of the biggest challenges for any artificial lift system (ALS). Progressing cavity pumping (PCP) is the preferred method for sand and heavy oil production; however, CO₂ presence in the form of carbonic acid, generates corrosion and pitting on the carbon-steel section of the Progressing Cavity stators. This condition results in short run life for PC pumps with standard materials historically installed. Taking advantage of the corrosion strength properties that Stainless Steel (SS) material has, a new SS PC pumps were manufactured to be installed in highly corrosive application and then determine the increase on run life for those wells previously affected by corrosion. This paper describes a section of the results from the flow assurance improvement plan obtained by the installation of PC pumps with SS technology in terms of workover (WO) intervention savings and extended run life in nine wells operating in Gabon, West Africa.

This paper describes the methodology applied in the selection of the PCP models to be manufactured with Stainless Steel technology considering the dimensional restrictions the PCP would have due the casing size of the well completions where the PC pump would be installed, as well as the pump design requirements related to the expected flow rate in the wells historically affected by corrosion. In addition, the paper shows the screening done on the well candidates for the installation of SS PCP, based on historical well intervention data specifically associated to corrosion.

Since the installation of the SS PCP technology, the client has performed several acid stimulations that have required pulling the PC pumps out of hole and re-running them multiple times. Throughout these operations, the PCPs have had no failures requiring intervention. The installation of SS technology has improved well run life across all nine candidates by 584% on average. The SS PCP technology continue to run in all nine wells with no corrosion-associated interventions. For an average of 326 days across all nine wells, there have been no WOs performed on the PCPs. The reduction in WOs has helped to avoid production losses, downtime, and associated costs. SS PCP has shown great results extending PC pump run life over 6 times compared to previous applications and has proven to be a good option for larger flow rates in 5.5 in casing completions.