Abstract
Abstract
The majority of oil production at the Kuwait Oil Company (KOC) rely on Electrical Submersible Pumping (ESP) systems. One such reservoir in Kuwait with over than 120 producing well equipped with electrical submersible Pumps are exposed to a harsh production environments including corrosive fluids (sweet corrosion due to presence of Co2). Historical data shows that over 40% of all pulled Electrical Submersible Pumps where dismantle inspection and failure analysis (DIFA) were performed in the past 4 to 5 years within the field have failed due to corrosion within the well completion (mainly corrosion in the tubing) or in Electrical Submersible Pump components. When analyzing existing data (reservoir, design, equipment specifications, operation and DIFA) the majority of failed wells equipped with Electrical Submersible Pump show signs of corrosion in the tubing although they rarely appear on the ESP components. Further analysis shows that 80% of these completion (mainly tubing) failures occur between 4 to 18 months where the tubing used in these cases are all found to be of carbon steel metallurgy.
Sweet corrosion is one of the major issues for wells equipped with electrical submersible Pump in one of reservoir located in Kuwait. An increase in water cut percentages in the reservoir has led to increased CO2 corrosion rate in the saline formation water (high chloride level). The collected data shows that more than 40% of all pulled electrical submersible Pumps where DIFA have been performed were due to corrosion in the completion components (mainly corrosion hole in the tubing).
As a proactive measure, KOC have been installing Internally Glass Reinforced Epoxy (GRE) lined carbon steel tubing for wells that have corrosion related tubing failures. In additional, KOC decided to enhance the Electrical Submersible Pump components specifications to mitigate the risk related to sweet corrosion.
This paper shows a field study for 36 cases where Internally Glass Reinforced Epoxy lined carbon steel tubing were used on existing failed wells due to corrosion to evaluate the effectiveness of using GRE lined tubing when exposed to the same harsh environments (sweet corrosion) and the resulting equipment run life. When compared with conventional carbon steel tubing, a significant increase in run life and reduction of numbers of completion failures are recorded. Over all, the average run life for all cases has improved by over 422 days.
This study will help ESP operators facing similar challenges to understand the effectiveness of using Internally Glass Reinforced Epoxy lined carbon steel tubing as a replacement for conventional carbon steel tubing towards mitigating sweet corrosion environments.