Problems and Solutions for Asphaltene Precipitation in High API Oil Reservoirs-Case Histories

Abstract

Abstract This study addresses the challenges associated with asphaltene precipitation in reservoirs containing high API gravity oil. Using case histories from the Western Desert in Egypt, the paper discusses problems associated with asphaltene deposition and solutions to mitigate production problems. Many Western Desert reservoirs produce moderate to high API oil with low asphaltenes content. However, solids/asphaltene precipitation was observed to cause plugging of the artificial lift systems. In many cases, this blockage led to a sharp decrease in oil production rate and a significant increase in the operating cost. The current failure analysis procedure was insufficient in effectively determining the causes of the blockage. A new integrated failure analysis approach revealed that the problem was asphaltene deposition. Solutions were suggested and treatments were implemented to restore production for twelve wells with minimum costs. This paper provides insights and learnings in these case histories. The integrated analysis approach was applied to several reservoirs in the Western Desert and appropriate treatments were designed and pumped in these wells. After the appropriate treatment, field applications results showed a significant increase in oil production rate by three to five times on average. Moreover, the operating cost significantly decreased from 5 to less than 0.5 $/STB. The field applications indicated that the continuous downhole injection of asphaltenes dispersant using a capillary tube with ESP completions is highly efficient and more efficient than continuous injection of diesel and/or periodic diesel backwash jobs. Moreover, the time between failures was increased from two months to more than 18 months for some of these wells. This technique was successfully used in five fields and restored production of around 12,000 BOPD with increased pump run life.