Mitigating Sand Production in Mature Oil Well with Microgel Technology

Abstract Many oil wells in Libya are affected by sand production problems. The accumulation of sand in the wellbore often forces operators to shut in the wells due to frequent cleanout operations, and, in more severe cases, to shut them down totally. This is precisely the case for Well A, which previously produced between 260 and 300 barrels of oil per day, with a low water cut (6 to 8%). Due to sand production, the well's output became erratic between 2009 and 2022. During that time, three workover operations were carried out for swabbing and ESP replacement. Ultimately, the well was shut in completely in 2022 due to excessive sand production/accumulation. In 2023, a decision was made to implement a polymer-based sand control technology. The principle involves injecting a polymer slug that stabilizes the formation around the wellbore by the coating of the pore walls using a polymeric film. Once production resumes, sand production is effectively mitigated. Polymer selection was based on laboratory tests using sand samples from the reservoir. After selecting the appropriate polymer, the well was swabbed and the treatment was injected using a bullheading technique. Following the injection, the well was swabbed again. Although production was initially planned to resume the following week, the workover required to install the ESP was delayed and only completed a year later. Once installed, the well was brought back online through a gradual production ramp-up. The polymer selected through lab testing was a Small Microgel (SMG), which outperformed conventional polymers used for sand control. This product is also used as a relative permeability modifier for water shut-off applications. It was diluted in a 2% KCl brine solution, and a total volume of 120 m³ was injected into the well. Swabbing was conducted immediately after the injection, with sand production less than 0.05%. One year later, after the ESP installation, production was resumed. Sand production was completely eliminated, and the well was able to produce at full capacity for at least five months with improvement in water cut confirming the added value of SMG. The SMG demonstrated excellent long-term stability and effectiveness. Notably, the long shut-in period of one year following the treatment had no negative impact on its performance. This marks the first time that Small Microgel has been used as sand control chemical. This case study demonstrates that the technology is effective even in wells producing dry oil.