Electro-Hydraulic Pulsing Used to Clear Barium Sulfate Scale and Improve Production on a Multi-Well Campaign

Abstract This paper focuses on the operation and successful use of electro-hydraulic pulsing technology (EHP) to remove scale from the sand screens of Statfjord wells in the Norwegian North Sea starting in 2023. Barite scale (BaSO4) was the most common type of scale present, which is very difficult to treat with chemicals. Mechanical methods are also not very successful, as although they can remove the scale inside the base pipe, they cannot reach the actual screen material behind the base pipe. The total liquid production of Well 1 had dropped to less than 40% of the original value. Mechanical solution was evaluated but was not feasible due to scale being present behind screens and chemical solution was unfeasible due to reservoir characteristics. It was decided to try EHP technology to remove the scale. EHP uses shock waves and pressure pulses to break up and mobilise the scale, without using chemicals or any controlled goods. The EHP service by Blue Spark Energy was chosen and was deployed by regular electrical wireline cable to the sand screens, with the service being completed without any difficulties. Multi-Finger Caliper (MFC) and Gamma Ray (GR) logs confirmed the removal of the scale. The initial increase in the total liquids production rate was 180%. A more extensive sand screen campaign was then planned and executed. When possible, multi-finger caliper surveys were carried out before and after the treatments, confirming the effectiveness of the technology to remove scale build-up. At the time of the writing of this paper, 5 wells had been treated by EHP, and the results are presented in this paper.