Sand Erosion and Deposition Risk Mapping Using Network Model: A Case Example from Offshore Malaysia

Abstract

Abstract Flowline erosion due to sand production is a common occurrence in oilfield environment, causing Loss of Primary Containment (LOPC), resulting in substantial economic, environment and reputation damage to operators. To be proactive in monitoring flowline erosion, operators periodically conduct Ultrasonic Thickness Gauge (UTTG) across expected erosion and corrosion hotspots such as at flowline bends and tees. Despite the efforts put in the monitoring activities, LOPC still occur which often attributed to prioritized monitoring due to UTTG backlogs where single flowline can have at least 100 monitoring points, coupled with inconsistency or errors when conducting UTTG. With the goal to identify sand erosion and deposition locations in the production system, a detailed network hydraulic model was developed with flowline dimensions and fittings arrangement based on isometric drawing and flowing conditions matched to latest well parameters. The hydraulic network model output for each flowline segment was then used to calculate sand erosion rate and critical velocity for sand transport using models available in the industry. Using this approach, high sand erosion and deposition risk locations were identified at the current flowing conditions. Additionally, sensitivity analysis was performed to assess the effect of various parameters such as production rates, sand rates and sand size. The identified sand erosion and deposition risk hot spots were then included in the UTTG plan for further monitoring. This paper will share the process of sand erosion and deposition risk mapping along the production system including data requirements, modelling workflow and results analysis. The approach can be replicated in other fields facing similar issues of LOPC due to sand erosion.