This paper presents the results obtained from decommissioning an offshore production loop (7.625 in., 19 km) by flushing with inhibited seawater and compares flow-assurance software simulations to data collected in the field. After completion of the subsea production system shutdown, the production loop was pigged for dead oil removal, which was routed into the production unit separator. Once the dead oil was removed, the system was configured into a closed loop and flushed with a filtration spread (slurry skid, filter press, and polishing filter) to reduce the oil and grease content. Oil-absorbent additive was added to the typical oilfield diatomaceous earth filtration process, and the system was flushed until the oil-in-water content was reduced to less than 29 ppm (to meet local regulations). The completion of flushing for oil removal allowed for the disconnection and replacement of subsea structures, such as jumpers and manifold, in compliance with local regulations for oil-in-water content. During the engineering phase before the offshore campaign, flow-assurance software simulations were used to verify that the proposed methodology would achieve the planned results. Based on these simulations, the production loop needed to be flushed 5.6 times its total volume to achieve the oil-in-water content specification. The offshore campaign required 5.9 flushes of the entire production loop volume and achieved an oil-in-water content of 3 ppm. Although software simulations and field results were similar, early filter-press saturation and washout produced issues during operations. For future operations, using an oily water separator before the filter press is recommended to extend the life of filtration/oil-absorbent media. The methodology validates the use of a filter press with oil-absorbent media as a cost-effective solution for oil removal in riser production or water injection loop systems. The presented application is typically used during routine completion fluid diatomaceous earth filtration with no significant impact on filtration performance. Oil removal in compliance with the environmental limitations of oil and grease was successfully implemented for the production loop decommissioning and can be used in other systems with similar configurations.