In an effort to increase oil production, the feasibility study about heavy crude oil from marginal field becomes important to do. This research discussed about the effect of blending heavy oil and marginal heavy oil in Sumatera towards pipeline transportation using Flow Assurance (FA) approach. Heavy oil from marginal field X, which has small production, was transported to Gathering Station (GS) to be blended with heavy oil Y before being transported to Refinery Unit (RU). FA analysis was carried out on existing pipeline from GS to RU. Blending Simulator with Blending Ratio (BR) variation was used to get the blended oil qualities. Then,FA simulators were used to obtain Temperature and Wax Deposition profiles. The results showed that heavy oil X is feasible to be produced by blending method, without having to build significant infrastructure or change the operating conditions of existing pipelines. This blending process can improve the oil quality while still ensuring the achievement of Flow Assurance. The projected pigging time is 298 days.