20″ 58 km Main Oil Line “Unpiggable” due to Peculiar Polymerized Deposition Made “Piggable” by Online Treatment Using Cutting-Edge Chemistry as a Cost-Effective Approach

A 20″ 58 km ascending Main Oil Line (MOL) transporting 28,500 m3/day of crude in Oman experienced sudden back pressure of 54 barG during routine pigging activity. The pig got stuck at 4.6 km and caused MOL to trip. It was retrieved by back-flow and found wrapped with a sticky polymerized organic substance. A novel specialty chemical technology was designed to disintegrate and disperse deposits into small, non-sticky fragments. The formulation was engineered to be an aqueous base to travel at the bottom part of the crude and to prevent any massive dilution. A non-corrosive chemical pill was injected into the pipeline from the inlet to provide a plug flow and pushed by a medium-density foam pig (online). Different flow rates were maintained to focus on the target location to allow maximum soaking/contact time. The foam pig was received at the receiver end, pushing all debris out, and leaving the MOL cleaned. The entire operation was performed online except for a short time of 2 h, which was utilized to inject the specialty formulation from the launcher section.