Managing Paraffins for Flow Assurance

Paraffin or wax (n-alkane) precipitation and deposition from crude oil, commonly referred to as "the cholesterol of the petroleum industry," has cost billions of dollars in additional capital and operating expenses. Paraffin deposition risk plays a significant role in development concept selection. On land or in offshore shelf waters, paraffin buildup has been primarily controlled by thermal management (insulation or active heating), routine pigging and wax chemicals or hot solvent treatments. The cost and technical challenges of managing paraffin for deep-water and ultra deep-water offshore prospects with marginal reserves are even higher. Long distances from the reservoir to the host facility via subsea tiebacks, dry tree risers and extended export pipelines in cold ambient water temperatures increase wax deposition potential. Industry is concerned about failure of long umbilical and capillary lines that deliver paraffin inhibitor chemicals, and consequent wax plugging. The traditional approach of installing dual flow lines, with round-trip pigging operations routinely performed from the host platform, has a high capital cost that can adversely impact the overall project economics. The offshore industry has a very limited experience with subsea pig launchers for routine single-trip pigging operations. If not managed properly, a wax plug may require the replacement of a pipeline, or lead to the premature abandonment of producing wells. Both industry and academia have made significant progress not only in understanding the physics of paraffin deposition and predicting the deposition rate in subsea pipelines, but also in synthesizing effective paraffin inhibitors. The take away message from this presentation is that industry and academia must continue their consolidated research efforts to promote novel ideas and to develop new game-changing technologies in order to overcome the deep-water challenges that lie ahead.