Paraffin Deposition During Single-phase Flow of Crude Oil in Pipes

Oris Hernandez, Master’s Student, Petroleum Engineering

 

Paraffin is the common name for high molecular weight aliphatic components of crude oil. When the oil temperature falls below the Wax Appearance Temperature of the liquid, these heavy organic compounds will form a paraffin solid phase that can deposit along the inner pipe wall. The production, transportation and processing of petroleum can be significantly affected by the reduced effective diameter caused by paraffin deposition in pipes, especially in cold environments encountered in deep water oil or gas condensate fields.

 

Paraffin problems are frequently mitigated using thermal fluid treatments, pigging, scraping and chemicals. Paraffin deposition causes a loss of billions of dollars per year worldwide due to the enormous cost of prevention and remediation, reduced or deferred production, well shut-ins, pipeline replacements and/or abandonment, equipment failures, extra horsepower requirements, and increased manpower needs. In order to optimize the design and operation of oil and gas production systems, as well as the proper strategies for prevention and remediation, it is very important to properly identify the conditions for paraffin precipitation and the prediction of paraffin deposition rates.

 

In May 1995 The University of Tulsa formed a Joint Industry Project (JIP) for the investigation of paraffin deposition in both single-phase and multiphase flow, and an extensive experimental program was executed. 37 domestic and international companies and government agencies funded the JIP for a period of 4.5 years and a cost of $4.5 million. From the studies conducted in the JIP it became clear that a much broader collection of experimental data is necessary to develop proper paraffin deposition models, and to understand some of the very complex mechanisms involved in paraffin deposition, such as aging and shear stripping.

 

Therefore, a new Paraffin Deposition Prediction Consortium was established on June 1, 2001 in order to continue the investigation. This project is part of the new consortium and will extend the experimental program in single-phase paraffin deposition in order to improve the current models used to predict this complex phenomenon.