One of the most critical challenges facing producers today is assuring the flow of oil and gas through complex and costly long subsea tiebacks. Petroleum fluids contain paraffin wax which precipitates as a solid phase when temperature falls below wax appearance temperature (WAT). Assessment of the potential of wax deposition is therefore a standard part of most field development studies, especially in subsea where the cost of removal of deposits is much higher. Estimation of WAT is a key parameter for designing the facilities and ensuring smooth oil and gas production. Several techniques are available for WAT measurement. Most of the studies are conducted on dead oil which does not account for the effect of pressure and dissolved solution gas on wax precipitation. It is suggested to study WAT on saturated crude samples to address the issue of flow assurance.

Traditionally the studies conducted for determination of WAT were carried out on dead oil. This paper presents the results of a case study aimed to estimate the effect of pressure and dissolved gases on wax deposition on live oil in deep-water fields in Eastern offshore. The oil has high wax content along with presence of small quantity of resins and asphaltenes. It was observed that the effect of solution gas on WAT is more prononunced than the effect of pressure. This case study illustrates a more realistic approach towards determination of WAT, the effects of solution gas and pressure on the WAT of live oil and the use of this knowledge to predict the depth at which wax deposition would occur in the production tubing/line. The data generated from this study provides a more effective approach towards combating the problem of wax deposition in flowlines.

You can access this article if you purchase or spend a download.