Effects of polymers on the structure and deposition behavior of waxy oils

Jack F. Tinsley, Robert K. Prud'homme, Guo Xuhong, Douglas H. Adamson, Shao Susan, Devang Amin, Scott Callahan, Heather D. Dettman, Robert Kriegel, Rajesh Saini

Research output: Contribution to journalConference article

3 Scopus citations

Abstract

Recent deposition studies have elucidated much of the underlying physics of wax deposition in crude oil pipelines. However, the physics behind polymer additives used to combat wax deposition has not been thoroughly studied. To this end, three types of polymers that have proved effective in reducing the yield stresses of waxy gels have been tested in yield closed-loop laboratory deposition cell. Tests with a multi-component wax solution with polymer additions of 0.1wt% showed that the thickness of the deposit could be estimated from calculations of the height of the cloud point above the cold surface. Such was the case with addition of poly(ethylene butene) polymers (PEB) and the wax solution with no polymer. Conversely, two maleic anhydride copolymers (MAC) decreased the cloud point and prevented deposition unless the temperature of the cold surface was lowered below the cloud point. However, predictions of the deposit thickness based on cloud point did not hold if erosion occurred. Erosion was always associated with degradation of the microscopic crystal structure, in terms of shape and/or size. The most effective polymers, the MACs, produced the largest change in crystal structure and the most significant erosion. The polymers also produced deposits with the lowest wax contents and the smallest fractions of high molecular weight n-paraffins. However, one EVA polymer that led to thinner, eroding deposits also significantly increased the deposit wax contents, creating hard deposits that would be more difficult to remediate by pigging. Polymers that increased the wax content did not lower the cloud point, even though they may degrade the crystal structure. Thus the importance of both cloud point reduction and degradation of crystal structure was shown. Tests indicated that inhibition of nucleation kinetics may be important for some polymers. Although all polymers reduced the yield stress of the waxy oil when gelled, they did not all decrease deposition. Efficacy in both yield stress reduction and decreasing deposition could be grouped according to polymer type.

Original languageEnglish (US)
Pages (from-to)439-449
Number of pages11
JournalProceedings - SPE International Symposium on Oilfield Chemistry
StatePublished - May 29 2007
EventSPE International Symposium on Oilfield Chemistry 2007 - Houston, TX, United States
Duration: Feb 28 2007Mar 2 2007

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Energy Engineering and Power Technology

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    Tinsley, J. F., Prud'homme, R. K., Xuhong, G., Adamson, D. H., Susan, S., Amin, D., Callahan, S., Dettman, H. D., Kriegel, R., & Saini, R. (2007). Effects of polymers on the structure and deposition behavior of waxy oils. Proceedings - SPE International Symposium on Oilfield Chemistry, 439-449.