0
Research Papers: Petroleum Transport/Pipelines/Multiphase Flow

Transient Wax Gel Formation Model for Shut-In Subsea Pipelines

[+] Author and Article Information
Chiedozie Ekweribe1

Faruk Civan

 University of Oklahoma Norman, OKfcivan@ou.edu

1

Current address: Chevron North America, LA.

J. Energy Resour. Technol 133(3), 033001 (Oct 03, 2011) (5 pages) doi:10.1115/1.4004965 History: Received March 19, 2010; Revised August 20, 2011; Accepted August 24, 2011; Published October 03, 2011

Physics of wax gel formation during shut-in is analyzed and described over a cross-section of a typical subsea pipeline. Two regions are identified during this process: the liquid and gel regions. Phase transition is assumed to occur at the liquid-gel interface. Unsteady-state heat and mass transfer models are proposed for each region. Two diffusion streams are evaluated: the dissolved wax molecules moving from the pipe center toward the wall due to temperature gradient and subsequently concentration gradient and the wax molecules diffusing from the liquid-gel interface into the gel deposit. This model is essentially the modification of the model given by Bhat [1] which considered transient heat transfer and neglected mass transfer of wax molecules through the gel deposit and the model by Singh [2] which considered transient mass transfer of molecules with carbon numbers higher than the` critical carbon number (CCN) necessary for wax diffusion into gel deposit but did not consider transient heat transfer effects during the cooling process. This paper presents a transient-state formulation circumventing the limitations of these previous models and better represents the true cooling and gelation process occurring in a shut-in subsea pipeline filled with waxy crude.

FIGURES IN THIS ARTICLE
<>
Copyright © 2011 by American Society of Mechanical Engineers
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Figure 1

Cross-sectional view of a pipe showing possible phase regions in solids deposition (after Bhat and Mehrotra [1])

Grahic Jump Location
Figure 2

Growth of waxy gel from pipe wall and subsequent aging due to diffusion of wax molecules into gel layer

Grahic Jump Location
Figure 3

Schematic of the evolution of waxy crude gel inside a cross-section of a shut-in subsea pipeline

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In