An Alternative Method for Paraffin Deposition Thickness Measurement on Pipelines

Abstract

Paraffin deposition thickness is a critical parameter for mathematical modelling and validation of deposition predictions. Various measurement techniques, such as LD-LD, pressure drop, heat transfer, and gravimetry, are commonly used, but many involve high costs and complex instrumentation. This study presents the development of a simpler, cost-effective method for measuring paraffin deposition thickness in pipelines. The approach involves placing steel coupons inside the pipeline, retrieving them after deposition, and measuring the accumulated layer. Results demonstrate that the proposed method yields thickness values within the uncertainty range of the widely accepted gravimetry method, making it a viable alternative for both scientific and industrial applications.

Introduction

Problem Background:
One of the key challenges in oil transportation is paraffin wax deposition inside pipelines. As hot oil from a reservoir (70–150?°C) cools during transit, paraffins begin to crystallize at the Wax Appearance Temperature (WAT), reducing flow, clogging pipes, and increasing energy costs. Effective monitoring and removal of these deposits are critical for maintaining flow efficiency.

Existing Measurement Methods:
Several techniques exist to measure paraffin layer thickness:

• Heat Transfer Method: Analyzes changes in heat resistance but is less accurate for thin deposits and unsuitable for multiphase flows.

• Pressure Drop Method: Measures flow pressure loss, correlating it with thickness.

• Gravimetric Method: Weighs samples before and after deposition; simple but requires flow interruption.

• Online Heat Pulse Method: Detects retained heat due to wax's insulating properties.

Proposed New Method:
The study introduces a coupon-based method using steel inserts (60?mm x 32?mm x 1?mm) magnetically attached inside a 14-inch test pipeline. These coupons collect paraffin deposits similarly to the pipe wall and are later removed for direct thickness measurement with a digital gauge.

Test Setup:

• Conducted using Petrobras crude oil (WAT: 63.84?°C).

• Paraffin deposition was tested with 3?kg and 5?kg oil in a rotating, cooled pipe.

• Nine coupons were placed at 250?mm, 500?mm, and 750?mm positions along a 1?m pipe section.

Results:

• 3 kg test: Average thickness: 2.71?mm, gravimetric reference: 2.96?mm.

• 5 kg test: Average thickness: 4.80?mm, gravimetric reference: 5.25?mm.

• Relative discrepancy: ~8.4–8.6%, considered acceptable.

• Deposition with 3?kg oil was more uniform than with 5?kg, due to greater dripping and irregularity in larger volumes.

Advantages of the Coupon Method:

• Simple and low-cost.

• No need for internal pipeline instrumentation.

• Allows localized analysis along pipe length and diameter.

• Results show good agreement with gravimetric method.

Conclusion

This study presents a novel, cost-effective method for measuring paraffin deposition thickness in pipelines, utilizing steel coupons to directly capture the deposited layer. The proposed method was successfully tested using paraffin deposition experiments with both 3 kg and 5 kg of crude oil. Results demonstrated that the proposed technique yields deposition thickness values that are within the uncertainty range of the widely accepted gravimetric method, validating its accuracy and reliability. The simplicity of the method, combined with its ability to assess the uniformity of paraffin deposits at multiple points along the pipeline, provides significant advantages over traditional techniques. Unlike other methods, which often require complex instrumentation or disrupt pipeline flow, this approach is straightforward, non-intrusive, and does not rely on instrumentation inside the pipeline. The findings also highlight the impact of oil volume on the uniformity of the deposition, with larger oil quantities resulting in more irregular deposition patterns. The method versatility makes it a promising alternative for both scientific research and industrial applications, offering a reliable tool for assessing paraffin deposition and enhancing the development of effective pipeline management strategies. Further studies could explore the method’s application to other types of crude oils and its integration with online monitoring systems to offer real-time deposition assessments.

References

[1] M. S. Khan, H. Mukhtar, and C. F. Kait, \"Study on wax deposition in crude oils,\" National Postgraduate Conference (NPC), IEEE, Malaysia, 2011. [2] N. B. M. Mustaffa, \"Oil pipeline wax deposition inhibition using chemical methods,\" 2010. [3] M. Lashkarboolooki, A. Seyfaee, F. Esmaeilzadeh, and D. Mowla, \"Experimental investigation of wax deposition in Kermanshah crude oil through a monitored flow loop apparatus,\" Energy and Fuels, vol. 24, no. 2, pp. 1234-1241, 2010. [4] A. S. P. Saraceno, \"Estudo do fenômeno de parafinação a partir de um óleo cru,\" M.S. thesis, Program de Pós-Graduação de Engenharia, UFRJ, 2007. [5] Q. Huang, W. Wang, W. Li, Y. Ren, and F. Zhu, \"A pigging model for wax removal in pipes,\" SPE Annual Technical Conference and Exhibition, Dubai, 2016. [6] R. Hoffmann, L. Amundsen, and R. Shuller, \"Online monitoring of wax deposition in sub-sea pipelines,\" Measurement Science and Technology, vol. 22, no. 7, p. 75701, 2011. [7] X. T. Chen, T. Butler, M. Volk, and J. P. Brill, \"Techniques for measuring wax thickness during single and multiphase flow,\" 1997. [8] J. F. Tinsley and R. K. Prud’homme, \"Deposition apparatus to study the effects of polymers and asphaltenes upon wax deposition,\" Journal of Petroleum Science and Engineering, vol. 72, no. 1-2, pp. 166-174, 2010. [9] J. Creek, H. Lund, J. Brill, and M. Volk, \"Wax deposition in single phase flow,\" Fluid Phase Equilibria, vol. 158-160, pp. 801-811, 1999. [10] A. J. Cordoba and C. A. Schall, \"Application of a heat transfer method to determine wax deposition in a hydrocarbon binary mixture,\" Fuel, vol. 80, no. 9, pp. 1285-1291, 2001. [11] J. P. Brill, X. T. Chen, and M. Volk, \"Wax deposition in crude oil pipelines,\" Journal of Energy Resources Technology, vol. 121, no. 3, pp. 174-180, 1999. [12] M. M. Handal and A. D. T. A. Handal, \"Wax deposition analysis in multiphase flow pipelines,\" SPE Journal, vol. 14, no. 2, pp. 156-165, 2009. [13] R. Hoffmann and L. Amundsen, \"Single-phase wax deposition experiments,\" Energy and Fuels, vol. 24, no. 2, pp. 1069-1080, 2010. [14] A. D. Handal, \"Analysis of some wax deposition experiments in a crude oil carrying pipe,\" M.S. thesis, Computational Science and Engineering, 2008. [15] G. G. Demetino, I. M. Pepe, I. J. Rodowanski, and L. C. Soares Junior, \"Development of an apparatus for producing wax deposition in pipe sections for pigging tests,\" in Proc. 24th ABCM Int. Congr. Mech. Eng., Curitiba, Brazil, 2017.

Copyright

Copyright © 2025 Geydison Gonzaga Demetino, Ivanoe Joao Rodowanski, Iuri Muniz Pepe. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.