Insight into heavy oil recovery of cyclic solvent injection (CSI) utilizing C₃H₈/CH₄ and C₃H₈/CH₄/CO₂

Abstract

In this study, a sandpack model with porosity and permeability of 32.3% and 9.4 D, and a heavy crude oil with viscosity of 6430 mPa.s were used to represent a typical thin heavy oil formation. First, different ratios of C₃H₈ to CH₄ stream were prepared and their performance on Cyclic Solvent Injection (CSI) method was examined to quantify the optimum solvent concentration. Second, CO₂ was introduced to the optimum quantified CH₄-C₃H₈ mixture to investigate the extent to which CSI behavior changes by partially replacement of CH₄ with CO₂.

Results showed that ultimate oil recovery factor (RF) increased from 24.3% to 33.4% original oil in place (OOIP) when C₃H₈ concentration increased from 15 to 50 mol% in the CH₄ stream. CSI tests with higher C₃H₈ concentration reached the maximum cyclic recovery with lower number of injection cycles -due to higher solubility of C₃H₈ compared with CH₄. Solvent utilization factor (SUF) data also confirmed this as lesser volume of solvent with higher C₃H₈ concentration was required to produce oil.

Visual observations showed that the produced foamy oil lasted longer with higher concentration of C₃H₈ in the solvent (5 min for 15% C₃H₈ -85% CH₄ case versus 180 min for 50% C₃H₈ -50% CH₄ case). Upon addition of CO₂ to the mixture, the solvent apparent solubility increased and foamy oil flow promoted. The highest cyclic C₃H₈-CH₄ apparent solubility of 0.175 gr. solvent/100 gr. remaining oil jumped to 0.53 gr. solvent/100 gr. remaining oil when 35% mole fraction of CO₂ replaced CH₄. The highest ultimate oil RF of 44.11% OOIP was measured from eight cycle injection of 50% C₃H₈ -15% CH₄ -35% CO₂. This solvent also benefited from the longest stability of produced-oil foamy shape with recorded time of 217 min (including production time).

According to the results of this experimental study, it seems that there is an optimum fraction of C₃H₈ in CH₄ stream injection in heavy oil systems (with viscosity in the vicinity of 6430 mPa s); the concentration beyond which ultimate oil recovery factor does not increase significantly (near 50 mol%). It is speculated that last cycles do not appreciably respond to heavy oil production mainly due to asphaltene getting precipitated within the model.

Keywords

CSI / Solubility / Heavy oil / Foam stability / Light hydrocarbons

Acknowledgments

The “Faculty of Graduate Studies and Research (FGSR) of University of Regina” and also “Petroleum Technology Research Centre” are acknowledged for providing financial support in order to carry out this experimental project.

References

[1] M. Dusseault, Comparing Venezuelan and Canadian heavy oil and tar sands, can, in: Int. Pet. Conf., 2001, pp. 1-20, https://doi.org/10.2118/2001-061.

[2] B. Jamaloei, M. Dong, P. Yang, D. Yang, N. Mahinpey, Impact of solvent type and injection sequence on Enhanced Cyclic Solvent Process (ECSP) for thin heavy oil reservoirs, J. Petrol. Sci. Eng. 110 (2013) 169-183, https://doi.org/10.1016/j.petrol.2013.08.028.

[3] K. Asghari, F. Torabi,Laboratory experimental results of huff-and-puff CO₂ flooding in a fractured core system, in: SPE Annu. Tech. Conf. Exhib., 11-14 November, Anaheim, California, U.S.A, 2007, https://doi.org/10.2523/110577-MS.

[4] F.S. Palmer, R.W. Landry, S. Bou-Mikael, Design and implementation of immiscible carbon dioxide displacement projects (CO₂ huff-puff) in South Louisiana, in: SPE Annu. Tech. Conf. Exhib., Society of Petroleum Engineers, 5-8 October, New Orleans, Louisiana, 1986, https://doi.org/10.2118/15497-MS.

[5] R. Santon, W. Loh, A. Bannwart, O. Trevisan, An overview of heavy oil properties and its recovery and transportation methods, Braz. J. Chem. Eng. 31 (2014) 571-590, https://doi.org/10.1590/0104-6632.20140313s00001853.

[6] N. Bjorndalen, W.E. Jossy, J.M. Alvarez, Foamy oil behaviour in solvent based production processes, in: SPE Heavy Oil Conf. -Canada, 2012.

[7] C. Yang, Y. Gu, Diffusion coefficients and oil swelling factors of carbon dioxide, methane, ethane, propane, and their mixtures in heavy oil, Fluid Phase Equil. 243 (2006) 64-73, https://doi.org/10.1016/j.fluid.2006.02.020.

[8] S.G. Sayegh, B.B. Maini, Laboratory evaluation of the CO₂ huff-N-puff process for heavy oil reservoirs, J. Can. Pet. Technol. 23 (1984) 29-36, https://doi.org/10.2118/84-03-02.

[9] B. Yadali Jamaloei, M. Dong, N. Mahinpey, B.B. Maini, Enhanced cyclic solvent process (ECSP) for heavy oil and bitumen recovery in thin reservoirs, Energy Fuels 26 (2012) 2865-2874, https://doi.org/10.1021/ef300152b.

[10] Z. Du, F. Zeng, C. Chan, An experimental study of the post-CHOPS cyclic solvent injection process, J. Energy Resour. Technol. 137 (2015), https://doi.org/10.1115/1.4029972.

[11] J. Ivory, J. Chang, R. Coates, K. Forshner, Investigation of cyclic solvent injection process for heavy oil recovery, J. Can. Pet. Technol. 49 (2010) 22-33, https://doi.org/10.2118/140662-PA.

[12] X. Jia, F. Zeng, Y. Gu, Pressure pulsing cyclic solvent injection (PP-CSI): a new way to enhance the recovery of heavy oil through solvent-based enhanced oil recovery techniques, in: SPE Annu. Tech. Conf. Exhib., Society of Petroleum Engineers, 2013, https://doi.org/10.2118/166453-MS , 30 September-2 October, New Orleans, Louisiana, USA.

[13] P. Luo, Y. Zhang, X. Wang, S. Huang, Propane-enriched CO₂ immiscible flooding for improved heavy oil recovery, Energy Fuels 26 (2012) 2124-2135, https://doi.org/10.1021/ef201653u.

[14] X. Jia, J. Li, Z. Chen, Mathermatical modeling of dynamic mass transfer in cyclic solvent injection, in: SPE Canada Heavy Oil Tech. Conf., Society of Petroleum Engineers, 2015, https://doi.org/10.2118/174519-MS , 9-11 June, Calgary, Alberta, Canada.

[15] F. Torabi, C. Chan, A. Kavousi, Experimental measurement of CO₂ solubility in heavy oil and its diffusion coefficient calculation at both static and dynamic conditions, in: Proc. SPE Heavy Oil Conf. -Canada, 2013, pp. 1-16, https://doi.org/10.2118/165559-MS.

[16] A.K. Tharanivasan, Y. Chaodong, Y. Gu, Measurements of molecular diffusion coefficients of carbon dioxide, methane, and propane in heavy oil under reservoir conditions, Energy Fuels 20 (2006) 2509-2517, https://doi.org/10.1021/ef060080d.

[17] A. Qazvini Firouz, F. Torabi, Feasibility study of solvent-based huff-n-puff method (cyclic solvent injection) to enhance heavy oil recovery, in: SPE Heavy Oil Conf. -Canada, 2012, pp. 1-18, https://doi.org/10.2118/157853-MS.

[18] M.B. Geilikman, M.B. Dusseaulf, F.A.L. Dullien, U. Waterloo, Dynamic effects of foamy fluid flow in sand production instability, in: SPE Int. Heavy Oil Symp., Society of Petroleum Engineers, Calgary, Alberta, Canada, 1995, pp. 113e124.

[19] J. Wang, Y. Yuan, L. Zhang, R. Wang, The influence of viscosity on stability of foamy oil in the process of heavy oil solution gas drive, J. Petrol. Sci. Eng. 66 (2009) 69-74, https://doi.org/10.1016/j.petrol.2009.01.007.