Journal of Canadian Petroleum Technology
Volume 50, Number 3, March 2011, pp. 43-56

SPE-137841-PA

Front Self-Correction for In-Situ Combustion

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DOI  More information 10.2118/137841-PA http://dx.doi.org/10.2118/137841-PA

Citation

  • Oskouei, S.J.P., Moore, R.G., Maini, B., and Mehta, S.A. 2011. Front Self-Correction for In-Situ Combustion. J Can Pet Technol  50 (3): 43-56. SPE-137841-PA. doi: 10.2118/137841-PA.

Discipline Categories

  • 6.4.5 Thermal Methods (e.g.,Steamflood, Cyclic Steam, THAI, Combustion)

Keywords

  • in-situ combustion, front stability, SAGD

Summary

Since it was discovered in the early 1920s, several improvements have been suggested for in-situ combustion (ISC) technology. Top-down combustion displacement is a process proposed for application with horizontal well technologies. In this configuration, air is injected near the top of the reservoir, close to the overburden, through a horizontal well or a number of vertical wells. Fluids are produced from the reservoir through horizontal wells placed near the bottom of the reservoir. In this configuration, the combustion front moves downward with gravity and displaces fluids to the production well.

Combustion front formation and its stability are major concerns in this arrangement. While the short distance between injector and producer addresses the cold oil blocking problem in the reservoir, it has the potential to create air fingers, which could prevent stable advance of the combustion zone in a horizontal plane. Front self-correction must occur to prevent oxygen from fingering to the production wells.

To prove this idea, experiments at reservoir pressure were carried in a 2D SAGD model with Athabasca bitumen. Air was injected into the SAGD steam chamber from the top, and fluids were produced from the bottom. Front advancing directions were monitored by a series of thermocouples located inside the model. It was found that the combustion zone starts spreading horizontally in the model until it reaches a limiting point, then it starts moving downward as a horizontal front. Despite heterogeneity of the oil saturation and relative permeability in the steam chamber and unswept zones, the combustion front moved almost as a horizontal plane and no sharp fingers were recorded in the experiments. These experiments show that stable top-down combustion is feasible.

© 2011. Society of Petroleum Engineers

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History

  • Original manuscript received: 16 September 2010
  • Meeting paper published: 19 October 2010
  • Revised manuscript received: 13 January 2011
  • Manuscript approved: 19 January 2011
  • Version of record: 1 March 2011