SPE Production & Operations
Volume 25, Number 1, February 2010, pp. 50-58

SPE-117854-PA

Optimization of SAGD Wellbore Completions: Short-Production-Tubing-String Sensitivities

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DOI  More information 10.2118/117854-PA http://dx.doi.org/10.2118/117854-PA

Citation

  • Cokar, M. and Graham, J. 2010. Optimization of SAGD Wellbore Completions: Short-Production-Tubing-String Sensitivities. SPE Prod & Oper  25 (1): 50-58. SPE-117854-PA. doi: 10.2118/117854-PA.

Discipline Categories

  • 5.1 Design and Optimization
  • 1.3 Wellbore Design/Construction
  • 6.5 Reservoir Simulation
  • 1.3.2 Horizontal/Multilateral Wells
  • 5.1.1 Tubing and Casing Design

Summary

A simulation study was conducted to examine the effects of changing the landing position of the short production-tubing string relative to the heel of a steam-assisted gravity-drainage (SAGD) production well. A homogeneous discretized wellbore model with the riser section was used in this study. Generally, a reservoir is modeled independently of the wellbore. However, this study models the reservoir and wellbore simultaneously in order to understand their interactions. SAGD performance is affected by many interrelated parameters; however, this paper is focused only on the effects of changing the short production-tubing string relative to the heel of the well.

This paper outlines two independent case studies:

  1. The first study involves shortening the short production-tubing string relative to the heel of the well. It was found that as the short tubing string was pulled back from the heel of the well, the bitumen-production rate decreased, and the amount of steam produced through the short production-tubing string increased.
  2. The second case study outlines the impact of extending the short production-tubing string past the heel of the well on bitumen production and steam/oil ratio (SOR). From this case study, it was found that as the short production-tubing string was pushed past the heel of the well, the bitumen-production rate stayed the same, but the steam-injection rate decreased, which consequently decreased the SOR. It was also observed that a lower pressure differential between the injector and producer well was established when the short production-tubing string was extended.

The results for this study will assist SAGD producers in re-evaluating the position of the short production-tubing string and find the most economical position for this string. This paper creates the foundation for further simulation efforts to incorporate a discretized model with the build section coupled to the reservoir. This will allow production engineers to optimize bitumen production by simultaneously simulating the reservoir and wellbore strings together. However, it must be kept in mind that the sensitivity study outlined in this paper only includes different placements of the short production-tubing string while keeping all other parameters constant. More work should be done in order to evaluate the interrelated effects of changing the location of the short production-tubing string with other wellbore and reservoir parameters.

© 2009. Society of Petroleum Engineers

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History

  • Original manuscript received: 21 August 2008
  • Meeting paper published: 20 October 2008
  • Revised manuscript received: 2 June 2009
  • Manuscript approved: 15 June 2009
  • Published online: 25 November 2009
  • Version of record: 1 March 2010