Journal of Canadian Petroleum Technology
Volume 50, Number 9, September/October 2011, pp. 37-50

SPE-149617-PA

Transient Nonisothermal Fully Coupled Wellbore/Reservoir Model for Gas-Well Testing, Part 1: Modelling

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DOI  More information 10.2118/149617-PA http://dx.doi.org/10.2118/149617-PA

Citation

  • Bahonar, M., Azaiez, J., and Chen, Z. 2011. Transient Nonisothermal Fully Coupled Wellbore/Reservoir Model for Gas-Well Testing, Part 1: Modelling. J Can Pet Technol  50 (9/10): 37-50. SPE-149617-PA. http://dx.doi.org/10.2118/149617-PA.

Discipline Categories

  • 6.5.1 Simulator Development
  • 6.6.3 Pressure Transient Testing
  • 6.3.1 Flow in Porous Media
  • 6.10.5 High Pressure-High Temperature (HPHT) Reservoirs
  • 5.1.1 Tubing and Casing Design

Keywords

  • wellbore/reservoir simulator, nonisothermal flow, wellbore fluid flow, heat loss, gas-well testing

Summary

A numerical fully implicit nonisothermal wellbore/reservoir simulator is developed. The model entails simultaneous solution of transient coupled mass-, momentum-, and energy-balance equations within the wellbore; energy-balance equations for the tubular and cement materials and the formation surrounding the wellbore; and mass-balance and flow-rate/pressure equations for the reservoir formation. A wellbore heat-loss model that is a strong feature of this study is developed and employed in the model to improve the accuracy of the simulator and to be able to estimate the casing temperature and formation-temperature distribution. The model formulation is completed with an equation of state (EOS) to estimate fluid properties and appropriate friction-factor correlations in the wellbore tubing to compute the frictional pressure drop for different flow regimes.

The developed model has several applications in the petroleum industry, particularly in the gas-well testing design and interpretation of both isothermal and nonisothermal gas reservoirs.

This nonisothermal simulator is validated through comparisons to both analytical models and an equivalent numerical isothermal coupled wellbore/reservoir simulator that is also developed in this paper. Applications of this simulator to analyzing gas-well testing problems, in addition to several important observations, are extensively studied in Part 2 of this research work (Bahonar et al. 2010).

Currently, it has been well accepted that the applicability and significance of a reservoir simulator depend on the behaviour of the wellbore and interaction between the wellbore and reservoir. A robust, accurate coupled wellbore and reservoir simulator is an invaluable tool for the petroleum engineer to help the petroleum industry understand production behaviour, make a meaningful prediction, and make correct decisions in all field-development and production stages.

© 2011. Society of Petroleum Engineers

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History

  • Original manuscript received: 21 September 2010
  • Revised manuscript received: 8 March 2011
  • Manuscript approved: 4 May 2011
  • Version of record: 13 September 2011