This paper describes the formulation of a thermal simulation model in a vectorized, general purpose reservoir simulator. The thermal simulation model, an option in this general purpose simulator, is equivalent to a three-phase, three-dimensional, thermal compositional simulator. It has a variety of options for modeling fluid properties and phase behavior. These include the EOS method (the three parameter Peng-Robinson equation of state) and the non-EOS methods (table look-ups and correlations). The model also considers the solubility of water in the oil phase. Furthermore, all calculations are extensively vectorized.

Test problems including problem No. 3 of the Fourth SPE Comparative Solution Project are used to evaluate the effectiveness of vectorization. Results show that the vectorized calculations outperform the nonvectorized ones by about an order of magnitude in computational speed on the Cray X-MP/48. Overall, this thermal model runs about 5 times faster than a previously reported conventional, partially vectorized thermal simulator.

Finally, the use of this thermal simulation option to study the sensitivity of simulation results to various fluid property and phase behavior calculation methods is illustrated with a hypothetical problem. Results show that simulation results can be used to determine the importance of different K-value and volume calculation methods, and the inclusion of water-in-oil solubility.

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