Prediction of the Combustion Characteristics in a Downhole Steam Generator.

摘要

Downhole steam generation is an attractive alternative to conventional surface steam generation for recovery of heavy oils from deep reservoirs. Downhole steam generation technique has been under development in the past five years in the United States, Canada and the United Kingdom. The main advantages of this method are very high thermal efficiency, flexibility of operation and lower environmental pollution load. In conjunction with experimental work on the development of a downhole steam generator at the University of Calgary, two computer models for prediction of the combustion characteristics in such generators have been developed. The first model is based on the assumption of a balanced reaction and complete combustion of the fuel. It determines the reaction temperature and the enthalpy of the product gases at different pressures, air/fuel ratios and water injection rates. The second model uses a modified version of the Dixon Lewis method to determine equilibrium for all species of the reaction system, including nitrogen oxides. A non-Jacobian numerical method is used for the solution of the resulting system of non-linear equations. The results show that to a fairly good approximation, the reaction temperature and the composition of product gases may be correlated with the main operating variables by simple logarithmic plots. This facilitates extrapolation of the experimental data by the use of allocation transformations.