A DYNAMIC ECONOMIC INDICATOR TO EVALUATE SAGD PERFORMANCE

The economics of a SAGD project are related to several production performance parameters. The most significant parameters are steam oil ratio (SOR), cumulative steam oil ratio (CSOR), calendar day oil rate (CDOR), ultimate recovery (recovery factor, RF), and project life.

In previous work, an economic indicator, the simple thermal efficiency parameter (STEP), was developed to evaluate the performance of a SAGD project. Its usefulness as an economic indicator was validated qualitatively as well as quantitatively. STEP is based on CSOR, CDOR and RF for the time, in a given project life, corresponding to SOR = 4. A higher STEP value relates to a higher net present value (NPV). STEP was found to be a useful quantitative economic indicator.

In reality, the economics of a thermal project strongly depends on the economic limit of SOR and heavy oil price. In this study, a dynamic model for STEP called STEP-D has been developed to be used as an economic indicator under these changing conditions. STEP-D is calculated from the original STEP value by including the two dynamic factors, heavy oil price and SOR economic limit.

For the STEP-D calculation, the economic limit of SOR was varied from 3 to 6 and the heavy oil price from $15 to $30, for three different oil sands reservoirs in Alberta. The results showed a good linear relationship between STEP-D and NPV, with a higher than 0.93 correlation coefficient. STEP-D may therefore be a useful economic indicator under dynamic situations.