The steam assisted gravity drainage (SAGD) process has proven to be an effective thermal recovery method for heavy oil and bitumen production. Recently, some innovative techniques based on the background SAGD operation have been applied such as conventional SAGD, Fast-SAGD, Hybrid SAGD, FA-SAGD. However, there has been much dispute over the question of economical efficiency due to high capital investment, operating costs, and the fluctuation of oil and gas prices. The integration of economic and technical aspects for SAGD performance plays an important role in field operation. Main problems to solve are how to design optimal operating conditions for a reasonable steam requirement with certain injection pressure to maximize economic feasibility under reservoir conditions.
The previous literatures implemented sensitivity analysis and optimization of SAGD performance by classical methods based on numerical simulations lead to a lack of confidence level and ignored interactions effects between considered parameters, which may cause low efficiency issues in a field operation. In addition, the SAGD economic model in previous studies have not fully information with limited consideration on few factors. These restrictions can be avoided by the application design of experiment and response surface methodology to determine the optimal operating conditions for the production prediction. Then, discontinuous SAGD technique was operated to control the amount of injected steam at several specific injection time intervals.
This study represented that the discontinuous SAGD performance is applied to three major formations of Alberta’s oil sands. The results showed that both oil recovery factor and economic profit are much higher than other techniques, especially the effective at deeper burial reservoirs of Clearwater and Bluesky formations. Moreover, amount of injected steam and water cut reduced significantly to cause lower operating costs as steam cost, led to increase NPV as well as minimal environmental damages.