New analytical equations for productivity estimation of the cyclic CO2-assisted steam stimulation process considering the non-Newtonian percolation characteristics

Abstract

Abstract The research course in the estimation of productivity of cyclic steam stimulation wells can be divided into three stages: (a) the mobility of heavy oil in the cold area is neglected, (b) the mobility of heavy oil in the cold area is considered—however, it is Newtonian fluid seepage, and (c) it is conserved as non-Newtonian fluid seepage in the cold area. However, the distribution of the value of starting pressure gradient in the heated area where heavy oil is still non-Newtonian fluid is neglected. In this paper, a new model is developed for productivity estimation of cyclic steam stimulation wells with consideration of the non-Newtonian fluid flow behaviors in the heated area where the temperature is higher than the turning point. New percolation equations are developed based on the new proposed concept of “the transition region” in the heated area. The results show that: (1) when the non-Newtonian fluid characteristic is neglected, the predicted results from the new model match the results from the numerical simulator perfectly, and (2) in oil field, the non-Newtonian fluid characteristic cannot be neglected. When the non-Newtonian fluid characteristic is considered in the model, the average oil production in each cycle can match the filed data better than Yang et al.’s model. This new model laid a basic reference for oil companies and researchers involved in the area when they are designing the well pattern, spacing or estimating the productivity of oil wells.

Keywords

• Heavy oil
• Cyclic CO2-steam stimulation
• Productivity estimation
• Non-Newtonian fluid
• Transition region