An investigation of production performance by cyclic steam stimulation using horizontal well in heavy oil reservoirs

Abstract

In this paper, a new semi-analytical model considering the non-isothermal effect is proposed to predict heated radius and production performance in a cyclic steam stimulated (CSS) horizontal well.Firstly, an assumption of three heated areas based non-isothermal distribution is introduced. Based on the fluid flow behavior of CSS process in a horizontal well, the spreading of heated area can be classified into three stages. And the heated radius can be derived using the energy conservation equation and area equivalent principle respectively. Then a new semi-analytical model for predicting the production performance by using the equivalent flow resistance method is established. After validation of the new model with numerical simulation and oil field data, the effect of non-isothermal on production performance is analyzed in detail. The results show that a larger injection rate, a bigger error caused by isothermal model when steam injection rate exceeds 200 m3/d. Also, the average water saturation rise has an increase of 1.85% and the average temperature has a drop of 21.12% if the non-isothermal effect is considered.This paper provides an accurate and quick method for estimating the heated radius and production performance in a horizontal well during CSS process.