Mechanism and evaluation method of extremely heavy oil production in Z411 block,Wangzhuang oilfield

In the standard of thermal production,there is no way to exploit the extremely heavy oil with the viscosity more than 10×10~4 mPa?s.Through the horizontal well and the steam soak assistant by the injection of CO_2,the heavy oil in Z411 block of Wangzhuang oil field is effectively produced while the viscosity of degassed oil is over 74×10~4 mPa?s. the mechanism of oil displacement by CO_2 and the steam soak are introduced and the production evaluation method is presented.The evaluation results show that the method is suitable to the production at the area.