Feasibility Study on Development of Heavy Oil Reservoir by Steam-Nitrogen Assisted Gravity Drainage

Abstract

Currently, the primary method for developing extra heavy oil is the steam assisted gravity drainage (SAGD) characterized by high recovery factor and gas-oil ratio. However, in the course of application of this technology, because the whole reservoir needs to be heated to a very high temperature, too much steam is needed, and simultaneously, the loss of heat of reservoir is also increased. For the purpose of exploiting the extra heavy oil more economically, a SAGP technique, the steam and gas push, is put forward in the oil industry world. This paper takes the adding of nitrogen as an example, conducts reservoir engineering theory analysis, numerical simulation study and physical modeling study, and concludes that when adopting SAGP technique, it is unnecessary to increase the temperature of the whole reservoir to a very high value; compared with SAGD, although the cumulative production of SAGP declines to some extent, the steam injection volume is only 68% of that of SAGD, which indicates that SAGP exploitation technique can save steam and thus reduce the production cost compared with SAGD.