Study on the effective characteristics of single-well nitrogen injection in Fracture-Vug reservoir.

To exploit the remaining oil in the high position of the reservoir, field test of nitrogen injection in single well has been carried out in Tahe Oilfield and good results have been achieved. However, the effect of nitrogen injection in single well is quite different, which has affected the large-scale application of gas injection in field. Through comprehensive analysis, it is recognized that the karst genesis and the type of reservoir space are the basis for determining the effect of nitrogen injection in a single well. Based on Karst genesis and reservoir space type, gas injection wells are divided into four types. By contrast from oil production, period of validity, water content and pressure, the effective characteristics of different types of wells after gas injection are compared and analyzed. According to these characteristics, some suggestions for field gas injection well selection are put forward, which can guide the practice and popularization of field gas injection test. [ABSTRACT FROM AUTHOR]