Abstract: In view of the present situation that the current analysis of well-testing with changing wellbore storage (CWS) is still at the theoretical research stage, and that it cannot suit the needs of oil and gas oilfield production, this paper establishes a novel model for welltesting with changing wellbore storage, and develops a theoretical plate for typical curves,such as hump-type curve, step-type curve and pseudo-standard-type curve, which are suitable for various changing well storage on the basis of a new method of calculating pressure derivate. This paper, by using a new CWS early-time approximate ,solves the parameter problem in the applicatiin of this novel plate, and in the end, make an analysis of an actual gas well.

Key words: Wellbore storage, Well-testing, Well test interpretation, Typical curve