EXPERIMENTAL INVESTIGATION ON FRACTAL CHARACTERIZATION OF IN-SITU FOAM IN POROUS MEDIA

Abstract

The in-situ foam technology has been extensively applied in the complex reservoir reconstruction since it improves the sweep efficiency by diverting the flow of injected fluids into areas with lower permeability and as a result enhances the oil recovery. The in-situ foam structure inside the pores can significantly affect the sweep efficiency, however, quantitative characterizations on foam structure are inadequate. Here, we propose a quantitative method based on fractal theory and the two-dimensional (2D) micro physical simulation experiment for the study of fractal characteristic, evolution law and sensitivity analysis. The findings demonstrate that foam confined within porous media exhibits fractal characteristics, as evidenced by the measured box-counting fractal dimensions ranging between 1.05 and 1.752 based on acquired structural images. Notably, a higher fractal dimension corresponds to a more irregular in-situ foam structure. Besides, in-situ foam in the porous media presents the “quasi check sign” evolution law, which can be divided into three time-dependent stages. Moreover, the evolution laws of in-situ foam within porous media remains consistent across varying temperatures and concentrations of foaming agents, and increasing temperature and decreasing concentration can shorten the time to reach the inflection point.