Abstract:

During the development process of gas reservoirs with high sulfur, when the pressure near the wellbore reduced to a critical value, the sulfur particles precipitated gradually and cloged the pores and fractures, decreasing the productivity of gas wells. Based on the fractal theory, this model for composite gas reservoirs with high sulfur, consisted of inner region and outer region, wass established. Taking wellbore fluid phase separation, wellbore storage factor, skin factor and varying permeability into consideration and by the Stehfest numerical inversion method, this model solved the bottom hole pseudo-pressure solutions in real space. Then with the assistance of Visual Basic 6.0 programming, the log-log type curves for pseudo-pressure and pseudo-pressure derivative were obtained. Finally, the influence of some factors such as skin factor, varying permeability index and mobility ratio on type curves were analyzed. The results had some essential practical significance.

Key words: gas reservoirs with high sulfur, composite model, permeability analytical expression, phase separation, well test type curves drawing