Abstract: In the process of developing sour gas well, the solubility of sulfur is reduced and separated out elemental sulfur with the fall of reservoir pressure. The deposition of elemental sulfur in pores reduces the permeability of gas reservoir, even causes sulfur block. Based on analysis of elemental sulfur deposition mechanism and theory of gas stable flow, a new model for forecasting sulfur deposition has been founded. By the model, the characteristic and law of the elemental sulfur deposition is predicted in
the early phase of producing sour gas, and the deposition law for
different productivity of gas can be analyzed. On the basis of these facts, logical producing rate can be selected and harmful influence of sulfur deposition on the productivity can be prevented.

Key words: elemental sulfur, deposition, model, productivity, sulfur block