Abstract: Liquid sulfur condensate phenomenon exists in ultra-deep sour gas reservoir,which affects the reservoir permeability and reduce the gas well productivity.A numerical simulation model proposed in this paper for sour gas reservoirs considers such a two phase flow with both liquid sulfur condensate and gas fluids.On basis of the model,a numerical simulator is developed and used in research of sour gas well production.The results shows liquid sulfur mainly gathers near wellbore,and never extend further during the entire production life.Compared with solid sulfur deposition,condensation of liquid sulfur has less effect on the gas well production.However,the peak production period of gas well reduces obviously.In heterogeneous formation,the liquid sulfur mainly gathers where better reservoir property is present.The liquid sulfur preferentially occupies high permeability zones such as fractures or vugs,which leads to reservoir permeability reduction and the well production decline.Based on this technology,the liquid sulfur condensate behavior in sour gas reservoir can be predicted quantitatively.Thus the technology can provide reliable results for decision-making.

Key words: numerical simulation, liquid sulfur condensate, velocity dependent relative permeability, gas well productivity, sour gas reservoir, Changxing Formation, Sichuan Basin