The impact of sulfur precipitation in developing a sour gas reservoir with pressure-sensitive effects

Abstract

During the development of high sulfur gas fields, gaseous sulfur is likely to precipitate and deposit in the reservoirs due to the changes of temperature, pressure, and gas compositions. Therefore, how to establish an accurate prediction model of elemental sulfur solubility in gas mixtures is a key issue. At present, most scholars use Roberts elemental sulfur solubility model (SPE Reserv. Eng. 1997, 12(2): 118-123) to describe the damage caused by sulfur deposition in high-sulfur gas reservoirs. However, some scholars believe that the Roberts model needs to be improved and relevant works have been done. In this study, a one-dimensional radial production model is established using the HU model (J. Nat. Gas Sci. Eng. 2014, 18: 31-38) and the Roberts elemental sulfur solubility model. These models can be used to describe the permeability and pressure changes caused by sulfur deposition more accurately. The results show that the permeability and pressure changes in the Roberts model are larger than that of which in the HU model and the pressure-sensitive effects may increase the reservoir damage. The comparison of the calculated results with the true values shows that the HU model is more accurate. This paper may change a number of views about sulfur deposition in high-sulfur gas reservoirs.