Sulfur Solubility in Sour Gas

Abstract

It is well known that sulfur is soluble in sour gas and often precipitates during production if the temperature and pressure decrease. Of more significance is the possibility of sulfur precipitation in the reservoir as the pressure is reduced. This applies particularly to high-temperature reservoirs, where sulfur is believed to be more viscous, or to moderate-temperature, low-permeability reservoirs. In either case, sulfur precipitation can impair well productivity and thus the economics of reserve depletion. In the U.S., large sour-gas reserves with reservoir temperatures between 390 and 500 K (242 and 440/sup 0/F) are being exploited. The purpose of the work was to obtain sufficient sulfur-solubility data in sour gas to develop a widely applicable predictive model of sulfur solubility vs. sour-gas conditions. The data include the effects of temperature, pressure, and gas composition, including variations in the amount and composition of gas-condensate components. Pressures and temperatures ranged from 6.7 to 155 MPa (970 to 22,500 psi) and 394 to 486 K (250 to 415/sup 0/F), respectively. The influence of H/sub 2/S on the melting curve was also reported. The value of the experiments was two-fold: to provide information that would allow production and reservoir engineers to predict more reliably themore » reservoir pressure at which sulfur will precipitate and to yield design data for production systems in which sulfur plugging problems in tubing, flowlines, and production facilities could be avoided.« less