Sulfur deposition experiment in the presence of non-movable water

With the decreasing of pressure and temperature near wellbore, elemental sulfur may precipitate and block sour gas reservoir pores. In order to analyze the effect of non-movable water on core permeability, depletion types of experiments were carried out to observe sulfur precipitation and plugging in carbonate rocks. During the experiment, reservoir carbonatite cores and supersaturated sour gas were adopted. Under a certain differential pressure, normal saline was used to establish non-movable water. The experimental pressure and temperature were set and maintained to simulate actual reservoir. The experimental results show that non-movable water can contribute to improve core permeability. The more non-movable water is, the more improvement would be. The reason is investigated that the acid environment which has been built when H2S dissolves in the water, reacted with reservoir carbonatite cores. As a result, core flow capacity is improved. Compared with the sulfur damage on dry reservoir core, the improvement arisen from this reaction lays more effect in this experiment, thus the core permeability is ultimately increased.

► Experiments are carried out to observe sulfur precipitation and plugging in carbonate rocks.
► The permeability of cores is improved and flow capacity is enhanced.
► Non-movable water is proved to contribute to improving core permeability in the experiments.