Hydrogen sulfide (H2S), a corrosive and toxic gas, when present in produced fluids such as condensate, gas and water, poses serious health and operational hazards. Non-regenerable H2S scavengers have been in use for H2S removal from sour gas and condensate for over a decade. Selection of an appropriate non-regenerable chemistry is dictated by the downstream treatment processes that the gas or condensate will be subjected to after H2S removal is accomplished. Successful selection and application of non-regenerable H2S scavengers requires a thorough evaluation of operating conditions such as temperature, pressure, mixing, etc., that affect H2S removal from sour fluids. Most of the applications require on-site optimization to achieve maximum scavenging performance. This paper presents results and observations from a field trial for sweetening a large volume of sour condensate held in a 70,000 bbl storage tank using a water-soluble triazine-based scavenger. Mode of application of the triazine-based scavenger was found to be one of the most important factors for successful reduction of H2S in liquid hydrocarbons held in large tanks. Another important factor affecting H2S scavenger performance was the presence of sulfide species other than H2S in the sour fluid. Experiences gained from the trial illustrate the importance of a systematic approach required for effective sweetening in liquid hydrocarbons. Introduction Non-regenerable type liquid H2S scavengers are being widely used for removal of H2S in a variety of applications in the oil and gas industry[1–6]. However, limited information is available in the literature on actual case studies and optimization techniques on the application of non-regenerable H2S scavengers in liquid hydrocarbons. This paper reports the results and observations from a field test using a non-regenerable liquid H2S scavenger in a difficult operational setting. Scavenger Selection Criteria. Operating conditions such as condensate temperature, pressure, volume, composition, degree of mixing and contact time with the scavenger strongly influence the selection of an H2S scavenger for removal of H2S from a given fluid[7]. One factor demanding particular consideration in scavenger selection for hydrocarbon liquids is the downstream processing of the condensate after the H2S has been removed. For example, processing of condensate in a refinery often requires maintaining a low nitrogen content in the condensate to avoid poisoning of the catalysts in the reforming process. Most of the non-regenerable liquid H2S scavengers are amine based. An oil-soluble scavenger will remain dissolved in the oil phase, which may cause an increase in the nitrogen content of the hydrocarbon liquids depending on the volume of scavenger used in the treatment. On the other hand, a water-soluble scavenger can separate from the hydrocarbon phase relatively easily due to solubility and density differences. Therefore, water-soluble scavengers tend to offer a chemical treatment option for H2S removal with little or no interference with the downstream refining processes.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractHydrogen sulfide (H 2 S), a corrosive and toxic gas, when present in produced fluids such as condensate, gas and water, poses serious health and operational hazards.Nonregenerable H 2 S scavengers have been in use for H 2 S removal from sour gas and condensate for over a decade. Selection of an appropriate non-regenerable chemistry is dictated by the downstream treatment processes that the gas or condensate will be subjected to after H 2 S removal is accomplished. Successful selection and application of non-regenerable H 2 S scavengers requires a thorough evaluation of operating conditions such as temperature, pressure, mixing, etc., that affect H 2 S removal from sour fluids. Most of the applications require on-site optimization to achieve maximum scavenging performance.This paper presents results and observations from a field trial for sweetening a large volume of sour condensate held in a 70,000 bbl storage tank using a water-soluble triazine-based scavenger.Mode of application of the triazine-based scavenger was found to be one of the most important factors for successful reduction of H 2 S in liquid hydrocarbons held in large tanks. Another important factor affecting H 2 S scavenger performance was the presence of sulfide species other than H 2 S in the sour fluid. Experiences gained from the trial illustrate the importance of a systematic approach required for effective sweetening in liquid hydrocarbons.