NOVEL TECHNOLOGIES FOR MERCAPTAN REMOVAL FROM PRODUCED SOUR NATURAL GAS

摘要

ChevronTexaco's Cymric Field in Kern County, California produces about 40,000 BBl/day of oil and around 7 MMscfd [7800 Nm~3/hr] of associated gas. The associated gas contains a variety of sulfur species, including hydrogen sulfide, methyl mercaptan, ethyl mercaptan, dimethyl sulfide, n-propyl mercaptan, and dimethyl disulfide. In 1996, the facility built a SulFerox~® plant, an iron-based liquid phase oxidation process, for hydrogen sulfide (H_2S) removal. The sweetened associated gas is utilized as fuel in generating steam for ChevronTexaco's Cymric Steamflood. In 2001, ChevronTexaco considered increasing oil production at the Cymric facility and it was determined that additional sulfur removal capacity for the additional produced gas might be required. Furthermore, sulfur-containing emissions had to be minimized due to regulations. The ChevronTexaco project team developed a list of alternatives that could accomplish this. Fluor Oil, Gas and Power was engaged by ChevronTexaco to evaluate these alternatives and provide input into the decision-making process. Various pre-treatment, acid gas removal, sulfur recovery, and tail gas treating technologies were considered, including physical solvents, liquid redox, Claus, non-aqueous direct treatment, direct oxidation, and caustic scrubbing. This paper reviews the technologies and process configurations that were selected for detailed evaluation. Qualification testing was completed for one of the selected technologies: conversion of mercaptans, sulfides, and disulfides in natural gas to H_2S and carbonyl sulfide (COS) using a cobalt-molybdenum (CoMo) catalyst. The purpose of the qualification testing was to verify the technical validity of this technology.